SciMesh/docs/api-contract.md

SciMesh coordinator ↔ worker API contract (v1)

Status marker: v1. This document is the single source of truth for the Go coordinator and the Python Worker Daemon. It is derived from PLAN.md §5 and must be updated in the same change as any behaviour it describes.

• Auth: every endpoint except readiness requires Authorization: Bearer <token>.
• Identity: every mutating worker request carries worker_id and attempt; they are checked against the current task lease in PostgreSQL. A stale attempt gets 409.
• Timestamps: UTC, RFC 3339 (e.g. 2026-07-22T12:05:00Z).
• Unknown JSON fields are rejected with 400.

Implementation status

Endpoint	Contract	Coordinator
GET /health	readiness incl. DB	✅ done
POST /workers/register	register + capabilities	✅ done
POST /tasks/claim	atomic lease	✅ done
POST /tasks/{id}/heartbeat	renew lease	✅ done
POST /tasks/{id}/result	complete	🟡 done, but result is a URI today; moves to artifact_id next
POST /tasks/{id}/failure	fail	✅ done
GET /jobs/{id}	progress	✅ done
PUT /tasks/{id}/artifacts/{name}	upload partial	✅ done
GET /artifacts/{id}/download	download by id	✅ done
GET /tasks/{id}/input	download shard	❌ needs input artifacts (upload+chunking)

---

Readiness

GET /health

200 {"status":"ok"} when the database is reachable; 503 {"status":"unavailable"} otherwise. Unauthenticated.

Register worker

POST /workers/register
Authorization: Bearer <token>
Content-Type: application/json

{
  "name": "lab-worker-01",
  "capabilities": ["similarity-search", "similarity-graph"],
  "cpu_count": 8,
  "memory_mb": 16384
}

201:

{ "worker_id": "uuid", "heartbeat_interval_seconds": 15 }

cpu_count/memory_mb are accepted for forward compatibility and not yet persisted. capabilities must be non-empty (an allowlisted workload set).

Claim task

POST /tasks/claim
Authorization: Bearer <token>
Content-Type: application/json

{ "worker_id": "uuid", "capabilities": ["similarity-search"], "max_concurrency": 1 }

• 204 No Content: no compatible task.
• 200 OK: a task is leased atomically.

{
  "task_id": "uuid",
  "attempt": 1,
  "lease_expires_at": "2026-07-22T12:05:00Z",
  "workload": "similarity-search",
  "input": { "uri": "https://coordinator/tasks/uuid/input", "sha256": "hex" },
  "parameters": { "query_id": "CHEMBL939", "top_k": 20 }
}

max_concurrency is accepted; the coordinator leases one task per call for now.

Renew lease (heartbeat)

POST /tasks/{task_id}/heartbeat
Authorization: Bearer <token>
Content-Type: application/json

{ "worker_id": "uuid", "attempt": 1 }

Response must contain a renewed deadline:

{ "lease_expires_at": "2026-07-22T12:10:00Z" }

The worker schedules the next heartbeat before half of the returned TTL, never on a fixed interval alone.

Download input or shard (CTX-05)

GET /tasks/{task_id}/input returns the artifact owned by the current task. The worker verifies its SHA-256 before execution. If the URI redirects to another origin, the worker removes the coordinator bearer token.

Upload a partial artifact (CTX-05)

PUT /tasks/{task_id}/artifacts/{filename}
Authorization: Bearer <token>
Content-Type: text/csv
X-Worker-ID: uuid
X-Task-Attempt: 1

<streamed bytes>

200:

{ "artifact_id": "uuid", "uri": "https://coordinator/artifacts/uuid/download",
  "sha256": "hex", "size_bytes": 1234 }

Complete or fail task

POST /tasks/{task_id}/result
Authorization: Bearer <token>
Content-Type: application/json

{
  "worker_id": "uuid",
  "attempt": 1,
  "result": { "artifact_id": "uuid", "sha256": "hex", "content_type": "text/csv" },
  "metrics": { "elapsed_seconds": 12.4, "processed_rows": 10000 }
}

Transitional: the coordinator currently accepts result_uri + result_sha256 instead of result.artifact_id. This switches to the artifact form in CTX-05, once upload exists. Until then no worker-supplied file:///worker:// URI is valid in persisted metadata.

POST /tasks/{task_id}/failure

Same identity fields, plus sanitized error_code, error_message, retryable. Never a traceback, token, or absolute worker path.

Idempotency and errors

Situation	Response
No compatible task	204
Worker/attempt does not own lease	409
Artifact does not belong to task/attempt	409
Same completion, same manifest	200 idempotent
Same attempt, different manifest	409
Invalid parameters/input	400
Auth failure	401
Unknown job/task	404