feat: add skill-guards plugin to enforce fresh execution on every skill invocation

.claude-plugin/marketplace.json

@@ -161,6 +161,15 @@
       "author": {
         "name": "JacobPEvans"
       }
+    },
+    {
+      "name": "skill-guards",
+      "source": "./skill-guards",
+      "description": "Ensures fresh execution of skills on every invocation via UserPromptSubmit hook",
+      "version": "2.3.2",
+      "author": {
+        "name": "JacobPEvans"
+      }
     }
   ]
 }

AGENTS.md

@@ -26,6 +26,7 @@ This is a **Claude Code plugins repository** containing production-ready hooks f
 | **process-cleanup** | PostToolUse | — | Cleanup orphaned MCP server processes on session exit |
 | **project-standards** | Skill | `/agentsmd-authoring`, `/workspace-standards`, `/skills-registry` | AgentsMD authoring standards, workspace management, and skills/tools registry lookup |
 | **session-analytics** | Skill | `/token-breakdown` | Session token analytics via Splunk OTEL telemetry |
+| **skill-guards** | UserPromptSubmit | — | Ensures fresh execution of skills on every invocation |
 
 ## Multi-Model Delegation
 

cspell.json

@@ -37,6 +37,7 @@
     "ENDJSON",
     "RLENGTH",
     "unrecognised",
-    "tokenisation"
+    "tokenisation",
+    "reinvocation"
   ]
 }

git-workflows/skills/refresh-repo/SKILL.md

@@ -8,6 +8,9 @@ description: Check PR merge readiness, sync local repo, and cleanup stale worktr
 Check open PR merge-readiness status, sync the local repository, and cleanup stale worktrees.
 **Note**: Does not automatically merge PRs - only reports readiness status for each PR.
 
+> **State warning**: Branch state, remote tracking, and PR status change between
+> invocations. Re-run all git/gh commands from Step 1.
+
 ## Steps
 
 ### 1. Identify Open PRs

git-workflows/skills/wrap-up/SKILL.md

@@ -5,6 +5,9 @@ description: "End-of-session cleanup after PR merge: refresh repo, run quick ret
 
 # Post-Merge Wrap-Up
 
+> **State warning**: Branch state, remote tracking, and PR status change between
+> invocations. Re-run all git/gh commands from Step 1.
+
 Run Steps 1 and 2 **in parallel** (they are independent). Step 3 starts as soon as
 Step 1 completes (depends on its remote prune). Step 4 runs after all prior steps finish.
 Provide a summary of actions taken.

github-workflows/skills/finalize-pr/SKILL.md

@@ -16,6 +16,10 @@ metadata:
 **FULLY AUTOMATIC** - Fully automates PR finalization: monitor, fix, prepare for merge. Assumes PR already exists.
 No manual intervention required. For manual review-focused workflows, use `/review-pr`.
 
+> **State warning**: Automated reviewers (CodeQL, Copilot, AI reviews) post
+> asynchronously. CI may have re-run. Merge conflicts may have appeared.
+> Re-fetch live PR state from Step 1.
+
 ## Critical Rules
 
 1. **Wait for user approval to merge** - Report ready status, then pause for user merge command

github-workflows/skills/resolve-pr-threads/SKILL.md

@@ -20,6 +20,9 @@ Orchestrates resolution of all unresolved PR review comments by grouping
 related threads, processing each group sequentially inline to implement
 fixes or provide explanations, then resolving threads via GitHub's GraphQL API.
 
