Keep agent-branch-finish fully automatic after PR merges (#16)

When GitHub merges a PR but fails only on local branch deletion (active worktree), the finish script previously treated that as a merge failure and skipped cleanup. This patch detects that specific gh error signature, treats merge as successful, and continues local/remote branch cleanup.

Constraint: Preserve existing PR fallback behavior for true policy/check blockers
Rejected: Retrying gh merge without --delete-branch | still leaves local/remote cleanup fragmented across manual steps
Confidence: high
Scope-risk: narrow
Reversibility: clean
Directive: If gh merge output format changes, keep this matcher aligned with real CLI error text before loosening detection
Tested: npm test (44/44), including new regression for local-branch-delete error path in PR mode
Not-tested: Live GitHub PR merge with this exact local-delete failure on every gh version

Co-authored-by: NagyVikt <nagy.viktordp@gmail.com>

Author: NagyVikt

scripts/agent-branch-finish.sh

@@ -196,6 +196,17 @@ merge_status="direct"
 direct_push_error=""
 pr_url=""
 
+is_local_branch_delete_error() {
+  local output="$1"
+  if [[ "$output" != *"failed to delete local branch"* ]]; then
+    return 1
+  fi
+  if [[ "$output" == *"cannot delete branch"* ]] || [[ "$output" == *"used by worktree"* ]]; then
+    return 0
+  fi
+  return 1
+}
+
 run_pr_flow() {
   if ! command -v "$GH_BIN" >/dev/null 2>&1; then
     echo "[agent-branch-finish] PR fallback requested but GitHub CLI not found: ${GH_BIN}" >&2
@@ -222,6 +233,10 @@ run_pr_flow() {
   if merge_output="$("$GH_BIN" pr merge "$SOURCE_BRANCH" --squash --delete-branch 2>&1)"; then
     return 0
   fi
+  if is_local_branch_delete_error "$merge_output"; then
+    echo "[agent-branch-finish] PR merged but gh could not delete the local branch (active worktree); continuing local cleanup." >&2
+    return 0
+  fi
 
   auto_output=""
   if auto_output="$("$GH_BIN" pr merge "$SOURCE_BRANCH" --squash --delete-branch --auto 2>&1)"; then

templates/scripts/agent-branch-finish.sh

@@ -196,6 +196,17 @@ merge_status="direct"
 direct_push_error=""
 pr_url=""
 
+is_local_branch_delete_error() {
+  local output="$1"
+  if [[ "$output" != *"failed to delete local branch"* ]]; then
+    return 1
+  fi
+  if [[ "$output" == *"cannot delete branch"* ]] || [[ "$output" == *"used by worktree"* ]]; then
+    return 0
+  fi
+  return 1
+}
+
 run_pr_flow() {
   if ! command -v "$GH_BIN" >/dev/null 2>&1; then
     echo "[agent-branch-finish] PR fallback requested but GitHub CLI not found: ${GH_BIN}" >&2
@@ -222,6 +233,10 @@ run_pr_flow() {
   if merge_output="$("$GH_BIN" pr merge "$SOURCE_BRANCH" --squash --delete-branch 2>&1)"; then
     return 0
   fi
+  if is_local_branch_delete_error "$merge_output"; then
+    echo "[agent-branch-finish] PR merged but gh could not delete the local branch (active worktree); continuing local cleanup." >&2
+    return 0
+  fi
 
   auto_output=""
   if auto_output="$("$GH_BIN" pr merge "$SOURCE_BRANCH" --squash --delete-branch --auto 2>&1)"; then

test/install.test.js

@@ -63,6 +63,14 @@ function createFakeCodexAuthScript(scriptBody) {
   return { fakeBin, fakePath };
 }
 
+function createFakeGhScript(scriptBody) {
+  const fakeBin = fs.mkdtempSync(path.join(os.tmpdir(), 'musafety-fake-gh-'));
+  const fakePath = path.join(fakeBin, 'gh');
+  fs.writeFileSync(fakePath, `#!/usr/bin/env bash\nset -e\n${scriptBody}\n`, 'utf8');
+  fs.chmodSync(fakePath, 0o755);
+  return { fakeBin, fakePath };
+}
+
 function initRepo() {
   const tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'musafety-'));
   const repoDir = path.join(tempDir, 'repo');
@@ -755,6 +763,70 @@ test('agent-branch-finish blocks when source branch is behind origin/dev', () =>
   assert.match(finish.stderr, /musafety sync --base dev/);
 });
 
+test('agent-branch-finish pr mode continues cleanup when gh merge only fails local branch deletion', () => {
+  const repoDir = initRepo();
+  seedCommit(repoDir);
+  attachOriginRemote(repoDir);
+
+  let result = runNode(['setup', '--target', repoDir, '--no-global-install'], repoDir);
+  assert.equal(result.status, 0, result.stderr || result.stdout);
+  result = runCmd('git', ['add', '.'], repoDir);
+  assert.equal(result.status, 0, result.stderr);
+  result = runCmd('git', ['commit', '-m', 'apply musafety setup'], repoDir, {
+    ALLOW_COMMIT_ON_PROTECTED_BRANCH: '1',
+  });
+  assert.equal(result.status, 0, result.stderr);
+  result = runCmd('git', ['push', 'origin', 'dev'], repoDir);
+  assert.equal(result.status, 0, result.stderr);
+
+  result = runCmd('git', ['checkout', '-b', 'agent/test-pr-delete-error'], repoDir);
+  assert.equal(result.status, 0, result.stderr);
+  commitFile(repoDir, 'agent-pr-delete.txt', 'agent change\n', 'agent change');
+
+  const { fakePath: fakeGhPath } = createFakeGhScript(`
+if [[ "$1" == "pr" && "$2" == "create" ]]; then
+  exit 0
+fi
+if [[ "$1" == "pr" && "$2" == "view" ]]; then
+  if [[ " $* " == *" --json url "* ]]; then
+    echo "https://example.test/pr/1"
+    exit 0
+  fi
+  echo "unexpected gh pr view args: $*" >&2
+  exit 1
+fi
+if [[ "$1" == "pr" && "$2" == "merge" ]]; then
+  echo "failed to delete local branch $3: error: cannot delete branch '$3' used by worktree at '/tmp/demo-worktree'" >&2
+  echo "/usr/bin/git: exit status 1" >&2
+  exit 1
+fi
+echo "unexpected gh args: $*" >&2
+exit 1
+`);
+
+  const finish = runCmd(
+    'bash',
+    ['scripts/agent-branch-finish.sh', '--branch', 'agent/test-pr-delete-error', '--mode', 'pr'],
+    repoDir,
+    { MUSAFETY_GH_BIN: fakeGhPath },
+  );
+  assert.equal(finish.status, 0, finish.stderr || finish.stdout);
+  assert.match(
+    finish.stderr,
+    /PR merged but gh could not delete the local branch \(active worktree\); continuing local cleanup\./,
+  );
+  assert.match(
+    finish.stdout,
+    /Merged 'agent\/test-pr-delete-error' into 'dev' via pr flow and removed branch\./,
+  );
+
+  result = runCmd('git', ['show-ref', '--verify', '--quiet', 'refs/heads/agent/test-pr-delete-error'], repoDir);
+  assert.notEqual(result.status, 0, 'agent branch should be deleted locally');
+
+  result = runCmd('git', ['ls-remote', '--heads', 'origin', 'agent/test-pr-delete-error'], repoDir);
+  assert.equal(result.stdout.trim(), '', 'agent branch should be deleted on origin');
+});
+
 test('OpenSpec plan workspace scaffold creates expected role/task structure', () => {
   const repoDir = initRepo();