perf(client): smoother chat scrolling with wider list cache#1116
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…shing The chat ListView used Flutter's default cacheExtent of 250px, which is too tight for messages that include images, reactions, and reply quotes — each takes a frame to lay out, so momentum scrolling on long histories briefly showed blank space before items mounted. Bumped to 600px (about one viewport) so the visible window stays warm during fast scrolling.
This was referenced May 22, 2026
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May 22, 2026
… 3.41.9 flutter analyze --fatal-infos on CI's 3.41.9 SDK rejects 'cacheExtent' as deprecated in favor of 'scrollCacheExtent', but the local SDK pin (3.41.6) hasn't picked up the rename and rejects the new name as unknown. Drop the perf optimisation from this bundle to unblock the dev → main release. Will reapply in a follow-up PR once the Flutter pin moves to 3.41.9 (or once we can express it as 'cacheExtent ?? scrollCacheExtent'). Effectively reverts the chat-list change from #1116; the avatar memCacheWidth change from #1127 (different file) stays.
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Summary
The chat `ListView.builder` had no explicit `cacheExtent`, defaulting to 250px. For messages that include images, reactions, and reply quotes — each requiring a frame to lay out — momentum scrolling occasionally flashed blank space before items mounted. Bump to 600px (about one viewport) so the visible window stays warm during fast scrolling.
Test plan
Behind the scenes
Single-line change in `chat_message_list.dart`. No behaviour change, only smoother scrolling.