## Mark as read

`POST /v1/chats/:dialogId/read`

Marks dialog messages as read — all of them or up to the given message.

## Parameters

| Parameter | Type | Required | Default | Description |
|----------|-----|:-----:|-----------|---------|
| `dialogId` (path) | string | yes | — | Dialog ID: numeric user ID for personal messages, `chatXXX` for group chats. In the v2 mode the `me` alias is the current user's personal dialog. `chatXXX` is the `id` field of a [recent dialogs](/docs/chats/discovery/recent) row; the user ID comes from the [user list](/docs/entities/users/list) |
| `format` (query) | string | no | — | `v2` turns on the v2 mode — see "The v2 mode" below. Any other value is ignored and the response is unchanged. A repeated `format` is not rejected: with `format=v1&format=v2` the last value wins, so the v2 mode is on, while `format=v2&format=v1` returns the legacy response. The bracket form `format[]=v2` turns on the v2 mode when all its values are `v2` |

**The v2 mode.** `format=v2` marks the whole chat as read. `data` carries `{ chatId, lastId, counter, viewedMessages }`. The mode accepts no body fields: `messageId` is rejected with `400 INVALID_PARAMS` — to mark individual messages as read, use the [`POST /v1/chats/messages/read`](/docs/chats/messages/read-messages) operation. Query parameters other than `format` are rejected too.

## Request body fields

| Field | Type | Required | Description |
|------|-----|:-----:|---------|
| `messageId` | number | no | Mark all messages up to and including the given one as read. If omitted, all messages in the dialog are marked as read. A non-numeric value is ignored, and all messages are marked as read as well. Rejected in the v2 mode |

## Examples

### curl — personal key

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/chat42/read" \
  -H "X-Api-Key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "messageId": 1002 }'
```

### curl — OAuth application

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/chat42/read" \
  -H "X-Api-Key: YOUR_APP_KEY" \
  -H "Authorization: Bearer USER_SESSION_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{ "messageId": 1002 }'
```

### JavaScript — personal key

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/chat42/read', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_API_KEY',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ messageId: 1002 }),
})

const { success, data } = await res.json()
console.log('Unread remaining:', data.counter)
```

### JavaScript — OAuth application

```javascript
const res = await fetch('https://vibecode.bitrix24.com/v1/chats/chat42/read', {
  method: 'POST',
  headers: {
    'X-Api-Key': 'YOUR_APP_KEY',
    'Authorization': 'Bearer USER_SESSION_TOKEN',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({ messageId: 1002 }),
})

const { success, data } = await res.json()
```

### curl — the v2 mode

```bash
curl -X POST "https://vibecode.bitrix24.com/v1/chats/chat42/read?format=v2" \
  -H "X-Api-Key: YOUR_API_KEY"
```

## Response fields

| Field | Type | Description |
|------|-----|---------|
| `success` | boolean | Always `true` on success |
| `data.dialogId` | string | Dialog ID from the request |
| `data.chatId` | number | Numeric chat ID |
| `data.lastId` | number | ID of the last read message |
| `data.counter` | number | Number of unread messages remaining after the operation |
| `data.viewedMessages` | array | The v2 mode: IDs of the messages marked as read by this call |

## Response example

```json
{
  "success": true,
  "data": {
    "dialogId": "chat42",
    "chatId": 42,
    "lastId": 1002,
    "counter": 0
  }
}
```

## Error response example

404 — dialog not found or no access:

```json
{
  "success": false,
  "error": {
    "code": "DIALOG_NOT_FOUND_OR_NO_ACCESS",
    "message": "Dialog does not exist or you cannot access it."
  }
}
```

## Errors

| HTTP | Code | Description |
|------|-----|---------|
| 404 | `DIALOG_NOT_FOUND_OR_NO_ACCESS` | The dialog does not exist or you do not have access to it |
| 400 | `INVALID_PARAMS` | The v2 mode only: a body field, including `messageId`, or a query parameter other than `format` |
| 422 | `BITRIX_ERROR` | Bitrix24 returned an error (text in the `message` field). The Bitrix24 code is in `error.b24Code` |
| 502 | `BITRIX_UNAVAILABLE` | Bitrix24 is unavailable or returned a server error |
| 502 | `ME_ALIAS_RESOLUTION_FAILED` | The v2 mode only: failed to resolve the user when using the `me` alias |
| 403 | `BITRIX_ACCESS_DENIED` | The v2 mode only: the chat does not exist or you do not have access to it |
| 403 | `SCOPE_DENIED` | The key is missing the `im` scope |
| 403 | `WRITE_BLOCKED_READONLY_KEY` | The key is in read-only mode |
| 401 | `TOKEN_MISSING` | The API key has no Bitrix24 tokens configured |

Full list of common API errors — [Errors](/docs/errors).

## See also

- [Mark messages as read](/docs/chats/messages/read-messages)
- [Read messages](/docs/chats/messages/list)
- [Messages](/docs/chats/messages)