diff --git a/.changeset/patch-configurable-memory-file-types.md b/.changeset/patch-configurable-memory-file-types.md
new file mode 100644
index 0000000000..7e11d491ce
--- /dev/null
+++ b/.changeset/patch-configurable-memory-file-types.md
@@ -0,0 +1,5 @@
+---
+"gh-aw": patch
+---
+
+Add configurable allowed extensions for cache-memory and repo-memory along with validation failure reporting
diff --git a/.changeset/patch-configure-memory-extensions.md b/.changeset/patch-configure-memory-extensions.md
new file mode 100644
index 0000000000..f991752b3f
--- /dev/null
+++ b/.changeset/patch-configure-memory-extensions.md
@@ -0,0 +1,5 @@
+---
+"gh-aw": patch
+---
+
+Documented cache-memory and repo-memory now support configuring allowed extensions, expose the defaults, and surface validation failures when invalid files are detected.
diff --git a/.github/workflows/agent-performance-analyzer.lock.yml b/.github/workflows/agent-performance-analyzer.lock.yml
index 0413dd1111..c369c67363 100644
--- a/.github/workflows/agent-performance-analyzer.lock.yml
+++ b/.github/workflows/agent-performance-analyzer.lock.yml
@@ -692,6 +692,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: **
@@ -700,10 +701,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -1054,6 +1058,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1243,6 +1249,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1277,6 +1286,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1288,6 +1298,7 @@ jobs:
           BRANCH_NAME: memory/meta-orchestrators
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "**"
         with:
           script: |
diff --git a/.github/workflows/agent-persona-explorer.lock.yml b/.github/workflows/agent-persona-explorer.lock.yml
index c886ab4097..5d0e5a0a7e 100644
--- a/.github/workflows/agent-persona-explorer.lock.yml
+++ b/.github/workflows/agent-persona-explorer.lock.yml
@@ -634,6 +634,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -652,6 +653,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -823,6 +825,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1186,6 +1201,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/audit-workflows.lock.yml b/.github/workflows/audit-workflows.lock.yml
index 79afe897c0..9dff4bf155 100644
--- a/.github/workflows/audit-workflows.lock.yml
+++ b/.github/workflows/audit-workflows.lock.yml
@@ -651,6 +651,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/audit-workflows/*.json, memory/audit-workflows/*.jsonl, memory/audit-workflows/*.csv, memory/audit-workflows/*.md
@@ -659,10 +660,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -730,6 +734,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -748,6 +753,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -982,6 +988,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1097,6 +1116,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1273,6 +1294,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1307,6 +1331,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1318,6 +1343,7 @@ jobs:
           BRANCH_NAME: memory/audit-workflows
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/audit-workflows/*.json memory/audit-workflows/*.jsonl memory/audit-workflows/*.csv memory/audit-workflows/*.md"
         with:
           script: |
@@ -1408,6 +1434,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/chroma-issue-indexer.lock.yml b/.github/workflows/chroma-issue-indexer.lock.yml
index 6482007bdd..ee0219e390 100644
--- a/.github/workflows/chroma-issue-indexer.lock.yml
+++ b/.github/workflows/chroma-issue-indexer.lock.yml
@@ -293,28 +293,8 @@ jobs:
           GH_AW_PROMPT_EOF
           cat "/opt/gh-aw/prompts/temp_folder_prompt.md" >> "$GH_AW_PROMPT"
           cat "/opt/gh-aw/prompts/markdown.md" >> "$GH_AW_PROMPT"
+          cat "/opt/gh-aw/prompts/cache_memory_prompt_multi.md" >> "$GH_AW_PROMPT"
           cat << 'GH_AW_PROMPT_EOF' >> "$GH_AW_PROMPT"
-          
-          ---
-          
-          ## Cache Folders Available
-          
-          You have access to persistent cache folders where you can read and write files to create memories and store information:
-          
-          - **chroma**: `/tmp/gh-aw/cache-memory-chroma/` - Persistent storage for Chroma vector database
-          
-          - **Read/Write Access**: You can freely read from and write to any files in these folders
-          - **Persistence**: Files in these folders persist across workflow runs via GitHub Actions cache
-          - **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved
-          - **File Share**: Use these as simple file shares - organize files as you see fit
-          
-          Examples of what you can store:
-          - `/tmp/gh-aw/cache-memory-chroma/notes.txt` - general notes and observations
-          - `/tmp/gh-aw/cache-memory-chroma/preferences.json` - user preferences and settings
-          - `/tmp/gh-aw/cache-memory-chroma/state/` - organized state files in subdirectories
-          
-          Feel free to create, read, update, and organize files in these folders as needed for your tasks.
-          
           <github-context>
           The following GitHub context information is available for this workflow:
           {{#if __GH_AW_GITHUB_ACTOR__ }}
@@ -360,6 +340,16 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
+          GH_AW_CACHE_EXAMPLES: '- `/tmp/gh-aw/cache-memory-chroma/notes.txt` - general notes and observations
+- `/tmp/gh-aw/cache-memory-chroma/notes.md` - markdown formatted notes
+- `/tmp/gh-aw/cache-memory-chroma/preferences.json` - user preferences and settings
+- `/tmp/gh-aw/cache-memory-chroma/history.jsonl` - activity history in JSON Lines format
+- `/tmp/gh-aw/cache-memory-chroma/data.csv` - tabular data
+- `/tmp/gh-aw/cache-memory-chroma/state/` - organized state files in subdirectories (with allowed file types)
+'
+          GH_AW_CACHE_LIST: '- **chroma**: `/tmp/gh-aw/cache-memory-chroma/` - Persistent storage for Chroma vector database
+'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
           GH_AW_GITHUB_EVENT_COMMENT_ID: ${{ github.event.comment.id }}
           GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: ${{ github.event.discussion.number }}
@@ -376,6 +366,9 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
+                GH_AW_CACHE_EXAMPLES: process.env.GH_AW_CACHE_EXAMPLES,
+                GH_AW_CACHE_LIST: process.env.GH_AW_CACHE_LIST,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
                 GH_AW_GITHUB_EVENT_COMMENT_ID: process.env.GH_AW_GITHUB_EVENT_COMMENT_ID,
                 GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: process.env.GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER,
@@ -515,6 +508,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types (chroma)
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory-chroma', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload agent artifacts
         if: always()
         continue-on-error: true
diff --git a/.github/workflows/ci-coach.lock.yml b/.github/workflows/ci-coach.lock.yml
index 2aa9112eef..685d8d220d 100644
--- a/.github/workflows/ci-coach.lock.yml
+++ b/.github/workflows/ci-coach.lock.yml
@@ -625,6 +625,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -644,6 +645,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -818,6 +820,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1198,6 +1213,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/ci-doctor.lock.yml b/.github/workflows/ci-doctor.lock.yml
index 7a335a23fd..b34124be7a 100644
--- a/.github/workflows/ci-doctor.lock.yml
+++ b/.github/workflows/ci-doctor.lock.yml
@@ -726,6 +726,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -750,6 +751,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -933,6 +935,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1321,6 +1336,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/claude-code-user-docs-review.lock.yml b/.github/workflows/claude-code-user-docs-review.lock.yml
index 0acd6caacc..8dcf1276ef 100644
--- a/.github/workflows/claude-code-user-docs-review.lock.yml
+++ b/.github/workflows/claude-code-user-docs-review.lock.yml
@@ -564,6 +564,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -582,6 +583,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -805,6 +807,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1159,6 +1174,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/cli-version-checker.lock.yml b/.github/workflows/cli-version-checker.lock.yml
index a6b2f0ca50..05e589214e 100644
--- a/.github/workflows/cli-version-checker.lock.yml
+++ b/.github/workflows/cli-version-checker.lock.yml
@@ -595,6 +595,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -613,6 +614,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -836,6 +838,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1181,6 +1196,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/cloclo.lock.yml b/.github/workflows/cloclo.lock.yml
index 28056e2072..d10dc0daa1 100644
--- a/.github/workflows/cloclo.lock.yml
+++ b/.github/workflows/cloclo.lock.yml
@@ -794,6 +794,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -818,6 +819,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1098,6 +1100,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1563,6 +1578,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/code-scanning-fixer.lock.yml b/.github/workflows/code-scanning-fixer.lock.yml
index e197541b9b..b8545ad97e 100644
--- a/.github/workflows/code-scanning-fixer.lock.yml
+++ b/.github/workflows/code-scanning-fixer.lock.yml
@@ -571,13 +571,17 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/history/` - organized history files
+          - `/tmp/gh-aw/repo-memory/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/history/` - organized history files (with allowed file types)
           
