perf: frame-limit Pen and Pencil interactions

[dompm]

Summary

• share one Pen resolver between hover and click
• frame-limit Pen hover publication
• capture Pencil samples in a mutable controller and isolate its overlay

Why

This reduces repeated pointer-path allocation and computation while preserving exact click-time snapping and every raw Pencil sample.

Stack

Depends on #123 (codex/interaction-performance).

Verification

• interaction test suite passes
• production build succeeds
• no new TypeScript errors beyond the documented baseline

This is a draft pending performance review and browser regression testing.

[dompm]

The shared resolver and Pencil buffer are useful improvements, but the Pen half does not yet meet the isolation checkpoint.

• [P1] Keep Pen preview state out of ResultPanel. The scheduled hover callback still invokes five panel-level setters. React batches them, but ResultPanel still rerenders and rebuilds its piece element map and surrounding UI once per hover frame. The plan calls for one Pen snapshot consumed by a focused overlay/status subscriber so stable panel work is skipped.
• [P2] Refresh the stationary-Shift resolver. The global keyboard effect depends only on activeTool, so it captures the resolver/index/project geometry from the render in which Pen was activated. If geometry or crop changes while the tool stays Pen (for example after committing a polygon), Shift press/release at a stationary cursor resolves against stale data. Keep the latest resolver in a ref or otherwise refresh the handler without losing keyboard behavior.
• [P2] Cancel queued hover work when clearing Pen UI. Pointer leave and tool changes clear state but do not cancel the pending animation-frame task. A previously scheduled task can run afterward and restore a stale hover/guides, including when Pen is selected again. Cancel the scheduler at every preview-cancellation boundary and add a scheduler race test.

Pencil does retain every raw tuple and removes the growing immutable copy from the raw-event path. Its drawing snapshot still copies the cumulative flat buffer once per frame, so describe the win as “no cumulative copy per raw event,” not no cumulative copies at all.

[cloudflare-workers-and-pages]

Deploying vitrai with    Cloudflare Pages

Latest commit:	27f999f
Status:	✅  Deploy successful!
Preview URL:	https://199e6238.vitrai.pages.dev
Branch Preview URL:	https://codex-interaction-pen-pencil.vitrai.pages.dev

View logs

[dompm]

The local Pen preview state is isolated, and the stale-resolver/cancellation fixes look correct. One high-frequency path still defeats that isolation:

• [P1] Keep Pen status out of App state. Every preview update runs onStatusChange, which is setPenStatus in App. That produces a new status object every frame, rerenders App, and invokes the non-memoized ResultPanel again. In other words, the overlay host's local state no longer directly rerenders the panel, but its status effect immediately causes the same broad render through the parent. Put the Pen status in the same stable external snapshot/controller and let only a focused status-bar subscriber render it (or provide an equivalently isolated route). Add a count test using the real status callback boundary, not only the preview host.

The unused isShiftDown panel state can also be removed; it is no longer read and is still part of the documented TypeScript baseline.