Understudy Labs Residency API

openapi: 3.1.0
info:
  title: Understudy Desktop Agent Capabilities Residency API
  version: 2.2.0
  description: Authenticated loopback API for agents operating a running Understudy Desktop app. The desktop capability file supplies the ephemeral base URL and bearer token. Prompts, images, traces, and model outputs remain local unless a caller explicitly selects a remote route.
servers:
- url: http://127.0.0.1:{port}
  description: Discovered from the private desktop capability file
  variables:
    port:
      default: '17790'
security:
- desktopBearer: []
tags:
- name: Residency
paths:
  /v1/residency:
    get:
      operationId: desktopResidency
      summary: Inspect local model residency and unified-memory budget
      responses:
        '200':
          description: Residency snapshot
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ResidencySnapshot'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
  /v1/residency/slots:
    post:
      operationId: desktopResidencyAddSlot
      summary: Add an empty local model residency slot
      responses:
        '200':
          description: Slot added
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SlotOperationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
  /v1/residency/assign:
    post:
      operationId: desktopResidencyAssign
      summary: Assign an installed model to a residency slot
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/AssignSlotRequest'
      responses:
        '200':
          description: Model assigned
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SlotOperationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
  /v1/residency/warm:
    post:
      operationId: desktopResidencyWarm
      summary: Warm the assigned model asynchronously
      requestBody:
        $ref: '#/components/requestBodies/SlotAction'
      responses:
        '200':
          description: Warm-up started
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SlotOperationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
  /v1/residency/cool:
    post:
      operationId: desktopResidencyCool
      summary: Stop the model process in a residency slot
      requestBody:
        $ref: '#/components/requestBodies/SlotAction'
      responses:
        '200':
          description: Slot cooled
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SlotOperationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
  /v1/residency/remove:
    post:
      operationId: desktopResidencyRemove
      summary: Remove a residency slot
      requestBody:
        $ref: '#/components/requestBodies/SlotAction'
      responses:
        '200':
          description: Slot removed
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/SlotOperationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
      tags:
      - Residency
components:
  requestBodies:
    SlotAction:
      required: true
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/SlotActionRequest'
  schemas:
    ErrorResponse:
      type: string
      description: A bounded plain-text error. Clients must not treat it as model output.
    SlotActionRequest:
      type: object
      required:
      - slot_id
      properties:
        slot_id:
          type: integer
          minimum: 1
      additionalProperties: false
    SlotOperationResponse:
      type: object
      required:
      - ok
      - slot_id
      properties:
        ok:
          const: true
        slot_id:
          type: integer
          minimum: 1
        state:
          type: string
      additionalProperties: true
    ResidencySnapshot:
      type: object
      required:
      - slots
      - used_gb
      - usable_gb
      properties:
        slots:
          type: array
          items:
            type: object
            required:
            - id
            - state
            properties:
              id:
                type: integer
                minimum: 1
              model_id:
                type:
                - string
                - 'null'
              model_path:
                description: Exact local weights path accepted by the slot's provider server.
                type:
                - string
                - 'null'
              state:
                type: string
                enum:
                - running
                - loading
                - stopped
                - error
            additionalProperties: true
        used_gb:
          type: number
          minimum: 0
        usable_gb:
          type: number
          minimum: 0
      additionalProperties: true
    AssignSlotRequest:
      type: object
      required:
      - slot_id
      - model_id
      properties:
        slot_id:
          type: integer
          minimum: 1
        model_id:
          type: string
          minLength: 1
      additionalProperties: false
  responses:
    Unauthorized:
      description: Missing or invalid desktop bearer token
      content:
        text/plain:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
    BadRequest:
      description: Invalid request
      content:
        text/plain:
          schema:
            $ref: '#/components/schemas/ErrorResponse'
  securitySchemes:
    desktopBearer:
      type: http
      scheme: bearer
      description: Ephemeral token read from the owner-only desktop capability file. Agents should use the Understudy CLI or MCP adapter instead of printing this token.
x-understudy-discovery:
  capability_file: ~/.understudy/desktop-api.json
  capability_schema: understudy.desktop_api.v2
  required_file_mode: '0600'
  recommended_adapter: understudy desktop
x-understudy-extension-surfaces:
  available_via_versioned_rest_mcp_and_cli:
  - runtime status
  - model inventory and certified catalog
  - model download lifecycle
  - residency slot lifecycle
  - local correction-pair export and supervision metrics
  not_yet_versioned_in_v2_rest:
  - conversation inspect, branch, compact, and resume
  - runtime and CLI diagnostics with repair actions
  - general capture export outside desktop supervision
  - resumable desktop-wide event subscription