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

# Create a new agent session



## OpenAPI

````yaml /api-reference/membrane-api.json post /agent/sessions
openapi: 3.0.0
info:
  title: Membrane API
  description: API documentation for Membrane Engine
  version: '1.0'
  contact: {}
servers:
  - url: https://api.getmembrane.com
security:
  - bearer: []
tags: []
paths:
  /agent/sessions:
    post:
      tags:
        - Sessions
      summary: Create a new agent session
      operationId: createAgentSession
      parameters: []
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateAgentSessionDto'
      responses:
        '200':
          description: ''
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AgentSessionDto'
components:
  schemas:
    CreateAgentSessionDto:
      type: object
      properties:
        workspaceElementType:
          type: string
          enum:
            - tenant
            - app
            - connector
            - integration
            - action
            - connection
            - data-table
            - data-table-record
            - data-sync
            - data-sync-run
            - external-event-subscription
            - external-event-log-record
            - external-event-pull
            - external-event-type
            - action-run-log-record
            - external-api-log-record
            - incoming-webhook-log-record
            - connected-product
            - external-agent
            - job
            - deliverable
            - deliverable-type
            - routine
            - task
            - canvas
            - file
            - knowledge-article
            - knowledge-sync
            - knowledge-sync-pull
        workspaceElementId:
          type: string
          minLength: 1
        prompt:
          type: string
          minLength: 1
        testTenantId:
          type: string
        isExternal:
          type: boolean
        modelId:
          type: string
          enum:
            - anthropic/claude-sonnet-5
            - anthropic/claude-sonnet-4.6
            - anthropic/claude-opus-4.6
            - anthropic/claude-sonnet-4.5
            - anthropic/claude-opus-4.5
            - anthropic/claude-haiku-4.5
            - openai/gpt-5.2
            - openai/gpt-5-nano
            - openai/gpt-4o-mini
            - google/gemini-3-pro-preview
            - moonshotai/kimi-k2.5
            - z-ai/glm-5.2
            - deepseek/deepseek-v4-pro
        preset:
          description: >-
            Which situation the agent runs in. Defaults from the bound element
            type, else `general`.
          type: string
          enum:
            - general
            - canvas
            - context
            - connection-build
            - action-build
            - task
            - work
            - universe
        surface:
          description: >-
            The UI surface this session is launched in — selects the affordance
            instruction the agent gets (whether it can render one-click buttons,
            whether a live user is watching, whether it is already inside the
            connect flow). Defaults to `background` for child / inline-build
            sessions, else unset.
          type: string
          enum:
            - console-chat
            - context-rail
            - table-chat
            - connect-popup
            - mcp-embedded
            - cli
            - desktop
            - background
            - default-external-agent
        launchContext:
          description: >-
            Where the session is launched from (surface / app route / anchored
            element). Merged with the top-level `surface` and
            `workspaceElementType`/`Id` fields (which win when both are set) and
            rendered into the agent's "Where you are" context.
          type: object
          properties:
            surface:
              description: >-
                The UI surface the session renders in (console chat, context
                rail, connect popup, …).
              type: string
              enum:
                - console-chat
                - context-rail
                - table-chat
                - connect-popup
                - mcp-embedded
                - cli
                - desktop
                - background
                - default-external-agent
            route:
              description: >-
                The app route the user was on when they launched the session,
                e.g. "/w/0?element=%2Fconnections%2F123".
              type: string
              maxLength: 2000
            element:
              description: >-
                The workspace element the launch is anchored to — the element
                the user is looking at, or an element type when launched from a
                list.
              type: object
              properties:
                type:
                  type: string
                  enum:
                    - tenant
                    - app
                    - connector
                    - integration
                    - action
                    - connection
                    - data-table
                    - data-table-record
                    - data-sync
                    - data-sync-run
                    - external-event-subscription
                    - external-event-log-record
                    - external-event-pull
                    - external-event-type
                    - action-run-log-record
                    - external-api-log-record
                    - incoming-webhook-log-record
                    - connected-product
                    - external-agent
                    - job
                    - deliverable
                    - deliverable-type
                    - routine
                    - task
                    - canvas
                    - file
                    - knowledge-article
                    - knowledge-sync
                    - knowledge-sync-pull
                id:
                  type: string
                  minLength: 1
              required:
                - type
        agentHarnessId:
          type: string
          minLength: 1
        promptAttachments:
          type: array
          items:
            type: object
            properties:
              title:
                type: string
              data:
                type: object
            required:
              - title
              - data
        parentSessionId:
          type: string
          minLength: 1
        synthetic:
          description: >-
            When true, the initial prompt is a hidden system kickoff: the model
            receives it, but the chat UI suppresses the user bubble. Mirrors the
            resume-path `synthetic` flag.
          type: boolean
      required:
        - prompt
    AgentSessionDto:
      type: object
      properties:
        userId:
          type: string
        tenantId:
          type: string
        ownerName:
          type: string
          nullable: true
        id:
          type: string
