GRM-20: fix: enforce GRM-N: conventional on master commits and PR titles

scripts/validate_commit_msg.py

@@ -2,8 +2,9 @@
 """Validate commit messages for GRM.
 
 Rules:
-- On master branch: allow anything (merge commits already have task ID).
-- On feature branches: must use conventional commit format, must NOT include GRM-N prefix.
+- On feature branches: conventional commits ONLY, must NOT include GRM-N prefix.
+- On master branch: must follow '<task-id>: <conventional commit>' pattern,
+  e.g. 'GRM-24: fix: resolve timeout'.
 """
 import re
 import subprocess
@@ -41,11 +42,23 @@ def main(args=None) -> None:
 
     branch = get_branch()
 
-    if branch == "master":
-        return
-
     subject = first_line(msg)
 
+    if branch == "master":
+        if not TASK_ID_RE.match(subject):
+            print("ERROR: Master branch commits must start with a task ID.")
+            print("  Expected: GRM-N: <conventional commit message>")
+            print(f"  Got:      {subject}")
+            sys.exit(1)
+        # Strip task-id prefix and validate the remainder as conventional
+        remainder = TASK_ID_RE.sub("", subject).strip()
+        if not CONVENTIONAL_RE.match(remainder):
+            print("ERROR: Master branch commit message must follow conventional format after task ID.")
+            print("  Expected: GRM-N: <type>: <description>")
+            print(f"  Got:      {subject}")
+            sys.exit(1)
+        return
+
     if TASK_ID_RE.match(subject):
         print("ERROR: Do not include task ID (GRM-N) in feature branch commits.")
         print("  Task ID will be added automatically on merge via CI.")