---
title: "Mark Chat Read"
method: PATCH
path: "/api/chats/{chat_id}/read"
tags: ["chats"]
---

# Mark Chat Read

`PATCH /api/chats/{chat_id}/read`

## Request

- Base URL: `https://app.thinqos.com` (the document declares no server; this is the origin it was published from)
- URL: `https://app.thinqos.com/api/chats/{chat_id}/read`
- Auth: none declared

Mark a chat as fully read for the current user.

Upserts read_states watermark to now().

TOS-4678: no-ops entirely while impersonating, for the same reason
``POST /me/presence`` does. A read receipt asserts that this person saw
this conversation, so an admin/owner browsing an identity's screen via
act-as must not write one under that identity. Without the guard the web
client - whose shared fetch attaches ``X-Impersonate-Identity-Id`` to
every request - marks each chat read as it is opened, which (a) moves the
real person's ``read_states`` watermark and silently clears their unread
badges, unrecoverably, since the watermark is one timestamp with no
history, and (b) writes an ``event_log`` ``chat.read`` row and broadcasts
a read receipt to the other participants under the target's name, with no
field recording that an impersonator did it. ``ChatsPage``'s "mark all
visible read" fans out over every unread chat at concurrency 8, so one
click wiped a whole inbox. Measured on production 2026-09-08: 5,152 of
41,684 ``chat.read`` events (12.4%) across 36 identities were written
inside an act-as window.

The access check still runs first, so an impersonated call to a chat the
target cannot see still 404s - only the write is skipped.

## Path parameters

- `chat_id` string, uuid, required

## Headers

- `x-impersonate-identity-id` string, nullable

## Response `200`

Successful Response

- OkResponse
  - `ok` boolean

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/thinqos/apis/thinqos-api.md) · [All operations](https://skmtc.dev/thinqos/apis/thinqos-api/llms.txt) · [OpenAPI document](https://skmtc.dev/thinqos/apis/thinqos-api/revisions/5387b4ded614?raw)