> ## Documentation Index > Fetch the complete documentation index at: https://docs.isnap.ai/llms.txt > Use this file to discover all available pages before exploring further. # Mark a chat as read > Sets read_at on the unread inbound messages of a chat and asks the line's device to send read receipts. * **Credential:** an API key. A trial key returns `401 unauthorized`. See [Read receipts](/guides/conversations#read-receipts). * **Line-scoped keys:** the list of a [line-scoped key](/authentication#line-scoped-keys) is not applied: such a key acts on any chat of the account. * **Test keys:** a call with an `isnap_test_` account key acts on the real chat: see [Test keys](/authentication#test-keys). * **`Idempotency-Key`:** not honored. A repeat marks only the inbound messages received since the previous call. * **Events:** sends one `message.read` per message marked, with `chat_id` and `read_at`. * **Personal data:** each `message.read` carries the whole message: its text, the sender's handle and the names of its files. The call marks every inbound message of the chat that iSnap still keeps and that is not marked read, including the messages that an earlier owner of the line received: ignore the events about messages from before you got the line, see [A chat is never deleted](/guides/receiving-messages#a-chat-is-never-deleted). Request this data only when needed, do not copy it into logs, tickets or other tools, and refer to a contact by an id of your own. * **What reaches the contact:** the line's device marks the Messages conversation read when it supports read receipts. Otherwise nothing reaches the contact, and the call still succeeds. The `status` of the marked messages stays `delivered`. ## Errors | Status | `error.code` | When | | - | - | - | | 404 | `not_found` | The chat is unknown, or its line is not yours. | | 422 | `sms_read_receipt_not_supported` | The chat's line is not an iMessage line. | | 422 | `unsupported_handle` | The chat's contact is not a phone number in E.164. | The errors that every operation shares are in [Errors](/errors-and-rate-limits#errors). ## OpenAPI ````yaml POST /v1/chats/{chat_id}/read openapi: 3.0.0 info: title: iSnap API version: 2.45.0 description: >- The iSnap API sends and receives iMessage, RCS and SMS on real phone lines, manages those lines, and reports events through webhooks. Every message is sent to a real recipient, with an `isnap_live_` key and with an `isnap_test_` key alike. Retry a `429` after `Retry-After` seconds. Retry a `500` or a `503` up to 2 times, with exponential backoff. Do not retry any other `4xx`: fix the request. Retry a write only on an operation that honors `Idempotency-Key`, with the key of the first attempt. Responses carry personal data: handles, names and message text. servers: - url: https://api.isnap.ai security: - bearerAuth: [] paths: /v1/chats/{chat_id}/read: post: summary: Mark a chat as read description: >- Sets `read_at` to the current time on every inbound message of the chat that has none, and asks the line's device to send read receipts to the contact. Returns `200` with `read_at` and `marked_count`, the number of messages this request marked: 0 when none was unread. Sends one `message.read` event for each message it marks, with `chat_id` and `read_at`. The `status` of those messages stays `delivered`, and the `unread_count` of the chat does not change. Each `message.read` carries the whole message: its text, the sender's handle and the names of its files. The messages marked include those that an earlier owner of the line received and that iSnap still keeps: after you get a line, ignore the events about messages from before you got it. The call succeeds even when no read receipt reaches the contact: when the line has no paired device, and on every shared line, the request to the device is dropped. The chat must be on an iMessage line and the handle of its contact must be a phone number in E.164: otherwise the API returns `422 sms_read_receipt_not_supported` or `422 unsupported_handle`. Accepts an API key. A line-scoped key can call it for any chat of the lines you own: its `line_ids` are not checked. Send no body, or an empty JSON object. parameters: - schema: type: string pattern: ^chat_[0-9A-Za-z]{25}$ description: 'Chat id: `chat_` followed by 25 letters or digits.' required: true description: 'Chat id: `chat_` followed by 25 letters or digits.' name: chat_id in: path requestBody: content: application/json: schema: type: object properties: {} description: 'An empty object: the request takes no field.' responses: '200': description: The inbound messages of the chat are marked as read. content: application/json: schema: $ref: '#/components/schemas/ChatMarkReadEnvelope' '400': description: >- Invalid request. `error.code` is `validation_failed` when a parameter, a header or the body does not match its schema: `error.issues` then lists each problem. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '401': description: No valid credential. `error.code` is `unauthorized`. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '403': description: >- Refused. `error.code` is `forbidden`: the request carries neither an API key in its `Authorization` header nor the header `X-Requested-With: XMLHttpRequest`. