/status does not say whether ingestion is actually working #333

Background

/status is defined at src/api/rest.ts:72 and is the endpoint an uptime
monitor will poll. It answers from the process's own point of view. It does not
report whether any ingester is running, when each venue last produced a price,
or whether an ingester has been crash-looping — which means a service with every
ingester dead still returns a healthy /status and a green uptime check.

This is the issue that makes L163 and L165 useful: both produce information that
currently has nowhere to go.

What to build

Extend /status with per-venue, per-network ingestion health:

• Last successful write time per (venue, network), and the age of it.
• Whether that age exceeds an expected interval for that venue.
• Restart count and last crash message, if L165 has landed; design for it being absent.
• An overall verdict that an uptime monitor can alert on.

Keep the existing fields — callers depend on them. The route is public: true
and allow-listed from rate limiting in src/app.ts, so it must stay cheap: no
unbounded queries, and do not add a Horizon round-trip to it.

Acceptance criteria

• /status reports last-write age per venue and network
• A stale venue is visibly distinct from a healthy one
• Existing response fields are unchanged
• The handler issues a bounded, small number of queries regardless of how many pairs exist
• A test asserts the stale case is reported as unhealthy

Drips Wave · Complexity: Intermediate · 150 points

Repo: Divinity-Labs/Lens. Node + TypeScript, Fastify, Prisma on Postgres,
Redis for queues, Prometheus via prom-client.

Run the tests: npm test. The tests are vitest, not jest. Running jest
against this repo reports "66 suites, 0 tests" and means nothing. A single file
is npx vitest run src/__tests__/yourfile.test.ts.

Load test (prices) is already failing on main and has been for some
time. It is not your PR that broke it. Every other check should be green.

This service prices real assets on Stellar mainnet. A number that is wrong
is worse than a number that is missing, because a caller cannot tell the
difference. Prefer failing loudly over returning a plausible value.

Never elide an address, a contract id or a key in code, a comment or a test
fixture. A previous batch wrote a shortened contract id in an issue text and
five contributors invented plausible-looking ids to fill the gap. Write the
whole thing or do not write it at all.

The house pattern for an outbound deadline already exists — see
src/alerts/delivery.ts, which passes signal: AbortSignal.timeout(10_000) to
fetch. Where an issue below asks for a timeout, copy that, do not invent a
second convention.

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