REST API Reference

This is the complete HTTP reference for the ChronosOS control plane started with chronos serve. The default base URL is http://localhost:8420.

:::tip Live, interactive reference The server ships an interactive Swagger UI at /swagger/ and the raw OpenAPI 3 document at /swagger/doc.json. The generated spec is the authoritative, always-in-sync source of truth — use it to try requests in the browser or to generate clients. This page mirrors it in prose. :::

Conventions

All request and response bodies are JSON (Content-Type: application/json), except /metrics (Prometheus text) and /api/events/stream (SSE).
Timestamps are RFC 3339 strings.
Auth requirement is shown per endpoint (viewer+ = read, user+ = mutating). It is enforced only when both an auth mode and RBAC are enabled (CHRONOS_AUTH=jwt|apikey and CHRONOS_RBAC=true — both default off; see Authentication). With auth on but RBAC off, any valid credential may call any /api/* route. Health, metrics, and Swagger endpoints are always public.
When auth is enabled, results are automatically scoped to the caller's tenant.

Common status codes

Code	Meaning
`200 OK`	Success
`201 Created`	Resource created
`400 Bad Request`	Malformed query/body or missing required parameter
`401 Unauthorized`	Missing/invalid credentials (auth enabled)
`403 Forbidden`	Authenticated but role lacks permission
`404 Not Found`	Resource does not exist (or belongs to another tenant)
`429 Too Many Requests`	Rate limit or per-key quota exceeded
`500 Internal Server Error`	Unhandled server error (panic-recovered)

Health

`GET /healthz` · `GET /health` · `GET /health/live` · `GET /health/ready`

Liveness and readiness probes. Always unauthenticated.

/healthz, /health, /health/live — the process is up.
/health/ready — dependencies (storage) are reachable and the server is ready to accept traffic.

Response 200 OK

{ "status": "ok" }

curl http://localhost:8420/health/ready

See Health & readiness for probe semantics.

Metrics

`GET /metrics`

Prometheus-format metrics. Always unauthenticated.

Response 200 OK (text/plain; version=0.0.4)

curl http://localhost:8420/metrics

Sessions

`GET /api/sessions`

List sessions, most recent first.

Auth: viewer+

Query param	Type	Default	Description
`agent_id`	string	—	Filter to one agent (optional)
`limit`	int	`50`	Page size
`offset`	int	`0`	Page offset

Response 200 OK

{
  "sessions": [
    {
      "id": "sess-8f2a",
      "agent_id": "support-bot",
      "tenant_id": "acme",
      "created_at": "2026-07-23T10:15:04Z",
      "updated_at": "2026-07-23T10:18:22Z"
    }
  ]
}

curl "http://localhost:8420/api/sessions?agent_id=support-bot&limit=20&offset=0"

`GET /api/sessions/state`

Fetch the latest checkpoint for a session.

Auth: viewer+

Query param	Type	Required	Description
`session_id`	string	yes	Session identifier

Response 200 OK

{
  "session_id": "sess-8f2a",
  "checkpoint_id": "ckpt-14",
  "node_id": "await_approval",
  "state": { "ticket_id": 4821, "status": "pending" },
  "seq_num": 14
}

curl "http://localhost:8420/api/sessions/state?session_id=sess-8f2a"

Errors: 400 if session_id is missing; 404 if the session has no checkpoint or belongs to another tenant.

`POST /api/sessions/state`

Merge a partial state patch into the latest checkpoint. This powers the edit-then-resume flow — an operator corrects state before the graph resumes.

Auth: user+

Query param	Type	Required	Description
`session_id`	string	yes	Session identifier

Request body

{ "state": { "status": "approved", "approver": "ops@acme.com" } }

The state object is shallow-merged into the current checkpoint state; existing keys not present in the patch are preserved.

Response 200 OK

{
  "session_id": "sess-8f2a",
  "checkpoint_id": "ckpt-15",
  "node_id": "await_approval",
  "state": { "ticket_id": 4821, "status": "approved", "approver": "ops@acme.com" },
  "seq_num": 15
}

curl -X POST "http://localhost:8420/api/sessions/state?session_id=sess-8f2a" \
  -H "Content-Type: application/json" \
  -d '{"state":{"status":"approved","approver":"ops@acme.com"}}'

Traces

`GET /api/traces`

Fetch trace spans for a session (for debugging and observability).

Auth: viewer+

Query param	Type	Required	Description
`session_id`	string	yes	Session identifier

Response 200 OK

{
  "traces": [
    {
      "span_id": "span-01",
      "parent_id": "",
      "name": "agent.chat",
      "start": "2026-07-23T10:15:04.001Z",
      "end": "2026-07-23T10:15:06.402Z",
      "attributes": { "model": "gpt-4o", "tokens": 512 }
    }
  ]
}

curl "http://localhost:8420/api/traces?session_id=sess-8f2a"

Events (SSE)

`GET /api/events/stream`

Long-lived server-sent events stream of graph/run events. Content-Type: text/event-stream. The connection stays open until the client disconnects (the server clears the write deadline for this route).

Auth: viewer+

Query param	Type	Required	Description
`session`	string	no	Scope to one session. Omit for the firehose (all sessions on this replica).

Response 200 OK — a sequence of SSE data: frames:

data: {"type":"node_start","session":"sess-8f2a","node":"classify"}

data: {"type":"node_end","session":"sess-8f2a","node":"classify","status":"ok"}

data: {"type":"completed","session":"sess-8f2a"}

# One session
curl -N "http://localhost:8420/api/events/stream?session=sess-8f2a"

# Firehose
curl -N "http://localhost:8420/api/events/stream"

See Streaming & SSE for event types and the broker.

