Add federation exchange status observability

[skulidropek]

Summary

Adds a live observability endpoint for the Lefine/ForgeFed exchange flow so we can see whether docker-git is connected and whether requests/tasks are arriving.

Changes:

• add GET /federation/exchange/status
• persist a bounded history of the latest 100 exchange events in federation state
• record follow.sent, inbox.follow.accept, inbox.follow.reject, inbox.issue.received, and poll.completed
• expose subscription counters, accepted/pending/rejected counts, issue count, processed outbox item count, lastInboxAt, and lastPollAt
• document the workflow in packages/api/README.md
• add service tests for status telemetry and event-history bounds

Related:

• Issue: Надо протестировать работает ли система с подписками для платформы Lefine #282
• Builds on the ForgeFed exchange work from Add ForgeFed exchange federation #234

How to use

Set the public federation origin to the public URL that Lefine can reach:

export API="https://<public-docker-git-origin>"
export DOCKER_GIT_FEDERATION_PUBLIC_ORIGIN="$API"
export DOCKER_GIT_EXCHANGE_PROJECT_REPO_URL="https://github.com/ProverCoderAI/docker-git"
export DOCKER_GIT_EXCHANGE_AGENT_PROVIDER="codex"

Create or reuse the Lefine exchange subscription:

curl -X POST "$API/federation/exchange/subscriptions" \
  -H 'Content-Type: application/json' \
  --data '{
    "target":"https://problemsets.lefine.pro/actor/code",
    "projectRepoUrl":"https://github.com/ProverCoderAI/docker-git",
    "agentProvider":"codex"
  }'

Check whether the connection is alive:

curl "$API/federation/exchange/status"

Important fields in the response:

• summary.accepted > 0 means Lefine accepted our Follow subscription.
• summary.lastInboxAt means something arrived in /federation/inbox, for example Lefine's Accept.
• summary.lastPollAt means docker-git successfully polled the remote Lefine outbox.
• summary.issues is the number of ForgeFed issues/Tickets currently persisted by docker-git.
• summary.processedOutboxItems is the number of outbox items already handled, used for deduplication.
• recentEvents shows the latest exchange activity: Follow sent, Follow accepted/rejected, issue received, poll completed.

Run a safe manual poll that does not start agents/projects:

curl -X POST "$API/federation/exchange/poll" \
  -H 'Content-Type: application/json' \
  --data '{"target":"code","runTasks":false}'

Run a normal poll that can create docker-git projects/agents when new Create(Ticket) items exist:

curl -X POST "$API/federation/exchange/poll" \
  -H 'Content-Type: application/json' \
  --data '{"target":"code"}'

View persisted incoming issues:

curl "$API/federation/issues"

Expected flow:

1. Subscription sends ActivityPub Follow to Lefine and records follow.sent.
2. Lefine answers with Accept into /federation/inbox; status becomes accepted, lastInboxAt is set, and inbox.follow.accept appears in recentEvents.
3. docker-git polls Lefine's outbox; each poll records poll.completed.
4. A Lefine Create(Ticket) creates a persisted issue and records inbox.issue.received.
5. If the Ticket is handled through outbox polling and runTasks is not false, docker-git starts the project/agent flow using the Ticket GitHub URL or DOCKER_GIT_EXCHANGE_PROJECT_REPO_URL fallback.

A subscription by itself does not create a docker-git task. It only establishes the ActivityPub connection. Tasks appear after Lefine publishes/sends a Create(Ticket).

Live smoke result

Smoke-tested with a public Cloudflare origin. Current observed state after subscribing to Lefine:

{
  "summary": {
    "subscriptions": 1,
    "accepted": 1,
    "pending": 0,
    "rejected": 0,
    "issues": 0,
    "processedOutboxItems": 0,
    "lastInboxAt": "2026-05-12T11:33:59.448Z"
  },
  "subscriptions": [
    {
      "target": "https://problemsets.lefine.pro/actor/code",
      "queue": "code",
      "status": "accepted",
      "remoteActor": "https://problemsets.lefine.pro/actor/code",
      "remoteOutbox": "https://problemsets.lefine.pro/outbox/code"
    }
  ]
}

Manual safe poll returned totalItems=0, newItems=0, processedItems=0, so the connection is accepted but Lefine had no new tasks in the outbox at that moment.

Verification

bun run api:typecheck
bun run --cwd packages/api lint
bun run api:test

Result: API tests passed, 18 files / 109 tests.