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

# Start a new session (deprecated)

> Deprecated. Use `POST /v1/sessions` instead. The legacy route wraps the session object under a `session` key; the v1 route accepts a bare session object.




## OpenAPI

````yaml https://raw.githubusercontent.com/honeyhiveai/honeyhive-openapi/main/openapi.yaml post /session/start
openapi: 3.1.0
info:
  title: HoneyHive Data Plane API
  license:
    name: MIT
    url: https://opensource.org/licenses/MIT
  version: 1.2.1
servers:
  - url: https://api.honeyhive.ai
security:
  - BearerAuth: []
tags:
  - name: Charts
    description: >
      Define and manage saved charts. Charts are visualizations that aggregate
      metrics over time with bucketing, filters, and groupings.
  - name: Configurations
    description: >
      Manage prompt configurations, i.e. model parameters, message templates,
      and response settings that can be versioned and deployed without code
      changes.
  - name: Datapoints
    description: >
      Manage individual records inside datasets, including batch creation and
      mapping to source events.
  - name: Datasets
    description: >
      Curate collections of datapoints used as test sets for evaluations and
      experiments.
  - name: Events
    description: >
      Read and write trace events. Events are the spans that capture every step
      of an AI application's execution.
  - name: Experiments
    description: >
      Run, retrieve, and compare evaluation runs to measure how prompt or
      configuration changes affect agent performance.
  - name: Metric Versions
    description: >
      Snapshot, list, and deploy versions of a metric's definition so changes
      can be reviewed and rolled back without losing history.
  - name: Metrics
    description: >
      Define and run evaluators, i.e. automated quality checks that score traces
      against criteria like accuracy, safety, or correctness.
  - name: Queues
    description: >
      Manage annotation queues for human review of traces, turning expert
      feedback into labeled datasets.
  - name: Sessions
    description: >
      Group related trace events into sessions, the top-level container for a
      multi-step or multi-service AI interaction.
paths:
  /session/start:
    post:
      tags:
        - Sessions
      summary: Start a new session (deprecated)
      description: >
        Deprecated. Use `POST /v1/sessions` instead. The legacy route wraps the
        session object under a `session` key; the v1 route accepts a bare
        session object.
      operationId: startSessionLegacy
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/LegacyStartSessionRequest'
      responses:
        '200':
          description: Session successfully started
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PostSessionStartResponse'
      deprecated: true
components:
  schemas:
    LegacyStartSessionRequest:
      type: object
      properties:
        session:
          $ref: '#/components/schemas/LegacyStartSessionRequestSession'
      required:
        - session
      description: >-
        Request body for POST /session/start (deprecated — use POST
        /v1/sessions)
      deprecated: true
    PostSessionStartResponse:
      type: object
      properties:
        event_id:
          type: string
        session_id:
          type: string
        parent_id:
          type:
            - string
            - 'null'
        children_ids:
          type: array
          items:
            type: string
        event_type:
          type:
            - string
            - 'null'
        event_name:
          type:
            - string
            - 'null'
        config: {}
        inputs: {}
        outputs: {}
        error:
          type:
            - string
            - 'null'
        source:
          type:
            - string
            - 'null'
        duration:
          type:
            - number
            - 'null'
        user_properties: {}
        metrics: {}
        feedback: {}
        metadata: {}
        org_id:
          type: string
        workspace_id:
          type: string
        project_id:
          type: string
        start_time:
          type:
            - number
            - 'null'
        end_time:
          type:
            - number
            - 'null'
      required:
        - event_id
        - session_id
        - org_id
        - workspace_id
        - project_id
      additionalProperties: {}
      description: Full session event object returned after starting a new session
    LegacyStartSessionRequestSession:
      type: object
      properties:
        session_id:
          type: string
          description: Client-provided session ID (server generates one if omitted)
        session_name:
          type: string
          description: Display name for the session
        event_name:
          type: string
          description: Fallback name if session_name is not provided
        source:
          type: string
          description: Source of the session (e.g., sdk-python)
        start_time:
          type: number
          description: Session start time as Unix milliseconds
        end_time:
          type: number
          description: Session end time as Unix milliseconds
        duration:
          type: number
          description: Session duration in milliseconds
        config:
          type: object
          additionalProperties: {}
          description: Configuration associated with the session
        inputs:
          type: object
          additionalProperties: {}
          description: Input data for the session
        outputs:
          type: object
          additionalProperties: {}
          description: Output data from the session
        metadata:
          type: object
          additionalProperties: {}
          description: Arbitrary metadata for the session
        user_properties:
          type: object
          additionalProperties: {}
          description: User properties associated with the session
        children_ids:
          type: array
          items:
            type: string
          description: IDs of child events in this session
      additionalProperties: {}
  securitySchemes:
    BearerAuth:
      type: http
      scheme: bearer

````