-          Feel free to create, read, update, and organize files in these folders as needed for your tasks.
+          Feel free to create, read, update, and organize files in these folders as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -636,6 +640,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -654,6 +659,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -834,6 +840,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/campaigns
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -935,6 +954,8 @@ jobs:
           GH_AW_WORKFLOW_ID: "code-scanning-fixer"
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_campaigns: ${{ needs.push_repo_memory.outputs.validation_failed_campaigns }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_campaigns: ${{ needs.push_repo_memory.outputs.validation_error_campaigns }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1151,6 +1172,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_campaigns: ${{ steps.push_repo_memory_campaigns.outputs.validation_error }}
+      validation_failed_campaigns: ${{ steps.push_repo_memory_campaigns.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1185,6 +1209,7 @@ jobs:
           name: repo-memory-campaigns
           path: /tmp/gh-aw/repo-memory/campaigns
       - name: Push repo-memory changes (campaigns)
+        id: push_repo_memory_campaigns
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1196,6 +1221,7 @@ jobs:
           BRANCH_NAME: memory/campaigns
           MAX_FILE_SIZE: 10240
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "security-alert-burndown/**"
         with:
           script: |
@@ -1312,6 +1338,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/copilot-agent-analysis.lock.yml b/.github/workflows/copilot-agent-analysis.lock.yml
index f02da153fc..9dabd98767 100644
--- a/.github/workflows/copilot-agent-analysis.lock.yml
+++ b/.github/workflows/copilot-agent-analysis.lock.yml
@@ -539,6 +539,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/copilot-agent-analysis/*.json, memory/copilot-agent-analysis/*.jsonl, memory/copilot-agent-analysis/*.csv, memory/copilot-agent-analysis/*.md
@@ -547,10 +548,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -618,6 +622,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -636,6 +641,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -891,6 +897,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -993,6 +1012,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1167,6 +1188,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1201,6 +1225,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1212,6 +1237,7 @@ jobs:
           BRANCH_NAME: memory/copilot-agent-analysis
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/copilot-agent-analysis/*.json memory/copilot-agent-analysis/*.jsonl memory/copilot-agent-analysis/*.csv memory/copilot-agent-analysis/*.md"
         with:
           script: |
@@ -1301,6 +1327,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/copilot-cli-deep-research.lock.yml b/.github/workflows/copilot-cli-deep-research.lock.yml
index 81093ff89f..3d724403fa 100644
--- a/.github/workflows/copilot-cli-deep-research.lock.yml
+++ b/.github/workflows/copilot-cli-deep-research.lock.yml
@@ -515,6 +515,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/copilot-cli-research/*.json, memory/copilot-cli-research/*.md
@@ -523,10 +524,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -902,6 +906,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1061,6 +1067,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1095,6 +1104,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1106,6 +1116,7 @@ jobs:
           BRANCH_NAME: memory/copilot-cli-research
           MAX_FILE_SIZE: 204800
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/copilot-cli-research/*.json memory/copilot-cli-research/*.md"
         with:
           script: |
diff --git a/.github/workflows/copilot-pr-nlp-analysis.lock.yml b/.github/workflows/copilot-pr-nlp-analysis.lock.yml
index 3965e67aa3..cb4bc68002 100644
--- a/.github/workflows/copilot-pr-nlp-analysis.lock.yml
+++ b/.github/workflows/copilot-pr-nlp-analysis.lock.yml
@@ -593,6 +593,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/nlp-analysis/*.json, memory/nlp-analysis/*.jsonl, memory/nlp-analysis/*.csv, memory/nlp-analysis/*.md
@@ -601,10 +602,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -675,6 +679,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -693,6 +698,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -878,6 +884,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -990,6 +1009,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1149,6 +1170,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1183,6 +1207,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1194,6 +1219,7 @@ jobs:
           BRANCH_NAME: memory/nlp-analysis
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/nlp-analysis/*.json memory/nlp-analysis/*.jsonl memory/nlp-analysis/*.csv memory/nlp-analysis/*.md"
         with:
           script: |
@@ -1283,6 +1309,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/copilot-pr-prompt-analysis.lock.yml b/.github/workflows/copilot-pr-prompt-analysis.lock.yml
index b3a6ce97ce..664abb744f 100644
--- a/.github/workflows/copilot-pr-prompt-analysis.lock.yml
+++ b/.github/workflows/copilot-pr-prompt-analysis.lock.yml
@@ -535,6 +535,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/prompt-analysis/*.json, memory/prompt-analysis/*.jsonl, memory/prompt-analysis/*.csv, memory/prompt-analysis/*.md
@@ -543,10 +544,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -614,6 +618,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -632,6 +637,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -814,6 +820,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -916,6 +935,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1075,6 +1096,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1109,6 +1133,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1120,6 +1145,7 @@ jobs:
           BRANCH_NAME: memory/prompt-analysis
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/prompt-analysis/*.json memory/prompt-analysis/*.jsonl memory/prompt-analysis/*.csv memory/prompt-analysis/*.md"
         with:
           script: |
@@ -1209,6 +1235,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/copilot-session-insights.lock.yml b/.github/workflows/copilot-session-insights.lock.yml
index 184fe22c2a..9ed7be1bcc 100644
--- a/.github/workflows/copilot-session-insights.lock.yml
+++ b/.github/workflows/copilot-session-insights.lock.yml
@@ -594,6 +594,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/session-insights/*.json, memory/session-insights/*.jsonl, memory/session-insights/*.csv, memory/session-insights/*.md
@@ -602,10 +603,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -682,6 +686,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -701,6 +706,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -937,6 +943,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1049,6 +1068,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1223,6 +1244,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1257,6 +1281,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1268,6 +1293,7 @@ jobs:
           BRANCH_NAME: memory/session-insights
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/session-insights/*.json memory/session-insights/*.jsonl memory/session-insights/*.csv memory/session-insights/*.md"
         with:
           script: |
@@ -1357,6 +1383,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-cli-performance.lock.yml b/.github/workflows/daily-cli-performance.lock.yml
index 988a490c3e..d7e724a927 100644
--- a/.github/workflows/daily-cli-performance.lock.yml
+++ b/.github/workflows/daily-cli-performance.lock.yml
@@ -705,6 +705,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/cli-performance/*.json, memory/cli-performance/*.jsonl, memory/cli-performance/*.txt
@@ -713,10 +714,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -1086,6 +1090,8 @@ jobs:
           GH_AW_WORKFLOW_ID: "daily-cli-performance"
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1247,6 +1253,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1281,6 +1290,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1292,6 +1302,7 @@ jobs:
           BRANCH_NAME: memory/cli-performance
           MAX_FILE_SIZE: 512000
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/cli-performance/*.json memory/cli-performance/*.jsonl memory/cli-performance/*.txt"
         with:
           script: |
diff --git a/.github/workflows/daily-code-metrics.lock.yml b/.github/workflows/daily-code-metrics.lock.yml
index 242c00b995..959341d554 100644
--- a/.github/workflows/daily-code-metrics.lock.yml
+++ b/.github/workflows/daily-code-metrics.lock.yml
@@ -582,6 +582,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: *.json, *.jsonl, *.csv, *.md
@@ -590,10 +591,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -661,6 +665,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -679,6 +684,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -911,6 +917,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1026,6 +1045,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1202,6 +1223,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1236,6 +1260,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1247,6 +1272,7 @@ jobs:
           BRANCH_NAME: daily/default
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "*.json *.jsonl *.csv *.md"
         with:
           script: |
@@ -1337,6 +1363,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-compiler-quality.lock.yml b/.github/workflows/daily-compiler-quality.lock.yml
index 053ad05728..f67068579c 100644
--- a/.github/workflows/daily-compiler-quality.lock.yml
+++ b/.github/workflows/daily-compiler-quality.lock.yml
@@ -571,6 +571,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -589,6 +590,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -782,6 +784,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1121,6 +1136,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-copilot-token-report.lock.yml b/.github/workflows/daily-copilot-token-report.lock.yml
index bf02fc26a0..568fd9629b 100644
--- a/.github/workflows/daily-copilot-token-report.lock.yml
+++ b/.github/workflows/daily-copilot-token-report.lock.yml
@@ -611,6 +611,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/token-metrics/*.json, memory/token-metrics/*.jsonl, memory/token-metrics/*.csv, memory/token-metrics/*.md
@@ -619,10 +620,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -687,6 +691,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -705,6 +710,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -889,6 +895,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1004,6 +1023,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1165,6 +1186,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1199,6 +1223,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1210,6 +1235,7 @@ jobs:
           BRANCH_NAME: memory/token-metrics
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/token-metrics/*.json memory/token-metrics/*.jsonl memory/token-metrics/*.csv memory/token-metrics/*.md"
         with:
           script: |
@@ -1300,6 +1326,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-doc-updater.lock.yml b/.github/workflows/daily-doc-updater.lock.yml
index 5ab9d20744..95d5f75b48 100644
--- a/.github/workflows/daily-doc-updater.lock.yml
+++ b/.github/workflows/daily-doc-updater.lock.yml
@@ -573,6 +573,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -591,6 +592,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -835,6 +837,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1230,6 +1245,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-firewall-report.lock.yml b/.github/workflows/daily-firewall-report.lock.yml
index 99b70bdf8d..d8916b2f47 100644
--- a/.github/workflows/daily-firewall-report.lock.yml
+++ b/.github/workflows/daily-firewall-report.lock.yml
@@ -689,6 +689,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -707,6 +708,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -881,6 +883,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1230,6 +1245,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-issues-report.lock.yml b/.github/workflows/daily-issues-report.lock.yml
index 772813a625..5f2718ea8d 100644
--- a/.github/workflows/daily-issues-report.lock.yml
+++ b/.github/workflows/daily-issues-report.lock.yml
@@ -717,6 +717,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -735,6 +736,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -891,6 +893,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1262,6 +1277,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-mcp-concurrency-analysis.lock.yml b/.github/workflows/daily-mcp-concurrency-analysis.lock.yml
index 4aad51a877..a927470497 100644
--- a/.github/workflows/daily-mcp-concurrency-analysis.lock.yml
+++ b/.github/workflows/daily-mcp-concurrency-analysis.lock.yml
@@ -623,6 +623,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -641,6 +642,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -835,6 +837,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1185,6 +1200,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-news.lock.yml b/.github/workflows/daily-news.lock.yml
index 0cabe98c04..99623d46e1 100644
--- a/.github/workflows/daily-news.lock.yml
+++ b/.github/workflows/daily-news.lock.yml
@@ -663,6 +663,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/daily-news/*.json, memory/daily-news/*.jsonl, memory/daily-news/*.csv, memory/daily-news/*.md
@@ -671,10 +672,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -748,6 +752,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -766,6 +771,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -951,6 +957,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1066,6 +1085,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1227,6 +1248,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1261,6 +1285,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1272,6 +1297,7 @@ jobs:
           BRANCH_NAME: memory/daily-news
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/daily-news/*.json memory/daily-news/*.jsonl memory/daily-news/*.csv memory/daily-news/*.md"
         with:
           script: |
@@ -1362,6 +1388,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-performance-summary.lock.yml b/.github/workflows/daily-performance-summary.lock.yml
index 6f645ed519..1db0cd3ede 100644
--- a/.github/workflows/daily-performance-summary.lock.yml
+++ b/.github/workflows/daily-performance-summary.lock.yml
@@ -1182,6 +1182,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -1200,6 +1201,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1365,6 +1367,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1707,6 +1722,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-repo-chronicle.lock.yml b/.github/workflows/daily-repo-chronicle.lock.yml
index b22e2f71dc..ac7813fe68 100644
--- a/.github/workflows/daily-repo-chronicle.lock.yml
+++ b/.github/workflows/daily-repo-chronicle.lock.yml
@@ -623,6 +623,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -641,6 +642,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -816,6 +818,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1165,6 +1180,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-safe-output-optimizer.lock.yml b/.github/workflows/daily-safe-output-optimizer.lock.yml
index 18f2515bb8..5945081dfe 100644
--- a/.github/workflows/daily-safe-output-optimizer.lock.yml
+++ b/.github/workflows/daily-safe-output-optimizer.lock.yml
@@ -669,6 +669,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -687,6 +688,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -922,6 +924,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1310,6 +1325,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/daily-testify-uber-super-expert.lock.yml b/.github/workflows/daily-testify-uber-super-expert.lock.yml
index 71c971dd34..10a42568c0 100644
--- a/.github/workflows/daily-testify-uber-super-expert.lock.yml
+++ b/.github/workflows/daily-testify-uber-super-expert.lock.yml
@@ -546,6 +546,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/testify-expert/*.json, memory/testify-expert/*.txt
@@ -554,10 +555,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -934,6 +938,8 @@ jobs:
           GH_AW_WORKFLOW_ID: "daily-testify-uber-super-expert"
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1138,6 +1144,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1172,6 +1181,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1183,6 +1193,7 @@ jobs:
           BRANCH_NAME: memory/testify-expert
           MAX_FILE_SIZE: 51200
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/testify-expert/*.json memory/testify-expert/*.txt"
         with:
           script: |
diff --git a/.github/workflows/deep-report.lock.yml b/.github/workflows/deep-report.lock.yml
index 6ba826a8f7..87f51649a8 100644
--- a/.github/workflows/deep-report.lock.yml
+++ b/.github/workflows/deep-report.lock.yml
@@ -738,6 +738,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/deep-report/*.md
@@ -746,10 +747,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -817,6 +821,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -835,6 +840,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -998,6 +1004,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1113,6 +1132,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1266,6 +1287,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1300,6 +1324,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1311,6 +1336,7 @@ jobs:
           BRANCH_NAME: memory/deep-report
           MAX_FILE_SIZE: 1048576
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/deep-report/*.md"
         with:
           script: |
@@ -1401,6 +1427,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/delight.lock.yml b/.github/workflows/delight.lock.yml
index 17afb0c02d..422dd815b4 100644
--- a/.github/workflows/delight.lock.yml
+++ b/.github/workflows/delight.lock.yml
@@ -591,6 +591,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/delight/*.json, memory/delight/*.md
@@ -599,10 +600,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -984,6 +988,8 @@ jobs:
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
           GH_AW_SAFE_OUTPUT_MESSAGES: "{\"footer\":\"\\u003e 📊 *User experience analysis by [{workflow_name}]({run_url})*\",\"runStarted\":\"📊 Delight Agent starting! [{workflow_name}]({run_url}) is analyzing user-facing aspects for improvement opportunities...\",\"runSuccess\":\"✅ Analysis complete! [{workflow_name}]({run_url}) has identified targeted improvements for user experience.\",\"runFailure\":\"⚠️ Analysis interrupted! [{workflow_name}]({run_url}) {status}. Please review the logs...\"}"
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1146,6 +1152,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1180,6 +1189,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1191,6 +1201,7 @@ jobs:
           BRANCH_NAME: memory/delight
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/delight/*.json memory/delight/*.md"
         with:
           script: |
diff --git a/.github/workflows/developer-docs-consolidator.lock.yml b/.github/workflows/developer-docs-consolidator.lock.yml
index b8a3a0e8fa..a502ec97e8 100644
--- a/.github/workflows/developer-docs-consolidator.lock.yml
+++ b/.github/workflows/developer-docs-consolidator.lock.yml
@@ -646,6 +646,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -664,6 +665,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -910,6 +912,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1301,6 +1316,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/discussion-task-miner.lock.yml b/.github/workflows/discussion-task-miner.lock.yml
index 6e2239ed30..c4608f7082 100644
--- a/.github/workflows/discussion-task-miner.lock.yml
+++ b/.github/workflows/discussion-task-miner.lock.yml
@@ -563,6 +563,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/discussion-task-miner/*.json, memory/discussion-task-miner/*.md
@@ -571,10 +572,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -950,6 +954,8 @@ jobs:
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_SAFE_OUTPUT_MESSAGES: "{\"footer\":\"\\u003e 🔍 *Task mining by [{workflow_name}]({run_url})*\",\"runStarted\":\"🔍 Discussion Task Miner starting! [{workflow_name}]({run_url}) is scanning discussions for code quality improvements...\",\"runSuccess\":\"✅ Task mining complete! [{workflow_name}]({run_url}) has identified actionable code quality tasks. 📊\",\"runFailure\":\"⚠️ Task mining interrupted! [{workflow_name}]({run_url}) {status}. Please review the logs...\"}"
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1112,6 +1118,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1146,6 +1155,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1157,6 +1167,7 @@ jobs:
           BRANCH_NAME: memory/discussion-task-miner
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/discussion-task-miner/*.json memory/discussion-task-miner/*.md"
         with:
           script: |
diff --git a/.github/workflows/firewall-escape.lock.yml b/.github/workflows/firewall-escape.lock.yml
index 8bcdc41a2a..7aa848d84b 100644
--- a/.github/workflows/firewall-escape.lock.yml
+++ b/.github/workflows/firewall-escape.lock.yml
@@ -533,6 +533,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Max File Size**: 524288 bytes (0.50 MB) per file
@@ -540,10 +541,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -602,6 +606,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -620,6 +625,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -801,6 +807,19 @@ jobs:
           path: /tmp/gh-aw/repo-memory/default
           retention-days: 1
           if-no-files-found: ignore
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -906,6 +925,8 @@ jobs:
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_CREATE_DISCUSSION_ERRORS: ${{ needs.safe_outputs.outputs.create_discussion_errors }}
           GH_AW_CREATE_DISCUSSION_ERROR_COUNT: ${{ needs.safe_outputs.outputs.create_discussion_error_count }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1127,6 +1148,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1161,6 +1185,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1172,6 +1197,7 @@ jobs:
           BRANCH_NAME: memory/firewall-escape
           MAX_FILE_SIZE: 524288
           MAX_FILE_COUNT: 50
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
         with:
           script: |
             const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
@@ -1261,6 +1287,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/github-mcp-structural-analysis.lock.yml b/.github/workflows/github-mcp-structural-analysis.lock.yml
index 7a0b782cac..d9f2d827cf 100644
--- a/.github/workflows/github-mcp-structural-analysis.lock.yml
+++ b/.github/workflows/github-mcp-structural-analysis.lock.yml
@@ -625,6 +625,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -643,6 +644,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -868,6 +870,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1226,6 +1241,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/github-mcp-tools-report.lock.yml b/.github/workflows/github-mcp-tools-report.lock.yml
index 7906845a03..039e13e5b0 100644
--- a/.github/workflows/github-mcp-tools-report.lock.yml
+++ b/.github/workflows/github-mcp-tools-report.lock.yml
@@ -633,6 +633,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -651,6 +652,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -872,6 +874,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1263,6 +1278,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/glossary-maintainer.lock.yml b/.github/workflows/glossary-maintainer.lock.yml
index 72fe80e011..39bcf51662 100644
--- a/.github/workflows/glossary-maintainer.lock.yml
+++ b/.github/workflows/glossary-maintainer.lock.yml
@@ -596,6 +596,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -614,6 +615,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -813,6 +815,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1186,6 +1201,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/go-fan.lock.yml b/.github/workflows/go-fan.lock.yml
index c3f21d8011..ca81bd97ce 100644
--- a/.github/workflows/go-fan.lock.yml
+++ b/.github/workflows/go-fan.lock.yml
@@ -583,6 +583,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -601,6 +602,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -842,6 +844,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1196,6 +1211,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/go-logger.lock.yml b/.github/workflows/go-logger.lock.yml
index efdb922f03..b257112908 100644
--- a/.github/workflows/go-logger.lock.yml
+++ b/.github/workflows/go-logger.lock.yml
@@ -727,6 +727,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -745,6 +746,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1001,6 +1003,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1390,6 +1405,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/gpclean.lock.yml b/.github/workflows/gpclean.lock.yml
index 56c5a6d6c6..312a1d7899 100644
--- a/.github/workflows/gpclean.lock.yml
+++ b/.github/workflows/gpclean.lock.yml
@@ -586,6 +586,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -604,6 +605,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -776,6 +778,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1106,6 +1121,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/grumpy-reviewer.lock.yml b/.github/workflows/grumpy-reviewer.lock.yml
index 4b68ebb815..3784645269 100644
--- a/.github/workflows/grumpy-reviewer.lock.yml
+++ b/.github/workflows/grumpy-reviewer.lock.yml
@@ -647,6 +647,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -667,6 +668,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -844,6 +846,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1239,6 +1254,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/instructions-janitor.lock.yml b/.github/workflows/instructions-janitor.lock.yml
index 74bddd11f7..09cb40bbc7 100644
--- a/.github/workflows/instructions-janitor.lock.yml
+++ b/.github/workflows/instructions-janitor.lock.yml
@@ -573,6 +573,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -591,6 +592,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -834,6 +836,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1222,6 +1237,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/jsweep.lock.yml b/.github/workflows/jsweep.lock.yml
index b398939b9f..9c20f031ea 100644
--- a/.github/workflows/jsweep.lock.yml
+++ b/.github/workflows/jsweep.lock.yml
@@ -587,6 +587,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -605,6 +606,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -778,6 +780,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1158,6 +1173,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/lockfile-stats.lock.yml b/.github/workflows/lockfile-stats.lock.yml
index aca5f08710..7d902b2b0f 100644
--- a/.github/workflows/lockfile-stats.lock.yml
+++ b/.github/workflows/lockfile-stats.lock.yml
@@ -567,6 +567,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -585,6 +586,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -806,6 +808,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1154,6 +1169,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/mcp-inspector.lock.yml b/.github/workflows/mcp-inspector.lock.yml
index 4f61568b99..46c4a01674 100644
--- a/.github/workflows/mcp-inspector.lock.yml
+++ b/.github/workflows/mcp-inspector.lock.yml
@@ -931,6 +931,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -949,6 +950,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1136,6 +1138,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1745,6 +1760,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/metrics-collector.lock.yml b/.github/workflows/metrics-collector.lock.yml
index 209c076921..b6d6ec54e9 100644
--- a/.github/workflows/metrics-collector.lock.yml
+++ b/.github/workflows/metrics-collector.lock.yml
@@ -353,6 +353,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: metrics/**
@@ -361,10 +362,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <github-context>
           The following GitHub context information is available for this workflow:
@@ -625,6 +629,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -659,6 +666,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -670,6 +678,7 @@ jobs:
           BRANCH_NAME: memory/meta-orchestrators
           MAX_FILE_SIZE: 10240
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "metrics/**"
         with:
           script: |
diff --git a/.github/workflows/org-health-report.lock.yml b/.github/workflows/org-health-report.lock.yml
index 6b075a6678..01b063c2f8 100644
--- a/.github/workflows/org-health-report.lock.yml
+++ b/.github/workflows/org-health-report.lock.yml
@@ -616,6 +616,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -634,6 +635,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -808,6 +810,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1151,6 +1166,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/pdf-summary.lock.yml b/.github/workflows/pdf-summary.lock.yml
index 1d1409b9dc..ef49e198a9 100644
--- a/.github/workflows/pdf-summary.lock.yml
+++ b/.github/workflows/pdf-summary.lock.yml
@@ -665,6 +665,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_EXPR_799BE623: ${{ github.event.issue.number || github.event.pull_request.number }}
@@ -688,6 +689,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_EXPR_799BE623: process.env.GH_AW_EXPR_799BE623,
@@ -871,6 +873,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1270,6 +1285,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/poem-bot.lock.yml b/.github/workflows/poem-bot.lock.yml
index 640f03c8f9..6edfee9260 100644
--- a/.github/workflows/poem-bot.lock.yml
+++ b/.github/workflows/poem-bot.lock.yml
@@ -1151,6 +1151,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -1172,6 +1173,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1377,6 +1379,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1845,6 +1860,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/portfolio-analyst.lock.yml b/.github/workflows/portfolio-analyst.lock.yml
index 7a5dad7224..cce2496c08 100644
--- a/.github/workflows/portfolio-analyst.lock.yml
+++ b/.github/workflows/portfolio-analyst.lock.yml
@@ -699,6 +699,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -717,6 +718,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -892,6 +894,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1241,6 +1256,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/pr-nitpick-reviewer.lock.yml b/.github/workflows/pr-nitpick-reviewer.lock.yml
index 7cc40dd789..6605482e04 100644
--- a/.github/workflows/pr-nitpick-reviewer.lock.yml
+++ b/.github/workflows/pr-nitpick-reviewer.lock.yml
@@ -727,6 +727,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -747,6 +748,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -925,6 +927,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1328,6 +1343,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/pr-triage-agent.lock.yml b/.github/workflows/pr-triage-agent.lock.yml
index d33be36f3e..9915af17da 100644
--- a/.github/workflows/pr-triage-agent.lock.yml
+++ b/.github/workflows/pr-triage-agent.lock.yml
@@ -592,6 +592,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: **
@@ -600,10 +601,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -952,6 +956,8 @@ jobs:
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
           GH_AW_SAFE_OUTPUT_MESSAGES: "{\"runStarted\":\"🔍 Starting PR triage analysis... [{workflow_name}]({run_url}) is categorizing and prioritizing agent-created PRs\",\"runSuccess\":\"✅ PR triage complete! [{workflow_name}]({run_url}) has analyzed and categorized PRs. Check the issue for detailed report.\",\"runFailure\":\"❌ PR triage failed! [{workflow_name}]({run_url}) {status}. Some PRs may not be triaged.\"}"
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1112,6 +1118,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1146,6 +1155,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1157,6 +1167,7 @@ jobs:
           BRANCH_NAME: memory/pr-triage
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "**"
         with:
           script: |
diff --git a/.github/workflows/prompt-clustering-analysis.lock.yml b/.github/workflows/prompt-clustering-analysis.lock.yml
index f9c93fa1ac..85cc36e6a3 100644
--- a/.github/workflows/prompt-clustering-analysis.lock.yml
+++ b/.github/workflows/prompt-clustering-analysis.lock.yml
@@ -698,6 +698,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -716,6 +717,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -937,6 +939,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1285,6 +1300,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/python-data-charts.lock.yml b/.github/workflows/python-data-charts.lock.yml
index 54cc91a74e..0f0f3ab3c2 100644
--- a/.github/workflows/python-data-charts.lock.yml
+++ b/.github/workflows/python-data-charts.lock.yml
@@ -688,6 +688,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -706,6 +707,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -882,6 +884,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1225,6 +1240,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/q.lock.yml b/.github/workflows/q.lock.yml
index 98005b6576..50ed08d561 100644
--- a/.github/workflows/q.lock.yml
+++ b/.github/workflows/q.lock.yml
@@ -748,6 +748,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_EXPR_799BE623: ${{ github.event.issue.number || github.event.pull_request.number }}
@@ -769,6 +770,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_EXPR_799BE623: process.env.GH_AW_EXPR_799BE623,
@@ -951,6 +953,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1396,6 +1411,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/repo-audit-analyzer.lock.yml b/.github/workflows/repo-audit-analyzer.lock.yml
index 23d061fdc4..dfda5643c0 100644
--- a/.github/workflows/repo-audit-analyzer.lock.yml
+++ b/.github/workflows/repo-audit-analyzer.lock.yml
@@ -507,28 +507,8 @@ jobs:
           GH_AW_PROMPT_EOF
           cat "/opt/gh-aw/prompts/temp_folder_prompt.md" >> "$GH_AW_PROMPT"
           cat "/opt/gh-aw/prompts/markdown.md" >> "$GH_AW_PROMPT"
+          cat "/opt/gh-aw/prompts/cache_memory_prompt_multi.md" >> "$GH_AW_PROMPT"
           cat << 'GH_AW_PROMPT_EOF' >> "$GH_AW_PROMPT"
-          
-          ---
-          
-          ## Cache Folders Available
-          
-          You have access to persistent cache folders where you can read and write files to create memories and store information:
-          
-          - **repo-audits**: `/tmp/gh-aw/cache-memory-repo-audits/`
-          
-          - **Read/Write Access**: You can freely read from and write to any files in these folders
-          - **Persistence**: Files in these folders persist across workflow runs via GitHub Actions cache
-          - **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved
-          - **File Share**: Use these as simple file shares - organize files as you see fit
-          
-          Examples of what you can store:
-          - `/tmp/gh-aw/cache-memory-repo-audits/notes.txt` - general notes and observations
-          - `/tmp/gh-aw/cache-memory-repo-audits/preferences.json` - user preferences and settings
-          - `/tmp/gh-aw/cache-memory-repo-audits/state/` - organized state files in subdirectories
-          
-          Feel free to create, read, update, and organize files in these folders as needed for your tasks.
-          
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
           <important>
@@ -589,6 +569,16 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
+          GH_AW_CACHE_EXAMPLES: '- `/tmp/gh-aw/cache-memory-repo-audits/notes.txt` - general notes and observations
+- `/tmp/gh-aw/cache-memory-repo-audits/notes.md` - markdown formatted notes
+- `/tmp/gh-aw/cache-memory-repo-audits/preferences.json` - user preferences and settings
+- `/tmp/gh-aw/cache-memory-repo-audits/history.jsonl` - activity history in JSON Lines format
+- `/tmp/gh-aw/cache-memory-repo-audits/data.csv` - tabular data
+- `/tmp/gh-aw/cache-memory-repo-audits/state/` - organized state files in subdirectories (with allowed file types)
+'
+          GH_AW_CACHE_LIST: '- **repo-audits**: `/tmp/gh-aw/cache-memory-repo-audits/`
+'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
           GH_AW_GITHUB_EVENT_COMMENT_ID: ${{ github.event.comment.id }}
           GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: ${{ github.event.discussion.number }}
@@ -606,6 +596,9 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
+                GH_AW_CACHE_EXAMPLES: process.env.GH_AW_CACHE_EXAMPLES,
+                GH_AW_CACHE_LIST: process.env.GH_AW_CACHE_LIST,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
                 GH_AW_GITHUB_EVENT_COMMENT_ID: process.env.GH_AW_GITHUB_EVENT_COMMENT_ID,
                 GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: process.env.GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER,
@@ -777,6 +770,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types (repo-audits)
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory-repo-audits', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact (repo-audits)
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1113,6 +1119,18 @@ jobs:
         with:
           name: cache-memory-repo-audits
           path: /tmp/gh-aw/cache-memory-repo-audits
+      - name: Validate cache-memory file types (repo-audits)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory-repo-audits', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (repo-audits)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/repository-quality-improver.lock.yml b/.github/workflows/repository-quality-improver.lock.yml
index 46c318a5b8..6a541b22a5 100644
--- a/.github/workflows/repository-quality-improver.lock.yml
+++ b/.github/workflows/repository-quality-improver.lock.yml
@@ -510,28 +510,8 @@ jobs:
           GH_AW_PROMPT_EOF
           cat "/opt/gh-aw/prompts/temp_folder_prompt.md" >> "$GH_AW_PROMPT"
           cat "/opt/gh-aw/prompts/markdown.md" >> "$GH_AW_PROMPT"
+          cat "/opt/gh-aw/prompts/cache_memory_prompt_multi.md" >> "$GH_AW_PROMPT"
           cat << 'GH_AW_PROMPT_EOF' >> "$GH_AW_PROMPT"
-          
-          ---
-          
-          ## Cache Folders Available
-          
-          You have access to persistent cache folders where you can read and write files to create memories and store information:
-          
-          - **focus-areas**: `/tmp/gh-aw/cache-memory-focus-areas/`
-          
-          - **Read/Write Access**: You can freely read from and write to any files in these folders
-          - **Persistence**: Files in these folders persist across workflow runs via GitHub Actions cache
-          - **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved
-          - **File Share**: Use these as simple file shares - organize files as you see fit
-          
-          Examples of what you can store:
-          - `/tmp/gh-aw/cache-memory-focus-areas/notes.txt` - general notes and observations
-          - `/tmp/gh-aw/cache-memory-focus-areas/preferences.json` - user preferences and settings
-          - `/tmp/gh-aw/cache-memory-focus-areas/state/` - organized state files in subdirectories
-          
-          Feel free to create, read, update, and organize files in these folders as needed for your tasks.
-          
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
           <important>
@@ -592,6 +572,16 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
+          GH_AW_CACHE_EXAMPLES: '- `/tmp/gh-aw/cache-memory-focus-areas/notes.txt` - general notes and observations
+- `/tmp/gh-aw/cache-memory-focus-areas/notes.md` - markdown formatted notes
+- `/tmp/gh-aw/cache-memory-focus-areas/preferences.json` - user preferences and settings
+- `/tmp/gh-aw/cache-memory-focus-areas/history.jsonl` - activity history in JSON Lines format
+- `/tmp/gh-aw/cache-memory-focus-areas/data.csv` - tabular data
+- `/tmp/gh-aw/cache-memory-focus-areas/state/` - organized state files in subdirectories (with allowed file types)
+'
+          GH_AW_CACHE_LIST: '- **focus-areas**: `/tmp/gh-aw/cache-memory-focus-areas/`
+'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
           GH_AW_GITHUB_EVENT_COMMENT_ID: ${{ github.event.comment.id }}
           GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: ${{ github.event.discussion.number }}
@@ -608,6 +598,9 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
+                GH_AW_CACHE_EXAMPLES: process.env.GH_AW_CACHE_EXAMPLES,
+                GH_AW_CACHE_LIST: process.env.GH_AW_CACHE_LIST,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
                 GH_AW_GITHUB_EVENT_COMMENT_ID: process.env.GH_AW_GITHUB_EVENT_COMMENT_ID,
                 GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER: process.env.GH_AW_GITHUB_EVENT_DISCUSSION_NUMBER,
@@ -778,6 +771,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types (focus-areas)
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory-focus-areas', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact (focus-areas)
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1111,6 +1117,18 @@ jobs:
         with:
           name: cache-memory-focus-areas
           path: /tmp/gh-aw/cache-memory-focus-areas
+      - name: Validate cache-memory file types (focus-areas)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory-focus-areas', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (focus-areas)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/safe-output-health.lock.yml b/.github/workflows/safe-output-health.lock.yml
index 3fd7d5f410..ed938546ef 100644
--- a/.github/workflows/safe-output-health.lock.yml
+++ b/.github/workflows/safe-output-health.lock.yml
@@ -645,6 +645,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -663,6 +664,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -898,6 +900,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1246,6 +1261,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/schema-consistency-checker.lock.yml b/.github/workflows/schema-consistency-checker.lock.yml
index 096470fbe7..642afb3484 100644
--- a/.github/workflows/schema-consistency-checker.lock.yml
+++ b/.github/workflows/schema-consistency-checker.lock.yml
@@ -569,6 +569,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -587,6 +588,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -807,6 +809,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1155,6 +1170,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/scout.lock.yml b/.github/workflows/scout.lock.yml
index 8b80bc3620..bc404a8fb9 100644
--- a/.github/workflows/scout.lock.yml
+++ b/.github/workflows/scout.lock.yml
@@ -678,6 +678,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_EXPR_799BE623: ${{ github.event.issue.number || github.event.pull_request.number }}
@@ -700,6 +701,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_EXPR_799BE623: process.env.GH_AW_EXPR_799BE623,
@@ -953,6 +955,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1374,6 +1389,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/security-compliance.lock.yml b/.github/workflows/security-compliance.lock.yml
index fa83360bb6..8bb3f96cdb 100644
--- a/.github/workflows/security-compliance.lock.yml
+++ b/.github/workflows/security-compliance.lock.yml
@@ -542,6 +542,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: memory/campaigns/security-compliance-*/**
@@ -550,10 +551,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -909,6 +913,8 @@ jobs:
           GH_AW_WORKFLOW_ID: "security-compliance"
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1066,6 +1072,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1100,6 +1109,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1111,6 +1121,7 @@ jobs:
           BRANCH_NAME: memory/campaigns
           MAX_FILE_SIZE: 10240
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "memory/campaigns/security-compliance-*/**"
         with:
           script: |
diff --git a/.github/workflows/security-review.lock.yml b/.github/workflows/security-review.lock.yml
index 9cfcfe772a..7ba8d6f45f 100644
--- a/.github/workflows/security-review.lock.yml
+++ b/.github/workflows/security-review.lock.yml
@@ -729,6 +729,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -749,6 +750,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -926,6 +928,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1321,6 +1336,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/sergo.lock.yml b/.github/workflows/sergo.lock.yml
index 8c5bbc697b..7e3834e97a 100644
--- a/.github/workflows/sergo.lock.yml
+++ b/.github/workflows/sergo.lock.yml
@@ -584,6 +584,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -602,6 +603,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -841,6 +843,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1195,6 +1210,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/slide-deck-maintainer.lock.yml b/.github/workflows/slide-deck-maintainer.lock.yml
index 2787170df3..6375972f9a 100644
--- a/.github/workflows/slide-deck-maintainer.lock.yml
+++ b/.github/workflows/slide-deck-maintainer.lock.yml
@@ -597,6 +597,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -617,6 +618,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -834,6 +836,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1257,6 +1272,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/smoke-claude.lock.yml b/.github/workflows/smoke-claude.lock.yml
index b9adaffe79..f537eaef5d 100644
--- a/.github/workflows/smoke-claude.lock.yml
+++ b/.github/workflows/smoke-claude.lock.yml
@@ -1386,6 +1386,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -1405,6 +1406,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1664,6 +1666,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -2063,6 +2078,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/smoke-codex.lock.yml b/.github/workflows/smoke-codex.lock.yml
index 22c9e089b3..db0cb743bd 100644
--- a/.github/workflows/smoke-codex.lock.yml
+++ b/.github/workflows/smoke-codex.lock.yml
@@ -950,6 +950,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -968,6 +969,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1132,6 +1134,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1507,6 +1522,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/smoke-copilot.lock.yml b/.github/workflows/smoke-copilot.lock.yml
index 4c37b1a40e..f1de782af9 100644
--- a/.github/workflows/smoke-copilot.lock.yml
+++ b/.github/workflows/smoke-copilot.lock.yml
@@ -27,7 +27,7 @@
 #     - shared/github-queries-safe-input.md
 #     - shared/reporting.md
 #
-# frontmatter-hash: ba8ac38783175d2491cfa23fdbc191b34f88eb3068c3e9b4c795c4c36094a988
+# frontmatter-hash: 23fb974caf81e30df69d8ee71fb9c8a011690ef75670f3f539f699673640002e
 
