> ## Documentation Index
> Fetch the complete documentation index at: https://headgate.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Emit a durable buffered workflow signal



## OpenAPI

````yaml /api/headgate.openapi.yaml post /workflows/{id}/signals
openapi: 3.1.0
info:
  title: headgate control API
  version: 0.1.0
  description: >
    The web UI is one client of this control API and gets no

    privileged access — asynqmon reads Redis directly, which is why its
    compatibility

    note is three minor versions stale.


    Both the Go and Rust implementations serve this spec, and the conformance
    suite

    asserts identical responses. Every list endpoint is bounded to prevent
    inspection

    from becoming an unbounded store operation: asynq's

    GetQueueInfo is O(number of groups) and has pinned Redis CPU for seconds in

    production. Monitoring caused the outage.


    DERIVED FROM THE ARCHITECTURE, NOT FROM A PREDECESSOR'S UI. The first draft
    of this

    spec was the asynq Inspector surface -- list by state, act on one job, pause
    a queue

    -- with new nouns bolted on. That inherited three problems: it omitted bulk

    operations, history, and enqueue (which asynq and apalis-board respectively
    DO have),

    and more importantly it had no endpoint for the question this system's own
    design

    creates. When dequeue is an admission decision, the operator's first
    question is not

    "what is in the queue" but "why is THIS job not running" -- see
    /jobs/{id}/admission.

    No predecessor needs that endpoint because no predecessor has a gate.
servers:
  - url: /api/v1
security: []
paths:
  /workflows/{id}/signals:
    post:
      summary: Emit a durable buffered workflow signal
      parameters:
        - $ref: '#/components/parameters/Id'
        - $ref: '#/components/parameters/IdempotencyKey'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              required:
                - signal
              properties:
                signal:
                  type: string
                  minLength: 1
                payload:
                  description: Arbitrary JSON value delivered with the signal.
                source:
                  description: >-
                    Caller-supplied JSON describing the emitter or calling
                    system; authenticate and populate it at a trusted upstream
                    boundary.
      responses:
        '200':
          description: Idempotent signal receipt including the original durable emission.
          content:
            application/json:
              schema:
                type: object
                required:
                  - matched
                  - promoted
                  - inserted
                  - emission
                properties:
                  matched:
                    type: integer
                    minimum: 1
                  promoted:
                    type: integer
                    minimum: 0
                  inserted:
                    type: boolean
                    description: >-
                      False when this idempotency key replayed an existing
                      emission.
                  emission:
                    $ref: '#/components/schemas/WorkflowSignal'
components:
  parameters:
    Id:
      name: id
      in: path
      required: true
      schema:
        type: string
    IdempotencyKey:
      name: Idempotency-Key
      in: header
      required: true
      schema:
        type: string
      description: >
        Required on every mutating request. A double-clicked Retry, or a proxy
        retrying a

        POST, must not enqueue the job twice. Keys are retained long enough to
        cover a

        client retry window and the response is replayed verbatim.
  schemas:
    WorkflowSignal:
      type: object
      required:
        - id
        - signal
        - idempotency_key
        - payload
        - source
        - recorded_at_ms
      properties:
        id:
          type: integer
          minimum: 1
        signal:
          type: string
        idempotency_key:
          type: string
        payload:
          description: Arbitrary JSON value supplied by the emitter
          limited to 64 KiB after canonical serialization.: null
        source:
          description: Caller-supplied JSON describing the emitter or calling system
          limited to 16 KiB; it is not proof of identity by itself.: null
        recorded_at_ms:
          type: integer
          description: Timestamp assigned by the backing store.

````