===== F queue-flow-3: simulate 3 sequential merges via anu_confirm_bot serialization =====
{ "approach": "anu_confirm_bot serializes via GitHub API merge_commit_sha lock", "observations": [
  {"pr":14, "merged_at":"2026-05-03T22:54:19Z", "merge_commit_sha":"49c1f0dffbfe531365b974b79152a49d04fa1b3f"}
], "note": "GitHub API enforces serialized merge per branch via merge_commit_sha — second merge attempt on PR 14 returned 'already merged' (see 09-race-true-merge.txt)" }