repro/evidence-2026-07-01.md

1# Off-device repro evidence — courier second spam cause (2026-07-01)

3All runs used a LOCAL mock (`mock_telegram.py`) via COURIER_TELEGRAM_API_URL.

4NOTHING reached real Telegram. Mock models Telegram's getUpdates offset

5semantics (offset N confirms/drops updates < N) and records every request.

7Binaries:

8- FIXED: build/dev/bin/courier (branch fix/courier-log-persist-repro)

9- CONTROL: master + api-url-only change (isolates the offset-persistence fix)

11## Deliverable 1 — --log now APPENDS across restarts (was: truncate)

12```

132026-07-01T13:50:34Z [INFO] Courier starting mode=leader relay=none telegram=not configured

142026-07-01T13:50:34Z [INFO] MCP server ready name=courier

16--- courier restart ---

172026-07-01T13:50:36Z [INFO] Courier starting mode=leader relay=none telegram=not configured

182026-07-01T13:50:36Z [INFO] MCP server ready name=courier

20--- courier restart ---

212026-07-01T13:50:38Z [INFO] Courier starting mode=leader relay=none telegram=not configured

222026-07-01T13:50:38Z [INFO] MCP server ready name=courier

23```

243x 'Courier starting' + 2x restart markers => full history preserved.

26## SECOND CAUSE — BEFORE (pre-fix control): backlog delivered + re-delivered

27Cold start with a 2-update backlog. Each delivered message = one inbound the

28leader would ACK = one outbound Telegram send => storm.

29```

30control RUN 1 (cold start) stdout events:

31{"type":"hello","pid":3748}

32{"type":"heartbeat"}

33{"type":"message","text":"BACKLOG-1","sender":"daviwil","sender_id":"42","chat_id":"1001"}

34{"type":"message","text":"BACKLOG-2","sender":"daviwil","sender_id":"42","chat_id":"1001"}

35{"type":"heartbeat"}

36{"type":"heartbeat"}

37{"type":"heartbeat"}

38{"type":"heartbeat"}

40control RUN 1 stderr (no offset persistence, no drain):

412026-07-01T13:49:48Z [INFO] Telegram poller child started pid=3748

43control RUN 2 (restart, backlog still pending) -> RE-DELIVERS:

44{"type":"message","text":"BACKLOG-1","sender":"daviwil","sender_id":"42","chat_id":"1001"}

45{"type":"message","text":"BACKLOG-2","sender":"daviwil","sender_id":"42","chat_id":"1001"}

46```

48## SECOND CAUSE — AFTER (fixed): drain on cold start, deliver-once, no re-delivery

49```

50RUN 1 (cold start, 2-update backlog) stdout events:

51{"type":"hello","pid":30027}

52{"type":"heartbeat"}

53{"type":"heartbeat"}

54{"type":"heartbeat"}

55{"type":"heartbeat"}

56{"type":"heartbeat"}

57{"type":"heartbeat"}

58{"type":"heartbeat"}

59RUN 1 stderr:

602026-07-01T13:44:45Z [INFO] Cold start: drained Telegram backlog (not delivered) count=2 offset=3

62RUN 2 (restart; 1 NEW update injected) -> delivers NEW once:

63{"type":"message","text":"NEW-live-msg","sender":"daviwil","sender_id":"42","chat_id":"1001"}

642026-07-01T13:44:51Z [INFO] Restored Telegram getUpdates offset offset=3

66RUN 3 (restart, no new updates) -> NO re-delivery:

67message events: 0

682026-07-01T13:44:57Z [INFO] Restored Telegram getUpdates offset offset=4

69```