fix(state): serialize WAL switch under the flock (fixes flaky concurrent open) - #65
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…y open) `TestConcurrentOpenSerializes` intermittently failed under `-race` with `ping state.db: database is locked (5) SQLITE_BUSY`. Root cause: `Open` called `sqlDB.Ping()` BEFORE taking the flock. Ping forces the first real connection, which applies the DSN `_pragma`s — including `journal_mode=WAL`. The WAL switch writes the DB header under a write lock, and that journal-mode change is NOT covered by `busy_timeout`, so concurrent first-opens racing the conversion get an immediate SQLITE_BUSY. Fix: move `Ping` inside the existing `lock.WithLock` block, alongside `migrate` + `ensureContext`, so the WAL conversion (a genuine mutation) is serialized across processes by the machine-global advisory lock — exactly the contract spec 08 already states for the mutating section. No behavior change for the single-open path. Verified with `-race -count=12`. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
TestConcurrentOpenSerializesintermittently fails in CI under-race:ping state.db: database is locked (5) SQLITE_BUSY. (It just flaked PR #64; a re-run went green.)Root cause
OpencalledsqlDB.Ping()before taking the flock.Pingforces the first real connection, which applies the DSN_pragmas — includingjournal_mode=WAL. The WAL switch writes the DB header under a write lock, and a journal-mode change is not governed bybusy_timeout, so concurrent first-opens racing the conversion get an immediateSQLITE_BUSY.Fix
Move
Pinginside the existinglock.WithLockblock, next tomigrate+ensureContext, so the WAL conversion (a real mutation) is serialized across processes by the machine-global advisory lock — exactly the contract spec 08 already states for the mutating section. No change to the steady-state single-open path.Verified with
-race -count=12locally (was flaking ~1 in 8 on CI).🤖 Generated with Claude Code