stream-chat-android-compose/src/main/java/io/getstream/chat/android/compose/ui/messages/list/Messages.kt (2)

313-318: Fix is correct — consider updating the accompanying comment to document the new key

The isMessageInThread key causes rememberSaveable to discard the saved state and re-run mutableStateOf(newMessageState) whenever the thread context changes. Because lastScrollToBottomOnNewMessage is then equal to the current newMessageState, the LaunchedEffect at line 321 never sees a difference on the first evaluation, which is exactly what prevents the spurious scroll-to-bottom. The approach is sound for both the bug scenario and config-change resilience.

The comment block above (lines 310–312) only mentions the config-change rationale. A one-liner noting why isMessageInThread is also a key input would help future maintainers:

✏️ Suggested comment update

     // Keep track of the last new message state that triggered a scroll to bottom.
     // If a configuration change happens, we want to keep the same state
     // and not scroll to bottom again if the newMessageState is the same as before the configuration change.
+    // The isMessageInThread key ensures the state is reset when switching between thread and main list contexts,
+    // preventing a stale comparison from triggering an unintended scroll after exiting a thread.
     var lastScrollToBottomOnNewMessage by rememberSaveable(
         isMessageInThread,
         saver = MutableStateNewMessageStateSaver,
     ) {
         mutableStateOf(newMessageState)
     }

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In
`@stream-chat-android-compose/src/main/java/io/getstream/chat/android/compose/ui/messages/list/Messages.kt`
around lines 313 - 318, Update the comment above the rememberSaveable block to
explicitly note that including isMessageInThread as a key causes the saved state
for lastScrollToBottomOnNewMessage (created via rememberSaveable and
mutableStateOf(newMessageState)) to be discarded when thread context changes,
ensuring the state is reset to newMessageState so the LaunchedEffect that
compares it sees no spurious difference on first evaluation; reference the
rememberSaveable call, the isMessageInThread key,
lastScrollToBottomOnNewMessage, newMessageState, and the LaunchedEffect in the
comment so future maintainers understand both the config-change and
thread-context rationale.

---

280-355: Consider adding a functional test (and Paparazzi snapshot) for the thread-exit scroll-position preservation

The PR checklist notes tests are unchecked. Given this is a scroll-state bug, a lightweight instrumented or unit-composed test that verifies lastScrollToBottomOnNewMessage is not stale after toggling isMessageInThread would guard against regressions. Based on learnings, Compose regressions in this module should also be covered by Paparazzi snapshots via verifyPaparazziDebug.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In
`@stream-chat-android-compose/src/main/java/io/getstream/chat/android/compose/ui/messages/list/Messages.kt`
around lines 280 - 355, Add a lightweight Compose unit/instrumented test plus a
Paparazzi snapshot that verifies the scroll-position preservation logic in
DefaultMessagesHelperContent when toggling thread state: create a test that
renders DefaultMessagesHelperContent (or the Messages container that uses it),
initialize messagesState so lastScrollToBottomOnNewMessage is set, toggle
isMessageInThread by changing messagesState.parentMessageId (enter/exit thread)
and then trigger a newMessageState change; assert that the component does not
re-scroll when newMessageState equals the previous saved state (i.e.,
lastScrollToBottomOnNewMessage is preserved) and add a verifyPaparazziDebug
snapshot to capture the UI before/after the toggle to prevent regressions;
target helpers like shouldScrollToBottomOnNewMessage,
lastScrollToBottomOnNewMessage, focusedItemIndex behavior, and the
ScrollToBottomButton visibility in your test.