refactor(web): composer editor stops mirroring props into refs with effects#25079

Problem

The Tiptap prompt editor copied six callback props into refs, each with its own useEffect. It also had an effect that copied the editor instance into a holder ref, and a layout effect that mirrored the controlled value. The composer's prompt-wrap measurement re-ran a layout effect keyed on an element held in state. The command-key hook copied prompt history into a ref with a layout effect on every render.

Change

• ComposerPromptEditorTiptap: the editor config is built once, so its handlers now read the current callbacks through a single useStableCallback. ProseMirror handlers get the editor from view.dom.editor instead of a holder ref. The controlled-value layout effect records the committed value itself. Copy/cut is a React handler, so it reads buildContextClipboardFragment from props directly.
• useComposerMultilinePrompt returns a ref callback. ChatComposer attaches it to the composer body, and it observes resizes and mutations while that element is mounted.
• useComposerCommandKey called no hooks once its mirror ref was gone, so it is now the plain composerCommandKeyHandler in composerCommandKey.ts. ChatComposer builds it inside the stable key handler, so prompt history is read on the keypress.

What this improves

• Removes 10 sync effects from the composer's typing path: 8 in the editor, 1 in the wrap measurement, 1 in the command-key hook.
• The wrap observer now follows the element's lifetime. It no longer goes through a setComposerMenuAnchor state commit followed by a layout effect.
• No bug fixes are claimed, and no user-visible behavior changes. Key handlers and editor callbacks still see the latest committed props.

Effects

• ComposerPromptEditorTiptap.tsx: 13 -> 5. The remaining effects are setEditable, the attribute push, controlled-value sync, skill reconcile and one more editor sync, all real editor/DOM synchronization.
• useComposerMultilinePrompt.ts: 1 -> 0
• useComposerCommandKey.ts -> composerCommandKey.ts: 1 -> 0
• ChatComposer.tsx: 26 -> 26. Only the wiring changed here.

Verification

• Rebased on current main (aa11f7002e).
• vp run check:changed: format, lint, knip, typecheck (34 packages) and tests (22 files, 525 tests) pass.
• ComposerPromptEditorTiptap.input.browser.test.tsx, ComposerPromptEditorTiptap.citationDraft.browser.test.tsx and ComposerStashMenu.browser.test.tsx also pass when run one at a time (16/16).
• I checked the output of the React Compiler build (oxc-transform-react, the one react({ compiler: true }) uses). It compiles ChatComposer, ComposerPromptEditorTiptap and useComposerMultilinePrompt without errors. It memoizes the composer body's inline ref callback on observeWrappedPrompt, so the observers are not detached and reattached on each render.

Model: Claude Opus 5.5, Claude Code harness.

🤖 Generated with Claude Code