## Summary
The replay side of the mollifier:
- `DrainerHandler`: reads buffered snapshots and replays them through
`engine.trigger` to materialise PG rows.
- `RunEngine.createCancelledRun`: new public method the handler uses to
write CANCELED rows directly from snapshots (bypass queue + waitpoint,
emit `runCancelled`). Tolerates the cjson empty-table tags edge case
found during validation.
- Drainer fairness: org → env rotation so a heavy env doesn't starve
light ones in the same org.
- Stale-entry sweep + telemetry + alertable gauge so a stuck/offline
drainer surfaces in alerts.
Both the drainer and sweep default-off; nothing fires unless flagged on
(`TRIGGER_MOLLIFIER_DRAINER_ENABLED`,
`TRIGGER_MOLLIFIER_STALE_SWEEP_ENABLED`).
Stacked on the trigger-time decisions PR.
## Test plan
- [x] \`pnpm run typecheck --filter webapp\` passes
- [x] \`pnpm run test --filter webapp
test/mollifierDrainerHandler.test.ts\` passes
- [x] \`pnpm run test --filter webapp test/mollifierStaleSweep.test.ts\`
passes
- [x] \`pnpm run test --filter @internal/run-engine
src/engine/tests/createCancelledRun.test.ts\` passes
- [x] \`pnpm run test --filter @trigger.dev/redis-worker
packages/redis-worker/src/mollifier/drainer.test.ts\` passes
---
## Ship-gate follow-up fix
**Drainer writes SYSTEM_FAILURE on max-attempts exhaustion.** Adds an
`onTerminalFailure` callback on `MollifierDrainerOptions` so the
customer's run lands a SYSTEM_FAILURE PG row even when the drainer
exhausts `MAX_ATTEMPTS` on a retryable PG error (previously
`buffer.fail()` was called with no row written → silent data loss). The
callback runs before `buffer.fail()` on every terminal path
(non-retryable AND max-attempts-exhausted), and re-throwing a retryable
error from the callback causes the drainer to requeue rather than fail.
Bumps `@trigger.dev/redis-worker` to a **minor** changeset (additive
option + new exported types). Includes 5 unit tests covering both
terminal causes plus the requeue-on-retryable-callback-failure path and
no-callback back-compat.
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Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Daniel Sutton
4745754a7a