 name: "Smoke Copilot"
 "on":
@@ -1347,6 +1347,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -1366,6 +1367,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1552,6 +1554,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1973,6 +1988,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/smoke-copilot.md b/.github/workflows/smoke-copilot.md
index bab2f477a1..33e1dca482 100644
--- a/.github/workflows/smoke-copilot.md
+++ b/.github/workflows/smoke-copilot.md
@@ -47,9 +47,9 @@ sandbox:
     container: "ghcr.io/github/gh-aw-mcpg"
 safe-outputs:
     add-comment:
+      allowed-repos: ["github/gh-aw"]
       hide-older-comments: true
       max: 2
-      allowed-repos: ["github/gh-aw"]
     create-issue:
       expires: 2h
       group: true
diff --git a/.github/workflows/stale-repo-identifier.lock.yml b/.github/workflows/stale-repo-identifier.lock.yml
index 437790b710..d442babe57 100644
--- a/.github/workflows/stale-repo-identifier.lock.yml
+++ b/.github/workflows/stale-repo-identifier.lock.yml
@@ -679,6 +679,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_ENV_ORGANIZATION: ${{ env.ORGANIZATION }}
@@ -698,6 +699,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_ENV_ORGANIZATION: process.env.GH_AW_ENV_ORGANIZATION,
@@ -876,6 +878,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1219,6 +1234,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/static-analysis-report.lock.yml b/.github/workflows/static-analysis-report.lock.yml
index 73fef47549..8e1ba397ed 100644
--- a/.github/workflows/static-analysis-report.lock.yml
+++ b/.github/workflows/static-analysis-report.lock.yml
@@ -641,6 +641,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -659,6 +660,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -881,6 +883,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1229,6 +1244,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/step-name-alignment.lock.yml b/.github/workflows/step-name-alignment.lock.yml
index 66288e1ece..30e9a801e3 100644
--- a/.github/workflows/step-name-alignment.lock.yml
+++ b/.github/workflows/step-name-alignment.lock.yml
@@ -584,6 +584,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -602,6 +603,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -838,6 +840,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1183,6 +1198,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/super-linter.lock.yml b/.github/workflows/super-linter.lock.yml
index 031c185061..4e1d195a12 100644
--- a/.github/workflows/super-linter.lock.yml
+++ b/.github/workflows/super-linter.lock.yml
@@ -593,6 +593,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -612,6 +613,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -788,6 +790,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1164,6 +1179,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/technical-doc-writer.lock.yml b/.github/workflows/technical-doc-writer.lock.yml
index 452787a5e4..333d5f67ad 100644
--- a/.github/workflows/technical-doc-writer.lock.yml
+++ b/.github/workflows/technical-doc-writer.lock.yml
@@ -672,6 +672,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -691,6 +692,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -867,6 +869,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1254,6 +1269,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/test-create-pr-error-handling.lock.yml b/.github/workflows/test-create-pr-error-handling.lock.yml
index ee075033e7..019ad0695d 100644
--- a/.github/workflows/test-create-pr-error-handling.lock.yml
+++ b/.github/workflows/test-create-pr-error-handling.lock.yml
@@ -570,6 +570,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -588,6 +589,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -808,6 +810,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1196,6 +1211,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/unbloat-docs.lock.yml b/.github/workflows/unbloat-docs.lock.yml
index dcf0d6270c..a2b0597706 100644
--- a/.github/workflows/unbloat-docs.lock.yml
+++ b/.github/workflows/unbloat-docs.lock.yml
@@ -705,6 +705,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -723,6 +724,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -1008,6 +1010,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1470,6 +1485,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/weekly-issue-summary.lock.yml b/.github/workflows/weekly-issue-summary.lock.yml
index e84ab26956..36d858dba0 100644
--- a/.github/workflows/weekly-issue-summary.lock.yml
+++ b/.github/workflows/weekly-issue-summary.lock.yml
@@ -595,6 +595,7 @@ jobs:
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
           GH_AW_PROMPT: /tmp/gh-aw/aw-prompts/prompt.txt
+          GH_AW_ALLOWED_EXTENSIONS: '.json, .jsonl, .txt, .md, .csv'
           GH_AW_CACHE_DESCRIPTION: ''
           GH_AW_CACHE_DIR: '/tmp/gh-aw/cache-memory/'
           GH_AW_GITHUB_ACTOR: ${{ github.actor }}
@@ -613,6 +614,7 @@ jobs:
             return await substitutePlaceholders({
               file: process.env.GH_AW_PROMPT,
               substitutions: {
+                GH_AW_ALLOWED_EXTENSIONS: process.env.GH_AW_ALLOWED_EXTENSIONS,
                 GH_AW_CACHE_DESCRIPTION: process.env.GH_AW_CACHE_DESCRIPTION,
                 GH_AW_CACHE_DIR: process.env.GH_AW_CACHE_DIR,
                 GH_AW_GITHUB_ACTOR: process.env.GH_AW_GITHUB_ACTOR,
@@ -788,6 +790,19 @@ jobs:
           # AWF runs with sudo, creating files owned by root
           sudo chmod -R a+r /tmp/gh-aw/sandbox/firewall/logs 2>/dev/null || true
           awf logs summary | tee -a "$GITHUB_STEP_SUMMARY"
+      - name: Validate cache-memory file types
+        if: always()
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Upload cache-memory data as artifact
         uses: actions/upload-artifact@b7c566a772e6b6bfb58ed0dc250532a479d7789f # v6.0.0
         if: always()
@@ -1136,6 +1151,18 @@ jobs:
         with:
           name: cache-memory
           path: /tmp/gh-aw/cache-memory
+      - name: Validate cache-memory file types (default)
+        uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
+        with:
+          script: |
+            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');
+            setupGlobals(core, github, context, exec, io);
+            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');
+            const allowedExtensions = [".json",".jsonl",".txt",".md",".csv"];
+            const result = validateMemoryFiles('/tmp/gh-aw/cache-memory', 'cache', allowedExtensions);
+            if (!result.valid) {
+              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only .json, .jsonl, .txt, .md, .csv are allowed.`);
+            }
       - name: Save cache-memory to cache (default)
         uses: actions/cache/save@0057852bfaa89a56745cba8c7296529d2fc39830 # v4.3.0
         with:
diff --git a/.github/workflows/workflow-health-manager.lock.yml b/.github/workflows/workflow-health-manager.lock.yml
index 3d73f9e172..075da22a3d 100644
--- a/.github/workflows/workflow-health-manager.lock.yml
+++ b/.github/workflows/workflow-health-manager.lock.yml
@@ -662,6 +662,7 @@ jobs:
           - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes
           - **Merge Strategy**: In case of conflicts, your changes (current version) win
           - **Persistence**: Files persist across workflow runs via git branch storage
+          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.
           
