Fix NaN coordinates in mouse wheel reports from touch fling inertia - #6059
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Fix NaN coordinates in mouse wheel reports from touch fling inertia#6059tajo wants to merge 1 commit into
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Inertia (fling momentum) CHANGE events carried only translationX/Y, while real touchmove CHANGE events also carry page/client coordinates. The mouse-report wheel path (_handleTouchScrollAsWheel) reads event.clientX/clientY to compute the reported cell position, which produced NaN coordinates that passed through getMouseReportCoords' clamping untouched and were serialized into wheel reports (e.g. `CSI < 64 ; NaN ; NaN M`) — applications with mouse tracking enabled (vim with mouse=a, tmux, agent TUIs) received them as garbage input on every fling release. Fix at the source by stamping the position the inertia animation already tracks onto the events (page coordinates; client derived via the window's scroll offsets), and defensively skip wheel reports for coordinate-less gesture events so malformed sequences can't reach the PTY from this path again. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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July 22, 2026 03:26
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Found this problem when using 6.1.0-beta.291 on iPhone running
claude codeinside. Scrolling (touch fling) was causing garbage chars likeNaN;NaNMbeing inputed into the prompt. This fixes it.The rest is generated by Claude Fable.
Problem
Inertia (fling momentum) CHANGE events dispatched by
Gesture._inertia(src/browser/scrollable/touch.ts) carried onlytranslationX/Y, while real touchmove CHANGE events also carry page/client coordinates. The mouse-report wheel path (MouseService._handleTouchScrollAsWheel) readsevent.clientX/clientYto compute the reported cell position, which produced NaN coordinates that passed throughgetMouseReportCoords' clamping untouched and were serialized into wheel reports (e.g.CSI < 64 ; NaN ; NaN M) — applications with mouse tracking enabled (vim withmouse=a, tmux, agent TUIs) received them as garbage input on every fling release.Fix
Two additive changes (+18 lines):
src/browser/scrollable/touch.ts— fix at the source by stamping the position the inertia animation already tracks onto the momentum events (page coordinates; client derived via the window's scroll offsets), matching what_handleTouchMovestamps on real frames.src/browser/services/MouseService.ts— defensively skip wheel reports for coordinate-less gesture events (!isFinite(e.clientX) || !isFinite(e.clientY)) so malformed sequences can't reach the PTY from this path again.To reproduce
On a touch device (or DevTools touch emulation), run any app that enables mouse tracking (e.g. vim with
set mouse=a) in the demo, flick-scroll and lift — the app receivesESC[<64;NaN;NaNMper momentum tick, visible as literalNaN;NaNMinput. Discovered embedding xterm.js in a web dashboard terminal running an agent TUI with mouse reporting.Validation
npm run build(tsgo) cleannpm run esbuildcleannpm run test-unit— 2403 passing, 0 failingNo new test added — the touch handlers are private/DOM-wired and the unit harness has no gesture mocks; happy to add coverage wherever you'd prefer it.
🤖 Generated with Claude Code