- Updated the EngagementMetrics interface to use ObservableGauge for tracking active WebSocket connections.
- Added detailed comments explaining the rationale for this change, highlighting the benefits of using a pull-based gauge over a delta-based counter.
- Implemented the ObservableGauge in the createChatWsHandlers function, ensuring it accurately reflects the live count of active connections.
- Removed the previous UpDownCounter logic to prevent issues with connection drift during process crashes or network interruptions.
- Added new metrics for email service including send, failures, and duration tracking.
- Introduced rate limit metrics to monitor blocked requests and improve abuse detection.
- Enhanced billing metrics to track credited and unbilled flux, as well as TTS character processing.
- Updated OpenAI and Stripe routes to utilize new metrics for better revenue tracking and rate limiting.
- Implemented a smoke test for OpenTelemetry metrics registration to ensure visibility at startup.
The Redis Stream `billing-events` + `worker` Railway role +
advisory-lock poller layered together didn't actually buy us reliability
— `debitFlux` swallowed XADD failures, leaving the door open to "balance
updated, ledger row never written". Collapse the whole thing back to:
`creditFlux` and `debitFlux` write `flux_transaction` ledger rows inline
within the same DB transaction that mutates `user_flux`, and `(user_id,
request_id)` remains the partial unique index that keeps retries safe.
Concrete changes:
- Inline ledger inserts in `BillingService.{debitFlux, creditFlux,
creditFluxFromStripeCheckout, creditFluxFromInvoice}`; drop `billingMq`
and `publishEvent` plumbing entirely.
- `routes/openai/v1` writes `llm_request_log` synchronously via the
existing `requestLogService`; the duplicate `llm-request-log.ts` service
module is removed.
- `bin/run-worker.ts`, `libs/mq/*`,
`services/billing/billing-events.ts`,
`services/billing/billing-consumer-handler.ts`, and matching tests are
deleted. CLI now exposes only `api`.
- `BILLING_EVENTS_*` env vars and the `DEFAULT_BILLING_EVENTS_STREAM`
helper are dropped; `docker-compose.yml` no longer ships a worker
service.
- `docs/ai-context/{workers-and-runtime, billing-architecture,
redis-boundaries-and-pubsub, data-model-and-state,
architecture-overview, README}.md`, `CLAUDE.md`, and the existing
verification docs are updated to describe the single-process synchronous
pipeline.
Tests: 29 files / 247 cases pass. Production deployments need to drop
the worker Railway service after this lands.