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '404': description: >- Not found. `error.code` is `not_found`: the chat does not exist, or its line is not yours. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '429': description: >- Too many requests. `error.code` is `rate_limit_exceeded` when more than 100 requests came from the same network address in 60 seconds, whatever their API key or account: wait `error.retry_after` seconds. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' '500': description: >- Unexpected failure. `error.code` is `internal_error`. An operation that takes a JSON body also returns it when the body, sent as `application/json`, is not valid JSON. Quote `trace_id` when you report it to iSnap. content: application/json: schema: $ref: '#/components/schemas/ErrorEnvelope' security: - bearerAuth: [] components: schemas: ChatMarkReadEnvelope: type: object properties: success: type: boolean enum: - true description: Always `true` on a success response. data: $ref: '#/components/schemas/ChatMarkRead' trace_id: type: string description: >- Trace id of the request that produced this response: 32 lowercase hexadecimal characters. Quote it when you report a problem to iSnap. request_id: type: string description: >- Id of the request that produced this response: `req_` followed by 25 letters or digits. required: - success - data - trace_id - request_id ErrorEnvelope: type: object properties: success: type: boolean enum: - false description: Always `false` on an error response. data: nullable: true description: Always `null` on an error response. error: type: object properties: status: type: integer description: The HTTP status of the response. code: type: string description: >- Stable machine-readable code that names the refusal. Branch on this value. message: type: string description: >- Text for a person. It can change between versions: do not branch on it. retry_after: type: integer nullable: true description: >- Seconds to wait before the next attempt. Set on the `429` responses that know a delay, where the `Retry-After` header carries the same value. When it is above 60 seconds, do not wait in a request: schedule the call, or report the time. `null` on every other error. retry_at: type: string nullable: true description: >- ISO 8601 timestamp at which the refusal ends. Set only on `429 rebind_cap_reached`. `null` on every other error. issues: type: array nullable: true items: type: object properties: path: type: array items: anyOf: - type: string - type: number description: >- Where the problem is: the field names and array indexes that lead to it. message: type: string description: Text for a person. code: type: string description: >- Kind of problem. On `validation_failed`, for example `invalid_type`, `invalid_value`, `invalid_format`, `invalid_union`, `invalid_key`, `invalid_element`, `too_small`, `too_big`, `not_multiple_of`, `unrecognized_keys` or `custom`. The list is open: read `path` and `message`. min: type: integer description: >- Smallest accepted value. Present only on `limit_out_of_bounds`, `mac_quantity_not_a_pack`, `byop_reduction_strands_mac_sessions` and `byop_reduction_strands_byod_lines`. max: type: integer description: >- Largest accepted value. Present only on `limit_out_of_bounds` and `mac_sessions_exceed_byop_lines`, and on the `too_big` issue of an `Idempotency-Key` header longer than 255 characters. required: - path - message - code description: >- Problems found in the request, one entry each. Set on most `400 validation_failed` responses and on the refusals that name a field: a refused `handle` of `POST /v1/lookup` has `issues: null`. `null` on every other error. required: - status - code - message - retry_after - retry_at - issues description: >- What went wrong. The six fields are always present; `retry_after`, `retry_at` and `issues` are `null` when they do not apply. trace_id: type: string description: >- Trace id of the request that produced this response: 32 lowercase hexadecimal characters. Quote it when you report a problem to iSnap. request_id: type: string description: >- Id of the request that produced this response: `req_` followed by 25 letters or digits. required: - success - data - error - trace_id - request_id description: The body of an error response. ChatMarkRead: type: object properties: chat_id: type: string description: Id of the chat. read_at: type: string description: The `read_at` set on the messages this request marked. marked_count: type: integer minimum: 0 description: >- Number of inbound messages this request marked as read. 0 when the chat had no inbound message without `read_at`. required: - chat_id - read_at - marked_count description: The result of `POST /v1/chats/{chat_id}/read`. securitySchemes: bearerAuth: type: http scheme: bearer description: >- An API key created in the iSnap dashboard, or a trial key, sent as `Authorization: Bearer `. An API key starts with `isnap_live_` or `isnap_test_`; both act on the same account, lines and billing. A trial key acts on its trial only. ```` This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.