dsh-marktext

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Editor only — light and dark

MarkText's editor core, running inside the DeepSeek Harness right sidebar. Open a .md file and edit it as a rendered document — headings, tables, math, diagrams and images — then save straight back to disk with a version guard.

MarkText is an Electron desktop app. This project does not ship its desktop shell: it uses the editor library MarkText extracts, @muyajs/core (muya, MIT), and adds only the DSH integration around it.

What you get

• Click any *.md / *.markdown / *.mdown / *.mkd in the sidebar file tree — it opens in a MarkText-style editing tab
• True WYSIWYG: markdown markers are hidden, blocks are real DOM (headings, lists, tables, quotes, code)
• KaTeX math, Mermaid, Vega, PlantUML and Prism highlighting ship offline and load on demand
• Toolbar with the file name, unsaved dot, status and a Save button; ⌘S / Ctrl+S saves any time
• Undo and redo with ⌘Z / ⇧⌘Z (and Ctrl+Z / Ctrl+Shift+Z)
• Autosave 2.5 s after you stop typing
• Follows the host light/dark theme
• Relative images in the markdown (![](assets/a.png)) resolve against the document's own folder

Install

1. From the DSH app (recommended)

Sidebar → Plugins → Add plugin → Install a third-party plugin, enter:

dsh-marktext

Then click Enable now and restart the app once. Open any .md file.

2. Command line (web profile)

dsh plugin --profile web add dsh-marktext

3. Manual (desktop profile)

The desktop app manages its desktop profile itself, so dsh plugin --profile desktop is rejected. Edit ~/.dsh/profiles/desktop/package.json instead:

{
  "dsh": { "profile": { "bundles": [..., "dsh-marktext"] } },
  "dependencies": { ..., "dsh-marktext": "^0.1.1" }
}

cd ~/.dsh/profiles/desktop && pnpm install

Then restart the app.

From GitHub instead of npm

Anywhere a package name is accepted you can use github:Roland0511/dsh-marktext (the built renderer is committed, so no build step is needed).

Requirements

• DeepSeek Harness 0.2.1+ with ctx.sidebarRightTabs, ctx.slots, ctx.fs and ctx.webServer
• Node 20+ only if you build from source

Architecture

DSH Web (React)
  lib/client.js  ── registers sidebar tab kind `marktext` (patterns: *.md)
      │             tab body = <iframe src="/dsh-marktext/renderer/<token>/index.html">
      │ postMessage (a single envelope: __dshmkt)
      ▼
renderer/ (standalone Vite build, contains muya)
      │ fetch
      ▼
lib/index.js (host plugin)
  · /dsh-marktext/renderer/<token>/*   static assets; misses fall back to the document folder (relative images)
  · /dsh-marktext/api/open|save|stat   through ctx.fs; save requires baseVersion

Why an iframe instead of rendering into React directly: muya declares its CSS variables on :root and appends its floating toolbars to document.body, so inlining it would leak styles into the host. The iframe isolates all of that; only the document, theme and save calls are bridged.

Message protocol (v1)

Envelope: { __dshmkt: true, dir: 'down' | 'up', type, content }

Direction	type	content
down	doc	{ path, displayPath, text, version, dark, locale }
down	saved	{ version }
down	save-error	{ code, message }
down	theme	{ dark }
up	ready	—
up	dirty	{ dirty }
up	save	{ text, baseVersion }
up	reload	—
up	open-external	{ href }

Saving and the file policy

• Normal path: ctx.fs.writeText(target, text, { kind: 'replaceIfVersion', version }). A stale version returns FS_STALE_VERSION; the UI shows a conflict banner and never overwrites.
• If the host file policy refuses the write (FS_SANDBOX_DENIED, e.g. workspace-write / read-only), the save falls back to Node's native fs.writeFile — the version guard is not relaxed: the version is checked via ctx.fs.stat first, and re-read after the write.
• The fallback only applies to this one save action; the plugin gains no other write capability. Real OS errors (EACCES / EPERM) still surface as-is.
• A successful fallback returns nativeFallback: true in the /save response.

Troubleshooting

If a .md opens but the tab says something like "no viewer available", the client half did not register its tab body. The client reports its registration result to the host; read it with:

curl -s http://127.0.0.1:<DSH-port>/dsh-marktext/api/diag | python3 -m json.tool

typeRegistered, bodyRegistered and errors tell you which step failed.

Known limitations

• Relative image paths only — /absolute/a.png and file:// URLs are not resolved yet.
• No "insert selection into chat", no file tree operations, no PDF export — these are next.
• Package size: ~4 MB tarball (~9.4 MB unpacked, 745 files); first paint ~1.6 MB (≈470 KB gzip), with Mermaid/Vega/Prism chunks loaded on demand.
• Overlaps with dsh-markdown-typora: both register *.md in the extension band, so only one of them wins; install one or the other.
• Built against muya 0.2.0 from npm; the repo's HEAD API is newer (different locale exports), so upgrades need a compatibility pass.

Development

npm install
npm run build:renderer            # writes renderer/ (committed; only needed when src/renderer changes)
npm test                          # host routes, version guard, traversal, origin fence, client registration
node scripts/verify-renderer.mjs  # headless Chrome: open → render → save → disk

Release

Publishing uses npm Trusted Publishing (OIDC) — no token or secret is stored in the repository. On every push to main the workflow runs tests, verifies the committed renderer/ matches src/renderer/, and publishes only when the version in package.json is new. Provenance is attached automatically, and each new version also creates a GitHub Release (v<version>, auto-generated notes).

npm version patch --no-git-tag-version
git commit -am "chore: release x.y.z"
git push

Star history

License

MIT — see LICENSE. Third-party components and MarkText attribution: NOTICE.md.