RSC Client Boundary Root-Cause Investigation

Goal

Find the real reason apps/www needs a package-level React client boundary on this branch, even though origin/main builds without it in the same environment.

Current Facts

• origin/main clean worktree builds apps/www without packages/plate/src/react/index.tsx containing 'use client'.
• This branch fails if that line is removed.
• The stable failure stays on:
  • packages/core/src/react/components/EditorHotkeysEffect.tsx
  • packages/core/src/react/components/PlateContent.tsx
  • packages/core/src/react/plugins/event-editor/useFocusEditorEvents.ts
• The first known bad commit is 1efb71b9a Simplify discussion UI.

Already Ruled Out

• local build cache
• playground-demo.tsx console logging
• suggestion-shared.ts / static helper placement
• TrailingBlockKit
• app-local proxy entry experiments
• simple tsconfig alias rewrites
• serverExternalPackages
• slate version drift alone

Best Current Hypothesis

Something introduced by 1efb71b9a changes the app import graph enough that Next/Turbopack starts analyzing the platejs/react graph as part of a server path on this branch but not on origin/main.

Next Checks

1. Compare the exact import graph changes introduced by 1efb71b9a around app routes, registry exposure, and generated registry output.
2. Identify the first server-side entry that starts pulling platejs/react on this branch.
3. Fix that graph edge instead of keeping 'use client' at the package entry if possible.

Result

• The misleading page trace was not the root cause.
• The decisive server path was:
  • src/app/api/registry/[name]/route.ts
  • src/lib/rehype-utils.ts
  • generated src/__registry__/index.tsx
• trailing-block-kit being exposed as a registry item pulled @platejs/suggestion/react into that server graph.
• The durable fix was not deleting the kit forever.
• The durable fix was converting trailing-block-kit into a real client-only kit (.tsx + 'use client') before exposing it through the registry.