Approvals

Human-in-the-loop approvals. Available when the server is started with an approval service (WithApproval).

`GET /api/approval/pending`

List pending approval requests awaiting a decision.

Auth: user+

Response 200 OK

{
  "pending": [
    {
      "id": "appr-77",
      "session_id": "sess-8f2a",
      "node_id": "await_approval",
      "prompt": "Refund $250 to customer?",
      "requested_at": "2026-07-23T10:16:00Z"
    }
  ]
}

curl http://localhost:8420/api/approval/pending

`POST /api/approval/respond`

Approve or reject a pending request, unblocking the paused graph.

Auth: user+

Request body

{ "id": "appr-77", "approved": true, "comment": "Within policy" }

Response 200 OK

{ "id": "appr-77", "status": "approved" }

curl -X POST http://localhost:8420/api/approval/respond \
  -H "Content-Type: application/json" \
  -d '{"id":"appr-77","approved":true,"comment":"Within policy"}'

Schedules

Cron-triggered agent runs. Available when the server is started with a scheduler (WithScheduler).

`GET /api/schedules`

List all schedules.

Auth: viewer+

Response 200 OK

{
  "schedules": [
    {
      "id": "sched-1",
      "agent_id": "digest-bot",
      "cron_expr": "0 9 * * *",
      "input": { "topic": "overnight incidents" },
      "new_session": true,
      "next_run": "2026-07-24T09:00:00Z"
    }
  ]
}

curl http://localhost:8420/api/schedules

`POST /api/schedules`

Create a schedule.

Auth: user+

Request body

{
  "agent_id": "digest-bot",
  "cron_expr": "0 9 * * *",
  "input": { "topic": "overnight incidents" },
  "new_session": true
}

Field	Type	Description
`agent_id`	string	Agent to run
`cron_expr`	string	Standard 5-field cron expression
`input`	object	State/input passed to the agent on each fire
`new_session`	bool	Start a fresh session per fire (`true`) or reuse one (`false`)

Response 201 Created

{
  "id": "sched-2",
  "agent_id": "digest-bot",
  "cron_expr": "0 9 * * *",
  "input": { "topic": "overnight incidents" },
  "new_session": true,
  "next_run": "2026-07-24T09:00:00Z"
}

curl -X POST http://localhost:8420/api/schedules \
  -H "Content-Type: application/json" \
  -d '{"agent_id":"digest-bot","cron_expr":"0 9 * * *","input":{"topic":"overnight incidents"},"new_session":true}'

`GET /api/schedules/{id}`

Fetch a single schedule by ID.

Auth: viewer+

Response 200 OK — same shape as a list item. 404 if not found.

curl http://localhost:8420/api/schedules/sched-2

`DELETE /api/schedules/{id}`

Delete a schedule.

Auth: user+

Response 200 OK

{ "id": "sched-2", "status": "deleted" }

curl -X DELETE http://localhost:8420/api/schedules/sched-2

`GET /api/schedules/{id}/history`

Fetch past fires for a schedule.

Auth: viewer+

Response 200 OK

{
  "history": [
    {
      "schedule_id": "sched-2",
      "session_id": "sess-9c1d",
      "fired_at": "2026-07-23T09:00:00Z",
      "status": "completed"
    }
  ]
}

curl http://localhost:8420/api/schedules/sched-2/history

Swagger / OpenAPI

`GET /swagger/`

Interactive Swagger UI. Always public.

`GET /swagger/doc.json`

The OpenAPI 3 document backing the UI — feed it to client generators. Always public.

:::note Disabling Swagger Both Swagger routes are served only when CHRONOS_SWAGGER=true (the default). Set CHRONOS_SWAGGER=false (SDK: chronosos.WithSwagger(false)) to remove them entirely — recommended on hardened production control planes, since they bypass auth. When disabled, both paths return 404. :::

curl http://localhost:8420/swagger/doc.json | jq '.paths | keys'

Conventions​

Common status codes​

Health​

GET /healthz · GET /health · GET /health/live · GET /health/ready​

Metrics​

GET /metrics​

Sessions​

GET /api/sessions​

GET /api/sessions/state​

POST /api/sessions/state​

Traces​

GET /api/traces​

Events (SSE)​

GET /api/events/stream​

Approvals​

GET /api/approval/pending​

POST /api/approval/respond​

Schedules​

GET /api/schedules​

POST /api/schedules​

GET /api/schedules/{id}​

DELETE /api/schedules/{id}​

GET /api/schedules/{id}/history​

Swagger / OpenAPI​

GET /swagger/​

GET /swagger/doc.json​

See also​

Conventions

Common status codes

Health

`GET /healthz` · `GET /health` · `GET /health/live` · `GET /health/ready`

Metrics

`GET /metrics`

Sessions

`GET /api/sessions`

`GET /api/sessions/state`

`POST /api/sessions/state`

Traces

`GET /api/traces`

Events (SSE)

`GET /api/events/stream`

Approvals

`GET /api/approval/pending`

`POST /api/approval/respond`

Schedules

`GET /api/schedules`

`POST /api/schedules`

`GET /api/schedules/{id}`

`DELETE /api/schedules/{id}`

`GET /api/schedules/{id}/history`

Swagger / OpenAPI

`GET /swagger/`

`GET /swagger/doc.json`

See also