dsh-visualize
Out-of-tree DSH (DeepSeek Harness) plugin: the visualize_html tool plus a
sandboxed HTML preview card in the Web chat — a Codex /vizualize analogue
rendered inside the conversation.
What it does
- Node half (
src/index.ts, mounts in the host loader tree): registers the
visualize_html(path) tool and the human-facing /visualize [path] command.
It resolves the path against the session workspace, reads the file through
ctx.fs (the profile's sandbox policy applies), shows the model only a short
summary, and embeds the capped HTML in the durable presentationMeta
(tool/result.meta → ToolResultNode.meta). The HTML never enters model
context; the canonical value is execution-local.
- Browser half (
src/client.tsx, a dsh.client dual-face package):
registers the visualize_html keyed view in the tool.call.toolview slot.
The settled card renders meta.html in an iframe with
sandbox="allow-scripts" (no allow-same-origin → opaque origin: scripts
run but cannot reach the page, cookies, storage, or same-origin resources),
plus Open in browser (existing host.openPath) and Copy HTML.
User-facing surface
/visualize <path> — slash command (discovered by the Web command menu):
steers a user turn that calls visualize_html, so the preview card appears
in the chat.- Bare
/visualize (no path) — a request to the model to create a
visualization: it thinks about what would be useful in the current context,
builds it as a self-contained HTML file, and renders it with visualize_html.
- The model also sees the
tool:visualize_html prompt section and the tool
schema itself — that guidance is what makes the command work end to end.
Install
Published to npm: dsh-visualize.
# the profile is a pnpm workspace root, so -w is required
dsh plugin --profile <name> add -w dsh-visualize
The package is a bundle — it declares dsh.bundle.patch and ships its own
cordis.patch.yml, so dsh plugin add registers it as a profile layer
automatically (no manual patch rows). Then restart the profile (the shipped web
surface disables HMR, so profile layers are not watched live):
dsh --profile <name> --port 3081
Local development checkout (live link, rebuilds picked up on page refresh):
dsh plugin --profile <name> add -w link:/path/to/dsh-plugins/visualize
Runtime config (row visualize):
config:
maxPreviewBytes: 262144 # cap on the HTML embedded in the durable result
Development
pnpm install # from the repo root (pnpm workspace)
pnpm --filter dsh-visualize build # tsdown → lib/index.mjs + lib/client.js
pnpm --filter dsh-visualize typecheck # tsc --noEmit
pnpm --filter dsh-visualize test # node --test (node half unit tests)
After a rebuild, refresh the browser page — the client bundle is served
no-cache; a server restart is only needed when the loader tree changes.
Limitations
- Sibling assets do not load —
srcdoc has no base URL, so relative
CSS/images next to the file are not fetched inside the preview; self-contained
HTML renders fully. (Deferred: a host RPC to serve sibling assets.)
- Preview truncation is a hard byte cap; the full file opens via the browser.
- The card is Web-only (keyed tool view); headless surfaces see the summary text.
