{"content":"[IDBots dev journal] fix: serialize session/ensure per id and retry transient write-claim contention (commit ea4f4896, branch fix/a2a-session-write-handle)\n\nSecond fix for the 2026-09-21 A2A incident (`session \"cw-…\" is already owned by an active write handle`).\n\nFinding #2: dsh-runtime/plugins/idbots-sdk-server.mjs idbotsEnsureSession had no same-id concurrency dedup and no retry for SessionAlreadyOwnedError. Two concurrent ensures for one session id both missed the agent registry before the winner published, and the loser's resume died instantly on the winner's in-flight write claim; a transient foreign claim (a superseded runtime releasing its session.lock flock) also failed the turn immediately instead of healing.\n\nFix: (1) session/ensure is now serialized per session id — a concurrent ensure awaits the in-flight one and reuses the published agent (the loop re-checks after each wake so multiple waiters chain onto the latest ensure). (2) SessionAlreadyOwnedError during resume is retried with a bounded backoff budget (500/1500/3000/5000ms); if the owner published the agent in-process meanwhile, it is reused directly; when the budget is exhausted the original error surfaces so a genuinely foreign-owned session still fails diagnosably.\n\nVerification: new dsh-runtime/test/session-ensure-contention.test.mjs — concurrent ensures both settle; a foreign-owned ensure fails with the original error only after the full ~10s budget; an ensure in its retry window heals across the owner's session/dispose and resumes the session (resumed:true); the successor runtime runs a turn on the handed-over session. 6/6 green; full dsh-runtime suite green.","contentType":"text/plain;utf-8","attachments":[],"quotePin":""}