           **Constraints:**
           - **Allowed Files**: Only files matching patterns: **
@@ -670,10 +671,13 @@ jobs:
           
           Examples of what you can store:
           - `/tmp/gh-aw/repo-memory/default/notes.md` - general notes and observations
+          - `/tmp/gh-aw/repo-memory/default/notes.txt` - plain text notes
           - `/tmp/gh-aw/repo-memory/default/state.json` - structured state data
-          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories
+          - `/tmp/gh-aw/repo-memory/default/history.jsonl` - activity history in JSON Lines format
+          - `/tmp/gh-aw/repo-memory/default/data.csv` - tabular data
+          - `/tmp/gh-aw/repo-memory/default/history/` - organized history files in subdirectories (with allowed file types)
           
-          Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
           
           <safe-outputs>
           <description>GitHub API Access Instructions</description>
@@ -1022,6 +1026,8 @@ jobs:
           GH_AW_WORKFLOW_ID: "workflow-health-manager"
           GH_AW_SECRET_VERIFICATION_RESULT: ${{ needs.agent.outputs.secret_verification_result }}
           GH_AW_CHECKOUT_PR_SUCCESS: ${{ needs.agent.outputs.checkout_pr_success }}
+          GH_AW_REPO_MEMORY_VALIDATION_FAILED_default: ${{ needs.push_repo_memory.outputs.validation_failed_default }}
+          GH_AW_REPO_MEMORY_VALIDATION_ERROR_default: ${{ needs.push_repo_memory.outputs.validation_error_default }}
         with:
           github-token: ${{ secrets.GH_AW_GITHUB_TOKEN || secrets.GITHUB_TOKEN }}
           script: |
@@ -1211,6 +1217,9 @@ jobs:
     runs-on: ubuntu-latest
     permissions:
       contents: write
+    outputs:
+      validation_error_default: ${{ steps.push_repo_memory_default.outputs.validation_error }}
+      validation_failed_default: ${{ steps.push_repo_memory_default.outputs.validation_failed }}
     steps:
       - name: Checkout actions folder
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -1245,6 +1254,7 @@ jobs:
           name: repo-memory-default
           path: /tmp/gh-aw/repo-memory/default
       - name: Push repo-memory changes (default)
+        id: push_repo_memory_default
         if: always()
         uses: actions/github-script@ed597411d8f924073f98dfc5c65a23a2325f34cd # v8
         env:
@@ -1256,6 +1266,7 @@ jobs:
           BRANCH_NAME: memory/meta-orchestrators
           MAX_FILE_SIZE: 102400
           MAX_FILE_COUNT: 100
+          ALLOWED_EXTENSIONS: '[".json",".jsonl",".txt",".md",".csv"]'
           FILE_GLOB_FILTER: "**"
         with:
           script: |
diff --git a/actions/setup/js/handle_agent_failure.cjs b/actions/setup/js/handle_agent_failure.cjs
index 9361024157..5b2d3f40a4 100644
--- a/actions/setup/js/handle_agent_failure.cjs
+++ b/actions/setup/js/handle_agent_failure.cjs
@@ -343,6 +343,20 @@ async function main() {
     const createDiscussionErrorCount = process.env.GH_AW_CREATE_DISCUSSION_ERROR_COUNT || "0";
     const checkoutPRSuccess = process.env.GH_AW_CHECKOUT_PR_SUCCESS || "";
 
+    // Collect repo-memory validation errors from all memory configurations
+    const repoMemoryValidationErrors = [];
+    for (const key in process.env) {
+      if (key.startsWith("GH_AW_REPO_MEMORY_VALIDATION_FAILED_")) {
+        const memoryID = key.replace("GH_AW_REPO_MEMORY_VALIDATION_FAILED_", "");
+        const failed = process.env[key] === "true";
+        if (failed) {
+          const errorKey = `GH_AW_REPO_MEMORY_VALIDATION_ERROR_${memoryID}`;
+          const errorMessage = process.env[errorKey] || "Unknown validation error";
+          repoMemoryValidationErrors.push({ memoryID, errorMessage });
+        }
+      }
+    }
+
     core.info(`Agent conclusion: ${agentConclusion}`);
     core.info(`Workflow name: ${workflowName}`);
     core.info(`Workflow ID: ${workflowID}`);
@@ -463,6 +477,16 @@ async function main() {
         // Build create_discussion errors context
         const createDiscussionErrorsContext = hasCreateDiscussionErrors ? buildCreateDiscussionErrorsContext(createDiscussionErrors) : "";
 
+        // Build repo-memory validation errors context
+        let repoMemoryValidationContext = "";
+        if (repoMemoryValidationErrors.length > 0) {
+          repoMemoryValidationContext = "\n**⚠️ Repo-Memory Validation Failed**: Invalid file types detected in repo-memory.\n\n**Validation Errors:**\n";
+          for (const { memoryID, errorMessage } of repoMemoryValidationErrors) {
+            repoMemoryValidationContext += `- Memory "${memoryID}": ${errorMessage}\n`;
+          }
+          repoMemoryValidationContext += "\n";
+        }
+
         // Build missing_data context
         const missingDataContext = buildMissingDataContext();
 
@@ -489,6 +513,7 @@ async function main() {
               : "",
           assignment_errors_context: assignmentErrorsContext,
           create_discussion_errors_context: createDiscussionErrorsContext,
+          repo_memory_validation_context: repoMemoryValidationContext,
           missing_data_context: missingDataContext,
           missing_safe_outputs_context: missingSafeOutputsContext,
         };
@@ -548,6 +573,16 @@ async function main() {
         // Build create_discussion errors context
         const createDiscussionErrorsContext = hasCreateDiscussionErrors ? buildCreateDiscussionErrorsContext(createDiscussionErrors) : "";
 
+        // Build repo-memory validation errors context
+        let repoMemoryValidationContext = "";
+        if (repoMemoryValidationErrors.length > 0) {
+          repoMemoryValidationContext = "\n**⚠️ Repo-Memory Validation Failed**: Invalid file types detected in repo-memory.\n\n**Validation Errors:**\n";
+          for (const { memoryID, errorMessage } of repoMemoryValidationErrors) {
+            repoMemoryValidationContext += `- Memory "${memoryID}": ${errorMessage}\n`;
+          }
+          repoMemoryValidationContext += "\n";
+        }
+
         // Build missing_data context
         const missingDataContext = buildMissingDataContext();
 
@@ -575,6 +610,7 @@ async function main() {
               : "",
           assignment_errors_context: assignmentErrorsContext,
           create_discussion_errors_context: createDiscussionErrorsContext,
+          repo_memory_validation_context: repoMemoryValidationContext,
           missing_data_context: missingDataContext,
           missing_safe_outputs_context: missingSafeOutputsContext,
         };
diff --git a/actions/setup/js/push_repo_memory.cjs b/actions/setup/js/push_repo_memory.cjs
index 1699f126c8..61417dd6a6 100644
--- a/actions/setup/js/push_repo_memory.cjs
+++ b/actions/setup/js/push_repo_memory.cjs
@@ -17,6 +17,7 @@ const { execGitSync } = require("./git_helpers.cjs");
  *   BRANCH_NAME: Branch name to push to
  *   MAX_FILE_SIZE: Maximum file size in bytes
  *   MAX_FILE_COUNT: Maximum number of files per commit
+ *   ALLOWED_EXTENSIONS: JSON array of allowed file extensions (e.g., '[".json",".txt"]')
  *   FILE_GLOB_FILTER: Optional space-separated list of file patterns (e.g., "*.md metrics/** data/**")
  *                     Supports * (matches any chars except /) and ** (matches any chars including /)
  *
@@ -43,6 +44,18 @@ async function main() {
   const maxFileSize = parseInt(process.env.MAX_FILE_SIZE || "10240", 10);
   const maxFileCount = parseInt(process.env.MAX_FILE_COUNT || "100", 10);
   const fileGlobFilter = process.env.FILE_GLOB_FILTER || "";
+
+  // Parse allowed extensions with error handling
+  let allowedExtensions = [".json", ".jsonl", ".txt", ".md", ".csv"];
+  if (process.env.ALLOWED_EXTENSIONS) {
+    try {
+      allowedExtensions = JSON.parse(process.env.ALLOWED_EXTENSIONS);
+    } catch (/** @type {any} */ error) {
+      core.setFailed(`Failed to parse ALLOWED_EXTENSIONS environment variable: ${error.message}. Expected JSON array format.`);
+      return;
+    }
+  }
+
   const ghToken = process.env.GH_TOKEN;
   const githubRunId = process.env.GITHUB_RUN_ID || "unknown";
 
@@ -51,6 +64,7 @@ async function main() {
   core.info(`  MEMORY_ID: ${memoryId}`);
   core.info(`  MAX_FILE_SIZE: ${maxFileSize}`);
   core.info(`  MAX_FILE_COUNT: ${maxFileCount}`);
+  core.info(`  ALLOWED_EXTENSIONS: ${JSON.stringify(allowedExtensions)}`);
   core.info(`  FILE_GLOB_FILTER: ${fileGlobFilter ? `"${fileGlobFilter}"` : "(empty - all files accepted)"}`);
   core.info(`  FILE_GLOB_FILTER length: ${fileGlobFilter.length}`);
 
@@ -241,6 +255,17 @@ async function main() {
     return;
   }
 
+  // Validate file types before copying
+  const { validateMemoryFiles } = require("./validate_memory_files.cjs");
+  const validation = validateMemoryFiles(sourceMemoryPath, "repo", allowedExtensions);
+  if (!validation.valid) {
+    const errorMessage = `File type validation failed: Found ${validation.invalidFiles.length} file(s) with invalid extensions. Only ${allowedExtensions.join(", ")} are allowed. Invalid files: ${validation.invalidFiles.join(", ")}`;
+    core.setOutput("validation_failed", "true");
+    core.setOutput("validation_error", errorMessage);
+    core.setFailed(errorMessage);
+    return;
+  }
+
   core.info(`Copying ${filesToCopy.length} validated file(s)...`);
 
