Non React Coverage Roadmap Phase 2 Execution

Scope

• Execute the locked Tier 1 and Tier 2 non-React files from 2026-03-24-non-react-coverage-roadmap-phase-2.md.
• Keep the work file-first.
• Add direct tests or expand existing specs only where the seam is still honest.

Current Plan

1. Inspect existing implementations and nearby specs.
2. Add Tier 1 coverage.
3. Add Tier 2 coverage.
4. Update roadmap statuses.
5. Run targeted tests, then build, typecheck, and lint for touched packages.

Notes

• Tier 2 already has decent harnesses for ViewPlugin, onDropNode, upsertLink, and convertNodesSerialize; expand those instead of cloning new suites.
• The likely touched packages are core, code-block, excalidraw, dnd, link, and markdown.
• The batch exposed one real runtime bug in withScrolling: it was writing mode / operations into the DOMPlugin store instead of scrollMode / scrollOperations, and it failed to restore state on thrown callbacks.