Slate v2 Document State Example Usability

status: done created: 2026-05-20 completion_id: 019e3627-238b-7993-a8cf-26be45504c47 scope: .tmp/slate-v2/site/examples/ts/document-state.tsx

Goal

Fix the Document State example so the body editor is plainly editable by mouse, and title-field typing never steals selection or focus back to the editor.

Reported Bug

The main editor cannot be clicked reliably enough to edit it.
Repro path: select main editor, select title, type in title, select editor again, type. The editor selection/focus behavior is wrong.
Playwright coverage should use real page interactions, not only the editor harness selection helper.

Current Finding

Existing document-state Playwright coverage inserts body text only after editor.selection.select(...), so it can pass while mouse editing is broken.
Prior Slate browser learnings warn that model selection helpers are not enough evidence for browser-owned text input and selection behavior.
A normal wrapper around the styled <Editable> intercepted clicks because the Slate root carries default z-index: -1; the example needs a non-intercepting wrapper and style={{ zIndex: 0 }} on the styled root.
useSetStateField state writes used default selection side effects, and selection.dom: 'preserve' was not honored by the React selection bridge.

Plan

done: Add a failing Playwright interaction row for click body -> type -> click title -> type -> click body -> type.
done: Fix the owning layer: example layout if the click target is bad, React state field setter/update options if state writes steal editor focus.
done: Verify with focused Playwright, site/root typecheck as needed, lint fix, and a real browser interaction pass.

Verification

pass: PLAYWRIGHT_RETRIES=0 bun playwright playwright/integration/examples/document-state.test.ts --project=chromium
pass: bun test ./packages/slate-react/test/selection-side-effect-policy-contract.ts
pass: bun --filter slate-react typecheck
pass: bun typecheck:site
pass: bun typecheck:root
pass: bun lint:fix
pass: dev-browser --connect http://127.0.0.1:9222 on http://localhost:3100/examples/document-state with click editor -> type, click title -> type, click editor -> type. Screenshot: /Users/zbeyens/.dev-browser/tmp/slate-document-state-usability.png
recorded: docs/solutions/ui-bugs/2026-05-20-slate-react-state-field-setters-must-preserve-external-focus.md