diff --git a/.github/workflows/reusable-check-built-files.yml b/.github/workflows/reusable-check-built-files.yml
index 033b2a46ac3e9..5a673bf496ace 100644
--- a/.github/workflows/reusable-check-built-files.yml
+++ b/.github/workflows/reusable-check-built-files.yml
@@ -24,9 +24,10 @@ jobs:
   # - Builds Emoji files.
   # - Builds bundled Root Certificate files.
   # - Builds WordPress.
-  # - Checks for changes to versioned files.
-  # - Displays the result of git diff for debugging purposes.
-  # - Saves the diff to a patch file.
+  # - Checks for uncommitted changes.
+  # - Stages all uncommitted changes and adds any unversioned files.
+  # - Displays a diff of all staged changes.
+  # - Saves staged changes to a .diff file.
   # - Uploads the patch file as an artifact.
   update-built-files:
     name: Check and update built files
@@ -78,22 +79,26 @@ jobs:
       - name: Build WordPress
         run: npm run build:dev
 
-      - name: Check for changes to versioned files
+      - name: Check for uncommitted changes
         id: built-file-check
         run: |
-          if git diff --quiet; then
+          if [ -z "$(git status --porcelain)" ]; then
             echo "uncommitted_changes=false" >> "$GITHUB_OUTPUT"
           else
             echo "uncommitted_changes=true" >> "$GITHUB_OUTPUT"
           fi
 
-      - name: Display changes to versioned files
+      - name: Stage all changes for diff generation
         if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
-        run: git diff
+        run: git add -A
+
+      - name: Display all uncommitted changes
+        if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
+        run: git diff --cached
 
       - name: Save diff to a file
         if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
-        run: git diff > ./changes.diff
+        run: git diff --cached --binary > ./changes.diff
 
       # Uploads the diff file as an artifact.
       - name: Upload diff file as artifact
diff --git a/.github/workflows/reusable-coding-standards-javascript.yml b/.github/workflows/reusable-coding-standards-javascript.yml
index eac5bbdc352f2..b15a5bacf6d46 100644
--- a/.github/workflows/reusable-coding-standards-javascript.yml
+++ b/.github/workflows/reusable-coding-standards-javascript.yml
@@ -24,7 +24,7 @@ jobs:
   # - Logs debug information about the GitHub Action runner.
   # - Installs npm dependencies.
   # - Run the WordPress JSHint checks.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   jshint:
     name: JavaScript checks
     runs-on: ubuntu-24.04
@@ -57,5 +57,10 @@ jobs:
       - name: Run JSHint
         run: npm run grunt jshint
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-coding-standards-php.yml b/.github/workflows/reusable-coding-standards-php.yml
index fab8bffb31e11..980d20b75f4b6 100644
--- a/.github/workflows/reusable-coding-standards-php.yml
+++ b/.github/workflows/reusable-coding-standards-php.yml
@@ -37,7 +37,7 @@ jobs:
   # - Generate a report for displaying issues as pull request annotations.
   # - Runs PHPCS on the `tests` directory without (warnings included).
   # - Generate a report for displaying `test` directory issues as pull request annotations.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   phpcs:
     name: PHP checks
     runs-on: ubuntu-24.04
@@ -105,5 +105,10 @@ jobs:
         if: ${{ inputs.old-branch }}
         run: phpcbf
 
