ci: enforce regression tests for fix commits (#517)

* ci: enforce regression tests for fix commits

Add a commit-msg hook and CI workflow that require test changes
alongside bug fix commits, ensuring every fix includes a regression
test that would have caught the bug.

- scripts/commit-msg-regression.sh: local git hook (blocks fix commits
  without test changes; exempts static/docs-only; bypass via
  [skip-regression-check] marker)
- .github/workflows/regression-test-check.yml: CI mirror on PRs
  (checks title + commit messages; skip via label)
- scripts/dev-setup.sh: install hook in step 6
- .github/scripts/create-labels.sh: add skip-regression-check label
- CLAUDE.md: document regression test policy

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: address PR review feedback on regression test enforcement

- Use here-strings instead of echo|grep to avoid misinterpreting
  special characters in variables
- Use git diff -W (whole-function context) to detect edits inside
  existing test functions, not just new #[test] attributes
- Honor [skip-regression-check] in commit messages in CI (not just
  the PR label)
- Use git rev-parse --git-path hooks for worktree-safe hook install

[skip-regression-check]

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* Update .github/workflows/regression-test-check.yml

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>
Co-authored-by: Copilot <[email protected]>

scripts/commit-msg-regression.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+# commit-msg hook: require regression tests for fix commits.
+#
+# Installed by scripts/dev-setup.sh as .git/hooks/commit-msg.
+# Bypass with [skip-regression-check] in the commit message.
+
+set -euo pipefail
+
+MSG_FILE="$1"
+FIRST_LINE=$(head -1 "$MSG_FILE")
+
+# --- 1. Is this a fix commit? ---
+if ! grep -qiE '^(fix(\(.*\))?|hotfix|bugfix):' <<< "$FIRST_LINE"; then
+  exit 0
+fi
+
+# --- 2. Skip marker ---
+if grep -qF '[skip-regression-check]' "$MSG_FILE"; then
+  exit 0
+fi
+
+# --- 3. Exempt static-only / docs-only changes ---
+# Get staged files (commit-msg runs after staging is finalized).
+STAGED_FILES=$(git diff --cached --name-only --diff-filter=ACMR)
+
+if [ -z "$STAGED_FILES" ]; then
+  exit 0
+fi
+
+ALL_EXEMPT=true
+while IFS= read -r file; do
+  case "$file" in
+    src/channels/web/static/*) ;;
+    *.md) ;;
+    *) ALL_EXEMPT=false; break ;;
+  esac
+done <<< "$STAGED_FILES"
+
+if [ "$ALL_EXEMPT" = true ]; then
+  exit 0
+fi
+
+# --- 4. Look for test changes in staged .rs files ---
+
+# Fast path: new test attributes or test modules in added lines.
+if git diff --cached -U0 -- '*.rs' | grep -qE '^\+.*(#\[test\]|#\[tokio::test\]|#\[cfg\(test\)\]|mod tests)'; then
+  exit 0
+fi
+
+# Whole-function context: detect edits inside existing test functions.
+# -W shows the full enclosing function, so #[test] appears in context
+# lines when changes are inside a test function.
+if git diff --cached -W -- '*.rs' | awk '
+  /^@@/           { if (has_test && has_add) { found=1; exit } has_test=0; has_add=0 }
+  /^ .*#\[test\]/ || /^ .*#\[tokio::test\]/ || /^ .*#\[cfg\(test\)\]/ || /^ .*mod tests/ { has_test=1 }
+  /^\+.*#\[test\]/ || /^\+.*#\[tokio::test\]/ || /^\+.*#\[cfg\(test\)\]/ || /^\+.*mod tests/ { has_test=1 }
+  /^\+[^+]/       { has_add=1 }
+  END             { if (has_test && has_add) found=1; exit !found }
+'; then
+  exit 0
+fi
+
+# Also check for new/modified files under tests/
+if grep -qE '^tests/' <<< "$STAGED_FILES"; then
+  exit 0
+fi
+
+# --- 5. No test found — block the commit ---
+echo ""
+echo "╔══════════════════════════════════════════════════════════════╗"
+echo "║  REGRESSION TEST REQUIRED                                   ║"
+echo "║                                                             ║"
+echo "║  This commit looks like a bug fix but has no test changes.  ║"
+echo "║  Every fix should include a test that reproduces the bug.   ║"
+echo "║                                                             ║"
+echo "║  Options:                                                   ║"
+echo "║    • Add a #[test] or #[tokio::test] that catches the bug  ║"
+echo "║    • Add [skip-regression-check] to your commit message    ║"
+echo "╚══════════════════════════════════════════════════════════════╝"
+echo ""
+exit 1

scripts/dev-setup.sh

@@ -24,14 +24,14 @@ if ! command -v rustup &>/dev/null; then
     echo "ERROR: rustup not found. Install from https://rustup.rs"
     exit 1
 fi
-echo "[1/5] rustup found: $(rustup --version 2>/dev/null | head -1)"
+echo "[1/6] rustup found: $(rustup --version 2>/dev/null | head -1)"
 
 # 2. Add WASM target (required by build.rs for channel compilation)
-echo "[2/5] Adding wasm32-wasip2 target..."
+echo "[2/6] Adding wasm32-wasip2 target..."
 rustup target add wasm32-wasip2
 
 # 3. Install wasm-tools (required by build.rs for WASM component model)
-echo "[3/5] Installing wasm-tools..."
+echo "[3/6] Installing wasm-tools..."
 if command -v wasm-tools &>/dev/null; then
     echo "  wasm-tools already installed: $(wasm-tools --version)"
 else
@@ -39,13 +39,25 @@ else
 fi
 
 # 4. Verify the project compiles
-echo "[4/5] Running cargo check..."
+echo "[4/6] Running cargo check..."
 cargo check
 
 # 5. Run tests using libsql temp DB (no Docker/external DB needed)
-echo "[5/5] Running tests (no external DB required)..."
+echo "[5/6] Running tests (no external DB required)..."
 cargo test
 
+# 6. Install git hooks
+echo "[6/6] Installing git hooks..."
+HOOKS_DIR=$(git rev-parse --git-path hooks 2>/dev/null) || true
+if [ -n "$HOOKS_DIR" ]; then
+    mkdir -p "$HOOKS_DIR"
+    SCRIPT_ABS="$(cd "$(dirname "$0")" && pwd)/commit-msg-regression.sh"
+    ln -sf "$SCRIPT_ABS" "$HOOKS_DIR/commit-msg"
+    echo "  commit-msg hook installed (regression test enforcement)"
+else
+    echo "  Skipped: not a git repository"
+fi
+
 echo ""
 echo "=== Setup complete ==="
 echo ""