InstantDB Realtime Sync API

asyncapi: '2.6.0'
id: 'urn:com:instantdb:runtime:session'
info:
  title: InstantDB Realtime Sync (WebSocket)
  version: '1.0.0'
  description: |
    AsyncAPI 2.6 description of InstantDB's **realtime sync** surface.

    Unlike a request/response REST API, InstantDB is a sync engine. The client
    SDK's **Reactor** opens a persistent WebSocket connection to
    `wss://api.instantdb.com/runtime/session` and exchanges JSON messages with
    the server's session manager. Each message is a JSON object whose `op`
    field names the operation. The client sends ops such as `init`,
    `add-query`, `remove-query`, `transact`, `set-presence`, `join-room`,
    `leave-room`, and `client-broadcast`; the server replies with and pushes
    ops such as `init-ok`, `add-query-ok`, `refresh-ok`, `transact-ok`,
    `patch-presence`, `refresh-presence`, `server-broadcast`, and `error`.

    The server tails the Postgres write-ahead log to detect novelty, then
    invalidates and re-pushes affected queries to subscribed clients via
    `refresh-ok` without any client polling. This is a genuine bidirectional
    WebSocket transport (RFC 6455), not HTTP Server-Sent Events.

    The companion server-side HTTP Admin API (POST /admin/query,
    POST /admin/transact, auth, storage) is modeled in
    `openapi/instantdb-openapi.yml`.
  contact:
    name: API Evangelist
    email: kin@apievangelist.com
    url: https://apievangelist.com
  license:
    name: API documentation - InstantDB Terms of Service
    url: https://www.instantdb.com/terms
  x-transport-notes:
    transport: WebSocket (RFC 6455)
    protocol: wss
    endpoint: wss://api.instantdb.com/runtime/session
    direction: bidirectional
    mediaType: application/json
    messageEnvelope: 'JSON object with an `op` discriminator field'
    novelty: 'Server tails Postgres WAL and pushes refresh-ok to affected subscribers'
    notSSE: true
    source: https://www.instantdb.com/essays/architecture
defaultContentType: application/json
servers:
  runtime:
    url: api.instantdb.com/runtime/session
    protocol: wss
    description: |
      InstantDB realtime sync endpoint. The client Reactor connects here over
      a secure WebSocket (wss://) and authenticates within the `init` message
      by sending the app id and a refresh token. All subsequent query
      subscriptions, transactions, presence, and broadcasts flow over this
      single connection.
channels:
  /runtime/session:
    description: |
      The single multiplexed WebSocket channel for an Instant app session.
      The client publishes operation messages (init, add-query, transact,
      presence, room, broadcast) and subscribes to the server's
      acknowledgements and pushed novelty. Messages are correlated with a
      client-generated `client-event-id`.
    bindings:
      ws:
        bindingVersion: '0.1.0'
    publish:
      operationId: sendClientOps
      summary: Operations the client Reactor sends to the sync server.
      description: |
        Each message is a JSON object with an `op` field. `init` must be sent
        first to authenticate and establish the session; afterwards the client
        registers queries, applies transactions, and manages presence/rooms.
      message:
        oneOf:
          - $ref: '#/components/messages/Init'
          - $ref: '#/components/messages/AddQuery'
          - $ref: '#/components/messages/RemoveQuery'
          - $ref: '#/components/messages/Transact'
          - $ref: '#/components/messages/JoinRoom'
          - $ref: '#/components/messages/LeaveRoom'
          - $ref: '#/components/messages/SetPresence'
          - $ref: '#/components/messages/ClientBroadcast'
    subscribe:
      operationId: receiveServerOps
      summary: Operations the sync server pushes to the client.
      description: |
        The server acknowledges client ops and proactively pushes query
        novelty and presence. `refresh-ok` carries updated query results
        whenever the server detects relevant changes in Postgres.
      message:
        oneOf:
          - $ref: '#/components/messages/InitOk'
          - $ref: '#/components/messages/AddQueryOk'
          - $ref: '#/components/messages/RefreshOk'
          - $ref: '#/components/messages/TransactOk'
          - $ref: '#/components/messages/JoinRoomOk'
          - $ref: '#/components/messages/PatchPresence'
          - $ref: '#/components/messages/RefreshPresence'
          - $ref: '#/components/messages/ServerBroadcast'
          - $ref: '#/components/messages/ErrorMessage'
components:
  messages:
    Init:
      name: init
      title: Initialize session
      summary: Authenticate and open the session.
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - app-id
        properties:
          op:
            type: string
            const: init
          app-id:
            type: string
          'refresh-token':
            type: string
            description: Optional auth token for the current user.
          'client-event-id':
            type: string
          versions:
            type: object
            description: SDK package versions (e.g. '@instantdb/core').
            additionalProperties:
              type: string
    AddQuery:
      name: add-query
      title: Subscribe to a query
      summary: Register an InstaQL query for live updates.
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - q
        properties:
          op:
            type: string
            const: add-query
          q:
            type: object
            description: An InstaQL query object.
            additionalProperties: true
          'client-event-id':
            type: string
    RemoveQuery:
      name: remove-query
      title: Unsubscribe from a query
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - q
        properties:
          op:
            type: string
            const: remove-query