-      - name: Ensure version-controlled files are not modified during the tests
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-end-to-end-tests.yml b/.github/workflows/reusable-end-to-end-tests.yml
index 87f90f1b53039..c39e03a6c0ab0 100644
--- a/.github/workflows/reusable-end-to-end-tests.yml
+++ b/.github/workflows/reusable-end-to-end-tests.yml
@@ -61,7 +61,7 @@ jobs:
   # - Install additional languages.
   # - Run the E2E tests.
   # - Uploads screenshots and HTML snapshots as an artifact.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   e2e-tests:
     name: SCRIPT_DEBUG ${{ inputs.LOCAL_SCRIPT_DEBUG && 'enabled' || 'disabled' }}
     runs-on: ubuntu-24.04
@@ -153,5 +153,10 @@ jobs:
           if-no-files-found: ignore
           include-hidden-files: true
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-javascript-tests.yml b/.github/workflows/reusable-javascript-tests.yml
index 3988ec9d6b055..d260dd71c4c11 100644
--- a/.github/workflows/reusable-javascript-tests.yml
+++ b/.github/workflows/reusable-javascript-tests.yml
@@ -25,7 +25,7 @@ jobs:
   # - Logs debug information about the GitHub Action runner.
   # - Installs npm dependencies.
   # - Run the WordPress QUnit tests.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   test-js:
     name: Run QUnit tests
     runs-on: ubuntu-24.04
@@ -67,5 +67,10 @@ jobs:
       - name: Run QUnit tests
         run: npm run grunt qunit:compiled
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-javascript-type-checking-v1.yml b/.github/workflows/reusable-javascript-type-checking-v1.yml
index 9dabd01e27fa0..d1f484c39c36c 100644
--- a/.github/workflows/reusable-javascript-type-checking-v1.yml
+++ b/.github/workflows/reusable-javascript-type-checking-v1.yml
@@ -23,7 +23,7 @@ jobs:
   # - Configures caching for TypeScript build info.
   # - Runs JavaScript type checking.
   # - Saves the TypeScript build info.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   typecheck:
     name: Run JavaScript type checking
     runs-on: ubuntu-24.04
@@ -72,5 +72,10 @@ jobs:
             *.tsbuildinfo
           key: "ts-build-info-${{ github.run_id }}"
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-performance-test-v2.yml b/.github/workflows/reusable-performance-test-v2.yml
index c0279c37fe64b..7bafb8fff4894 100644
--- a/.github/workflows/reusable-performance-test-v2.yml
+++ b/.github/workflows/reusable-performance-test-v2.yml
@@ -102,7 +102,7 @@ jobs:
   # - Install MU plugin.
   # - Run performance tests.
   # - Archive artifacts.
-  # - Ensure version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   performance:
     name: Test ${{ inputs.subject == 'base' && inputs.BASE_TAG || inputs.subject }}
     runs-on: ubuntu-24.04
@@ -272,5 +272,10 @@ jobs:
           if-no-files-found: error
           include-hidden-files: true
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-php-compatibility.yml b/.github/workflows/reusable-php-compatibility.yml
index 7756330282e6f..ed7cf3abbfae2 100644
--- a/.github/workflows/reusable-php-compatibility.yml
+++ b/.github/workflows/reusable-php-compatibility.yml
@@ -30,7 +30,7 @@ jobs:
   # - Make Composer packages available globally.
   # - Runs the PHP compatibility tests.
   # - Generate a report for displaying issues as pull request annotations.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   php-compatibility:
     name: Run compatibility checks
     runs-on: ubuntu-24.04
@@ -86,5 +86,10 @@ jobs:
         if: ${{ always() && steps.phpcs.outcome == 'failure' }}
         run: cs2pr ./.cache/phpcs-compat-report.xml
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-phpstan-static-analysis-v1.yml b/.github/workflows/reusable-phpstan-static-analysis-v1.yml
index c73c1e5e692fe..e2976df943817 100644
--- a/.github/workflows/reusable-phpstan-static-analysis-v1.yml
+++ b/.github/workflows/reusable-phpstan-static-analysis-v1.yml
@@ -33,7 +33,7 @@ jobs:
   # - Configures caching for PHPStan static analysis scans.
   # - Runs PHPStan static analysis (with Pull Request annotations).
   # - Saves the PHPStan result cache.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   phpstan:
     name: Run PHP static analysis
     runs-on: ubuntu-24.04
@@ -102,5 +102,10 @@ jobs:
           path: .cache
           key: "phpstan-result-cache-${{ github.run_id }}"
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-phpunit-tests-v2.yml b/.github/workflows/reusable-phpunit-tests-v2.yml
index 5e078b6ef0c2e..21f71546bdb2d 100644
--- a/.github/workflows/reusable-phpunit-tests-v2.yml
+++ b/.github/workflows/reusable-phpunit-tests-v2.yml
@@ -84,7 +84,7 @@ jobs:
   # - Logs debug information from inside the WordPress Docker container.
   # - Install WordPress within the Docker container.
   # - Run the PHPUnit tests.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   test-php:
     name: PHP ${{ inputs.php }} / ${{ inputs.multisite && ' Multisite' || 'Single Site' }}${{ inputs.split_slow && ' slow tests' || '' }}${{ inputs.memcached && ' with memcached' || '' }}
     runs-on: ${{ inputs.os }}
@@ -208,5 +208,10 @@ jobs:
         if: ${{ ! inputs.split_slow }}
         run: LOCAL_PHP_XDEBUG=true npm run "test:${PHPUNIT_SCRIPT}" -- -v --group xdebug --exclude-group __fakegroup__
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-phpunit-tests-v3.yml b/.github/workflows/reusable-phpunit-tests-v3.yml
index 64507323a617b..e08ef2d3c6824 100644
--- a/.github/workflows/reusable-phpunit-tests-v3.yml
+++ b/.github/workflows/reusable-phpunit-tests-v3.yml
@@ -113,7 +113,7 @@ jobs:
   # - Install WordPress within the Docker container.
   # - Run the PHPUnit tests.
   # - Upload the code coverage report to Codecov.io.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   # - Checks out the WordPress Test reporter repository.
   # - Submit the test results to the WordPress.org host test results.
   phpunit-tests:
@@ -268,8 +268,13 @@ jobs:
           flags: ${{ inputs.multisite && 'multisite' || 'single' }},php
           fail_ci_if_error: true
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
 
