Table Shift Arrow Eager Selection

Goal

Remove the transient native text-range flash when Shift+Arrow expands from one table cell into another.

Plan

• [completed] Add keydown-level regression coverage for eager single-cell Shift+Arrow.
• [completed] Route single-cell Shift+Arrow through table-owned selection movement before native selection applies.
• [completed] Remove withApplyTable repair behavior and delete overrideSelectionFromCell.
• [completed] Update coverage and docs to reflect keydown-only ownership.
• [completed] Run focused tests, package build, typecheck, lint.

Findings

• Multi-cell Shift+Arrow already goes through onKeyDownTable.
• Single-cell cross-cell expansion still waits for set_selection and setTimeout, which causes visible flash.
• The quick fix is to take ownership in onKeyDownTable for the one-cell boundary-crossing case too.
• overrideSelectionFromCell is now a redundant apply-time fallback unless a real non-keydown caller still depends on it.

Progress

• Created plan for eager single-cell Shift+Arrow interception.
• Added onKeyDownTable coverage for eager single-cell Shift+Down and Shift+Right.
• Extracted the visual-line boundary check into a shared helper so plain arrows and shifted arrows use the same vertical edge rule.
• Routed one-cell cross-cell Shift+Arrow through onKeyDownTable before native selection applies.
• Removed the apply-time fallback and deleted overrideSelectionFromCell plus its dedicated tests.
• Added a package changeset and a solution doc for the timing seam.
• Follow-up refactor: extracted shared single-cell table movement context and adjacent-block checks used by both moveLine and onKeyDownTable.
• Follow-up tests: added Shift+Up, Shift+Left, and multi-cell Shift+Right keydown coverage.

Verification

• bun test packages/table/src/react/onKeyDownTable.spec.tsx
• bun test packages/table/src/react/onKeyDownTable.spec.tsx packages/table/src/lib/withApplyTable.spec.ts packages/table/src/lib/withTable.spec.tsx packages/table/src/lib/transforms/moveSelectionFromCell.spec.tsx
• pnpm install
• pnpm turbo build --filter=./packages/table
• pnpm turbo typecheck --filter=./packages/table
• pnpm lint:fix
• bun test packages/table/src/react/onKeyDownTable.spec.tsx
• bun test packages/table/src/lib/withTable.spec.tsx packages/table/src/lib/transforms/shouldMoveSelectionFromCell.spec.ts packages/table/src/lib/transforms/moveSelectionFromCell.spec.tsx packages/table/src/lib/withApplyTable.spec.ts