> ## Documentation Index > Fetch the complete documentation index at: https://docs.protodesk.io/llms.txt > Use this file to discover all available pages before exploring further. # Send a reply > Sends as an agent on the conversation's channel. Email and WhatsApp delivery is queued atomically with the message; queued does not mean delivered. Chat replies appear in the visitor stream. Internal notes and test-thread replies stay in Protodesk. Requires messages:send; messages:write alone never authorizes delivery. Reuse the same Idempotency-Key and request body for uncertain retries. ## OpenAPI ````yaml POST /conversations/{conversationId}/send openapi: 3.1.0 info: title: Protodesk API version: 0.1.0 description: > The Protodesk Platform API: sync your customers in, attach your own business objects (orders, bookings, listings) to conversations, post and read messages across channels, and receive every workspace event via signed webhooks or a resumable SSE stream. Authenticate every request with a workspace-scoped API key: `Authorization: Bearer pk_live_...`. Create endpoints accept an `Idempotency-Key` header so retries are always safe. Lists use opaque cursor pagination (`data` / `hasMore` / `nextCursor`). Task-oriented guides: [docs.protodesk.io](https://docs.protodesk.io). servers: - url: https://api.protodesk.io/v1 description: Production - url: http://localhost:8080/v1 description: Local development security: [] tags: - name: Evelin description: >- Human-owned AI connections using the existing Evelin runtime. Generation never sends a customer message. - name: Customers description: People or companies contacting a workspace across channels. - name: Conversations description: Customer conversations attached to channels and external business objects. - name: Messages description: Customer, agent, AI, system, and internal messages inside conversations. - name: Channel identities description: >- The same customer across WhatsApp, email, chat, and more — linked identities per channel. - name: Statuses & priorities description: The workspace's conversation statuses and priority levels. - name: Assignments description: >- Who a conversation has been assigned to, over time. Assign via POST /conversations/{conversationId}/assign. - name: Webhooks description: Webhook subscriptions for receiving workspace events. - name: Realtime description: Server-sent event stream of workspace events. - name: API Keys description: Create, list, and revoke workspace API keys. - name: Account description: The workspace and scopes behind your API key. - name: System description: Service metadata and health endpoints. paths: /conversations/{conversationId}/send: post: tags: - Messages summary: Send a reply to a customer description: > Sends as an agent on the conversation's channel. Email and WhatsApp delivery is queued atomically with the message; queued does not mean delivered. Chat replies appear in the visitor stream. Internal notes and test-thread replies stay in Protodesk. Requires messages:send; messages:write alone never authorizes delivery. Reuse the same Idempotency-Key and request body for uncertain retries. operationId: sendMessage parameters: - name: conversationId in: path required: true schema: type: string - name: Idempotency-Key in: header required: true schema: type: string minLength: 8 maxLength: 255 requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/SendMessageRequest' responses: '201': description: >- Reply recorded; inspect queued and message.metadata.deliveryStatus for delivery state. headers: Idempotency-Replayed: $ref: '#/components/headers/IdempotencyReplayed' content: application/json: schema: $ref: '#/components/schemas/SendMessageResponse' default: $ref: '#/components/responses/Error' security: - ApiKeyAuth: [] components: schemas: SendMessageRequest: type: object additionalProperties: false properties: body: type: string description: Reply text; required unless attachments are provided. internal: type: boolean default: false description: Store an internal note without customer delivery. sendAt: type: string format: date-time description: Optional future email delivery time, at most 30 days ahead. attachments: type: array items: $ref: '#/components/schemas/MessageAttachmentInput' description: >- Durable /api/media references owned by this workspace; arbitrary URLs are not accepted for sending. SendMessageResponse: type: object required: - message - queued - undoMsec properties: message: $ref: '#/components/schemas/Message' queued: type: boolean description: True only when provider delivery has been durably queued. undoMsec: type: integer description: >- Normal undo window in milliseconds; zero for scheduled or unqueued replies. scheduledFor: type: string format: date-time MessageAttachmentInput: type: object additionalProperties: false properties: id: type: string url: type: string filename: type: string contentType: type: string sizeBytes: type: integer minimum: 0 metadata: type: object additionalProperties: true Message: type: object description: | Every key is always present; optional fields are null when unset. required: - id - externalId - conversationId - sender - body - channel - attachments - metadata - internal - createdAt properties: id: type: string example: msg_x6q5vl75f5d53m7oet2k4r5w6a externalId: type: - string - 'null' example: msg_123 conversationId: type: string example: conv_x6q5vl75f5d53m7oet2k4r5w6a sender: $ref: '#/components/schemas/MessageSender' body: type: string example: Hi, is this villa available for yearly rental? channel: type: string example: whatsapp attachments: type: array items: $ref: '#/components/schemas/Attachment' metadata: type: object additionalProperties: true internal: type: boolean createdAt: type: string format: date-time ErrorEnvelope: type: object required: - error properties: error: $ref: '#/components/schemas/Error' MessageSender: type: string enum: - customer - agent - ai - system Attachment: type: object description: > A file on a message, referenced by URL (and/or your own id). Every key is always present; unset fields are null. Provide at least id or url. required: - id - url - filename - contentType - sizeBytes - metadata properties: id: type: - string - 'null' description: Your external attachment id, if any. example: file_123 url: type: - string - 'null' format: uri example: https://example.com/files/inquiry.png filename: type: - string - 'null' example: inquiry.png contentType: type: - string - 'null' example: image/png sizeBytes: type: integer format: int64 minimum: 0 example: 12345 metadata: type: object additionalProperties: true example: kind: screenshot Error: type: object required: - code - message - requestId properties: code: type: string example: route.not_found message: type: string example: Not found requestId: type: string example: req_x6q5vl75f5d53m7oet2k4r5w6a headers: IdempotencyReplayed: description: Present with true when a response was replayed from an idempotency key. schema: type: string enum: - 'true' RequestId: description: Request id for tracing this request in logs and support. schema: type: string example: req_x6q5vl75f5d53m7oet2k4r5w6a RateLimitLimit: description: >- Request budget for the route class (read or write) applied to this request. schema: type: integer example: 40 RateLimitRemaining: description: Requests remaining in the current budget after this request. schema: type: integer example: 39 RateLimitReset: description: Seconds until the budget refills to its full limit. schema: type: integer example: 1 RetryAfter: description: Seconds to wait before retrying, sent with 429 responses. schema: type: integer example: 1 responses: Error: description: >- Error response. All /v1 responses carry RateLimit-Limit, RateLimit-Remaining, and RateLimit-Reset headers. A 429 (rate_limit.exceeded) additionally carries Retry-After. Request bodies exceeding the route-class limit (1KB reads, 64KB writes) return 413 (request.body_too_large). headers: X-Request-Id: $ref: '#/components/headers/RequestId' RateLimit-Limit: $ref: '#/components/headers/RateLimitLimit' RateLimit-Remaining: $ref: '#/components/headers/RateLimitRemaining' RateLimit-Reset: $ref: '#/components/headers/RateLimitReset' Retry-After: $ref: '#/components/headers/RetryAfter' content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' securitySchemes: ApiKeyAuth: type: http scheme: bearer bearerFormat: Protodesk API key description: > Use a workspace API key in the Authorization header. Keys use pk_live__ for production and pk_test__ for test mode. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.