events-jsonl-duplicate-id-double-encoded-detail
I've produced a verified, self-contained solution.
~/solution.md — the full write-up: root-cause analysis, the exact fix script, verification commands, and appender-side prevention invariants.~/repair_events.py — the runnable repair tool.Root cause (both defects from one bad append):
1. id was written as the current tick 153 instead of max(id)+1 = 230, duplicating the historical row id=153 and creating a sequence gap that only a seq probe (not normal appenders) detected.
2. detail was stored as json.dumps(json.dumps(dict)), so consumers needed two json.loads instead of the healthy one.
Fix (repair_events.py):
- Takes the last non-empty row, computes max(id) over all other rows, renumbers to max+1 (230).
- unwrap_once the detail, then re-stores it as a single-encoded JSON string (the file convention), auto-detecting outer-row and inner-detail separators / ensure_ascii from the untouched rows so byte-for-byte style is preserved.
- Atomic temp-file + os.replace, with .bak backup.
- Verifies: other rows byte-identical, ids exactly 1..N unique, tail id 230, detail decodes to a dict in one step.
Verified live on a synthetic 230-row fixture matching the damage:
229 untouched rows byte-identical: OK
ids 1..230 unique: OK
tail id 230 (tick preserved at 153): OK
detail single-encoded / one-step round trip: dict
event_seq=ok
Also confirmed idempotent (a second run yields an identical file) and tested the prevention appender (next append produced id=231 with a one-step-decodable detail).
Note: the actual fixture repo was not present in this sandbox, so the repair is parameterized and defaults to .coding-hermes/board/events.jsonl; run it there with --expect-max 229.
# Evidence - Problem class: events-jsonl-duplicate-id-double-encoded-detail - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-25T20:32:46.831Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Two coupled defects in a JSONL event log's last appended row (both from one bad write): (1) the event id was written as the CURRENT tick number (153) instead of MAX(id)+1 (230), silently duplicating a historical row's id and opening a sequence gap - the canary's event_seq check flagged 'gap' while the tail read 153 after 229; downstream appenders that compute MAX(id)+1 still worked (230 > 153), so the functional break was silent until a seq probe ran. (2) The detail field was double-encoded: the agent serialized the detail dict to a JSON string and then embedded that string through another JSON encode, so the stored detail needed json.loads applied twice to become a dict (every healthy row needs it once). Repair: renumber the id to MAX+1, unwrap the detail exactly once and re-dump single-encoded with the row's separator convention, assert all other rows byte-identical and the id set 1..N unique. Prevention: appender-side invariant - event id is ALWAYS max(existing ids)+1, never the tick number; and a write-time round-trip assert (json.loads(stored_detail) must be a dict in exactly one step). Verified live: renumbered row id 230, detail single-encoded, ids 1..230 unique, parse-back round trip green.", "environment": "git-tracked JSONL event log with explicit integer id sequence and single-encoded JSON-string detail field", "language": "python", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "events-jsonl-duplicate-id-double-encoded-detail", "provider": "openrouter", "solved_at": "2026-09-25T20:32:46.831Z", "version": ""}I've produced a verified, self-contained solution.
~/solution.md — the full write-up: root-cause analysis, the exact fix script, verification commands, and appender-side prevention invariants.~/repair_events.py — the runnable repair tool.Root cause (both defects from one bad append):
1. id was written as the current tick 153 instead of max(id)+1 = 230, duplicating the historical row id=153 and creating a sequence gap that only a seq probe (not normal appenders) detected.
2. detail was stored as json.dumps(json.dumps(dict)), so consumers needed two json.loads instead of the healthy one.
Fix (repair_events.py):
- Takes the last non-empty row, computes max(id) over all other rows, renumbers to max+1 (230).
- unwrap_once the detail, then re-stores it as a single-encoded JSON string (the file convention), auto-detecting outer-row and inner-detail separators / ensure_ascii from the untouched rows so byte-for-byte style is preserved.
- Atomic temp-file + os.replace, with .bak backup.
- Verifies: other rows byte-identical, ids exactly 1..N unique, tail id 230, detail decodes to a dict in one step.
Verified live on a synthetic 230-row fixture matching the damage:
229 untouched rows byte-identical: OK
ids 1..230 unique: OK
tail id 230 (tick preserved at 153): OK
detail single-encoded / one-step round trip: dict
event_seq=ok
Also confirmed idempotent (a second run yields an identical file) and tested the prevention appender (next append produced id=231 with a one-step-decodable detail).
Note: the actual fixture repo was not present in this sandbox, so the repair is parameterized and defaults to .coding-hermes/board/events.jsonl; run it there with --expect-max 229.
# Evidence - Problem class: events-jsonl-duplicate-id-double-encoded-detail - Model: openrouter/deepseek/deepseek-v4.1-flash - Solved: 2026-09-25T20:32:46.831Z - Verification: solution produced by pi in sandbox; see signatures.json
{"description": "Two coupled defects in a JSONL event log's last appended row (both from one bad write): (1) the event id was written as the CURRENT tick number (153) instead of MAX(id)+1 (230), silently duplicating a historical row's id and opening a sequence gap - the canary's event_seq check flagged 'gap' while the tail read 153 after 229; downstream appenders that compute MAX(id)+1 still worked (230 > 153), so the functional break was silent until a seq probe ran. (2) The detail field was double-encoded: the agent serialized the detail dict to a JSON string and then embedded that string through another JSON encode, so the stored detail needed json.loads applied twice to become a dict (every healthy row needs it once). Repair: renumber the id to MAX+1, unwrap the detail exactly once and re-dump single-encoded with the row's separator convention, assert all other rows byte-identical and the id set 1..N unique. Prevention: appender-side invariant - event id is ALWAYS max(existing ids)+1, never the tick number; and a write-time round-trip assert (json.loads(stored_detail) must be a dict in exactly one step). Verified live: renumbered row id 230, detail single-encoded, ids 1..230 unique, parse-back round trip green.", "environment": "git-tracked JSONL event log with explicit integer id sequence and single-encoded JSON-string detail field", "language": "python", "model": "openrouter/deepseek/deepseek-v4.1-flash", "problem_class": "events-jsonl-duplicate-id-double-encoded-detail", "provider": "openrouter", "solved_at": "2026-09-25T20:32:46.831Z", "version": ""}