+> **State warning**: Thread IDs and resolution status change as reviews arrive.
+> Re-fetch all open threads — cached thread lists from earlier are unreliable.
+
 ## Usage
 
 ```text

github-workflows/skills/ship/SKILL.md

@@ -11,6 +11,10 @@ allowed-tools: Bash(git *), Bash(gh *), Bash(pre-commit *), Bash(npm run lint*),
 **Single command to commit, push, create PR(s), and auto-finalize everything.**
 Handles commit, push, PR creation, and `/finalize-pr` in one pipeline. Never merges.
 
+> **State warning**: Automated reviewers (CodeQL, Copilot, AI reviews) post
+> asynchronously. CI may have re-run. Merge conflicts may have appeared.
+> Re-fetch live PR state from Step 1.
+
 ## Rate Limit Awareness
 
 This skill orchestrates many downstream API calls via `/finalize-pr`,

github-workflows/skills/squash-merge-pr/SKILL.md

@@ -14,6 +14,9 @@ Validates PR readiness and executes squash merge. If the PR is not ready,
 errors immediately and suggests `/finalize-pr` to fix issues. Never fixes
 issues — only merges.
 
+> **State warning**: Branch state, remote tracking, and PR status change between
+> invocations. Re-run all git/gh commands from Step 1.
+
 ## Critical Rules
 
 - **Never fix issues** — only merge. If PR isn't ready, error and suggest `/finalize-pr`

skill-guards/.claude-plugin/plugin.json

@@ -0,0 +1,9 @@
+{
+  "name": "skill-guards",
+  "version": "2.3.2",
+  "description": "Ensures fresh execution of skills on every invocation via UserPromptSubmit hook",
+  "author": {"name": "JacobPEvans"},
+  "homepage": "https://github.com/JacobPEvans/claude-code-plugins",
+  "keywords": ["skills", "execution", "guards", "hooks"],
+  "license": "Apache-2.0"
+}

skill-guards/README.md

@@ -0,0 +1,38 @@
+# skill-guards
+
+Ensures fresh execution of skills on every invocation via a UserPromptSubmit hook.
+
+## Problem
+
+When a skill like `/ship` is called a second time in a session, Claude may shortcut
+by assuming previous results are still valid instead of re-running all commands against
+live state.
+
+## Solution
+
+A UserPromptSubmit hook detects `/skill-name` patterns in user prompts and injects a
+systemMessage reminding Claude to execute every step from scratch using current live state.
+
+## Installation
+
+```bash
+claude plugins add jacobpevans-cc-plugins/skill-guards
+```
+
+## Usage
+
+No manual invocation required. The hook activates automatically on every user prompt.
+
+## Hook Behavior
+
+- **Fires on**: Every user prompt submission
+- **Detects**: `/lowercase-with-hyphens` skill invocation patterns
+- **Excludes**: Common filesystem paths (`/usr`, `/tmp`, `/etc`, `/nix`, etc.)
+- **Output**: `{"systemMessage": "FRESH EXECUTION: /skill — ..."}` or `{}`
+- **Exit code**: Always 0 (never blocks prompts)
+
+## Part of a Three-Layer System
+
+1. **Global rule** (`skill-execution-integrity`) — establishes the mental model
+2. **This hook** — tactical trigger at moment of invocation
+3. **Skill preambles** — skill-specific state warnings in SKILL.md files

skill-guards/hooks/hooks.json

@@ -0,0 +1,16 @@
+{
+  "hooks": {
+    "UserPromptSubmit": [
+      {
+        "matcher": "*",
+        "hooks": [
+          {
+            "type": "command",
+            "command": "${CLAUDE_PLUGIN_ROOT}/scripts/skill-reinvocation-guard.sh",
+            "timeout": 3
+          }
+        ]
+      }
+    ]
+  }
+}

skill-guards/scripts/skill-reinvocation-guard.sh

@@ -0,0 +1,21 @@
+#!/bin/bash
+# UserPromptSubmit hook — inject fresh-execution reminder on skill invocation.
+
+input=$(cat)
+prompt=$(echo "$input" | jq -r '.tool_input.prompt // .tool_input.content // .prompt // .content // empty' 2>/dev/null) || { echo '{}'; exit 0; }
+
+[[ -z "$prompt" ]] && { echo '{}'; exit 0; }
+
+if [[ "$prompt" =~ (^|[[:space:]])/([a-z][a-z0-9-]+) ]]; then
+    skill_name="${BASH_REMATCH[2]}"
+    case "$skill_name" in
+        usr|tmp|etc|var|bin|dev|opt|home|nix|proc|sys|run|lib|mnt|srv|boot) echo '{}'; exit 0 ;;
+    esac
+    jq -n --arg skill "$skill_name" '{
+        systemMessage: ("FRESH EXECUTION: /" + $skill + " — Step 1 now. New invocation, new live state. All prior outputs in this session are stale. Re-run every git, gh, and API command.")
+    }'
+else
+    echo '{}'
+fi
+
+exit 0

tests/skill-guards/skill-reinvocation-guard/skill-reinvocation-guard.bats

@@ -0,0 +1,133 @@
+#!/usr/bin/env bats
+# Test suite for skill-guards/scripts/skill-reinvocation-guard.sh
+#