       - name: Checkout the WordPress Test Reporter
         if: ${{ github.ref == 'refs/heads/trunk' && inputs.report }}
diff --git a/.github/workflows/reusable-test-core-build-process.yml b/.github/workflows/reusable-test-core-build-process.yml
index 1566d1583a807..e931f43145050 100644
--- a/.github/workflows/reusable-test-core-build-process.yml
+++ b/.github/workflows/reusable-test-core-build-process.yml
@@ -49,15 +49,16 @@ jobs:
   # Verifies that installing npm dependencies and building WordPress works as expected.
   #
   # Performs the following steps:
+  # - Prevent line ending conversions (Windows only).
   # - Checks out the repository.
   # - Sets up Node.js.
   # - Logs debug information about the GitHub Action runner.
   # - Installs npm dependencies.
   # - Builds WordPress to run from the desired location (src or build).
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes after building.
   # - Creates a ZIP of the built WordPress files (when building to the build directory).
   # - Cleans up after building WordPress.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes after cleaning.
   # - Uploads the ZIP as a GitHub Actions artifact (when building to the build directory).
   # - Saves the pull request number to a text file.
   # - Uploads the pull request number as an artifact.
@@ -69,6 +70,13 @@ jobs:
     timeout-minutes: 20
 
     steps:
+      # Windows can convert LF to CRLF on checkout, which can make built/generated files appear as modified.
+      - name: Prevent line ending conversions on Windows
+        if: ${{ contains( inputs.os, 'windows-' ) }}
+        run: |
+          git config --global core.autocrlf false
+          git config --global core.eol lf
+
       - name: Checkout repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
@@ -119,8 +127,14 @@ jobs:
       - name: Build WordPress to run from ${{ inputs.directory }}
         run: npm run ${{ inputs.directory == 'src' && 'build:dev' || 'build' }}
 
-      - name: Ensure version-controlled files are not modified or deleted during building
-        run: git diff --exit-code
+      - name: Check for uncommitted changes after building
+        shell: bash
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
 
       - name: Create ZIP of built files
         if: ${{ inputs.directory == 'build' && contains( inputs.os, 'ubuntu-' ) }}
@@ -129,8 +143,14 @@ jobs:
       - name: Clean after building to run from ${{ inputs.directory }}
         run: npm run grunt ${{ inputs.directory == 'src' && 'clean -- --dev' || 'clean' }}
 
-      - name: Ensure version-controlled files are not modified or deleted during cleaning
-        run: git diff --exit-code
+      - name: Check for uncommitted changes after cleaning
+        shell: bash
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
 
       - name: Upload ZIP as a GitHub Actions artifact
         uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
diff --git a/.github/workflows/reusable-test-gutenberg-build-process.yml b/.github/workflows/reusable-test-gutenberg-build-process.yml
index 4a780d08ee07f..ae5e4cd74d298 100644
--- a/.github/workflows/reusable-test-gutenberg-build-process.yml
+++ b/.github/workflows/reusable-test-gutenberg-build-process.yml
@@ -39,7 +39,7 @@ jobs:
   # - Installs Core npm dependencies.
   # - Builds WordPress to run from the relevant location (src or build).
   # - Builds Gutenberg.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes after building.
   build-process-tests:
     name: ${{ contains( inputs.os, 'macos-' ) && 'MacOS' || contains( inputs.os, 'windows-' ) && 'Windows' || 'Linux' }}
     permissions:
@@ -96,5 +96,11 @@ jobs:
         run: npm run build
         working-directory: ${{ env.GUTENBERG_DIRECTORY }}
 
