Mirror the previous commit's Windows-EPERM retry on the companion
`writeWarnState` in `scripts/hooks/ecc-context-monitor.js`. Same
race: two PostToolUse subprocesses writing concurrent debounce
state racing on `MoveFileExW`, target-in-use throwing EPERM on
Windows even though each writer's tmp path is now unique.
Implementation: import `renameWithRetry` from `scripts/lib/session-bridge.js`
(exported in the previous commit) instead of duplicating the helper.
The retry policy, backoff schedule, and main-thread `Atomics.wait`
strategy stay identical to `writeBridgeAtomic`.
Three writers in the repo now share the same atomic-write contract:
- `writeBridgeAtomic` (scripts/lib/session-bridge.js) — round 1 +
this round's retry
- `writeWarnState` (this file) — round 1 + this round's retry via shared helper
- `writeCostWarningIfChanged` (scripts/hooks/ecc-metrics-bridge.js) —
out of scope for this PR (already uses unique tmp suffix; a future
consolidation could move it to the shared helper too).
Local: `yarn test` green, `yarn lint` clean. The companion test
suite for `ecc-context-monitor.js` does not currently exercise
concurrent `writeWarnState` writes, but the helper it now uses is
covered by the `tests/lib/session-bridge.test.js` concurrent-write
regression added in round 1's last commit.
Mirror the previous commit's `writeBridgeAtomic` fix on the
companion `writeWarnState` in `ecc-context-monitor.js`. Same shape:
fixed `${target}.tmp` → `${target}.${process.pid}.${randomNonce}.tmp`,
plus best-effort cleanup of the tmp file on `renameSync` failure
(throws original error after cleanup).
`writeWarnState` debounces the context-monitor's threshold alarms
(`COST_NOTICE_USD`, `COST_WARNING_USD`, `COST_CRITICAL_USD`, plus the
context-remaining and loop-detection ones). Without unique suffixes,
two PostToolUse subprocesses racing on the warn-state file produce
either a corrupted JSON debounce-state on disk or an ENOENT throw
that the hook catches and swallows — either way the next warn-state
read returns the default `{callsSinceWarn: 0, lastSeverity: null}`
and the threshold alarms re-fire or stop firing erratically. Users
see warning messages flicker or vanish; debounce no longer works.
Three call sites in this repo now share the same atomic-write
contract:
- `writeBridgeAtomic` (scripts/lib/session-bridge.js) — primary
- `writeCostWarningIfChanged` (scripts/hooks/ecc-metrics-bridge.js) — cost cache
- `writeWarnState` (this file) — debounce state
`yarn lint` clean. Regression test covering both `writeBridgeAtomic`
and `writeWarnState` under concurrent load lands in the next commit.
Salvages the useful statusline/context monitor work from stale PR #1504 while preserving the current continuous-learning hook runner wiring.
Adds the metrics bridge, context monitor, statusline script, shared cost/session bridge utilities, and tests. Fixes the reviewed false loop-detection hash collision for non-file tools, avoids default-session cost inflation, sanitizes statusline task lookup, and records hook payload session IDs in cost-tracker.
