Document model

Own virtual document kernel for on-codemerge. No ProseMirror / TipTap / Lexical / BlockNote / Slate / CKEditor as foundation.

Source of truth

EditorState = { doc, selection } in memory. DOM is a projection. All writes go through dispatch(transaction | command).

Dependency verdict (R0)

Candidate	Verdict
ProseMirror / TipTap / Lexical / …	Forbidden as editor core
dompurify	Accepted for HTML import/paste sanitization only
yjs	Deferred — custom binding later; not y-prosemirror
edix	Rejected for now — experimental; own InputBridge covers typing
selection-ranges	Rejected for now — own path/offset mapping
rope-sequence	Deferred — own tree + structural sharing sufficient for Phase 0–2

JSON shape

{
  "version": 1,
  "doc": {
    "type": "doc",
    "content": [
      {
        "type": "paragraph",
        "id": "p1",
        "content": [{ "type": "text", "text": "Hello", "marks": [{ "type": "bold" }] }]
      }
    ]
  }
}

Layers

• packages/kernel — pure model (no DOM); published as on-codemerge/kernel
• src/view — reconcile + input bridge
• src/platform — sealed extensions
• src/io — JSON / HTML / Markdown adapters (importHTML, exportMarkdown, … on on-codemerge)
• src/editor — public Editor facade
• packages/sdk — definePlugin, UI services (on-codemerge/sdk) — SDK reference

Boundaries

API	Role
getJSON / setJSON	Source of truth
getHTML / setHTML	Semantic HTML (atoms as empty data-node)
getMarkdown / setMarkdown	Markdown subset
getPublishedHTML / getPublishedDocument	Hydrated public pages

Details and headless helpers: Editor API.

TDD

All kernel modules have __tests__. Red → green → refactor. pnpm test required before release.