# @goodgo/contracts-events

Cross-runtime (Node + Python) event contracts for RFC-004's async messaging
backbone. See [GOO-95](/GOO/issues/GOO-95) for the RFC and
[GOO-172](/GOO/issues/GOO-172) for Phase 0.

## What lives here

- `src/envelope.ts` — `EventEnvelope<T>` TypeScript type + `EVENT_ENVELOPE_SCHEMA_VERSION`.
- `src/uuid-v7.ts` — pure-Node UUIDv7 generator (no runtime deps).
- `src/event-types.ts` — string-literal union of all known event types.
- `schemas/envelope.schema.json` — JSON Schema for the envelope itself.
- `schemas/<event-type>.schema.json` — JSON Schema for each event payload.

The `schemas/` directory is consumed by the Python AI services
(`libs/ai-services`) via `redis-py` consumers — JSON Schema is the single
source of truth across runtimes.

## Envelope shape

```ts
interface EventEnvelope<TPayload = unknown> {
  schemaVersion: number;     // bump when envelope itself changes
  eventId: string;           // UUIDv7 — time-ordered, idempotency key
  eventType: string;         // dotted: "payment.completed"
  occurredAt: string;        // ISO-8601 UTC
  producer: string;          // service name, e.g. "api"
  traceId: string;           // OpenTelemetry-compatible (32 hex chars or "00…")
  payload: TPayload;         // event-specific, validated by per-type schema
}
```

`schemaVersion` starts at `1`. Bump only when the **envelope** changes;
payload changes are versioned per event-type schema independently.

## First 3 schemas (Phase 0 deliverable)

| Event type           | Trigger                                          |
|----------------------|--------------------------------------------------|
| `payment.completed`  | Payment moves to `succeeded` after gateway IPN   |
| `listing.approved`   | Moderation approves a listing                    |
| `kyc.verified`       | KYC review marks a user verified                 |

Phase 1 (notifications cutover, [GOO-173](/GOO/issues/GOO-173)) will add
the rest of the production event surface.

## Adding a new event type

1. Pick a stable dotted name (`<aggregate>.<past-tense-verb>`).
2. Add a `schemas/<name>.schema.json` JSON Schema describing the payload.
3. Add the literal to `src/event-types.ts`.
4. (Optional) Re-export a typed payload alias from `src/index.ts`.
5. Land + dual-publish for at least one sprint before any consumer hard-fails on it.
