> ## Documentation Index > Fetch the complete documentation index at: https://docs.erstan.com/llms.txt > Use this file to discover all available pages before exploring further. # Reply to a waiting run > Answers a pending `user_input` interaction and durably queues the same run to resume from its checkpoint. Only the same API key that started the run may reply. A simple `message` maps to the sole question; use `answers` for a multi-question interaction. Concurrent or repeated replies fail with `409` rather than replaying the checkpoint. Every request must echo the exact `pendingInteraction.interactionId` returned by `GET /v1/public/runs/{runId}`; a stale id cannot answer a later wait. ## OpenAPI ````yaml /openapi/public-api.yaml post /v1/public/runs/{runId}/reply openapi: 3.1.0 info: title: Erstan Public Agent API version: 1.2.0 description: >- Start published Erstan agents from external systems and poll for results. API keys carry scopes (`agents:list`, `agents:read`, `agents:write`, `agents:run`, `runs:read`, `tasks:execute`, `documents:read`, `documents:write`, `files:read`, `files:write`). Agent access follows the key creator's current workspace and team permissions. Project and team allowlists (`allowedProjectIds`, `allowedTeamIds`) further restrict task and document and file access. Agent draft authoring and task/document/file tools are exposed through the MCP server at `/v1/mcp` rather than REST routes. servers: - url: https://api.erstan.com description: Public endpoint security: - PublicApiKey: [] tags: - name: Agents description: >- Discover and run published agents available to the key creator under their current permissions. - name: Runs description: Read run status and results. - name: MCP description: >- Model Context Protocol server for external clients. Agent Builder tools use `agents:read`, `agents:write`, or both, plus the key creator's live Erstan permissions. Task and content tools also apply project/team allowlists. paths: /v1/public/runs/{runId}/reply: post: tags: - Runs summary: Reply to a waiting run description: >- Answers a pending `user_input` interaction and durably queues the same run to resume from its checkpoint. Only the same API key that started the run may reply. A simple `message` maps to the sole question; use `answers` for a multi-question interaction. Concurrent or repeated replies fail with `409` rather than replaying the checkpoint. Every request must echo the exact `pendingInteraction.interactionId` returned by `GET /v1/public/runs/{runId}`; a stale id cannot answer a later wait. operationId: replyToPublicRun parameters: - name: runId in: path required: true description: Waiting run ID returned by `POST /v1/public/agents/{agentId}/runs`. schema: type: string format: uuid requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/RunReplyRequest' examples: oneQuestion: value: interactionId: 8ed08c7f-21e6-47ee-a862-f9fbb7e46b74 message: '2' questionnaire: value: interactionId: 8ed08c7f-21e6-47ee-a862-f9fbb7e46b74 answers: iterations: '2' output_format: concise userMessage: Submitted the requested run settings. skip: value: interactionId: 8ed08c7f-21e6-47ee-a862-f9fbb7e46b74 skip: true responses: '202': description: Reply accepted and the run queued to resume. content: application/json: schema: $ref: '#/components/schemas/RunReplyResponse' '400': $ref: '#/components/responses/BadRequest' '401': $ref: '#/components/responses/Unauthorized' '403': $ref: '#/components/responses/Forbidden' '404': $ref: '#/components/responses/NotFound' '409': description: >- The run is not waiting for a reply, has a non-replyable interaction, or another reply already claimed it. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' '503': description: >- The reply was valid but could not be queued; the waiting state is restored and the caller may retry. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' security: - PublicApiKey: [] components: schemas: RunReplyRequest: type: object additionalProperties: false required: - interactionId properties: interactionId: type: string minLength: 1 maxLength: 512 description: Exact value from the current get_run pendingInteraction. message: type: string description: >- Free-text response; maps to the sole question when exactly one exists. userMessage: type: string description: User-facing transcript text and free-text response alias. answers: type: object additionalProperties: true description: >- Answers keyed by question ID for structured or multi-question interactions. answerLabels: type: object additionalProperties: true questionIds: type: array items: type: string action: type: string enum: - submit - skip skip: type: boolean skipped: type: boolean anyOf: - required: - message - required: - userMessage - required: - answers - required: - skip - required: - skipped - required: - action RunReplyResponse: type: object additionalProperties: false required: - runId - agentId - status properties: runId: type: string format: uuid agentId: type: string status: type: string const: running ErrorResponse: type: object required: - error properties: error: type: object required: - code - message properties: code: type: string message: type: string details: type: array items: $ref: '#/components/schemas/ErrorDetail' requestId: type: string ErrorDetail: type: object required: - code - message properties: field: type: string code: type: string message: type: string responses: BadRequest: description: Request validation failed. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' Unauthorized: description: Missing, invalid, expired, revoked, or inactive API key. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' Forbidden: description: >- The API key lacks scope or the creator lacks current permission for the requested operation. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' NotFound: description: The requested agent or run was not found. content: application/json: schema: $ref: '#/components/schemas/ErrorResponse' securitySchemes: PublicApiKey: type: http scheme: bearer bearerFormat: ers_live API key description: >- Workspace API key created in Erstan Settings. Keys carry scopes (`agents:list`, `agents:read`, `agents:write`, `agents:run`, `runs:read`, `tasks:execute`, `documents:read`, `documents:write`, `files:read`, `files:write`). Agent access follows the key creator's current workspace, team, and agent permissions. Agent draft creation requires `agents:write`; update, validation, and publishing require both `agents:read` and `agents:write`; draft testing also requires `agents:run`. Keys with `tasks:execute` must include at least one allowed project or team (`allowedProjectIds` / `allowedTeamIds`); keys with document or file scopes must include at least one allowed team. Empty allowlists mean no access — the API fails closed. ````