> ## 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. # Submit a message to a lane > Submits a message into a specific lane — the side conversation, or a subagent lane. Same 202 contract as the session-level message: a turn is accepted and its results stream over events, never on this response. One case answers 204 instead: a lane STOPPED on a question takes the message as the answer to that question, which unblocks the agent already running on it and opens no turn of its own. ## OpenAPI ````yaml /pt/openapi/v3-current/narya.yaml post /v1/sessions/{sessionId}/lanes/{laneId}/messages openapi: 3.1.0 info: title: Narya Host API version: 1.0.0 description: >- The contract between the Narya host and every client. On your own machine, 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. On your own machine, the host also accepts a request with no token from your own operating system user. Once signed-in work has claimed the home for an organization, it does so only while this machine is signed in to that organization. Such a request gets 401 with NRY-0011 on work that reaches your organization beyond the machine. An operation that declares another security scheme also accepts that credential. Any other 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}/lanes/{laneId}/messages: parameters: - $ref: '#/components/parameters/SessionIdParam' - $ref: '#/components/parameters/LaneIdParam' post: tags: - lanes summary: Submit a message to a lane description: >- Submits a message into a specific lane — the side conversation, or a subagent lane. Same 202 contract as the session-level message: a turn is accepted and its results stream over events, never on this response. One case answers 204 instead: a lane STOPPED on a question takes the message as the answer to that question, which unblocks the agent already running on it and opens no turn of its own. operationId: createLaneMessage requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/MessageCreate' responses: '202': description: Accepted; results stream over the event stream. content: application/json: schema: $ref: '#/components/schemas/TurnAccepted' '204': description: >- The message answered the question this lane was stopped on. The agent carries on inside the turn it was already running, so there is no new turn to correlate and no body to return. '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '409': $ref: '#/components/responses/Conflict' '413': description: >- The message's attachments together weigh more than one supplier request can carry (NRY-0027). Nothing was admitted; the bytes stored for the files earlier in the list were removed with the refusal. The same status answers a request body past this operation's own ceiling (NRY-0024), which the host refuses at the door before any handler reads it; the code says which of the two happened. content: application/json: schema: $ref: '#/components/schemas/Error' '422': $ref: '#/components/responses/UnprocessableEntity' '500': $ref: '#/components/responses/InternalServerError' '503': $ref: '#/components/responses/ProductNotLoaded' components: parameters: SessionIdParam: name: sessionId in: path required: true description: The session's id. schema: type: string format: uuid LaneIdParam: name: laneId in: path required: true description: The lane's id. schema: type: string format: uuid schemas: MessageCreate: type: object description: >- A user message submitted into a session or lane. Posted while work is running it is a steering message, queued and delivered between tool batches without discarding work already done. required: - content properties: content: type: string minLength: 1 description: The message text. attachments: type: array maxItems: 32 description: Absolute paths of files to attach. items: type: string maxLength: 4096 queueKind: type: string enum: - steer - follow-up default: steer description: >- While a turn is running, steer delivers after a complete tool batch and follow-up starts a fresh turn after turn-finished. During a final stream with no subsequent tool batch, steer is durably converted to follow-up with the same admitted entry and turn id. agent: type: string pattern: ^[^\s/\\]+$ maxLength: 128 description: >- Named agent recipe this message runs under: its prompt replaces the system prompt for the turn, its model overrides the session's, and its tool allowlist is the only catalogue the turn can see. The session's own behaviour when absent. Recorded on the admitted message, so the transcript says which agent each turn ran under — there is no session-wide current agent. Ignored on a side lane, exactly as LaneCreate ignores it there: a side conversation always runs the host's read-only explorer, and that is not the caller's to change on any road. idempotencyKey: type: string minLength: 1 maxLength: 255 description: >- A key the client chooses for this one message, so a send whose answer was lost can be repeated safely. A message carrying a key its session already holds admits nothing and starts nothing: it is answered as the first one was, 202 with its turn id or 204 when it answered a lane's question, whatever else this body says. Absent, every send is a new message. A message's key is stored with it and outlives a host restart; an answer's key is held by the running host only, so after a restart its resend is handled as a new send: it answers the question the lane asks then, or starts a turn. examples: - content: Run the ledger test suite and fix the flaky test. attachments: - /Users/dev/repos/midaz/components/ledger/test.log TurnAccepted: type: object description: >- Acknowledgement of a submitted message. Everything the turn produces streams over GET /v1/events, correlated by this turn id — never over the submitting response. required: - turnId properties: turnId: type: string format: uuid description: Correlates this turn's events on the stream. examples: - turnId: 4d8e2f6a-0b1c-4d3e-9f5a-7b9c1d3e5f0a 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' Unauthorized: description: >- Authentication required — a request carrying no valid identity token (NRY-0011). content: application/json: schema: $ref: '#/components/schemas/Error' Forbidden: description: >- The caller is authenticated and is not allowed this operation (NRY-0028 or NRY-0030). 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' 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' ProductNotLoaded: description: >- A product session's product has no tools loaded on this home yet (NRY-0021): nothing was admitted, and sending it again does. 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 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 — except a request with no token on a laptop's socket from the OS user the kernel names as the host's own, which is that machine's user. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.