-      - name: Ensure version-controlled files are not modified or deleted during building
-        run: git diff --exit-code
+      - name: Check for uncommitted changes after building
+        shell: bash
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/reusable-test-local-docker-environment-v1.yml b/.github/workflows/reusable-test-local-docker-environment-v1.yml
index 8f1a556afa2b4..50118d45045ee 100644
--- a/.github/workflows/reusable-test-local-docker-environment-v1.yml
+++ b/.github/workflows/reusable-test-local-docker-environment-v1.yml
@@ -71,7 +71,7 @@ jobs:
   # - Runs a WP CLI command.
   # - Tests the logs command.
   # - Tests the reset command.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for any uncommitted changes.
   local-docker-environment-tests:
     name: ${{ 'mariadb' == inputs.db-type && 'MariaDB' || 'MySQL' }} ${{ inputs.db-version }}${{ inputs.memcached && ' with memcached' || '' }}${{ 'example.org' != inputs.tests-domain && format( ' {0}', inputs.tests-domain ) || '' }}
     permissions:
@@ -166,5 +166,10 @@ jobs:
       - name: Reset the Docker environment
         run: npm run env:reset
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected:"
+            git status --porcelain
+            exit 1
+          fi
diff --git a/.github/workflows/test-and-zip-default-themes.yml b/.github/workflows/test-and-zip-default-themes.yml
index 1a44a8ff12e3a..604f531462a67 100644
--- a/.github/workflows/test-and-zip-default-themes.yml
+++ b/.github/workflows/test-and-zip-default-themes.yml
@@ -112,7 +112,12 @@ jobs:
   # - Sets up Node.js.
   # - Installs npm dependencies.
   # - Runs the theme build script.
-  # - Ensures version-controlled files are not modified or deleted.
+  # - Checks for uncommitted changes.
+  # - Stages all uncommitted changes and adds any unversioned files.
+  # - Displays a diff of all staged changes.
+  # - Saves staged changes to a .diff file.
+  # - Uploads the diff file as an artifact.
+  # - Fails the job when uncommitted changes are detected.
   test-build-scripts:
     name: Test ${{ matrix.theme }} build script
     runs-on: ubuntu-24.04
@@ -156,23 +161,27 @@ jobs:
       - name: Build theme
         run: npm run build
 
-      - name: Check for changes to versioned files
+      - name: Check for uncommitted changes
         id: built-file-check
         if: ${{ github.event_name == 'pull_request' }}
         run: |
-          if git diff --quiet; then
+          if [ -z "$(git status --porcelain)" ]; then
             echo "uncommitted_changes=false" >> "$GITHUB_OUTPUT"
           else
             echo "uncommitted_changes=true" >> "$GITHUB_OUTPUT"
           fi
 
-      - name: Display changes to versioned files
+      - name: Stage all changes for diff generation
         if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
-        run: git diff
+        run: git add -A
+
+      - name: Display all uncommitted changes
+        if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
+        run: git diff --cached
 
       - name: Save diff to a file
         if: ${{ steps.built-file-check.outputs.uncommitted_changes == 'true' }}
-        run: git diff > ./changes.diff
+        run: git diff --cached --binary > ./changes.diff
 
       # Uploads the diff file as an artifact.
       - name: Upload diff file as artifact
@@ -182,13 +191,21 @@ jobs:
           name: pr-built-file-changes
           path: src/wp-content/themes/${{ matrix.theme }}/changes.diff
 
-      - name: Ensure version-controlled files are not modified or deleted
-        run: git diff --exit-code
+      - name: Check for uncommitted changes after building
+        run: |
+          if [ -n "$(git status --porcelain)" ]; then
+            echo "Uncommitted changes detected after build:"
+            git status --porcelain
+            exit 1
+          fi
 
   # Prepares bundled themes for release.
   #
   # Performs the following steps:
   # - Checks out the repository.
+  # - Sets up Node.js.
+  # - Installs npm dependencies.
+  # - Runs the theme build script.
   # - Uploads the theme files as a workflow artifact (files uploaded as an artifact are automatically zipped).
   bundle-theme:
     name: Create ${{ matrix.theme }} ZIP file
diff --git a/.gitignore b/.gitignore
index 15876fa47fee8..5a7f9b5aef66e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,6 +48,11 @@ wp-tests-config.php
 /artifacts
 /setup.log
 /coverage
+/codecov
+codecov.*
+before.zip
+wordpress.zip
+wp-code-coverage-*.xml
 
 # Files and folders that get created in wp-content
 /src/wp-content/blogs.dir