   // Copy files to destination (preserving directory structure)
diff --git a/actions/setup/js/validate_memory_files.cjs b/actions/setup/js/validate_memory_files.cjs
new file mode 100644
index 0000000000..fbfcd3b1ba
--- /dev/null
+++ b/actions/setup/js/validate_memory_files.cjs
@@ -0,0 +1,78 @@
+// @ts-check
+/// <reference types="@actions/github-script" />
+
+const fs = require("fs");
+const path = require("path");
+
+/**
+ * Validate that all files in a memory directory have allowed file extensions
+ * Default allowed extensions: .json, .jsonl, .txt, .md, .csv
+ *
+ * @param {string} memoryDir - Path to the memory directory to validate
+ * @param {string} memoryType - Type of memory ("cache" or "repo") for error messages
+ * @param {string[]} [allowedExtensions] - Optional custom list of allowed extensions (defaults to [".json", ".jsonl", ".txt", ".md", ".csv"])
+ * @returns {{valid: boolean, invalidFiles: string[]}} Validation result with list of invalid files
+ */
+function validateMemoryFiles(memoryDir, memoryType = "cache", allowedExtensions) {
+  // Use default extensions if not provided or if empty array
+  const defaultExtensions = [".json", ".jsonl", ".txt", ".md", ".csv"];
+  const rawExtensions = allowedExtensions && allowedExtensions.length > 0 ? allowedExtensions : defaultExtensions;
+  // Normalize extensions to lowercase and trim whitespace
+  const extensions = rawExtensions.map(ext => ext.trim().toLowerCase());
+  const invalidFiles = [];
+
+  // Check if directory exists
+  if (!fs.existsSync(memoryDir)) {
+    core.info(`Memory directory does not exist: ${memoryDir}`);
+    return { valid: true, invalidFiles: [] };
+  }
+
+  /**
+   * Recursively scan directory for files
+   * @param {string} dirPath - Directory to scan
+   * @param {string} relativePath - Relative path from memory directory
+   */
+  function scanDirectory(dirPath, relativePath = "") {
+    const entries = fs.readdirSync(dirPath, { withFileTypes: true });
+
+    for (const entry of entries) {
+      const fullPath = path.join(dirPath, entry.name);
+      const relativeFilePath = relativePath ? path.join(relativePath, entry.name) : entry.name;
+
+      if (entry.isDirectory()) {
+        // Recursively scan subdirectory
+        scanDirectory(fullPath, relativeFilePath);
+      } else if (entry.isFile()) {
+        // Check file extension
+        const ext = path.extname(entry.name).toLowerCase();
+        if (!extensions.includes(ext)) {
+          invalidFiles.push(relativeFilePath);
+        }
+      }
+    }
+  }
+
+  try {
+    scanDirectory(memoryDir);
+  } catch (error) {
+    core.error(`Failed to scan ${memoryType}-memory directory: ${error instanceof Error ? error.message : String(error)}`);
+    return { valid: false, invalidFiles: [] };
+  }
+
+  if (invalidFiles.length > 0) {
+    core.error(`Found ${invalidFiles.length} file(s) with invalid extensions in ${memoryType}-memory:`);
+    invalidFiles.forEach(file => {
+      const ext = path.extname(file).toLowerCase();
+      core.error(`  - ${file} (extension: ${ext || "(no extension)"})`);
+    });
+    core.error(`Allowed extensions: ${extensions.join(", ")}`);
+    return { valid: false, invalidFiles };
+  }
+
+  core.info(`All files in ${memoryType}-memory directory have valid extensions`);
+  return { valid: true, invalidFiles: [] };
+}
+
+module.exports = {
+  validateMemoryFiles,
+};
diff --git a/actions/setup/js/validate_memory_files.test.cjs b/actions/setup/js/validate_memory_files.test.cjs
new file mode 100644
index 0000000000..5767a116aa
--- /dev/null
+++ b/actions/setup/js/validate_memory_files.test.cjs
@@ -0,0 +1,202 @@
+// @ts-check
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import fs from "fs";
+import path from "path";
+import os from "os";
+
+const { validateMemoryFiles } = require("./validate_memory_files.cjs");
+
+// Mock core globally
+global.core = {
+  info: () => {},
+  error: () => {},
+  warning: () => {},
+  debug: () => {},
+};
+
+describe("validateMemoryFiles", () => {
+  let tempDir = "";
+
+  beforeEach(() => {
+    // Create a temporary directory for testing
+    tempDir = fs.mkdtempSync(path.join(os.tmpdir(), "validate-memory-test-"));
+  });
+
+  afterEach(() => {
+    // Clean up temporary directory
+    if (tempDir && fs.existsSync(tempDir)) {
+      fs.rmSync(tempDir, { recursive: true, force: true });
+    }
+  });
+
+  it("returns valid for empty directory", () => {
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("returns valid for non-existent directory", () => {
+    const nonExistentDir = path.join(tempDir, "does-not-exist");
+    const result = validateMemoryFiles(nonExistentDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts .json files", () => {
+    fs.writeFileSync(path.join(tempDir, "data.json"), '{"test": true}');
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts .jsonl files", () => {
+    fs.writeFileSync(path.join(tempDir, "data.jsonl"), '{"line": 1}\n{"line": 2}');
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts .txt files", () => {
+    fs.writeFileSync(path.join(tempDir, "notes.txt"), "Some notes");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts .md files", () => {
+    fs.writeFileSync(path.join(tempDir, "README.md"), "# Title");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts .csv files", () => {
+    fs.writeFileSync(path.join(tempDir, "data.csv"), "col1,col2\nval1,val2");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("accepts multiple valid files", () => {
+    fs.writeFileSync(path.join(tempDir, "data.json"), "{}");
+    fs.writeFileSync(path.join(tempDir, "notes.txt"), "notes");
+    fs.writeFileSync(path.join(tempDir, "README.md"), "# Title");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("rejects .log files", () => {
+    fs.writeFileSync(path.join(tempDir, "app.log"), "log entry");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual(["app.log"]);
+  });
+
+  it("rejects .yaml files", () => {
+    fs.writeFileSync(path.join(tempDir, "config.yaml"), "key: value");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual(["config.yaml"]);
+  });
+
+  it("rejects .xml files", () => {
+    fs.writeFileSync(path.join(tempDir, "data.xml"), "<root></root>");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual(["data.xml"]);
+  });
+
+  it("rejects files without extension", () => {
+    fs.writeFileSync(path.join(tempDir, "noext"), "content");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual(["noext"]);
+  });
+
+  it("rejects multiple invalid files", () => {
+    fs.writeFileSync(path.join(tempDir, "app.log"), "log");
+    fs.writeFileSync(path.join(tempDir, "config.yaml"), "yaml");
+    fs.writeFileSync(path.join(tempDir, "valid.json"), "{}");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toHaveLength(2);
+    expect(result.invalidFiles).toContain("app.log");
+    expect(result.invalidFiles).toContain("config.yaml");
+  });
+
+  it("validates files in subdirectories", () => {
+    const subdir = path.join(tempDir, "subdir");
+    fs.mkdirSync(subdir);
+    fs.writeFileSync(path.join(subdir, "valid.json"), "{}");
+    fs.writeFileSync(path.join(subdir, "invalid.log"), "log");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual([path.join("subdir", "invalid.log")]);
+  });
+
+  it("validates files in deeply nested directories", () => {
+    const level1 = path.join(tempDir, "level1");
+    const level2 = path.join(level1, "level2");
+    const level3 = path.join(level2, "level3");
+    fs.mkdirSync(level1);
+    fs.mkdirSync(level2);
+    fs.mkdirSync(level3);
+    fs.writeFileSync(path.join(level3, "deep.json"), "{}");
+    fs.writeFileSync(path.join(level3, "invalid.bin"), "binary");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual([path.join("level1", "level2", "level3", "invalid.bin")]);
+  });
+
+  it("is case-insensitive for extensions", () => {
+    fs.writeFileSync(path.join(tempDir, "data.JSON"), "{}");
+    fs.writeFileSync(path.join(tempDir, "notes.TXT"), "text");
+    fs.writeFileSync(path.join(tempDir, "README.MD"), "# Title");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("handles mixed valid and invalid files in subdirectories", () => {
+    const subdir1 = path.join(tempDir, "valid-files");
+    const subdir2 = path.join(tempDir, "invalid-files");
+    fs.mkdirSync(subdir1);
+    fs.mkdirSync(subdir2);
+    fs.writeFileSync(path.join(subdir1, "data.json"), "{}");
+    fs.writeFileSync(path.join(subdir1, "notes.txt"), "text");
+    fs.writeFileSync(path.join(subdir2, "app.log"), "log");
+    fs.writeFileSync(path.join(subdir2, "config.ini"), "ini");
+    const result = validateMemoryFiles(tempDir, "cache");
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toHaveLength(2);
+    expect(result.invalidFiles).toContain(path.join("invalid-files", "app.log"));
+    expect(result.invalidFiles).toContain(path.join("invalid-files", "config.ini"));
+  });
+
+  it("accepts custom allowed extensions", () => {
+    fs.writeFileSync(path.join(tempDir, "config.yaml"), "key: value");
+    fs.writeFileSync(path.join(tempDir, "data.xml"), "<root></root>");
+    const customExts = [".yaml", ".xml"];
+    const result = validateMemoryFiles(tempDir, "cache", customExts);
+    expect(result.valid).toBe(true);
+    expect(result.invalidFiles).toEqual([]);
+  });
+
+  it("rejects files not in custom allowed extensions", () => {
+    fs.writeFileSync(path.join(tempDir, "data.json"), "{}");
+    const customExts = [".yaml", ".xml"];
+    const result = validateMemoryFiles(tempDir, "cache", customExts);
+    expect(result.valid).toBe(false);
+    expect(result.invalidFiles).toEqual(["data.json"]);
+  });
+
+  it("uses default extensions when custom array is empty", () => {
+    fs.writeFileSync(path.join(tempDir, "data.json"), "{}");
+    fs.writeFileSync(path.join(tempDir, "notes.txt"), "text");
+    const result = validateMemoryFiles(tempDir, "cache", []);
+    expect(result.valid).toBe(true); // Empty array falls back to defaults
+    expect(result.invalidFiles).toEqual([]);
+  });
+});
diff --git a/actions/setup/md/agent_failure_comment.md b/actions/setup/md/agent_failure_comment.md
index 7d1089bb6f..93d5c23b54 100644
--- a/actions/setup/md/agent_failure_comment.md
+++ b/actions/setup/md/agent_failure_comment.md
@@ -1,3 +1,3 @@
 Agent job [{run_id}]({run_url}) failed.
 
-{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{missing_data_context}{missing_safe_outputs_context}
+{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}
diff --git a/actions/setup/md/agent_failure_issue.md b/actions/setup/md/agent_failure_issue.md
index 974a957bdc..88a5a84e68 100644
--- a/actions/setup/md/agent_failure_issue.md
+++ b/actions/setup/md/agent_failure_issue.md
@@ -4,7 +4,7 @@
 **Branch:** {branch}  
 **Run URL:** {run_url}{pull_request_info}
 
-{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{missing_data_context}{missing_safe_outputs_context}
+{secret_verification_context}{assignment_errors_context}{create_discussion_errors_context}{repo_memory_validation_context}{missing_data_context}{missing_safe_outputs_context}
 
 ### Action Required
 
diff --git a/docs/src/content/docs/reference/frontmatter-full.md b/docs/src/content/docs/reference/frontmatter-full.md
index dc127ac500..c1414d47af 100644
--- a/docs/src/content/docs/reference/frontmatter-full.md
+++ b/docs/src/content/docs/reference/frontmatter-full.md
@@ -1517,6 +1517,12 @@ tools:
     # (optional)
     scope: "workflow"
 
+    # List of allowed file extensions (e.g., [".json", ".txt"]). Default: [".json",
+    # ".jsonl", ".txt", ".md", ".csv"]
+    # (optional)
+    allowed-extensions: []
+      # Array of strings
+
   # Option 4: Array of cache-memory configurations for multiple caches
   cache-memory: []
     # Array items: object
@@ -1714,6 +1720,12 @@ tools:
     # (optional)
     create-orphan: true
 
+    # List of allowed file extensions (e.g., [".json", ".txt"]). Default: [".json",
+    # ".jsonl", ".txt", ".md", ".csv"]
+    # (optional)
+    allowed-extensions: []
+      # Array of strings
+
   # Option 4: Array of repo-memory configurations for multiple memory locations
   repo-memory: []
     # Array items: object
diff --git a/pkg/constants/constants.go b/pkg/constants/constants.go
index 47146c8215..4adaafed10 100644
--- a/pkg/constants/constants.go
+++ b/pkg/constants/constants.go
@@ -824,3 +824,7 @@ var SharedWorkflowForbiddenFields = []string{
 func GetWorkflowDir() string {
 	return filepath.Join(".github", "workflows")
 }
+
+// DefaultAllowedMemoryExtensions is the default list of allowed file extensions for cache-memory and repo-memory storage.
+// These file types are considered safe for AI agent memory storage.
+var DefaultAllowedMemoryExtensions = []string{".json", ".jsonl", ".txt", ".md", ".csv"}
diff --git a/pkg/parser/schemas/main_workflow_schema.json b/pkg/parser/schemas/main_workflow_schema.json
index e7529f1e12..bb674fe47f 100644
--- a/pkg/parser/schemas/main_workflow_schema.json
+++ b/pkg/parser/schemas/main_workflow_schema.json
@@ -3127,6 +3127,13 @@
                   "enum": ["workflow", "repo"],
                   "default": "workflow",
                   "description": "Cache restore key scope: 'workflow' (default, only restores from same workflow) or 'repo' (restores from any workflow in the repository). Use 'repo' with caution as it allows cross-workflow cache sharing."
+                },
+                "allowed-extensions": {
+                  "type": "array",
+                  "items": {
+                    "type": "string"
+                  },
+                  "description": "List of allowed file extensions (e.g., [\".json\", \".txt\"]). Default: [\".json\", \".jsonl\", \".txt\", \".md\", \".csv\"]"
                 }
               },
               "additionalProperties": false,
@@ -3173,6 +3180,13 @@
                     "enum": ["workflow", "repo"],
                     "default": "workflow",
                     "description": "Cache restore key scope: 'workflow' (default, only restores from same workflow) or 'repo' (restores from any workflow in the repository). Use 'repo' with caution as it allows cross-workflow cache sharing."
+                  },
+                  "allowed-extensions": {
+                    "type": "array",
+                    "items": {
+                      "type": "string"
+                    },
+                    "description": "List of allowed file extensions (e.g., [\".json\", \".txt\"]). Default: [\".json\", \".jsonl\", \".txt\", \".md\", \".csv\"]"
                   }
                 },
                 "required": ["id", "key"],
@@ -3459,6 +3473,13 @@
                 "create-orphan": {
                   "type": "boolean",
                   "description": "Create orphaned branch if it doesn't exist (default: true)"
+                },
+                "allowed-extensions": {
+                  "type": "array",
+                  "items": {
+                    "type": "string"
+                  },
+                  "description": "List of allowed file extensions (e.g., [\".json\", \".txt\"]). Default: [\".json\", \".jsonl\", \".txt\", \".md\", \".csv\"]"
                 }
               },
               "additionalProperties": false,
@@ -3533,6 +3554,13 @@
                   "create-orphan": {
                     "type": "boolean",
                     "description": "Create orphaned branch if it doesn't exist (default: true)"
+                  },
+                  "allowed-extensions": {
+                    "type": "array",
+                    "items": {
+                      "type": "string"
+                    },
+                    "description": "List of allowed file extensions (e.g., [\".json\", \".txt\"]). Default: [\".json\", \".jsonl\", \".txt\", \".md\", \".csv\"]"
                   }
                 },
                 "additionalProperties": false
diff --git a/pkg/workflow/cache.go b/pkg/workflow/cache.go
index d70803547b..2e02097406 100644
--- a/pkg/workflow/cache.go
+++ b/pkg/workflow/cache.go
@@ -1,10 +1,13 @@
 package workflow
 
 import (
+	"encoding/json"
 	"fmt"
 	"os"
+	"sort"
 	"strings"
 
+	"github.com/github/gh-aw/pkg/constants"
 	"github.com/github/gh-aw/pkg/logger"
 	"github.com/goccy/go-yaml"
 )
@@ -18,12 +21,13 @@ type CacheMemoryConfig struct {
 
 // CacheMemoryEntry represents a single cache-memory configuration
 type CacheMemoryEntry struct {
-	ID            string `yaml:"id"`                       // cache identifier (required for array notation)
-	Key           string `yaml:"key,omitempty"`            // custom cache key
-	Description   string `yaml:"description,omitempty"`    // optional description for this cache
-	RetentionDays *int   `yaml:"retention-days,omitempty"` // retention days for upload-artifact action
-	RestoreOnly   bool   `yaml:"restore-only,omitempty"`   // if true, only restore cache without saving
-	Scope         string `yaml:"scope,omitempty"`          // scope for restore keys: "workflow" (default) or "repo"
+	ID                string   `yaml:"id"`                           // cache identifier (required for array notation)
+	Key               string   `yaml:"key,omitempty"`                // custom cache key
+	Description       string   `yaml:"description,omitempty"`        // optional description for this cache
+	RetentionDays     *int     `yaml:"retention-days,omitempty"`     // retention days for upload-artifact action
+	RestoreOnly       bool     `yaml:"restore-only,omitempty"`       // if true, only restore cache without saving
+	Scope             string   `yaml:"scope,omitempty"`              // scope for restore keys: "workflow" (default) or "repo"
+	AllowedExtensions []string `yaml:"allowed-extensions,omitempty"` // allowed file extensions (default: [".json", ".jsonl", ".txt", ".md", ".csv"])
 }
 
 // generateDefaultCacheKey generates a default cache key for a given cache ID
@@ -34,6 +38,99 @@ func generateDefaultCacheKey(cacheID string) string {
 	return fmt.Sprintf("memory-%s-${{ github.workflow }}-${{ github.run_id }}", cacheID)
 }
 
