perf(desktop): stop re-rendering the app shell on every keystroke#1692
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noahjalex wants to merge 2 commits into
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perf(desktop): stop re-rendering the app shell on every keystroke#1692noahjalex wants to merge 2 commits into
noahjalex wants to merge 2 commits into
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usePresenceSession stored raw Date.now() activity timestamps in React state and bumped them from capture-phase keydown/pointerdown listeners, so every keystroke anywhere in the app re-rendered AppShell (the app root) and swept context changes through the whole tree. Track activity in a ref and keep only the derived automatic status in state, updated solely when it actually flips (online <-> away, on activity, interval tick, or visibility change). Probe: AppShell renders during a 74-keystroke burst drop 70 -> 1. Benchmark keystroke input-to-paint medians halve across every scenario (32 -> 16ms channel, 48 -> 24ms in a 68-reply thread at 4x throttle); thread keystrokes over the 50ms frame budget drop 76 -> 1-3. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Why
Noah: Typing in a thread with lots of agents working was painfully slow and building. I basically couldn't send messages, this fixes it for me.
AI: Every keystroke, anywhere in the app, re-rendered the entire app shell.
usePresenceSession(mounted in AppShell) stored rawDate.now()activity timestamps in React state and updated them from capture-phasekeydown/pointerdownlisteners — new state at the app root per keystroke. This was the largest single contributor to typing feeling slow, on every surface.What
online/away) in state.Repro / Verify
React DevTools → Profiler → record → type a sentence in any composer → stop.
main: one AppShell-rooted commit per keystroke (the whole tree re-renders).Quantified (render-count probe + Event Timing benchmark, 4x CPU throttle):
Risk Assessment
Low — single hook, derived-state refactor with identical semantics. 2266 unit tests and messaging/thread/status e2e specs pass.
Related: #1652 (thread-panel render fixes; same investigation, independent change).
🤖 Generated with AI