        workspaceId:
          type: string
        orgWorkspaceId:
          type: string
        workspaceElementType:
          type: string
          enum:
            - tenant
            - app
            - connector
            - integration
            - action
            - connection
            - data-table
            - data-table-record
            - data-sync
            - data-sync-run
            - external-event-subscription
            - external-event-log-record
            - external-event-pull
            - external-event-type
            - action-run-log-record
            - external-api-log-record
            - incoming-webhook-log-record
            - connected-product
            - external-agent
            - job
            - routine
            - task
            - canvas
            - knowledge-article
            - knowledge-sync
            - knowledge-sync-pull
        workspaceElementId:
          type: string
        type:
          type: string
        status:
          type: string
          enum:
            - queued
            - starting
            - running
            - completed
            - failed
            - cancelled
        prompt:
          type: string
        error:
          $ref: '#/components/schemas/AgentSessionDto__schema0'
        lastActivityAt:
          type: string
          format: date-time
          pattern: >-
            ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
          description: >-
            Last meaningful session progress timestamp used for inactivity
            timeout checks.
        archivedAt:
          description: >-
            When set, the session is archived (soft-deleted) and hidden from
            lists.
          type: string
          format: date-time
          pattern: >-
            ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
        title:
          type: string
        summary:
          type: string
        cost:
          type: number
        state:
          default: busy
          type: string
          enum:
            - busy
            - idle
        hasWorker:
          type: boolean
        isExternal:
          type: boolean
        preset:
          description: >-
            Which situation the one membrane agent runs in — selects the skills
            + context it loads.
          type: string
          enum:
            - general
            - canvas
            - context
            - connection-build
            - action-build
            - task
            - work
            - universe
        launchContext:
          description: >-
            Where the session was launched from — the resolved surface / route /
            element envelope shared by the console UI and the agent.
          type: object
          properties:
            surface:
              description: >-
                The UI surface the session renders in (console chat, context
                rail, connect popup, …).
              type: string
              enum:
                - console-chat
                - context-rail
                - table-chat
                - connect-popup
                - mcp-embedded
                - cli
                - desktop
                - background
            route:
              description: >-
                The app route the user was on when they launched the session,
                e.g. "/w/0?element=%2Fconnections%2F123".
              type: string
              maxLength: 2000
            element:
              description: >-
                The workspace element the launch is anchored to — the element
                the user is looking at, or an element type when launched from a
                list.
              type: object
              properties:
                type:
                  type: string
                  enum:
                    - tenant
                    - app
                    - connector
                    - integration
                    - action
                    - connection
                    - data-table
                    - data-table-record
                    - data-sync
                    - data-sync-run
                    - external-event-subscription
                    - external-event-log-record
                    - external-event-pull
                    - external-event-type
                    - action-run-log-record
                    - external-api-log-record
                    - incoming-webhook-log-record
                    - connected-product
                    - external-agent
                    - job
                    - routine
                    - task
                    - canvas
                    - knowledge-article
                    - knowledge-sync
                    - knowledge-sync-pull
                id:
                  type: string
                  minLength: 1
              required:
                - type
        agentHarnessId:
          type: string
        agentHarnessSnapshotId:
          type: string
        output:
          type: object
          additionalProperties:
            type: object
        outputAttachments:
          type: array
          items:
            type: object
            properties:
              title:
                type: string
              data:
                type: object
            required:
              - title
              - data
        parentSessionId:
          type: string
        createdAt:
          type: string
          format: date-time
          pattern: >-
            ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
        updatedAt:
          type: string
          format: date-time
          pattern: >-
            ^(?:(?:\d\d[2468][048]|\d\d[13579][26]|\d\d0[48]|[02468][048]00|[13579][26]00)-02-29|\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\d|30)|(?:02)-(?:0[1-9]|1\d|2[0-8])))T(?:(?:[01]\d|2[0-3]):[0-5]\d(?::[0-5]\d(?:\.\d+)?)?(?:Z))$
      required:
        - id
        - workspaceId
        - type
        - status
        - prompt
        - lastActivityAt
        - hasWorker
        - createdAt
        - updatedAt
    AgentSessionDto__schema0:
      type: object
      properties:
        type:
          type: string
          enum:
            - bad_request
            - connection
            - configuration
            - dependency_error
            - flow_run
            - flow_instance_setup
            - concurrency
            - internal
            - action_run
            - action_instance_setup
            - unit_run
            - custom_code
            - insufficient_credit
            - openrouter_not_configured
        key:
          type: string
        message:
          type: string
        data:
          type: object
        stack:
          type: object
        causedByError:
          $ref: '#/components/schemas/AgentSessionDto__schema0'
        logs:
          type: array
          items:
            type: object
      required:
        - message
  securitySchemes:
    bearer:
      scheme: bearer
      bearerFormat: JWT
      type: http

````