+// parseCacheMemoryEntry parses a single cache-memory entry from a map
+func parseCacheMemoryEntry(cacheMap map[string]any, defaultID string) (CacheMemoryEntry, error) {
+	entry := CacheMemoryEntry{
+		ID:  defaultID,
+		Key: generateDefaultCacheKey(defaultID),
+	}
+
+	// Parse ID (for array notation)
+	if id, exists := cacheMap["id"]; exists {
+		if idStr, ok := id.(string); ok {
+			entry.ID = idStr
+		}
+	}
+	// Update key if ID changed
+	if entry.ID != defaultID {
+		entry.Key = generateDefaultCacheKey(entry.ID)
+	}
+
+	// Parse custom key
+	if key, exists := cacheMap["key"]; exists {
+		if keyStr, ok := key.(string); ok {
+			entry.Key = keyStr
+			// Automatically append -${{ github.run_id }} if the key doesn't already end with it
+			runIdSuffix := "-${{ github.run_id }}"
+			if !strings.HasSuffix(entry.Key, runIdSuffix) {
+				entry.Key = entry.Key + runIdSuffix
+			}
+		}
+	}
+
+	// Parse description
+	if description, exists := cacheMap["description"]; exists {
+		if descStr, ok := description.(string); ok {
+			entry.Description = descStr
+		}
+	}
+
+	// Parse retention days
+	if retentionDays, exists := cacheMap["retention-days"]; exists {
+		if retentionDaysInt, ok := retentionDays.(int); ok {
+			entry.RetentionDays = &retentionDaysInt
+		} else if retentionDaysFloat, ok := retentionDays.(float64); ok {
+			retentionDaysIntValue := int(retentionDaysFloat)
+			entry.RetentionDays = &retentionDaysIntValue
+		} else if retentionDaysUint64, ok := retentionDays.(uint64); ok {
+			retentionDaysIntValue := int(retentionDaysUint64)
+			entry.RetentionDays = &retentionDaysIntValue
+		}
+		// Validate retention-days bounds
+		if entry.RetentionDays != nil {
+			if err := validateIntRange(*entry.RetentionDays, 1, 90, "retention-days"); err != nil {
+				return entry, err
+			}
+		}
+	}
+
+	// Parse restore-only flag
+	if restoreOnly, exists := cacheMap["restore-only"]; exists {
+		if restoreOnlyBool, ok := restoreOnly.(bool); ok {
+			entry.RestoreOnly = restoreOnlyBool
+		}
+	}
+
+	// Parse scope field
+	if scope, exists := cacheMap["scope"]; exists {
+		if scopeStr, ok := scope.(string); ok {
+			entry.Scope = scopeStr
+		}
+	}
+	// Default to "workflow" scope if not specified
+	if entry.Scope == "" {
+		entry.Scope = "workflow"
+	}
+
+	// Parse allowed-extensions field
+	if allowedExts, exists := cacheMap["allowed-extensions"]; exists {
+		if extArray, ok := allowedExts.([]any); ok {
+			entry.AllowedExtensions = make([]string, 0, len(extArray))
+			for _, ext := range extArray {
+				if extStr, ok := ext.(string); ok {
+					entry.AllowedExtensions = append(entry.AllowedExtensions, extStr)
+				}
+			}
+		}
+	}
+	// Default to standard allowed extensions if not specified
+	if len(entry.AllowedExtensions) == 0 {
+		entry.AllowedExtensions = constants.DefaultAllowedMemoryExtensions
+	}
+
+	return entry, nil
+}
+
 // extractCacheMemoryConfig extracts cache-memory configuration from tools section
 // Updated to use ToolsConfig instead of map[string]any
 func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMemoryConfig, error) {
@@ -52,8 +149,9 @@ func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMem
 	if cacheMemoryValue == nil {
 		config.Caches = []CacheMemoryEntry{
 			{
-				ID:  "default",
-				Key: generateDefaultCacheKey("default"),
+				ID:                "default",
+				Key:               generateDefaultCacheKey("default"),
+				AllowedExtensions: constants.DefaultAllowedMemoryExtensions,
 			},
 		}
 		return config, nil
@@ -65,8 +163,9 @@ func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMem
 			// Create a single default cache entry
 			config.Caches = []CacheMemoryEntry{
 				{
-					ID:  "default",
-					Key: generateDefaultCacheKey("default"),
+					ID:                "default",
+					Key:               generateDefaultCacheKey("default"),
+					AllowedExtensions: constants.DefaultAllowedMemoryExtensions,
 				},
 			}
 		}
@@ -80,79 +179,10 @@ func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMem
 		config.Caches = make([]CacheMemoryEntry, 0, len(cacheArray))
 		for _, item := range cacheArray {
 			if cacheMap, ok := item.(map[string]any); ok {
-				entry := CacheMemoryEntry{}
-
-				// ID is required for array notation
-				if id, exists := cacheMap["id"]; exists {
-					if idStr, ok := id.(string); ok {
-						entry.ID = idStr
-					}
-				}
-				// Use "default" if no ID specified
-				if entry.ID == "" {
-					entry.ID = "default"
-				}
-
-				// Parse custom key
-				if key, exists := cacheMap["key"]; exists {
-					if keyStr, ok := key.(string); ok {
-						entry.Key = keyStr
-						// Automatically append -${{ github.run_id }} if the key doesn't already end with it
-						runIdSuffix := "-${{ github.run_id }}"
-						if !strings.HasSuffix(entry.Key, runIdSuffix) {
-							entry.Key = entry.Key + runIdSuffix
-						}
-					}
-				}
-				// Set default key if not specified
-				if entry.Key == "" {
-					entry.Key = generateDefaultCacheKey(entry.ID)
-				}
-
-				// Parse description
-				if description, exists := cacheMap["description"]; exists {
-					if descStr, ok := description.(string); ok {
-						entry.Description = descStr
-					}
-				}
-
-				// Parse retention days
-				if retentionDays, exists := cacheMap["retention-days"]; exists {
-					if retentionDaysInt, ok := retentionDays.(int); ok {
-						entry.RetentionDays = &retentionDaysInt
-					} else if retentionDaysFloat, ok := retentionDays.(float64); ok {
-						retentionDaysIntValue := int(retentionDaysFloat)
-						entry.RetentionDays = &retentionDaysIntValue
-					} else if retentionDaysUint64, ok := retentionDays.(uint64); ok {
-						retentionDaysIntValue := int(retentionDaysUint64)
-						entry.RetentionDays = &retentionDaysIntValue
-					}
-					// Validate retention-days bounds
-					if entry.RetentionDays != nil {
-						if err := validateIntRange(*entry.RetentionDays, 1, 90, "retention-days"); err != nil {
-							return nil, err
-						}
-					}
-				}
-
-				// Parse restore-only flag
-				if restoreOnly, exists := cacheMap["restore-only"]; exists {
-					if restoreOnlyBool, ok := restoreOnly.(bool); ok {
-						entry.RestoreOnly = restoreOnlyBool
-					}
-				}
-
-				// Parse scope field
-				if scope, exists := cacheMap["scope"]; exists {
-					if scopeStr, ok := scope.(string); ok {
-						entry.Scope = scopeStr
-					}
-				}
-				// Default to "workflow" scope if not specified
-				if entry.Scope == "" {
-					entry.Scope = "workflow"
+				entry, err := parseCacheMemoryEntry(cacheMap, "default")
+				if err != nil {
+					return nil, err
 				}
-
 				config.Caches = append(config.Caches, entry)
 			}
 		}
@@ -168,67 +198,10 @@ func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMem
 	// Handle object configuration (single cache, backward compatible)
 	// Convert to array with single entry
 	if configMap, ok := cacheMemoryValue.(map[string]any); ok {
-		entry := CacheMemoryEntry{
-			ID:  "default",
-			Key: generateDefaultCacheKey("default"),
-		}
-
-		// Parse custom key
-		if key, exists := configMap["key"]; exists {
-			if keyStr, ok := key.(string); ok {
-				entry.Key = keyStr
-				// Automatically append -${{ github.run_id }} if the key doesn't already end with it
-				runIdSuffix := "-${{ github.run_id }}"
-				if !strings.HasSuffix(entry.Key, runIdSuffix) {
-					entry.Key = entry.Key + runIdSuffix
-				}
-			}
-		}
-
-		// Parse description
-		if description, exists := configMap["description"]; exists {
-			if descStr, ok := description.(string); ok {
-				entry.Description = descStr
-			}
-		}
-
-		// Parse retention days
-		if retentionDays, exists := configMap["retention-days"]; exists {
-			if retentionDaysInt, ok := retentionDays.(int); ok {
-				entry.RetentionDays = &retentionDaysInt
-			} else if retentionDaysFloat, ok := retentionDays.(float64); ok {
-				retentionDaysIntValue := int(retentionDaysFloat)
-				entry.RetentionDays = &retentionDaysIntValue
-			} else if retentionDaysUint64, ok := retentionDays.(uint64); ok {
-				retentionDaysIntValue := int(retentionDaysUint64)
-				entry.RetentionDays = &retentionDaysIntValue
-			}
-			// Validate retention-days bounds
-			if entry.RetentionDays != nil {
-				if err := validateIntRange(*entry.RetentionDays, 1, 90, "retention-days"); err != nil {
-					return nil, err
-				}
-			}
-		}
-
-		// Parse restore-only flag
-		if restoreOnly, exists := configMap["restore-only"]; exists {
-			if restoreOnlyBool, ok := restoreOnly.(bool); ok {
-				entry.RestoreOnly = restoreOnlyBool
-			}
-		}
-
-		// Parse scope field
-		if scope, exists := configMap["scope"]; exists {
-			if scopeStr, ok := scope.(string); ok {
-				entry.Scope = scopeStr
-			}
-		}
-		// Default to "workflow" scope if not specified
-		if entry.Scope == "" {
-			entry.Scope = "workflow"
+		entry, err := parseCacheMemoryEntry(configMap, "default")
+		if err != nil {
+			return nil, err
 		}
-
 		config.Caches = []CacheMemoryEntry{entry}
 		return config, nil
 	}
@@ -236,6 +209,7 @@ func (c *Compiler) extractCacheMemoryConfig(toolsConfig *ToolsConfig) (*CacheMem
 	return nil, nil
 }
 
+// extractCacheMemoryConfigFromMap is a backward compatibility wrapper for extractCacheMemoryConfig
 // extractCacheMemoryConfigFromMap is a backward compatibility wrapper for extractCacheMemoryConfig
 // that accepts map[string]any instead of *ToolsConfig. This allows gradual migration of calling code.
 func (c *Compiler) extractCacheMemoryConfigFromMap(tools map[string]any) (*CacheMemoryConfig, error) {
@@ -473,6 +447,56 @@ func generateCacheMemorySteps(builder *strings.Builder, data *WorkflowData) {
 	}
 }
 
+// generateCacheMemoryValidation generates validation steps for cache-memory file types
+// This should be called after agent execution to validate files before upload/save
+func generateCacheMemoryValidation(builder *strings.Builder, data *WorkflowData) {
+	if data.CacheMemoryConfig == nil || len(data.CacheMemoryConfig.Caches) == 0 {
+		return
+	}
+
+	cacheLog.Printf("Generating cache-memory validation steps for %d caches", len(data.CacheMemoryConfig.Caches))
+
+	// Use backward-compatible paths only when there's a single cache with ID "default"
+	useBackwardCompatiblePaths := len(data.CacheMemoryConfig.Caches) == 1 && data.CacheMemoryConfig.Caches[0].ID == "default"
+
+	for _, cache := range data.CacheMemoryConfig.Caches {
+		// Skip restore-only caches
+		if cache.RestoreOnly {
+			continue
+		}
+
+		// Default cache uses /tmp/gh-aw/cache-memory/ for backward compatibility
+		// Other caches use /tmp/gh-aw/cache-memory-{id}/ to prevent overlaps
+		var cacheDir string
+		if cache.ID == "default" {
+			cacheDir = "/tmp/gh-aw/cache-memory"
+		} else {
+			cacheDir = fmt.Sprintf("/tmp/gh-aw/cache-memory-%s", cache.ID)
+		}
+
+		// Prepare allowed extensions array for JavaScript
+		allowedExtsJSON, _ := json.Marshal(cache.AllowedExtensions)
+
+		// Build validation script
+		var validationScript strings.Builder
+		validationScript.WriteString("            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');\n")
+		validationScript.WriteString("            setupGlobals(core, github, context, exec, io);\n")
+		validationScript.WriteString("            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');\n")
+		fmt.Fprintf(&validationScript, "            const allowedExtensions = %s;\n", allowedExtsJSON)
+		fmt.Fprintf(&validationScript, "            const result = validateMemoryFiles('%s', 'cache', allowedExtensions);\n", cacheDir)
+		validationScript.WriteString("            if (!result.valid) {\n")
+		fmt.Fprintf(&validationScript, "              core.setFailed(`File type validation failed: Found $${result.invalidFiles.length} file(s) with invalid extensions. Only %s are allowed.`);\n", strings.Join(cache.AllowedExtensions, ", "))
+		validationScript.WriteString("            }\n")
+
+		// Generate validation step using helper
+		stepName := "Validate cache-memory file types"
+		if !useBackwardCompatiblePaths {
+			stepName = fmt.Sprintf("Validate cache-memory file types (%s)", cache.ID)
+		}
+		builder.WriteString(generateInlineGitHubScriptStep(stepName, validationScript.String(), "always()"))
+	}
+}
+
 // generateCacheMemoryArtifactUpload generates artifact upload steps for cache-memory
 // This should be called after agent execution steps to ensure cache is uploaded after the agent has finished
 func generateCacheMemoryArtifactUpload(builder *strings.Builder, data *WorkflowData) {
@@ -549,30 +573,28 @@ func buildCacheMemoryPromptSection(config *CacheMemoryConfig) *PromptSection {
 			descriptionText = " " + cache.Description
 		}
 
-		cacheLog.Printf("Building cache memory prompt section with env vars: cache_dir=%s, description=%s", cacheDir, descriptionText)
+		// Build allowed extensions text
+		allowedExtsText := strings.Join(cache.AllowedExtensions, ", ")
+
+		cacheLog.Printf("Building cache memory prompt section with env vars: cache_dir=%s, description=%s, allowed_extensions=%v", cacheDir, descriptionText, cache.AllowedExtensions)
 
 		// Return prompt section with template file and environment variables for substitution
 		return &PromptSection{
 			Content: cacheMemoryPromptFile,
 			IsFile:  true,
 			EnvVars: map[string]string{
-				"GH_AW_CACHE_DIR":         cacheDir,
-				"GH_AW_CACHE_DESCRIPTION": descriptionText,
+				"GH_AW_CACHE_DIR":          cacheDir,
+				"GH_AW_CACHE_DESCRIPTION":  descriptionText,
+				"GH_AW_ALLOWED_EXTENSIONS": allowedExtsText,
 			},
 		}
 	}
 
-	// Multiple caches or non-default single cache - generate content inline
-	var content strings.Builder
-	content.WriteString("\n")
-	content.WriteString("---\n")
-	content.WriteString("\n")
-	content.WriteString("## Cache Folders Available\n")
-	content.WriteString("\n")
-	content.WriteString("You have access to persistent cache folders where you can read and write files to create memories and store information:\n")
-	content.WriteString("\n")
+	// Multiple caches or non-default single cache - use template file with substitutions
+	cacheLog.Print("Building cache memory prompt section for multiple caches using template")
 
-	// List all caches
+	// Build cache list
+	var cacheList strings.Builder
 	for _, cache := range config.Caches {
 		var cacheDir string
 		if cache.ID == "default" {
@@ -581,21 +603,51 @@ func buildCacheMemoryPromptSection(config *CacheMemoryConfig) *PromptSection {
 			cacheDir = fmt.Sprintf("/tmp/gh-aw/cache-memory-%s/", cache.ID)
 		}
 		if cache.Description != "" {
-			fmt.Fprintf(&content, "- **%s**: `%s` - %s\n", cache.ID, cacheDir, cache.Description)
+			fmt.Fprintf(&cacheList, "- **%s**: `%s` - %s\n", cache.ID, cacheDir, cache.Description)
 		} else {
-			fmt.Fprintf(&content, "- **%s**: `%s`\n", cache.ID, cacheDir)
+			fmt.Fprintf(&cacheList, "- **%s**: `%s`\n", cache.ID, cacheDir)
 		}
 	}
 
-	content.WriteString("\n")
-	content.WriteString("- **Read/Write Access**: You can freely read from and write to any files in these folders\n")
-	content.WriteString("- **Persistence**: Files in these folders persist across workflow runs via GitHub Actions cache\n")
-	content.WriteString("- **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved\n")
-	content.WriteString("- **File Share**: Use these as simple file shares - organize files as you see fit\n")
-	content.WriteString("\n")
-	content.WriteString("Examples of what you can store:\n")
+	// Build allowed extensions text
+	// Check if all caches have the same allowed extensions
+	allowedExtsText := strings.Join(config.Caches[0].AllowedExtensions, ", ")
+	allSame := true
+	for i := 1; i < len(config.Caches); i++ {
+		if len(config.Caches[i].AllowedExtensions) != len(config.Caches[0].AllowedExtensions) {
+			allSame = false
+			break
+		}
+		for j, ext := range config.Caches[i].AllowedExtensions {
+			if ext != config.Caches[0].AllowedExtensions[j] {
+				allSame = false
+				break
+			}
+		}
+		if !allSame {
+			break
+		}
+	}
 
-	// Add examples for each cache
+	// If not all the same, build a union of all extensions
+	if !allSame {
+		extensionSet := make(map[string]bool)
+		for _, cache := range config.Caches {
+			for _, ext := range cache.AllowedExtensions {
+				extensionSet[ext] = true
+			}
+		}
+		// Convert set to sorted slice for consistent output
+		var allExtensions []string
+		for ext := range extensionSet {
+			allExtensions = append(allExtensions, ext)
+		}
+		sort.Strings(allExtensions)
+		allowedExtsText = strings.Join(allExtensions, ", ")
+	}
+
+	// Build cache examples
+	var cacheExamples strings.Builder
 	for _, cache := range config.Caches {
 		var cacheDir string
 		if cache.ID == "default" {
@@ -603,17 +655,22 @@ func buildCacheMemoryPromptSection(config *CacheMemoryConfig) *PromptSection {
 		} else {
 			cacheDir = fmt.Sprintf("/tmp/gh-aw/cache-memory-%s", cache.ID)
 		}
-		fmt.Fprintf(&content, "- `%s/notes.txt` - general notes and observations\n", cacheDir)
-		fmt.Fprintf(&content, "- `%s/preferences.json` - user preferences and settings\n", cacheDir)
-		fmt.Fprintf(&content, "- `%s/state/` - organized state files in subdirectories\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/notes.txt` - general notes and observations\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/notes.md` - markdown formatted notes\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/preferences.json` - user preferences and settings\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/history.jsonl` - activity history in JSON Lines format\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/data.csv` - tabular data\n", cacheDir)
+		fmt.Fprintf(&cacheExamples, "- `%s/state/` - organized state files in subdirectories (with allowed file types)\n", cacheDir)
 	}
 
