> ## Documentation Index > Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt > Use this file to discover all available pages before exploring further. # Start a monitor > Runs command under the session's repository and streams what it says into the conversation as it happens — batched on the pauses between bursts, so one test failure is one piece of news rather than forty lines. The monitor is announced in the transcript, listed until it is stopped, and killed with the host. A name already in use in this session is refused rather than replaced. ## OpenAPI ````yaml /es/openapi/v3-current/narya.yaml post /v1/sessions/{sessionId}/monitors openapi: 3.1.0 info: title: Narya Host API version: 1.0.0 description: >- The contract between the Narya host and every client. One long-lived host serves this API over a Unix socket in your Narya home. The terminal client and the one-shot command that Lerian ships drive this API, and a client you write drives the same one. Requests authenticate with a bearer token issued by the identity provider the host is configured with. An operation that declares another security scheme also accepts that credential. A request without a valid credential gets 401 with NRY-0011. A caller whose role lacks the permission an operation needs gets 403 with NRY-0028. Submitting a message returns 202 with a turn id. Everything the turn produces streams over GET /v1/events as server-sent events with a typed envelope, and a stream resumes from a Last-Event-ID header. One error envelope: code, title and message. Codes are NRY- followed by four digits. Cursors are opaque. servers: [] security: - bearerAuth: [] tags: - name: host description: The host process itself — version, uptime, mode, store. - name: sessions description: Durable conversation containers. Archive, never destroy. - name: messages description: Submitting work into a session and interrupting it. - name: events description: The server-sent event stream every client consumes. - name: lanes description: Parallel tracks inside a session — main, subagent, side. - name: agents description: Named recipes — instructions, tools, model, policy. Read-only in v1. - name: ladder description: >- What a person can type: the skills and command files in force for one repository, and expanding one into text. Five origins merged, nearest winning a name, the repository's own rungs gated on trust. - name: permissions description: Pending permission asks, decisions, and the decision audit. - name: intercom description: Sessions on one machine finding and messaging each other. - name: packages description: The one thing a user installs — resources, Go code, or both. - name: extensions description: >- Host-side extensions and the operations each exposes over the wire. This is the generic lane a host extension uses to serve its own client half (a TUI component, a web panel) or any API-only consumer, without adding routes to this contract. - name: workflows description: Deterministic multi-agent orchestration runs. - name: providers description: Model suppliers, their auth state, and the model catalogue. - name: monitors description: >- Long-running watchers a session keeps beside its conversation — a test runner in watch mode, a build, a log being followed. Started by the model or by the person, always listed, always killable. - name: records description: The queryable local record of everything that happened. - name: environments description: >- Where a session's code lives and its commands run — this machine, or a container narya operates. A session that names none runs here. - name: schedules description: >- Work the host's own clock starts with nobody present — a repository, a prompt, a rule and what one fire may spend. Cancel, never destroy. - name: sharing description: >- Publishing a session from a developer's own home to the organisation's, and what is held back before a byte leaves the machine. - name: refinements description: >- What this owner has taught narya and allowed it to keep — distilled facts, and the skills, agents and commands the model wrote for itself. Propose, read, consent, roll back. Nothing here fires until a person answers. - name: platform description: >- Calls Lerian's control plane made to a home it hosts, as this home recorded them. paths: /v1/sessions/{sessionId}/monitors: parameters: - $ref: '#/components/parameters/SessionIdParam' post: tags: - monitors summary: Start a monitor description: >- Runs command under the session's repository and streams what it says into the conversation as it happens — batched on the pauses between bursts, so one test failure is one piece of news rather than forty lines. The monitor is announced in the transcript, listed until it is stopped, and killed with the host. A name already in use in this session is refused rather than replaced. operationId: startMonitor requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/MonitorStart' responses: '201': description: The monitor, now running. content: application/json: schema: $ref: '#/components/schemas/Monitor' '400': $ref: '#/components/responses/BadRequest' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '413': $ref: '#/components/responses/RequestBodyTooLarge' '422': $ref: '#/components/responses/UnprocessableEntity' '500': $ref: '#/components/responses/InternalServerError' components: parameters: SessionIdParam: name: sessionId in: path required: true description: The session's id. schema: type: string format: uuid schemas: MonitorStart: type: object description: >- A request to run a watcher. Monitors started this way are recorded as the person's; the model starts its own through its tool. required: - name - command properties: name: type: string description: >- The watcher's name. Bounded to what a URL path segment carries unchanged, because this same name is the address the request that stops the watcher is sent to. minLength: 1 maxLength: 64 pattern: ^[A-Za-z0-9][A-Za-z0-9._-]*$ command: type: string minLength: 1 maxLength: 4096 filter: type: string maxLength: 512 examples: - name: tests command: go test ./... -run Ledger filter: ^(FAIL|ok) Monitor: type: object description: One long-running watcher a session is keeping beside its conversation. required: - name - command - startedBy - startedAt properties: name: type: string description: Unique within its session; this is what stops it. command: type: string description: What runs, under the session's repository. filter: type: string description: >- A regular expression keeping only the output lines that match it. Absent means every line. startedBy: type: string enum: - model - user description: >- Which hand reached the switch. Both may, and the registry treats them identically; this says which one it was, so the model knows before it stops something it did not start. startedAt: type: string format: date-time examples: - name: tests command: go test ./... -run Ledger startedBy: model startedAt: '2026-08-23T12:01:03.000Z' Error: type: object description: >- The single error envelope every operation returns. Codes are NRY- followed by four digits and are catalogued in the top-level x-error-catalog extension. required: - code - title - message properties: code: type: string pattern: ^NRY-[0-9]{4}$ description: Machine-readable error code from the NRY catalogue. title: type: string maxLength: 256 description: Short human-readable summary of the error class. message: type: string maxLength: 4096 description: Specific, actionable description of what went wrong. fields: type: object description: Per-field validation problems. additionalProperties: type: string examples: - code: NRY-0002 title: Session not found message: >- No session with id 6b9f6d2e-1c3a-4f5b-9d7e-2a8c4e6f0b1d exists on this host. responses: BadRequest: description: Malformed request — invalid parameter, cursor, or JSON body. content: application/json: schema: $ref: '#/components/schemas/Error' NotFound: description: The addressed resource does not exist on this host. content: application/json: schema: $ref: '#/components/schemas/Error' Conflict: description: >- The resource's current state rejects the request — archived session, busy lane, slot conflict, failed build, already-final state. content: application/json: schema: $ref: '#/components/schemas/Error' RequestBodyTooLarge: description: >- The request body weighs more than this operation accepts (NRY-0024). The host holds one ceiling per operation and refuses at the door, in front of every handler: a body whose declared Content-Length is past the ceiling is refused before a byte of it is read, and a body that declares no length is read only as far as the ceiling and refused there. Nothing was read past that point and nothing was written. content: application/json: schema: $ref: '#/components/schemas/Error' UnprocessableEntity: description: The request was well-formed but failed validation. content: application/json: schema: $ref: '#/components/schemas/Error' InternalServerError: description: The host failed — including a store that refuses writes (NRY-0012). content: application/json: schema: $ref: '#/components/schemas/Error' securitySchemes: bearerAuth: type: http scheme: bearer bearerFormat: JWT description: >- Enforced on every transport, with no exempt operation. A person's request — over the default local unix socket exactly as over a TCP listener — must carry a JWT issued by the configured identity provider, which the host verifies itself against that issuer's key set: signature, issuer, expiry, and the person and organisation it names. Requests without a valid one receive 401 NRY-0011. The socket's file permissions are transport and are not an authorisation. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.