          q:
            type: object
            additionalProperties: true
          'client-event-id':
            type: string
    Transact:
      name: transact
      title: Apply a transaction
      summary: Send InstaML transaction steps over the socket.
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - 'tx-steps'
        properties:
          op:
            type: string
            const: transact
          'tx-steps':
            type: array
            items:
              type: array
          'client-event-id':
            type: string
    JoinRoom:
      name: join-room
      title: Join a presence room
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - 'room-id'
        properties:
          op:
            type: string
            const: join-room
          'room-id':
            type: string
          'client-event-id':
            type: string
    LeaveRoom:
      name: leave-room
      title: Leave a presence room
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - 'room-id'
        properties:
          op:
            type: string
            const: leave-room
          'room-id':
            type: string
          'client-event-id':
            type: string
    SetPresence:
      name: set-presence
      title: Set presence data
      summary: Publish this client's ephemeral presence into a room.
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - 'room-id'
        properties:
          op:
            type: string
            const: set-presence
          'room-id':
            type: string
          data:
            type: object
            additionalProperties: true
          'client-event-id':
            type: string
    ClientBroadcast:
      name: client-broadcast
      title: Broadcast a topic message
      summary: Send an ephemeral topic event to others in a room.
      contentType: application/json
      payload:
        type: object
        required:
          - op
          - 'room-id'
          - topic
        properties:
          op:
            type: string
            const: client-broadcast
          'room-id':
            type: string
          topic:
            type: string
          data:
            type: object
            additionalProperties: true
          'client-event-id':
            type: string
    InitOk:
      name: init-ok
      title: Session initialized
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: init-ok
          'session-id':
            type: string
          'client-event-id':
            type: string
    AddQueryOk:
      name: add-query-ok
      title: Query registered
      summary: Acknowledges a query subscription and returns initial results.
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: add-query-ok
          q:
            type: object
            additionalProperties: true
          result:
            type: array
            items:
              type: object
              additionalProperties: true
          'client-event-id':
            type: string
    RefreshOk:
      name: refresh-ok
      title: Query novelty pushed
      summary: Server-pushed updated results when underlying data changes.
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: refresh-ok
          computations:
            type: array
            description: Updated query computations and their results.
            items:
              type: object
              additionalProperties: true
          attrs:
            type: array
            items:
              type: object
              additionalProperties: true
    TransactOk:
      name: transact-ok
      title: Transaction committed
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: transact-ok
          'tx-id':
            type: integer
          'client-event-id':
            type: string
    JoinRoomOk:
      name: join-room-ok
      title: Room joined
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: join-room-ok
          'room-id':
            type: string
          'client-event-id':
            type: string
    PatchPresence:
      name: patch-presence
      title: Presence patch
      summary: Incremental presence change for peers in a room.
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: patch-presence
          'room-id':
            type: string
          edits:
            type: array
            items:
              type: object
              additionalProperties: true
    RefreshPresence:
      name: refresh-presence
      title: Full presence refresh
      summary: Full presence snapshot for a room.
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: refresh-presence
          'room-id':
            type: string
          data:
            type: object
            additionalProperties: true
    ServerBroadcast:
      name: server-broadcast
      title: Broadcast received
      summary: A topic event broadcast by another client in the room.
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: server-broadcast
          'room-id':
            type: string
          topic:
            type: string
          data:
            type: object
            additionalProperties: true
    ErrorMessage:
      name: error
      title: Error
      summary: An error tied to a prior client op (by client-event-id).
      contentType: application/json
      payload:
        type: object
        required:
          - op
        properties:
          op:
            type: string
            const: error
          status:
            type: integer
          message:
            type: string
          type:
            type: string
          'client-event-id':
            type: string
  securitySchemes:
    refreshToken:
      type: userPassword
      description: >-
        Authentication is performed inside the `init` message by supplying the
        app id and an optional user refresh token; there is no separate
        WebSocket auth header.