-	content.WriteString("\n")
-	content.WriteString("Feel free to create, read, update, and organize files in these folders as needed for your tasks.\n")
-
 	return &PromptSection{
-		Content: content.String(),
-		IsFile:  false,
+		Content: cacheMemoryPromptMultiFile,
+		IsFile:  true,
+		EnvVars: map[string]string{
+			"GH_AW_CACHE_LIST":         cacheList.String(),
+			"GH_AW_ALLOWED_EXTENSIONS": allowedExtsText,
+			"GH_AW_CACHE_EXAMPLES":     cacheExamples.String(),
+		},
 	}
 }
 
@@ -661,6 +718,24 @@ func (c *Compiler) buildUpdateCacheMemoryJob(data *WorkflowData, threatDetection
 		fmt.Fprintf(&downloadStep, "          path: %s\n", cacheDir)
 		steps = append(steps, downloadStep.String())
 
+		// Prepare allowed extensions array for JavaScript
+		allowedExtsJSON, _ := json.Marshal(cache.AllowedExtensions)
+
+		// Build validation script
+		var validationScript strings.Builder
+		validationScript.WriteString("            const { setupGlobals } = require('/opt/gh-aw/actions/setup_globals.cjs');\n")
+		validationScript.WriteString("            setupGlobals(core, github, context, exec, io);\n")
+		validationScript.WriteString("            const { validateMemoryFiles } = require('/opt/gh-aw/actions/validate_memory_files.cjs');\n")
+		fmt.Fprintf(&validationScript, "            const allowedExtensions = %s;\n", allowedExtsJSON)
+		fmt.Fprintf(&validationScript, "            const result = validateMemoryFiles('%s', 'cache', allowedExtensions);\n", cacheDir)
+		validationScript.WriteString("            if (!result.valid) {\n")
+		fmt.Fprintf(&validationScript, "              core.setFailed(`File type validation failed: Found ${result.invalidFiles.length} file(s) with invalid extensions. Only %s are allowed.`);\n", strings.Join(cache.AllowedExtensions, ", "))
+		validationScript.WriteString("            }\n")
+
+		// Generate validation step using helper
+		stepName := fmt.Sprintf("Validate cache-memory file types (%s)", cache.ID)
+		steps = append(steps, generateInlineGitHubScriptStep(stepName, validationScript.String(), ""))
+
 		// Generate cache key (same logic as in generateCacheMemorySteps)
 		cacheKey := cache.Key
 		if cacheKey == "" {
diff --git a/pkg/workflow/cache_memory_import_test.go b/pkg/workflow/cache_memory_import_test.go
index e30b3792e1..5d7b1b0f0e 100644
--- a/pkg/workflow/cache_memory_import_test.go
+++ b/pkg/workflow/cache_memory_import_test.go
@@ -87,7 +87,7 @@ Test cache-memory import without local definition.
 		"- name: Create cache-memory directory (logs)",
 		"path: /tmp/gh-aw/cache-memory-logs",
 		"key: shared-logs-${{ github.run_id }}",
-		"## Cache Folders Available",
+		"cache_memory_prompt_multi.md", // Template file reference instead of literal content
 		"- **session**: `/tmp/gh-aw/cache-memory-session/`",
 		"- **logs**: `/tmp/gh-aw/cache-memory-logs/`",
 	}
diff --git a/pkg/workflow/cache_memory_integration_test.go b/pkg/workflow/cache_memory_integration_test.go
index 7f56b17529..5d315c83a8 100644
--- a/pkg/workflow/cache_memory_integration_test.go
+++ b/pkg/workflow/cache_memory_integration_test.go
@@ -49,7 +49,7 @@ tools:
 			notExpectedInLock: []string{
 				// Should NOT upload artifact when detection is disabled
 				"- name: Upload cache-memory data as artifact",
-				"## Cache Folders Available",
+				"cache_memory_prompt_multi.md", // Should not use multi template for default-only cache
 				"cache-memory/default/",
 				"cache-memory/session/",
 			},
@@ -85,7 +85,7 @@ tools:
 				"- name: Cache cache-memory file share data (session)",
 				"key: memory-session-${{ github.run_id }}",
 				"path: /tmp/gh-aw/cache-memory-session",
-				"## Cache Folders Available",
+				"cache_memory_prompt_multi.md", // Template file reference for multiple caches
 				"- **default**: `/tmp/gh-aw/cache-memory/`",
 				"- **session**: `/tmp/gh-aw/cache-memory-session/`",
 			},
@@ -124,7 +124,7 @@ tools:
 				"mkdir -p /tmp/gh-aw/cache-memory-logs",
 				"key: memory-logs-${{ github.workflow }}-${{ github.run_id }}",
 				"path: /tmp/gh-aw/cache-memory-logs",
-				"## Cache Folders Available",
+				"cache_memory_prompt_multi.md", // Template file reference for multiple caches
 				"- **data**: `/tmp/gh-aw/cache-memory-data/`",
 				"- **logs**: `/tmp/gh-aw/cache-memory-logs/`",
 			},
diff --git a/pkg/workflow/cache_memory_prompt_test.go b/pkg/workflow/cache_memory_prompt_test.go
index 0f1b92f6b4..c07fee7455 100644
--- a/pkg/workflow/cache_memory_prompt_test.go
+++ b/pkg/workflow/cache_memory_prompt_test.go
@@ -75,15 +75,24 @@ func TestBuildCacheMemoryPromptSection_MultipleCaches(t *testing.T) {
 	section := buildCacheMemoryPromptSection(config)
 
 	require.NotNil(t, section, "Should return a prompt section for multiple caches")
-	assert.False(t, section.IsFile, "Should use inline content for multiple caches")
-	assert.Contains(t, section.Content, "## Cache Folders Available", "Should have plural header")
-	assert.Contains(t, section.Content, "- **default**: `/tmp/gh-aw/cache-memory/`", "Should list default cache")
-	assert.Contains(t, section.Content, "- **session**: `/tmp/gh-aw/cache-memory-session/` - Session-specific cache", "Should list session cache with description")
-	assert.Contains(t, section.Content, "/tmp/gh-aw/cache-memory/notes.txt", "Should have examples for default cache")
-	assert.Contains(t, section.Content, "/tmp/gh-aw/cache-memory-session/notes.txt", "Should have examples for session cache")
-
-	// Verify no environment variables for inline content
-	assert.Empty(t, section.EnvVars, "Inline content should not have environment variables")
+	assert.True(t, section.IsFile, "Should use template file for multiple caches")
+	assert.Equal(t, cacheMemoryPromptMultiFile, section.Content, "Should reference template file")
+
+	// Verify environment variables are set
+	require.NotNil(t, section.EnvVars, "Should have environment variables for template substitution")
+	assert.Contains(t, section.EnvVars, "GH_AW_CACHE_LIST", "Should have cache list env var")
+	assert.Contains(t, section.EnvVars, "GH_AW_CACHE_EXAMPLES", "Should have cache examples env var")
+	assert.Contains(t, section.EnvVars, "GH_AW_ALLOWED_EXTENSIONS", "Should have allowed extensions env var")
+
+	// Verify cache list content
+	cacheList := section.EnvVars["GH_AW_CACHE_LIST"]
+	assert.Contains(t, cacheList, "- **default**: `/tmp/gh-aw/cache-memory/`", "Should list default cache")
+	assert.Contains(t, cacheList, "- **session**: `/tmp/gh-aw/cache-memory-session/` - Session-specific cache", "Should list session cache with description")
+
+	// Verify cache examples content
+	cacheExamples := section.EnvVars["GH_AW_CACHE_EXAMPLES"]
+	assert.Contains(t, cacheExamples, "/tmp/gh-aw/cache-memory/notes.txt", "Should have examples for default cache")
+	assert.Contains(t, cacheExamples, "/tmp/gh-aw/cache-memory-session/notes.txt", "Should have examples for session cache")
 }
 
 func TestBuildCacheMemoryPromptSection_SingleNonDefaultCache(t *testing.T) {
@@ -100,10 +109,16 @@ func TestBuildCacheMemoryPromptSection_SingleNonDefaultCache(t *testing.T) {
 	section := buildCacheMemoryPromptSection(config)
 
 	require.NotNil(t, section, "Should return a prompt section")
-	assert.False(t, section.IsFile, "Should use inline content for non-default single cache")
-	assert.Contains(t, section.Content, "## Cache Folders Available", "Should have plural header even for single non-default cache")
-	assert.Contains(t, section.Content, "- **custom**: `/tmp/gh-aw/cache-memory-custom/` - Custom cache", "Should list custom cache")
-	assert.Empty(t, section.EnvVars, "Inline content should not have environment variables")
+	assert.True(t, section.IsFile, "Should use template file for non-default single cache")
+	assert.Equal(t, "cache_memory_prompt_multi.md", section.Content, "Should reference template file")
+
+	// Verify environment variables
+	require.NotNil(t, section.EnvVars, "Should have environment variables for template substitution")
+	assert.Contains(t, section.EnvVars, "GH_AW_CACHE_LIST", "Should have cache list env var")
+
+	// Verify cache list content
+	cacheList := section.EnvVars["GH_AW_CACHE_LIST"]
+	assert.Contains(t, cacheList, "- **custom**: `/tmp/gh-aw/cache-memory-custom/` - Custom cache", "Should list custom cache")
 }
 
 func TestBuildCacheMemoryPromptSection_NilConfig(t *testing.T) {
@@ -144,15 +159,21 @@ func TestBuildCacheMemoryPromptSection_MultipleCachesWithMixedDescriptions(t *te
 	section := buildCacheMemoryPromptSection(config)
 
 	require.NotNil(t, section, "Should return a prompt section")
-	assert.False(t, section.IsFile, "Should use inline content for multiple caches")
+	assert.True(t, section.IsFile, "Should use template file for multiple caches")
+	assert.Equal(t, "cache_memory_prompt_multi.md", section.Content, "Should reference template file")
 
-	// Verify all caches are listed with correct formatting
-	assert.Contains(t, section.Content, "- **default**: `/tmp/gh-aw/cache-memory/` - Main cache", "Should list default with description")
-	assert.Contains(t, section.Content, "- **temp**: `/tmp/gh-aw/cache-memory-temp/`\n", "Should list temp without description")
-	assert.Contains(t, section.Content, "- **persistent**: `/tmp/gh-aw/cache-memory-persistent/` - Long-term storage", "Should list persistent with description")
+	// Verify environment variables are set
+	require.NotNil(t, section.EnvVars, "Should have environment variables")
 
-	// Verify examples for all caches
-	assert.Contains(t, section.Content, "/tmp/gh-aw/cache-memory/notes.txt", "Should have examples for default")
-	assert.Contains(t, section.Content, "/tmp/gh-aw/cache-memory-temp/notes.txt", "Should have examples for temp")
-	assert.Contains(t, section.Content, "/tmp/gh-aw/cache-memory-persistent/notes.txt", "Should have examples for persistent")
+	// Verify all caches are listed in cache list env var
+	cacheList := section.EnvVars["GH_AW_CACHE_LIST"]
+	assert.Contains(t, cacheList, "- **default**: `/tmp/gh-aw/cache-memory/` - Main cache", "Should list default with description")
+	assert.Contains(t, cacheList, "- **temp**: `/tmp/gh-aw/cache-memory-temp/`\n", "Should list temp without description")
+	assert.Contains(t, cacheList, "- **persistent**: `/tmp/gh-aw/cache-memory-persistent/` - Long-term storage", "Should list persistent with description")
+
+	// Verify examples for all caches in cache examples env var
+	cacheExamples := section.EnvVars["GH_AW_CACHE_EXAMPLES"]
+	assert.Contains(t, cacheExamples, "/tmp/gh-aw/cache-memory/notes.txt", "Should have examples for default")
+	assert.Contains(t, cacheExamples, "/tmp/gh-aw/cache-memory-temp/notes.txt", "Should have examples for temp")
+	assert.Contains(t, cacheExamples, "/tmp/gh-aw/cache-memory-persistent/notes.txt", "Should have examples for persistent")
 }
diff --git a/pkg/workflow/compiler_yaml_helpers.go b/pkg/workflow/compiler_yaml_helpers.go
index 4223bc1d2c..c35f646f5a 100644
--- a/pkg/workflow/compiler_yaml_helpers.go
+++ b/pkg/workflow/compiler_yaml_helpers.go
@@ -233,6 +233,30 @@ func generateGitHubScriptWithRequire(scriptPath string) string {
 	return script.String()
 }
 
+// generateInlineGitHubScriptStep generates a simple inline github-script step
+// for validation or utility operations that don't require artifact downloads.
+//
+// Parameters:
+//   - stepName: The name of the step (e.g., "Validate cache-memory file types")
+//   - script: The JavaScript code to execute (pre-formatted with proper indentation)
+//   - condition: Optional if condition (e.g., "always()"). Empty string means no condition.
+//
+// Returns a string containing the complete YAML for the github-script step.
+func generateInlineGitHubScriptStep(stepName, script, condition string) string {
+	var step strings.Builder
+
+	step.WriteString("      - name: " + stepName + "\n")
+	if condition != "" {
+		step.WriteString("        if: " + condition + "\n")
+	}
+	step.WriteString("        uses: " + GetActionPin("actions/github-script") + "\n")
+	step.WriteString("        with:\n")
+	step.WriteString("          script: |\n")
+	step.WriteString(script)
+
+	return step.String()
+}
+
 // generateSetupStep generates the setup step based on the action mode.
 // In script mode, it runs the setup.sh script directly from the checked-out source.
 // In other modes (dev/release), it uses the setup action.
diff --git a/pkg/workflow/compiler_yaml_main_job.go b/pkg/workflow/compiler_yaml_main_job.go
index 692a1bca7f..5b1b25f73d 100644
--- a/pkg/workflow/compiler_yaml_main_job.go
+++ b/pkg/workflow/compiler_yaml_main_job.go
@@ -387,6 +387,10 @@ func (c *Compiler) generateMainJobSteps(yaml *strings.Builder, data *WorkflowDat
 	// Add repo-memory artifact upload to save state for push job
 	generateRepoMemoryArtifactUpload(yaml, data)
 
+	// Add cache-memory validation (after agent execution)
+	// This validates file types before cache is saved or uploaded
+	generateCacheMemoryValidation(yaml, data)
+
 	// Add cache-memory artifact upload (after agent execution)
 	// This ensures artifacts are uploaded after the agent has finished modifying the cache
 	generateCacheMemoryArtifactUpload(yaml, data)
diff --git a/pkg/workflow/notify_comment.go b/pkg/workflow/notify_comment.go
index 83f75c2c76..99faeb77a6 100644
--- a/pkg/workflow/notify_comment.go
+++ b/pkg/workflow/notify_comment.go
@@ -178,6 +178,16 @@ func (c *Compiler) buildConclusionJob(data *WorkflowData, mainJobName string, sa
 		}
 	}
 
+	// Pass repo-memory validation failure outputs if repo-memory is configured
+	// This allows the agent failure handler to report validation issues
+	if data.RepoMemoryConfig != nil && len(data.RepoMemoryConfig.Memories) > 0 {
+		for _, memory := range data.RepoMemoryConfig.Memories {
+			// Add validation status for each memory
+			agentFailureEnvVars = append(agentFailureEnvVars, fmt.Sprintf("          GH_AW_REPO_MEMORY_VALIDATION_FAILED_%s: ${{ needs.push_repo_memory.outputs.validation_failed_%s }}\n", memory.ID, memory.ID))
+			agentFailureEnvVars = append(agentFailureEnvVars, fmt.Sprintf("          GH_AW_REPO_MEMORY_VALIDATION_ERROR_%s: ${{ needs.push_repo_memory.outputs.validation_error_%s }}\n", memory.ID, memory.ID))
+		}
+	}
+
 	// Build the agent failure handling step
 	agentFailureSteps := c.buildGitHubScriptStepWithoutDownload(data, GitHubScriptStepConfig{
 		StepName:      "Handle Agent Failure",
diff --git a/pkg/workflow/prompts/cache_memory_prompt.md b/pkg/workflow/prompts/cache_memory_prompt.md
index dfaba014dd..a8cb059515 100644
--- a/pkg/workflow/prompts/cache_memory_prompt.md
+++ b/pkg/workflow/prompts/cache_memory_prompt.md
@@ -8,11 +8,14 @@ You have access to a persistent cache folder at `__CACHE_DIR__` where you can re
 - **Persistence**: Files in this folder persist across workflow runs via GitHub Actions cache
 - **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved
 - **File Share**: Use this as a simple file share - organize files as you see fit
+- **Allowed File Types**: Only the following file extensions are allowed: `__ALLOWED_EXTENSIONS__`. Files with other extensions will be rejected during validation.
 
