Slate v2 React 19.2 Cleanup

Supporting plan. For current queue and roadmap truth, see master-roadmap.md.

Goal

Remove the obvious React 18-era compatibility patterns from the current slate-v2 React surface.

Scope

1. Replace the flagged forwardRef chains in slate-react primitives and EditableText with React 19 ref-prop components.
2. Remove the memo(forwardRef(...)) wrapper in TextString.
3. Replace one-shot editor construction useMemo with lazy useState in the flagged example.

Learnings

• React 19.2 convergence doc says to use modern React features where they earn their keep, not as theater.
• EditableDescendantNode memo is still justified by the huge-document paste learning, so this batch should not rip out memoization that is benchmark backed.
• Editable useLayoutEffect is justified by DOM selection sync and should not be downgraded just to look newer.

Progress

• Reviewed the flagged files and repo-wide React pattern matches.
• Confirmed the real cleanup targets are:
  • editable-text.tsx
  • slate-element.tsx
  • slate-text.tsx
  • slate-placeholder.tsx
  • text-string.tsx
  • site/examples/ts/huge-document.tsx
• Confirmed EditableDescendantNode memo and Editable layout effects stay.
• Replaced the flagged forwardRef surfaces with React 19 ref props in:
  • slate-element.tsx
  • slate-text.tsx
  • slate-placeholder.tsx
  • editable-text.tsx
  • site example helper chrome
• Removed memo(forwardRef(...)) from TextString.
• Replaced one-shot useMemo editor construction with lazy useState in the huge-document example.
• Kept the benchmark-backed and correctness-backed survivors:
  • EditableDescendantNode memo
  • Editable layout effects

Verification

• yarn workspace slate-react run test
• yarn exec eslint packages/slate-react/src/components/slate-element.tsx packages/slate-react/src/components/editable-element.tsx packages/slate-react/src/components/slate-text.tsx packages/slate-react/src/components/slate-placeholder.tsx packages/slate-react/src/components/text-string.tsx packages/slate-react/src/components/editable-text.tsx site/examples/ts/huge-document.tsx site/examples/ts/components/index.tsx
• yarn prettier --check packages/slate-react/src/components/slate-element.tsx packages/slate-react/src/components/slate-text.tsx packages/slate-react/src/components/slate-placeholder.tsx packages/slate-react/src/components/text-string.tsx packages/slate-react/src/components/editable-text.tsx site/examples/ts/huge-document.tsx site/examples/ts/components/index.tsx /Users/zbeyens/git/plate-2/docs/plans/2026-04-07-slate-v2-react-19-2-cleanup.md
• rm -f /Users/zbeyens/git/slate-v2/site/tsconfig.example.tsbuildinfo && yarn tsc:examples
• ROLLUP_PACKAGES=slate-react yarn build:rollup
• bash ./scripts/run-slate-browser-local.sh 3100 /examples/rich-inline "yarn exec playwright test playwright/integration/examples/rich-inline.test.ts --project=chromium --workers=1 --grep 'release-shaped lifecycle'"
• bash ./scripts/run-slate-browser-local.sh 3100 /examples/rich-inline "yarn exec playwright test playwright/integration/examples/rich-inline.test.ts playwright/integration/examples/richtext.test.ts --project=chromium --workers=1"

Notes

• yarn build:slate-browser:playwright still emits unrelated pre-existing slate core type noise outside this cleanup slice. The targeted slate-react build is green.