dsh-pele-plugin

Mermaid diagrams as themeable SVG cards in the DeepSeek Harness chat, rendered with Pele.

The model calls a mermaid tool with Mermaid source. The Host half validates that source with Pele before it reaches the browser, so a broken diagram comes back as a fixable error naming the line and column. The Client half draws it in the conversation with the same renderer, in the Harness's own theme.

Pele renders every diagram type built into Mermaid 12, ships no dependencies, and themes through CSS variables — this plugin maps those onto the Harness's design tokens, so light and dark follow the host.

What you get

• A card per diagram in the conversation, with the diagram type, a title you can pass, and a copy-the-source action.
• The same diagram again at the end of the turn. A completed turn folds its process rows, so the card alone would disappear; the turn-tail copy is what stays visible.
• One toolbar on every card: zoom out, zoom in, reset, fullscreen, and copy as identical 24px buttons, so nothing floats over the diagram and nothing appears only on hover. Drag-to-pan, pinch, and the + / - / 0 / Esc shortcuts still work on the diagram itself.
• Failures stay in the card: the tool error, including the position Pele reported.

Requirements

• A DeepSeek Harness build with agent plugin profiles (the conversation.chat.turnTail and shell.overlay slots).
• Node 22 or newer, only to build from source. The published package ships built artifacts.

Install

Install the bundle into your Harness profile by package name:

@phatg/dsh-pele

The bundle's cordis.patch.yml inserts its own plugin row, so selecting the bundle is the whole setup. There is no configuration to write: the plugin adds the mermaid tool and a short standing instruction telling models to call it for diagrams instead of writing a fenced block.

Use

Ask for a diagram the way you would ask a person — "draw the request lifecycle through these services" — and the model calls the tool. Diagrams written as ```mermaid fences are plain code blocks; the plugin does not rewrite model output.

Development

pnpm install
pnpm build        # dist/index.js, dist/client.js, dist/client.pele.js
pnpm typecheck
pnpm test         # Vitest: host in Node, client in real Chromium
pnpm check        # all three

The browser suite needs a headless browser once per machine:

pnpm exec playwright install chromium-headless-shell

dist/ is build output and is not committed. A link: install into a Harness profile does not run prepare, so run pnpm build before reloading the Harness after a change.

Releasing

prepack rebuilds dist/, so pnpm pack and npm publish always ship fresh artifacts. Pushing a v* tag runs .github/workflows/release.yml, which checks the package and publishes with provenance; it needs an NPM_TOKEN repository secret.

License

MIT. Pele itself is MIT, by kepano.