fix: avoid redraw backlogs during rapid mouse scrolling

docs/development.md

@@ -38,7 +38,7 @@ Rust tests live alongside their modules; native LSP integration checks are in [`
 - Session and Ruby checks exercise real Ruby execution, command/capability ownership, effect validation, configuration fallback, plugin retirement, crash/timeout recovery, and inherited-pipe cleanup.
 - Unix terminal-hook checks use isolated child processes and real PTYs to keep process-global hooks out of the parallel runner. They cover raw/alternate-screen/mouse-capture cleanup on entry failure, normal return, I/O errors, and panics during synchronized redraw, including original panic-payload propagation.
 - Redraw checks inspect actual Crossterm output during repeated scrolling: supporting terminals receive synchronized frames, terminals ignoring synchronization never paint with a visible hardware cursor, and the final caret remains visible.
-- Wheel checks render document/panel views and cover three-row scrolling, unchanged carets/selections/text, first/last-page clamping, offscreen cursor hiding, no-op/custom-bound navigation reveal, manual persistence through idle/resize/palette updates, and floating/unfocused-docked explorer selection and focus preservation.
+- Wheel checks render document/panel views and cover three-row scrolling, unchanged carets/selections/text, first/last-page clamping, offscreen cursor hiding, no-op/custom-bound navigation reveal, manual persistence through idle/resize/palette updates, and floating/unfocused-docked explorer selection and focus preservation. Queued-input checks verify that the next frame shows ordered wheel steps without crossing a key or resize boundary.
 - Native LSP integration checks launch framed-protocol fixture subprocesses, covering initialization/settings, opt-in startup, synchronization, UTF-16/file-URI conversion, dirty targets, stale requests/diagnostics, and transport failures. Stack checks cover independent initialization, diagnostic merging/clearing, sibling failure isolation in active/parked buffers, same-revision rename/close identity, aggregate limits, first-server position routing, and both shutdowns. Semantic ordering uses protocol/file gates; elapsed deadlines only bound stuck subprocesses.
 - Hover regression checks cover content forms, sanitization, cancelled/superseded replies, invalid results, scrolling/dismissal, Unicode clipping, and preserved editing state.
 - Semantic-token checks cover full/range requests, legend/modifier remapping, UTF-16 boundaries and grapheme rounding, ASCII tab and Unicode column bounds, refresh/change coalescing, stale rename/close replies, null/empty/error fallback, primary/sibling retirement, and rendered cell precedence with syntax, diagnostics, search, selections, and carets.
@@ -48,6 +48,7 @@ Clipboard checks use isolated providers rather than reading or overwriting the d
 ## Performance and process limits
 
 - Undo uses full-buffer snapshots and movement scans the current line. This favors straightforward correctness over large-file performance.
+- Rapid-wheel verification must replay bursts against the running editor and measure arrival at the final viewport after input stops, not just individual frame duration. Cheap frames can still accumulate a visible backlog if each queued report requires its own redraw.
 - Annotation coordinate validation fast-paths ASCII grapheme lengths using byte lengths with CRLF pair accounting, retaining Unicode segmentation for non-ASCII text. Validation remains atomic and still checks every token; large Unicode buffers or diagnostic batches can require foreground work.
 - Legacy synchronous plugin invocation may pause input for up to 500 ms before a host timeout. Async plugins opt into background replies; pending requests and transport queues are bounded. Config/plugin startup has a 2-second deadline per host. Buffer context/document snapshots must fit within a 4 MiB JSON frame; a too-large frame disables that plugin, not editing.