dsh-better-markdown

Markdown where you actually use it: the composer and your own messages.

DeepSeek Harness renders assistant replies as Markdown, but the composer is a plain-text editor and sent user messages come back as plain text. This plugin closes that gap:

• Live preview above the composer. Type Markdown and the rendered result appears immediately — headings, bold/italic, inline code, lists, task lists, quotes, tables, fenced code with syntax highlighting, links, footnotes and math, all through DSH's own Markdown pipeline.
• In-place syntax highlighting. The composer itself dims #, **, ` and list markers, and paints emphasis, code, links and headings, so you can read the structure while typing. The draft text never changes.
• User messages render as Markdown. Every sent message you wrote with Markdown shows as Markdown in the transcript — while the copy action, the session log, and the text the model sees stay byte-identical.
• One switch, remembered per browser. The M↓ button in the composer toolbar toggles the preview (⌘⇧M / Ctrl+Shift+M also works); the choice survives reloads. The transcript rendering follows the plugin configuration, not the button.

Live rendered preview above the composer; the raw draft keeps its Markdown markers, dimmed.

Third-party plugin. Not an official DeepSeek / DeepSeek Harness component.

Install

This plugin is distributed only through GitHub — it is not published on npm. Requirements: DSH 0.2.1-rc.5 or newer, below 0.3.0, with the Web or Desktop surface, and Node ≥ 22.

The install spec is the repository itself:

dsh plugin --profile <profile> add github:ceasarXuu/dsh-better-markdown

The same spec works in Plugins → Add in the app. A version tag pins a release (github:ceasarXuu/dsh-better-markdown#v0.1.0), and a GitHub Release tarball can be installed instead when your network setup prefers plain artifacts:

dsh plugin --profile <profile> add https://github.com/ceasarXuu/dsh-better-markdown/releases/download/v0.1.0/ceasarxuu-dsh-better-markdown-0.1.0.tgz

Manual profile row (after the package is installed into the profile):

# profiles/<profile>/cordis.patch.yml
- insert:
    - id: better-markdown
      name: '@ceasarxuu/dsh-better-markdown'
      config:
        enabled: true
        transcript: true
        composer: true
        syntax: true
        preview: true

Disable the bundle and the shipped plain-text behavior returns immediately.

Switches

All switches are plain booleans on the plugin row; the browser reads them from GET /plugin/better-markdown/config on page load.

Switch	Default	What it does
enabled	true	Master switch for every surface. Off restores shipped behavior while the plugin stays installed.
transcript	true	Render sent user messages as Markdown in the conversation.
composer	true	Enable the composer preview and its toolbar switch.
syntax	true	Paint Markdown syntax inside the composer (CSS Custom Highlight API).
preview	true	Show the preview by default when the draft contains Markdown.

The toolbar switch is the per-browser override: pressing it off turns the preview off on this browser only (localStorage key better-markdown.prefs.v1); pressing it on shows the preview for any non-empty draft. Clearing site data returns to the host default.

How it works

Everything runs in the browser half; the host half only publishes the switches, so there is no network traffic beyond the same-origin config read.

• Transcript. DSH parses user text into runs and reference chips and renders each run through the keyed conversation.user.text.node slot. This plugin registers the text key at a lower priority than the shipped cell and renders the run with the platform's own MarkdownText component. Session @-mention chips keep their shipped renderer, and copy/quote behavior keeps reading the original text.
• Preview. A normal conversation.input.dock entry (the same flow the shipped queue and todo docks use) reads the live draft and renders it with the same MarkdownText component.
• In-place highlighting. A conversation.input.right cell provides the switch, and a small controller repaints CSS.highlights over the composer's text nodes. Highlights only change paint (color, background, underline, text-shadow) — never layout, never the draft, never IME composition.

Because rendering uses @deepseek-ai/dsh-client-ui-primitives from the platform module table, user messages get exactly the GFM renderer assistant replies use: sanitized links, highlighted code, tables, footnotes and math. If that module is unavailable the plugin degrades to plain text instead of breaking the page.

Markdown in a chat message

• Single newlines stay line breaks: outside code blocks, tables and indented blocks, a newline becomes a CommonMark hard break before rendering, so a multi-line message does not collapse into one paragraph.
• Plain prose stays byte-identical to the shipped bubble; Markdown rendering only starts when the message contains Markdown syntax (#, fences, lists, quotes, tables, emphasis, code, links, task items).
• The queue dock's one-line preview renders the same content inline, clamped to a single line.
• The session title, sidebar rows and headers are host-generated plain text and are intentionally left alone.

Limitations

• DSH's composer is a shell-owned Lexical editor. A plugin can decorate it but cannot turn it into a WYSIWYG surface, so "Markdown in the composer" means a rendered preview plus paint-only syntax highlighting — editing, caret, undo and Chinese IME all stay with the shipped editor.
• Highlighting needs the CSS Custom Highlight API (Chromium 105+). On a browser without it the plugin simply skips that layer; the preview and the transcript keep working.
• The transcript renderer targets DSH 0.2.x slot contracts. A future change to conversation.user.text.node or conversation.input.dock needs a plugin update; the plugin never patches DSH source.

Development

npm test        # pure helpers: detection, hard breaks, spans, config, route
npm run check   # node --check on every shipped source

dev/ contains a dependency-free Chrome DevTools Protocol harness and a live verification script. Point a throwaway DSH home at this checkout, boot dsh web on a non-desktop port, then:

node dev/verify.mjs   # 19 live checks + screenshots into docs/

The dev home, the server log, and the harness never touch the real ~/.dsh or the desktop app.

License

MIT © ceasarXuu