fix: bug: claude_run_with_watchdog leaks orphan bash children — review-pr.sh lock stuck for 47 min when Claude Bash-tool command hangs (#1055)

Fixes orphan process issue by:

1. lib/agent-sdk.sh: Use setsid to run claude in a new process group
   - All children of claude inherit this process group
   - Changed all kill calls to target the process group with -PID syntax
   - Affected lines: setsid invocation, SIGTERM kill, SIGKILL kill, watchdog cleanup

2. review/review-pr.sh: Add defensive cleanup trap
   - Added cleanup_on_exit() trap that removes lockfile if we own it
   - Kills any residual children (e.g., bash -c from Claude's Bash tool)
   - Added explicit lockfile removal on all early-exit paths
   - Added lockfile removal on successful completion

3. tests/test-watchdog-process-group.sh: New test to verify orphan cleanup
   - Creates fake claude stub that spawns sleep 3600 child
   - Verifies all children are killed when watchdog fires

Acceptance criteria met:
- [x] setsid is used for the Claude invocation
- [x] All three kill call sites target the process group (-PID)
- [x] review/review-pr.sh has EXIT/INT/TERM trap for lockfile removal
- [x] shellcheck clean on all modified files

review/review-pr.sh

@@ -52,8 +52,35 @@ REVIEW_TMPDIR=$(mktemp -d)
 
 log() { printf '[%s] PR#%s %s\n' "$(date -u '+%Y-%m-%d %H:%M:%S UTC')" "$PR_NUMBER" "$*" >> "$LOGFILE"; }
 status() { printf '[%s] PR #%s: %s\n' "$(date -u '+%Y-%m-%d %H:%M:%S UTC')" "$PR_NUMBER" "$*" > "$STATUSFILE"; log "$*"; }
-cleanup() { rm -rf "$REVIEW_TMPDIR" "$LOCKFILE" "$STATUSFILE" "/tmp/${PROJECT_NAME}-review-graph-${PR_NUMBER}.json"; }
-trap cleanup EXIT
+
+# cleanup — remove temp files (NOT lockfile — cleanup_on_exit handles that)
+cleanup() {
+  rm -rf "$REVIEW_TMPDIR" "$STATUSFILE" "/tmp/${PROJECT_NAME}-review-graph-${PR_NUMBER}.json"
+}
+
+# cleanup_on_exit — defensive cleanup: remove lockfile if we own it, kill residual children
+# This handles the case where review-pr.sh is terminated unexpectedly (e.g., watchdog SIGTERM)
+cleanup_on_exit() {
+  local ec=$?
+  # Remove lockfile only if we own it (PID matches $$)
+  if [ -f "$LOCKFILE" ] && [ -n "$(cat "$LOCKFILE" 2>/dev/null)" ]; then
+    if [ "$(cat "$LOCKFILE" 2>/dev/null)" = "$$" ]; then
+      rm -f "$LOCKFILE"
+      log "cleanup_on_exit: removed lockfile (we owned it)"
+    fi
+  fi
+  # Kill any direct children that may have been spawned by this process
+  # (e.g., bash -c commands from Claude's Bash tool that didn't get reaped)
+  pkill -P $$ 2>/dev/null || true
+  # Call the main cleanup function to remove temp files
+  cleanup
+  exit "$ec"
+}
+trap cleanup_on_exit EXIT INT TERM
+
+# Note: EXIT trap is already set above. The cleanup function is still available for
+# non-error exits (e.g., normal completion via exit 0 after verdict posted).
+# When review succeeds, we want to skip lockfile removal since the verdict was posted.
 
 # =============================================================================
 # LOG ROTATION
@@ -104,6 +131,7 @@ if [ "$PR_STATE" != "open" ]; then
   log "SKIP: state=${PR_STATE}"
   worktree_cleanup "$WORKTREE"
   rm -f "$OUTPUT_FILE" "$SID_FILE" 2>/dev/null || true
+  rm -f "$LOCKFILE"
   exit 0
 fi
 
@@ -113,7 +141,7 @@ fi
 CI_STATE=$(ci_commit_status "$PR_SHA")
 CI_NOTE=""
 if ! ci_passed "$CI_STATE"; then
-  ci_required_for_pr "$PR_NUMBER" && { log "SKIP: CI=${CI_STATE}"; exit 0; }
+  ci_required_for_pr "$PR_NUMBER" && { log "SKIP: CI=${CI_STATE}"; rm -f "$LOCKFILE"; exit 0; }
   CI_NOTE=" (not required — non-code PR)"
 fi
 
@@ -123,10 +151,10 @@ fi
 ALL_COMMENTS=$(forge_api_all "/issues/${PR_NUMBER}/comments")
 HAS_CMT=$(printf '%s' "$ALL_COMMENTS" | jq --arg s "$PR_SHA" \
   '[.[]|select(.body|contains("<!-- reviewed: "+$s+" -->"))]|length')
-[ "${HAS_CMT:-0}" -gt 0 ] && [ "$FORCE" != "--force" ] && { log "SKIP: reviewed ${PR_SHA:0:7}"; exit 0; }
+[ "${HAS_CMT:-0}" -gt 0 ] && [ "$FORCE" != "--force" ] && { log "SKIP: reviewed ${PR_SHA:0:7}"; rm -f "$LOCKFILE"; exit 0; }
 HAS_FML=$(forge_api_all "/pulls/${PR_NUMBER}/reviews" | jq --arg s "$PR_SHA" \
   '[.[]|select(.commit_id==$s)|select(.state!="COMMENT")]|length')
-[ "${HAS_FML:-0}" -gt 0 ] && [ "$FORCE" != "--force" ] && { log "SKIP: formal review"; exit 0; }
+[ "${HAS_FML:-0}" -gt 0 ] && [ "$FORCE" != "--force" ] && { log "SKIP: formal review"; rm -f "$LOCKFILE"; exit 0; }
 
 # =============================================================================
 # RE-REVIEW DETECTION
@@ -324,3 +352,7 @@ esac
 profile_write_journal "review-${PR_NUMBER}" "Review PR #${PR_NUMBER} (${VERDICT})" "${VERDICT,,}" "" || true
 
 log "DONE: ${VERDICT} (re-review: ${IS_RE_REVIEW})"
+
+# Remove lockfile on successful completion (cleanup_on_exit will also do this,
+# but we do it here to avoid the trap running twice)
+rm -f "$LOCKFILE"