> ## Documentation Index > Fetch the complete documentation index at: https://doc.featherhq.com/llms.txt > Use this file to discover all available pages before exploring further. # Run one v2 conversation turn with an SSE response > SSE counterpart to ``POST /conversations/{id}/turns``. Token streaming: the v2 ``ConversationTurnDriver`` prepares a snapshot, computes without a checked-out connection, and then finalizes atomically. It accepts an ``on_token`` callback that the orchestrators/runnables fire as the *answer* streams (speculative losers and transferring members are filtered upstream — a Supervisor buffers the speculation and flushes only on ``continue``). We bridge that push-callback to this pull-generator with an :class:`asyncio.Queue`: the driver runs as a task that enqueues each token delta, and the generator drains the queue into ``delta`` frames as they arrive. When the driver finishes we emit a ``complete`` frame carrying the v2 ``TurnResponse`` JSON (including the server-measured ``turn_ttft_ms``). The wire contract (``delta`` / ``complete`` / ``error`` frames) matches ``/v1/runtime/turn/stream`` so the UI needs no change. DB session lifecycle: the per-request ``session`` commits admission before the response is constructed, is connection-free while the driver task computes, and commits finalization before the ``complete`` frame. The generator only touches the session after the driver task has finished, so the two never race on it. ## OpenAPI ````yaml /api-reference/openapi.json post /v1/conversations/{conversation_id}/turns/stream openapi: 3.1.0 info: title: Feather API description: >- Unified customer experience platform API. Manages identity, conversations, memory, agents, procedures, policies, model routing, knowledge bases, integrations, and runtime execution. version: 1.87.0 servers: - url: https://api-sandbox.featherhq.com description: Sandbox - url: http://localhost:8000 description: Local dev security: [] paths: /v1/conversations/{conversation_id}/turns/stream: post: tags: - conversations summary: Run one v2 conversation turn with an SSE response description: >- SSE counterpart to ``POST /conversations/{id}/turns``. Token streaming: the v2 ``ConversationTurnDriver`` prepares a snapshot, computes without a checked-out connection, and then finalizes atomically. It accepts an ``on_token`` callback that the orchestrators/runnables fire as the *answer* streams (speculative losers and transferring members are filtered upstream — a Supervisor buffers the speculation and flushes only on ``continue``). We bridge that push-callback to this pull-generator with an :class:`asyncio.Queue`: the driver runs as a task that enqueues each token delta, and the generator drains the queue into ``delta`` frames as they arrive. When the driver finishes we emit a ``complete`` frame carrying the v2 ``TurnResponse`` JSON (including the server-measured ``turn_ttft_ms``). The wire contract (``delta`` / ``complete`` / ``error`` frames) matches ``/v1/runtime/turn/stream`` so the UI needs no change. DB session lifecycle: the per-request ``session`` commits admission before the response is constructed, is connection-free while the driver task computes, and commits finalization before the ``complete`` frame. The generator only touches the session after the driver task has finished, so the two never race on it. operationId: runV2ConversationTurnStream parameters: - name: conversation_id in: path required: true schema: type: string format: uuid title: Conversation Id - name: trace in: query required: false schema: type: boolean default: false title: Trace requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/TurnRequest' responses: '200': description: Successful Response content: application/json: schema: {} '400': description: Bad request content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '401': description: Authentication required content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '404': description: Resource not found content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '409': description: >- The conversation changed during computation. Safe to retry after the advertised delay; model and tool work was not replayed internally. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '422': description: Validation Error content: application/json: schema: $ref: '#/components/schemas/HTTPValidationError' '503': description: >- The turn outcome is uncertain after output, a possible external action, or an unresolved commit. Do not retry automatically. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: - APIKeyHeader: [] components: schemas: TurnRequest: properties: user_message: type: string title: User Message for_update: type: boolean title: For Update description: >- Deprecated compatibility field; all turns use optimistic guarded finalization and this value has no effect. default: false deprecated: true include_evidence: type: boolean title: Include Evidence default: false evidence_view: type: string enum: - display - full title: Evidence View default: display type: object required: - user_message title: TurnRequest description: Drive one turn of a v2 conversation (Phase F1). ErrorResponse: properties: error: type: string title: Error message: type: string title: Message retryable: anyOf: - type: boolean - type: 'null' title: Retryable retry_after: anyOf: - type: integer - type: 'null' title: Retry After type: object required: - error - message title: ErrorResponse description: Standard error response returned by all API error handlers. HTTPValidationError: properties: detail: items: $ref: '#/components/schemas/ValidationError' type: array title: Detail type: object title: HTTPValidationError ValidationError: properties: loc: items: anyOf: - type: string - type: integer type: array title: Location msg: type: string title: Message type: type: string title: Error Type input: title: Input ctx: type: object title: Context type: object required: - loc - msg - type title: ValidationError securitySchemes: APIKeyHeader: type: apiKey in: header name: x-api-key ````