openapi: 3.0.3
info:
  title: tRPC OpenAPI Example
  description: >-
    This is a representative OpenAPI specification demonstrating how tRPC procedures
    are exposed as REST endpoints using the trpc-openapi adapter. tRPC itself is a
    TypeScript framework for building end-to-end typesafe APIs. When combined with
    trpc-openapi (or trpc-to-openapi), tRPC procedures are mapped to standard HTTP
    REST endpoints with full OpenAPI documentation.

    This spec represents the standard HTTP API surface exposed by a tRPC server
    using the fetch or standalone adapter, following tRPC's HTTP protocol conventions.
  version: 11.0.0
  contact:
    name: tRPC
    url: https://trpc.io
  license:
    name: MIT
    url: https://github.com/trpc/trpc/blob/main/LICENSE
servers:
  - url: https://your-server.example.com/api/trpc
    description: tRPC server endpoint
security:
  - BearerAuth: []
tags:
  - name: Procedures
    description: tRPC procedures exposed as REST endpoints
  - name: Router
    description: tRPC router metadata
paths:
  /health:
    get:
      summary: Health Check
      description: >-
        Returns the health status of the tRPC server. This is a standard
        unauthenticated endpoint for monitoring and load balancer health checks.
      operationId: healthCheck
      tags:
        - Procedures
      security: []
      responses:
        '200':
          description: Server is healthy
          content:
            application/json:
              schema:
                type: object
                properties:
                  ok:
                    type: boolean
                    example: true
  /batch:
    post:
      summary: Batch Procedures
      description: >-
        Execute multiple tRPC procedures in a single HTTP request. tRPC clients
        automatically batch requests made concurrently using httpBatchLink.
      operationId: batchProcedures
      tags:
        - Procedures
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              description: >-
                A map of procedure call index to the procedure input.
                Keys are numeric indices (0, 1, 2...) for each procedure.
              additionalProperties:
                type: object
                properties:
                  json:
                    description: Procedure input serialized as JSON
      responses:
        '207':
          description: Multi-status batch response
          content:
            application/json:
              schema:
                type: array
                items:
                  oneOf:
                    - $ref: '#/components/schemas/TRPCSuccessResult'
                    - $ref: '#/components/schemas/TRPCErrorResult'
        '400':
          $ref: '#/components/responses/BadRequest'
  /{procedure}:
    get:
      summary: Query Procedure
      description: >-
        Invoke a tRPC query procedure. Queries are read-only operations and
        map to HTTP GET requests. Input is passed via the `input` query parameter
        as a JSON-encoded string.
      operationId: queryProcedure
      tags:
        - Procedures
      parameters:
        - name: procedure
          in: path
          required: true
          description: >-
            The procedure path (e.g., `userRouter.getUser`, `post.list`).
            Nested routers use dot notation.
          schema:
            type: string
        - name: input
          in: query
          description: JSON-encoded procedure input
          schema:
            type: string
        - name: batch
          in: query
          description: Enables batching mode for this single request
          schema:
            type: string
            enum:
              - "1"
      responses:
        '200':
          description: Procedure result
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TRPCSuccessResult'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
    post:
      summary: Mutation Procedure
      description: >-
        Invoke a tRPC mutation procedure. Mutations cause side effects and
        map to HTTP POST requests. Input is passed in the request body.
      operationId: mutationProcedure
      tags:
        - Procedures
      parameters:
        - name: procedure
          in: path
          required: true
          description: The mutation procedure path
          schema:
            type: string
      requestBody:
        required: false
        content:
          application/json:
            schema:
              type: object
              properties:
                json:
                  description: Procedure input
      responses:
        '200':
          description: Procedure result
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TRPCSuccessResult'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
components:
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer
      description: Bearer token for protected procedures
  schemas:
    TRPCSuccessResult:
      type: object
      description: A successful tRPC procedure result
      properties:
        result:
          type: object
          properties:
            data:
              description: The procedure output, serialized as JSON
              type: object
              properties:
                json:
                  description: The actual return value from the procedure
    TRPCErrorResult:
      type: object
      description: A tRPC procedure error result
      properties:
        error:
          type: object
          properties:
            json:
              type: object
              properties:
                message:
                  type: string
                  description: Human-readable error message
                code:
                  type: integer
                  description: tRPC error code
                data:
                  type: object
                  properties:
                    code:
                      type: string
                      description: tRPC error type (e.g., NOT_FOUND, UNAUTHORIZED)
                    httpStatus:
                      type: integer
                    stack:
                      type: string
                      description: Stack trace (development only)
                    path:
                      type: string
                      description: The procedure path that errored
    TRPCRouter:
      type: object
      description: A tRPC router definition with procedures
      properties:
        procedures:
          type: object
          additionalProperties:
            $ref: '#/components/schemas/TRPCProcedure'
    TRPCProcedure:
      type: object
      description: A single tRPC procedure (query, mutation, or subscription)
      properties:
        type:
          type: string
          enum:
            - query
            - mutation
            - subscription
        input:
          type: object
          description: Zod schema for input validation
        output:
          type: object
          description: Zod schema for output validation
        meta:
          type: object
          description: Procedure metadata including OpenAPI mapping
  responses:
    BadRequest:
      description: Bad request - invalid input or procedure not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/TRPCErrorResult'
    Unauthorized:
      description: Unauthorized - protected procedure requires authentication
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/TRPCErrorResult'
    NotFound:
      description: Procedure not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/TRPCErrorResult'