4485 Markdown Empty List Deserialization Error

Goal

Finish issue #4485 end-to-end:

• keep the markdown deserializer fix and regression
• keep the task branch-rule clarification
• finish verification after moving unrelated slow fast-lane specs into *.slow.tsx
• commit remaining changes
• push branch
• open PR
• sync back to the GitHub issue if PR exists

Current State

• Branch: codex/4485-markdown-empty-list-deserialization-error
• Pushed commit already on branch: dfb11f375
• Remaining uncommitted changes are the fast-lane threshold fix:
  • moved packages/dnd/src/DndPlugin.spec.tsx -> packages/dnd/src/DndPlugin.slow.tsx
  • moved packages/table/src/lib/merge/tableMergeBehavior.spec.tsx -> packages/table/src/lib/merge/tableMergeBehavior.slow.tsx

What Is Done

1. Fixed classic markdown empty list item deserialization so li always contains lic.
2. Added regression coverage for foo\n\n*\n\nbar.
3. Tightened .agents/rules/task.mdc so unrelated non-main branches are not reused for new tasks.
4. Synced generated task skill with bun install.
5. Repaired local env drift with pnpm run reinstall.
6. Moved two unrelated threshold offenders to slow lane.

Verified Evidence So Far

• bun test ./apps/www/src/__tests__/package-integration/markdown-deserializer/deserializeMd.slow.tsx
• pnpm install
• pnpm turbo build --filter=./packages/markdown
• pnpm turbo typecheck --filter=./packages/markdown
• pnpm lint:fix
• pnpm run reinstall
• bun test ./packages/udecode/react-utils/src/useStableFn.spec.tsx
• bun test ./packages/table/src/lib/merge/tableMergeBehavior.slow.tsx
• bun test ./packages/dnd/src/DndPlugin.slow.tsx
• pnpm test:slowest -- --top 10

Open Items

1. Run or confirm final pnpm check after slow-lane moves.
2. If green, stage all current task changes.
3. Commit slow-lane move fix.
4. Push branch.
5. Open PR with final handoff as body.
6. Post concise issue comment pointing to PR.
7. Evaluate whether a ce:compound doc is worth writing.

Risks / Notes

• The slow-lane move is unrelated to issue #4485, but repo PR gate requires check, so it is part of the ship path now.
• Do not reopen branch hygiene rabbit holes. Current branch is already correct.