# SQLite startup concurrency repair

## Scope and reproduced failure

The [patched-source run](CURRENT_FAILURES.md) was explicitly stopped05:55:08UTC after144passing and3failing logged cases out of351discovered cases. This is an interrupted failure, not a completed result. [Portable raw hashes](evidence/lock-observation.json) retain its command, traces and log even when later execution archives their paths.

Two unchanged client assertions receive SQLite error5/HTTP500: owned restored-job readback and language preference persistence. Read-only inspection of the isolated database reports `journal_mode=delete`, `locking_mode=normal`. Actual bootstrap opens the file during reconciliation before EF's normal database creation path can establish WAL. A deterministic regression invokes that bootstrap without starting a listener, worker or provider, holds a SELECT cursor on one connection and attempts the actual usage reservation on another. Before repair it reproduces the browser's `SqliteDataRecord.Dispose → NextResult → AffectedCountModificationCommandBatch → AiUsageMeter.ReserveAsync` failure. The separate startup assertion reports expected`wal`, actual`delete`.

The precise competing connection in the browser was not identified. The deterministic mechanism and unsafe journal mode are demonstrated; no claim is made that WAL eliminates all possible SQLite writer contention.

## Bounded change and preservation

Startup executes `PRAGMA journal_mode = WAL` once before SQLite reconciliation. The existing provider branch excludes MariaDB/MySQL. No schema, stored field, tenant filter, Identity contract, quota rule, summary output, write payload or save semantics changes. There is no new retry, swallowed exception, relaxed timeout or disabled assertion. Existing `VACUUM INTO` backup already supports WAL; [database guidance](../../../database/migrations.md) explains consistent snapshots.

The new ordinary backend cases verify fresh and populated startup, reopening persistent mode after a deliberately DELETE-mode database, unchanged owned/foreign rows and completed migration history; usage INSERT and Identity preference UPDATE while the SELECT cursor remains open; committed WAL contents in an independent integrity-checked backup that does not change after later source writes. Local file cleanup stays within the uniquely named disposable fixture directory.

## Validation

| Run | Actual result | Qualification |
|---|---|---|
| Original focused RED,05:58:07–05:58:24UTC | 4PASS/2FAIL/0skipped | Startup mode and actual held-reader usage write fail; backup cases pass |
| Initial focused successor,05:58:44–05:58:53UTC | 5PASS/1FAIL/0skipped | Actual concurrent writes pass; populated-mode verification still used the external connection that set DELETE |
| Reopened-verification successor,05:59:34–05:59:41UTC | 6PASS/0FAIL/0skipped | Fixture closes the DELETE-setting connection before restart and reopens for the original expected`wal` assertion; no production change or weaker expectation |
| Fresh full backend,05:59:54–06:00:10UTC | **1060PASS/0FAIL/0skipped** | Current patched Release assemblies; plus3from1057:2startup/concurrency cases and1backup case |
| Ordinary affected browser vector,06:00:43–06:03:24UTC | **17PASS/0FAIL/0skipped/0flaky** | Actual Audit, application forms and paginated Users cases; zero configured retries |
| Release build,06:03:48–06:03:50UTC | PASS/0warnings/0errors | API and backend test projects, locked existing restore, warnings treated as errors |

[Portable repair evidence](evidence/sqlite-repair.json) records the exact command/TRX/log paths and byte hashes for every backend attempt and the17-case native vector. Release build is recorded under `.artifacts/phase7/current/backend-career/p702-release-20261021T060348Z/`; its historical helper label does not make it Phase2 evidence. Complete351-case regression and the separate lanes remain required.

PRES-E02/E08/E09, S03/S04/S05, W01/W04 and the wider57-group matrix remain binding. This finite regression does not supply human/device acceptance or production restore, ingress/configuration/schema/rollback evidence. Production readiness stays **NO-GO**. No Phase8 or withheld P5-13 implementation is introduced.