Phase 4 Table Execution

Goal

Complete the phase-4 table slice only. Add high-ROI non-React logic coverage for merge-heavy table behavior plus the remaining small sizing and selection helpers in packages/table/src/lib.

Checklist

• [completed] Audit table merge and transform seams plus current test helpers
• [completed] Add merge-focused table lib specs
• [completed] Add size and selection helper specs
• [completed] Fix any real runtime bug exposed by the new specs
• [completed] Run table package verification
• [completed] Record learnings and final results

Findings

• Existing table coverage is decent on insert/basic-query seams but still light on the merge cluster that carries the real branchy behavior.
• The highest-value uncovered behaviors are:
  • mergeTableCells
  • splitTableCell
  • deleteRowWhenExpanded
  • deleteColumnWhenExpanded
  • setTableColSize
  • setTableRowSize
  • moveSelectionFromCell
• deleteRowWhenExpanded only removes rows when the expanded selection spans the full row width of the first selected row.
• deleteColumnWhenExpanded only removes a column when the expanded selection spans both the first and last table rows.

Progress

• Re-read the phase-4 plan, task.mdc, testing.mdc, and tdd.
• Audited current table lib specs, helper placement, and merge-path wrappers.
• Probed live merge/delete/selection behavior with temporary Bun scripts to pin the actual public contracts before adding specs.
• Added a merge-focused lib spec cluster that covers:
  • mergeTableCells
  • splitTableCell
  • deleteRowWhenExpanded
  • deleteColumnWhenExpanded
• Added a size/selection helper cluster that covers:
  • setTableColSize
  • setTableRowSize
  • moveSelectionFromCell
• Tightened the collapsed-selection fixture in moveSelectionFromCell so it proves real movement from 21 to 22 instead of accidentally passing with the selection already at the destination.

Verification

• bun test packages/table/src/lib/merge/tableMergeBehavior.spec.tsx packages/table/src/lib/transforms/tableSelectionAndSizing.spec.tsx
• bun test packages/table/src/lib
• bun run test:slowest -- --top 15 packages/table/src/lib
• pnpm install
• pnpm turbo build --filter=./packages/table
  • failed outside table scope when turbo pulled @platejs/resizable
  • error: rolldown on Node 20.12.1 calling node:util.styleText with ['underline', 'gray']
• pnpm turbo typecheck --filter=./packages/table
• pnpm lint:fix

Learnings

• package reality: deleteRowWhenExpanded is narrower than its name sounds. It only deletes rows when the expanded selection covers the full width of the first selected row.
• package reality: deleteColumnWhenExpanded only deletes a column when the expanded selection spans the first and last rows of the table.
• package reality: splitTableCell owns missing-row creation, so the honest split test is the row-creation branch, not only the easy “fill an existing row” path.
• verification blocker: package build is still blocked outside the slice by the same external rolldown + Node 20.12.1 styleText failure, here reached through @platejs/resizable.