 Examples of what you can store:
 - `__CACHE_DIR__notes.txt` - general notes and observations
+- `__CACHE_DIR__notes.md` - markdown formatted notes
 - `__CACHE_DIR__preferences.json` - user preferences and settings
-- `__CACHE_DIR__history.log` - activity history and logs
-- `__CACHE_DIR__state/` - organized state files in subdirectories
+- `__CACHE_DIR__history.jsonl` - activity history in JSON Lines format
+- `__CACHE_DIR__data.csv` - tabular data
+- `__CACHE_DIR__state/` - organized state files in subdirectories (with allowed file types)
 
-Feel free to create, read, update, and organize files in this folder as needed for your tasks.
+Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.
diff --git a/pkg/workflow/prompts/cache_memory_prompt_multi.md b/pkg/workflow/prompts/cache_memory_prompt_multi.md
new file mode 100644
index 0000000000..13a69935d8
--- /dev/null
+++ b/pkg/workflow/prompts/cache_memory_prompt_multi.md
@@ -0,0 +1,20 @@
+
+---
+
+## Cache Folders Available
+
+You have access to persistent cache folders where you can read and write files to create memories and store information:
+
+__CACHE_LIST__
+
+- **Read/Write Access**: You can freely read from and write to any files in these folders
+- **Persistence**: Files in these folders persist across workflow runs via GitHub Actions cache
+- **Last Write Wins**: If multiple processes write to the same file, the last write will be preserved
+- **File Share**: Use these as simple file shares - organize files as you see fit
+- **Allowed File Types**: Only the following file extensions are allowed: `__ALLOWED_EXTENSIONS__`. Files with other extensions will be rejected during validation.
+
+Examples of what you can store:
+
+__CACHE_EXAMPLES__
+
+Feel free to create, read, update, and organize files in these folders as needed for your tasks, using only the allowed file types.
diff --git a/pkg/workflow/prompts_test.go b/pkg/workflow/prompts_test.go
index 27b4d8086c..9509b949be 100644
--- a/pkg/workflow/prompts_test.go
+++ b/pkg/workflow/prompts_test.go
@@ -305,12 +305,12 @@ This is a test workflow with multiple cache-memory entries.
 		t.Error("Expected 'Create prompt with built-in context' step in generated workflow")
 	}
 
-	// Test 2: Verify plural form is used for multiple caches
-	if !strings.Contains(lockStr, "Cache Folders Available") {
-		t.Error("Expected 'Cache Folders Available' (plural) header for multiple caches")
+	// Test 2: Verify multi-cache template file is referenced
+	if !strings.Contains(lockStr, "cache_memory_prompt_multi.md") {
+		t.Error("Expected 'cache_memory_prompt_multi.md' template file reference for multiple caches")
 	}
 
-	// Test 3: Verify both cache directories are mentioned
+	// Test 3: Verify both cache directories are mentioned in environment variables
 	if !strings.Contains(lockStr, "/tmp/gh-aw/cache-memory/") {
 		t.Error("Expected '/tmp/gh-aw/cache-memory/' reference for default cache")
 	}
diff --git a/pkg/workflow/repo_memory.go b/pkg/workflow/repo_memory.go
index 77ed9057ca..ccdb446a62 100644
--- a/pkg/workflow/repo_memory.go
+++ b/pkg/workflow/repo_memory.go
@@ -18,10 +18,12 @@
 package workflow
 
 import (
+	"encoding/json"
 	"fmt"
 	"regexp"
 	"strings"
 
+	"github.com/github/gh-aw/pkg/constants"
 	"github.com/github/gh-aw/pkg/logger"
 )
 
@@ -41,14 +43,15 @@ type RepoMemoryConfig struct {
 
 // RepoMemoryEntry represents a single repo-memory configuration
 type RepoMemoryEntry struct {
-	ID           string   `yaml:"id"`                       // memory identifier (required for array notation)
-	TargetRepo   string   `yaml:"target-repo,omitempty"`    // target repository (default: current repo)
-	BranchName   string   `yaml:"branch-name,omitempty"`    // branch name (default: memory/{memory-id})
-	FileGlob     []string `yaml:"file-glob,omitempty"`      // file glob patterns for allowed files
-	MaxFileSize  int      `yaml:"max-file-size,omitempty"`  // maximum size per file in bytes (default: 10KB)
-	MaxFileCount int      `yaml:"max-file-count,omitempty"` // maximum file count per commit (default: 100)
-	Description  string   `yaml:"description,omitempty"`    // optional description for this memory
-	CreateOrphan bool     `yaml:"create-orphan,omitempty"`  // create orphaned branch if missing (default: true)
+	ID                string   `yaml:"id"`                           // memory identifier (required for array notation)
+	TargetRepo        string   `yaml:"target-repo,omitempty"`        // target repository (default: current repo)
+	BranchName        string   `yaml:"branch-name,omitempty"`        // branch name (default: memory/{memory-id})
+	FileGlob          []string `yaml:"file-glob,omitempty"`          // file glob patterns for allowed files
+	MaxFileSize       int      `yaml:"max-file-size,omitempty"`      // maximum size per file in bytes (default: 10KB)
+	MaxFileCount      int      `yaml:"max-file-count,omitempty"`     // maximum file count per commit (default: 100)
+	Description       string   `yaml:"description,omitempty"`        // optional description for this memory
+	CreateOrphan      bool     `yaml:"create-orphan,omitempty"`      // create orphaned branch if missing (default: true)
+	AllowedExtensions []string `yaml:"allowed-extensions,omitempty"` // allowed file extensions (default: [".json", ".jsonl", ".txt", ".md", ".csv"])
 }
 
 // RepoMemoryToolConfig represents the configuration for repo-memory in tools
@@ -112,11 +115,12 @@ func (c *Compiler) extractRepoMemoryConfig(toolsConfig *ToolsConfig) (*RepoMemor
 		repoMemoryLog.Print("Using default repo-memory configuration (nil value)")
 		config.Memories = []RepoMemoryEntry{
 			{
-				ID:           "default",
-				BranchName:   generateDefaultBranchName("default", config.BranchPrefix),
-				MaxFileSize:  10240, // 10KB
-				MaxFileCount: 100,
-				CreateOrphan: true,
+				ID:                "default",
+				BranchName:        generateDefaultBranchName("default", config.BranchPrefix),
+				MaxFileSize:       10240, // 10KB
+				MaxFileCount:      100,
+				CreateOrphan:      true,
+				AllowedExtensions: constants.DefaultAllowedMemoryExtensions,
 			},
 		}
 		return config, nil
@@ -129,11 +133,12 @@ func (c *Compiler) extractRepoMemoryConfig(toolsConfig *ToolsConfig) (*RepoMemor
 			// Create a single default memory entry
 			config.Memories = []RepoMemoryEntry{
 				{
-					ID:           "default",
-					BranchName:   generateDefaultBranchName("default", config.BranchPrefix),
-					MaxFileSize:  10240, // 10KB
-					MaxFileCount: 100,
-					CreateOrphan: true,
+					ID:                "default",
+					BranchName:        generateDefaultBranchName("default", config.BranchPrefix),
+					MaxFileSize:       10240, // 10KB
+					MaxFileCount:      100,
+					CreateOrphan:      true,
+					AllowedExtensions: constants.DefaultAllowedMemoryExtensions,
 				},
 			}
 		} else {
@@ -260,6 +265,22 @@ func (c *Compiler) extractRepoMemoryConfig(toolsConfig *ToolsConfig) (*RepoMemor
 					}
 				}
 
+				// Parse allowed-extensions field
+				if allowedExts, exists := memoryMap["allowed-extensions"]; exists {
+					if extArray, ok := allowedExts.([]any); ok {
+						entry.AllowedExtensions = make([]string, 0, len(extArray))
+						for _, ext := range extArray {
+							if extStr, ok := ext.(string); ok {
+								entry.AllowedExtensions = append(entry.AllowedExtensions, extStr)
+							}
+						}
+					}
+				}
+				// Default to standard allowed extensions if not specified
+				if len(entry.AllowedExtensions) == 0 {
+					entry.AllowedExtensions = constants.DefaultAllowedMemoryExtensions
+				}
+
 				config.Memories = append(config.Memories, entry)
 			}
 		}
@@ -369,6 +390,22 @@ func (c *Compiler) extractRepoMemoryConfig(toolsConfig *ToolsConfig) (*RepoMemor
 			}
 		}
 
+		// Parse allowed-extensions field
+		if allowedExts, exists := configMap["allowed-extensions"]; exists {
+			if extArray, ok := allowedExts.([]any); ok {
+				entry.AllowedExtensions = make([]string, 0, len(extArray))
+				for _, ext := range extArray {
+					if extStr, ok := ext.(string); ok {
+						entry.AllowedExtensions = append(entry.AllowedExtensions, extStr)
+					}
+				}
+			}
+		}
+		// Default to standard allowed extensions if not specified
+		if len(entry.AllowedExtensions) == 0 {
+			entry.AllowedExtensions = constants.DefaultAllowedMemoryExtensions
+		}
+
 		config.Memories = []RepoMemoryEntry{entry}
 		return config, nil
 	}
@@ -601,6 +638,7 @@ func (c *Compiler) buildPushRepoMemoryJob(data *WorkflowData, threatDetectionEna
 		// Build step with github-script action
 		var step strings.Builder
 		fmt.Fprintf(&step, "      - name: Push repo-memory changes (%s)\n", memory.ID)
+		fmt.Fprintf(&step, "        id: push_repo_memory_%s\n", memory.ID)
 		step.WriteString("        if: always()\n")
 		fmt.Fprintf(&step, "        uses: %s\n", GetActionPin("actions/github-script"))
 		step.WriteString("        env:\n")
@@ -612,6 +650,9 @@ func (c *Compiler) buildPushRepoMemoryJob(data *WorkflowData, threatDetectionEna
 		fmt.Fprintf(&step, "          BRANCH_NAME: %s\n", memory.BranchName)
 		fmt.Fprintf(&step, "          MAX_FILE_SIZE: %d\n", memory.MaxFileSize)
 		fmt.Fprintf(&step, "          MAX_FILE_COUNT: %d\n", memory.MaxFileCount)
+		// Pass allowed extensions as JSON array
+		allowedExtsJSON, _ := json.Marshal(memory.AllowedExtensions)
+		fmt.Fprintf(&step, "          ALLOWED_EXTENSIONS: '%s'\n", allowedExtsJSON)
 		if fileGlobFilter != "" {
 			// Quote the value to prevent YAML alias interpretation of patterns like *.md
 			fmt.Fprintf(&step, "          FILE_GLOB_FILTER: \"%s\"\n", fileGlobFilter)
@@ -647,6 +688,15 @@ func (c *Compiler) buildPushRepoMemoryJob(data *WorkflowData, threatDetectionEna
 		jobCondition = "always() && needs.detection.outputs.success == 'true'"
 	}
 
+	// Build outputs map for validation failures from all memory steps
+	outputs := make(map[string]string)
+	for _, memory := range data.RepoMemoryConfig.Memories {
+		stepID := fmt.Sprintf("push_repo_memory_%s", memory.ID)
+		// Add outputs for each memory's validation status
+		outputs[fmt.Sprintf("validation_failed_%s", memory.ID)] = fmt.Sprintf("${{ steps.%s.outputs.validation_failed }}", stepID)
+		outputs[fmt.Sprintf("validation_error_%s", memory.ID)] = fmt.Sprintf("${{ steps.%s.outputs.validation_error }}", stepID)
+	}
+
 	job := &Job{
 		Name:        "push_repo_memory",
 		DisplayName: "", // No display name - job ID is sufficient
@@ -655,6 +705,7 @@ func (c *Compiler) buildPushRepoMemoryJob(data *WorkflowData, threatDetectionEna
 		Permissions: "permissions:\n      contents: write",
 		Needs:       []string{"agent"}, // Detection dependency added by caller if needed
 		Steps:       steps,
+		Outputs:     outputs,
 	}
 
 	return job, nil
diff --git a/pkg/workflow/repo_memory_prompt.go b/pkg/workflow/repo_memory_prompt.go
index 9d09c679d9..ff4d5385fa 100644
--- a/pkg/workflow/repo_memory_prompt.go
+++ b/pkg/workflow/repo_memory_prompt.go
@@ -2,6 +2,7 @@ package workflow
 
 import (
 	"fmt"
+	"sort"
 	"strings"
 
 	"github.com/github/gh-aw/pkg/logger"
@@ -44,6 +45,7 @@ func generateRepoMemoryPromptSection(yaml *strings.Builder, config *RepoMemoryCo
 		yaml.WriteString("          - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes\n")
 		yaml.WriteString("          - **Merge Strategy**: In case of conflicts, your changes (current version) win\n")
 		yaml.WriteString("          - **Persistence**: Files persist across workflow runs via git branch storage\n")
+		yaml.WriteString("          - **Allowed File Types**: Only the following file extensions are allowed: `.json`, `.jsonl`, `.txt`, `.md`, `.csv`. Files with other extensions will be rejected during validation.\n")
 
 		// Add file constraints if specified
 		if len(memory.FileGlob) > 0 || memory.MaxFileSize > 0 || memory.MaxFileCount > 0 {
@@ -63,10 +65,13 @@ func generateRepoMemoryPromptSection(yaml *strings.Builder, config *RepoMemoryCo
 		yaml.WriteString("          \n")
 		yaml.WriteString("          Examples of what you can store:\n")
 		fmt.Fprintf(yaml, "          - `%snotes.md` - general notes and observations\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%snotes.txt` - plain text notes\n", memoryDir)
 		fmt.Fprintf(yaml, "          - `%sstate.json` - structured state data\n", memoryDir)
-		fmt.Fprintf(yaml, "          - `%shistory/` - organized history files in subdirectories\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%shistory.jsonl` - activity history in JSON Lines format\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%sdata.csv` - tabular data\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%shistory/` - organized history files in subdirectories (with allowed file types)\n", memoryDir)
 		yaml.WriteString("          \n")
-		yaml.WriteString("          Feel free to create, read, update, and organize files in this folder as needed for your tasks.\n")
+		yaml.WriteString("          Feel free to create, read, update, and organize files in this folder as needed for your tasks, using only the allowed file types.\n")
 	} else {
 		// Multiple memories or non-default single memory
 		repoMemoryPromptLog.Printf("Generating multiple repo memory prompts: count=%d", len(config.Memories))
@@ -92,13 +97,52 @@ func generateRepoMemoryPromptSection(yaml *strings.Builder, config *RepoMemoryCo
 		yaml.WriteString("          - **Automatic Push**: Changes are automatically committed and pushed after the workflow completes\n")
 		yaml.WriteString("          - **Merge Strategy**: In case of conflicts, your changes (current version) win\n")
 		yaml.WriteString("          - **Persistence**: Files persist across workflow runs via git branch storage\n")
+		// Build allowed extensions text - check if all memories have the same extensions
+		allowedExtsText := strings.Join(config.Memories[0].AllowedExtensions, "`, `")
+		allSame := true
+		for i := 1; i < len(config.Memories); i++ {
+			if len(config.Memories[i].AllowedExtensions) != len(config.Memories[0].AllowedExtensions) {
+				allSame = false
+				break
+			}
+			for j, ext := range config.Memories[i].AllowedExtensions {
+				if ext != config.Memories[0].AllowedExtensions[j] {
+					allSame = false
+					break
+				}
+			}
+			if !allSame {
+				break
+			}
+		}
+
+		// If not all the same, build a union of all extensions
+		if !allSame {
+			extensionSet := make(map[string]bool)
+			for _, mem := range config.Memories {
+				for _, ext := range mem.AllowedExtensions {
+					extensionSet[ext] = true
+				}
+			}
+			// Convert set to sorted slice for consistent output
+			var allExtensions []string
+			for ext := range extensionSet {
+				allExtensions = append(allExtensions, ext)
+			}
+			sort.Strings(allExtensions)
+			allowedExtsText = strings.Join(allExtensions, "`, `")
+		}
+		fmt.Fprintf(yaml, "          - **Allowed File Types**: Only the following file extensions are allowed: `%s`. Files with other extensions will be rejected during validation.\n", allowedExtsText)
 		yaml.WriteString("          \n")
 		yaml.WriteString("          Examples of what you can store:\n")
 		memoryDir := "/tmp/gh-aw/repo-memory"
 		fmt.Fprintf(yaml, "          - `%s/notes.md` - general notes and observations\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%s/notes.txt` - plain text notes\n", memoryDir)
 		fmt.Fprintf(yaml, "          - `%s/state.json` - structured state data\n", memoryDir)
-		fmt.Fprintf(yaml, "          - `%s/history/` - organized history files\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%s/history.jsonl` - activity history in JSON Lines format\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%s/data.csv` - tabular data\n", memoryDir)
+		fmt.Fprintf(yaml, "          - `%s/history/` - organized history files (with allowed file types)\n", memoryDir)
 		yaml.WriteString("          \n")
-		yaml.WriteString("          Feel free to create, read, update, and organize files in these folders as needed for your tasks.\n")
+		yaml.WriteString("          Feel free to create, read, update, and organize files in these folders as needed for your tasks, using only the allowed file types.\n")
 	}
 }