+# Tests the UserPromptSubmit hook's skill detection and systemMessage injection:
+#   - No skill in prompt → empty JSON, exit 0
+#   - /ship → systemMessage with "FRESH EXECUTION" and skill name
+#   - /finalize-pr 42 → systemMessage with skill name
+#   - Regular text → empty JSON, exit 0
+#   - Filesystem path /usr/bin → empty JSON (false positive exclusion)
+#   - Empty prompt → empty JSON, exit 0
+#
+# Run with: bats tests/skill-guards/skill-reinvocation-guard/skill-reinvocation-guard.bats
+
+setup() {
+  REPO_ROOT="$(cd "$(dirname "$BATS_TEST_FILENAME")/../../.." && pwd)"
+  SCRIPT="$REPO_ROOT/skill-guards/scripts/skill-reinvocation-guard.sh"
+
+  if [[ ! -f "$SCRIPT" ]]; then
+    echo "ERROR: Script not found at $SCRIPT" >&2
+    return 1
+  fi
+}
+
+# Run the hook with a given prompt string
+run_hook_with_prompt() {
+  local prompt="$1"
+  run bash -c "echo '{\"tool_input\":{\"prompt\":\"$prompt\"}}' | /bin/bash '$SCRIPT'"
+}
+
+# ---------------------------------------------------------------------------
+# TC1: No skill invocation → empty JSON, exit 0
+# ---------------------------------------------------------------------------
+
+@test "TC1: prompt without skill outputs empty JSON" {
+  run_hook_with_prompt "help me fix this bug"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC2: /ship → systemMessage with FRESH EXECUTION and skill name
+# ---------------------------------------------------------------------------
+
+@test "TC2: /ship triggers fresh execution message" {
+  run_hook_with_prompt "/ship"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "systemMessage" ]]
+  [[ "$output" =~ "FRESH EXECUTION" ]]
+  [[ "$output" =~ "ship" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC3: /finalize-pr 42 → systemMessage with skill name
+# ---------------------------------------------------------------------------
+
+@test "TC3: /finalize-pr with argument triggers fresh execution message" {
+  run_hook_with_prompt "/finalize-pr 42"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "systemMessage" ]]
+  [[ "$output" =~ "FRESH EXECUTION" ]]
+  [[ "$output" =~ "finalize-pr" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC4: /resolve-pr-threads all → systemMessage with skill name
+# ---------------------------------------------------------------------------
+
+@test "TC4: /resolve-pr-threads triggers fresh execution message" {
+  run_hook_with_prompt "/resolve-pr-threads all"
+  [ "$status" -eq 0 ]
+  [[ "$output" =~ "systemMessage" ]]
+  [[ "$output" =~ "resolve-pr-threads" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC5: Regular text without slash → empty JSON
+# ---------------------------------------------------------------------------
+
+@test "TC5: text mentioning 'ship' without slash outputs empty JSON" {
+  run_hook_with_prompt "help me ship this feature"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC6: Filesystem path /usr/bin → empty JSON (false positive exclusion)
+# ---------------------------------------------------------------------------
+
+@test "TC6: filesystem path /usr excluded as false positive" {
+  run_hook_with_prompt "check /usr/bin/python"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC7: Filesystem path /tmp → empty JSON (false positive exclusion)
+# ---------------------------------------------------------------------------
+
+@test "TC7: filesystem path /tmp excluded as false positive" {
+  run_hook_with_prompt "read /tmp/output.log"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC8: Empty/missing prompt → empty JSON, exit 0
+# ---------------------------------------------------------------------------
+
+@test "TC8: empty input outputs empty JSON" {
+  run bash -c "echo '{}' | /bin/bash '$SCRIPT'"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC9: Malformed JSON input → empty JSON, exit 0 (fail-open)
+# ---------------------------------------------------------------------------
+
+@test "TC9: malformed JSON input outputs empty JSON" {
+  run bash -c "echo 'not json at all' | /bin/bash '$SCRIPT'"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}
+
+# ---------------------------------------------------------------------------
+# TC10: /nix path excluded as false positive
+# ---------------------------------------------------------------------------
+
+@test "TC10: filesystem path /nix excluded as false positive" {
+  run_hook_with_prompt "look at /nix/store/abc123"
+  [ "$status" -eq 0 ]
+  [[ "$output" == "{}" ]]
+}