fix(hooks): add local commitlint validation hook (#868)

* fix(hooks): add local commitlint validation hook

Validates commit messages before execution, catching violations
that would otherwise only fail in CI. Checks type-enum,
type-case, subject-empty, subject-full-stop, header-max-length,
and body/footer-max-line-length rules from config-conventional.

* fix(hooks): skip heredoc commits and fix file-after-message regex

Add a guard to skip heredoc-style commit messages ($(cat <<'EOF'...))
that cannot be validated pre-execution. Also fix the double-quote
terminator regex to match trailing whitespace or end-of-string,
which correctly handles `git commit -m "msg" src/foo.ts` patterns.

Addresses Greptile P1 and P2 review feedback on #868.

Author: carlos-alm

.claude/hooks/commitlint-check.js

@@ -0,0 +1,72 @@
+#!/usr/bin/env node
+// commitlint-check.js — Local commitlint validation
+// Mirrors @commitlint/config-conventional + project commitlint.config.ts.
+// Called by commitlint-local.sh with the commit message as argv[1].
+
+const MAX = 100;
+const TYPES = [
+  "feat", "fix", "docs", "refactor", "test", "chore",
+  "ci", "perf", "build", "style", "revert", "release", "merge",
+];
+
+const msg = process.argv[2];
+if (!msg) process.exit(0);
+
+// Skip merge commits (matches commitlint ignores config)
+if (/^merge[:\s]/i.test(msg)) process.exit(0);
+
+const lines = msg.split("\n");
+const header = lines[0] || "";
+const errors = [];
+
+// --- Header checks ---
+
+// type-empty + subject-empty: header must match type(scope)?: subject
+const headerMatch = header.match(/^(\w+)(\(.+\))?(!)?:\s*(.*)$/);
+if (!headerMatch) {
+  errors.push("header must match format: type(scope)?: subject");
+} else {
+  const [, type, , , subject] = headerMatch;
+
+  // type-case: must be lowercase
+  if (type !== type.toLowerCase()) {
+    errors.push(`type must be lowercase: "${type}"`);
+  }
+
+  // type-enum: must be in allowed list
+  if (!TYPES.includes(type.toLowerCase())) {
+    errors.push(`type "${type}" not in allowed types: ${TYPES.join(", ")}`);
+  }
+
+  // subject-empty
+  if (!subject || !subject.trim()) {
+    errors.push("subject must not be empty");
+  }
+
+  // subject-full-stop
+  if (subject && subject.trimEnd().endsWith(".")) {
+    errors.push("subject must not end with a period");
+  }
+}
+
+// header-max-length
+if (header.length > MAX) {
+  errors.push(
+    `header is ${header.length} chars (max ${MAX}): ${header.substring(0, 60)}...`
+  );
+}
+
+// --- Body/footer line length checks ---
+for (let i = 2; i < lines.length; i++) {
+  if (lines[i].length > MAX) {
+    errors.push(
+      `line ${i + 1} is ${lines[i].length} chars (max ${MAX}): ${lines[i].substring(0, 60)}...`
+    );
+  }
+}
+
+if (errors.length > 0) {
+  // Output one error per line to stdout
+  process.stdout.write(errors.join("\n"));
+  process.exit(1);
+}

.claude/hooks/commitlint-local.sh

@@ -0,0 +1,81 @@
+#!/usr/bin/env bash
+# commitlint-local.sh — PreToolUse hook for Bash (git commit)
+# Validates commit message format locally before the commit runs,
+# catching violations that would fail CI commitlint.
+# Delegates validation to commitlint-check.js.
+
+set -euo pipefail
+
+INPUT=$(cat)
+
+# Extract the command from tool_input JSON
+COMMAND=$(echo "$INPUT" | node -e "
+  let d='';
+  process.stdin.on('data',c=>d+=c);
+  process.stdin.on('end',()=>{
+    const p=JSON.parse(d).tool_input?.command||'';
+    if(p)process.stdout.write(p);
+  });
+" 2>/dev/null) || true
+
+if [ -z "$COMMAND" ]; then
+  exit 0
+fi
+
+# Only trigger on git commit commands
+if ! echo "$COMMAND" | grep -qE '(^|\s|&&\s*)git\s+commit\b'; then
+  exit 0
+fi
+
+# Skip --amend without -m (reuses existing message)
+if echo "$COMMAND" | grep -qE '\-\-amend' && ! echo "$COMMAND" | grep -qE '\s-m\s'; then
+  exit 0
+fi
+
+# Skip heredoc-style messages (shell code only; can't validate pre-execution)
+if echo "$COMMAND" | grep -qE '\$\(cat <<'; then
+  exit 0
+fi
+
+# Extract the commit message from -m flag using node for robust parsing
+MSG=$(echo "$COMMAND" | node -e "
+  let d='';
+  process.stdin.on('data',c=>d+=c);
+  process.stdin.on('end',()=>{
+    const cmd = d;
+    let msg = '';
+    // Match -m \"...\" or -m '...'
+    const dq = cmd.match(/-m\s+\"([\\s\\S]*?)\"(?:\s|$)/);
+    if (dq) { msg = dq[1]; }
+    else {
+      const sq = cmd.match(/-m\s+'([^']*)'/);
+      if (sq) { msg = sq[1]; }
+    }
+    // Unescape \\n to real newlines
+    msg = msg.replace(/\\\\n/g, '\\n');
+    process.stdout.write(msg);
+  });
+" 2>/dev/null) || true
+
+if [ -z "$MSG" ]; then
+  exit 0
+fi
+
+# Run commitlint checks
+HOOK_DIR="$(cd "$(dirname "$0")" && pwd)"
+VIOLATIONS=$(node "$HOOK_DIR/commitlint-check.js" "$MSG" 2>/dev/null) || true
+
+if [ -n "$VIOLATIONS" ]; then
+  REASON="Commit message fails commitlint rules:"$'\n'"${VIOLATIONS}"$'\n'"Fix the message to match conventional commit format."
+  node -e "
+    console.log(JSON.stringify({
+      hookSpecificOutput: {
+        hookEventName: 'PreToolUse',
+        permissionDecision: 'deny',
+        permissionDecisionReason: process.argv[1]
+      }
+    }));
+  " "$REASON"
+fi
+
+exit 0

.claude/settings.json

@@ -19,6 +19,11 @@
             "command": "bash \"$CLAUDE_PROJECT_DIR/.claude/hooks/guard-pr-body.sh\"",
             "timeout": 10
           },
+          {
+            "type": "command",
+            "command": "bash \"$CLAUDE_PROJECT_DIR/.claude/hooks/commitlint-local.sh\"",
+            "timeout": 10
+          },
           {
             "type": "command",
             "command": "bash \"$CLAUDE_PROJECT_DIR/.claude/hooks/pre-commit.sh\"",