dsh-code-highlight

Syntax-highlighted diffs in the DeepSeek Harness chat's edit / write / apply_patch tool cards.

DSH already highlights read cards and the side-panel change review, but the chat's file-mutation diff card renders every line as plain text. This client plugin re-renders those three cards with DSH's own highlighter (useCodeHighlighter(languageForPath(path)) from @deepseek-ai/dsh-client-ui-primitives). It bundles no Shiki and no grammars, so languages and colours are exactly DSH's (--shiki-* theme tokens) and themes apply unchanged.

Install

dsh plugin --profile desktop add @dsh-labs/dsh-code-highlight

Restart DSH, or reload the window, after installing. For the browser profile, use --profile web.

What it does

• Each hunk's old side (context + removed lines) and new side (context + added lines) is tokenized separately, then the tokens are mapped back onto the diff lines, the same way the official change review does it.
• Highlighting starts only when a card is expanded and scrolled into view.
• The card otherwise matches the stock one: title, path link, NKB size, +N −M, language header with wrap/copy, 9-row fold, Inspect.
• Registered in the keyed tool.call.toolview slot for edit, write and apply_patch only, at priority −10. No Host service and no settings. Card text reuses DSH's conversation locale strings.

Limits

Inherited from DSH, deliberately not worked around:

• Languages are chosen by file extension only, using DSH's table. There is no shebang detection, so an extension-less script such as deploy stays plain.
• Lines of 1000 or more characters stay plain.

One row differs from the stock card on purpose: the collapsed apply_patch row shows only the +N −M totals. Stock names the patched files there, and since DSH 0.2.2-rc.2 it links each file of a multi-file patch individually; this card names the files once it is expanded instead.

Cases that render with the stock card, unchanged:

• languages DSH does not map;
• diffs over 2000 rows;
• preparing, failed or stopped calls;
• calls nested inside a PTC program.

Compatibility

DSH	Status
0.2.2-rc.2	Contract-checked against its public npm packages; not verified in the GUI
0.2.2-rc.1	Contract-checked; verified in the GUI
0.2.1-rc.5	Contract-checked against its public npm packages; not verified in the GUI

node scripts/contract.mjs downloads the public packages of all three releases from npm. It fails if tool.call.toolview, useCodeHighlighter, languageForPath or the reused primitives change shape.

Develop

pnpm install --frozen-lockfile
pnpm run typecheck && pnpm run build && pnpm test
node scripts/contract.mjs          # public DSH contracts
scripts/check-reproducible.sh      # two clean builds must be byte-identical

Release

CI (.github/workflows/ci.yml) runs on pushes to main and on pull requests. Pushing a v* tag runs .github/workflows/release.yml, which:

1. checks that the tag equals the package.json version;
2. checks that .github/release-notes/<tag>.md exists with ## Highlights, ## Breaking changes, ## Fixes and ## Compatibility;
3. runs the same checks as CI;
4. publishes to npm with provenance, under next for prerelease versions and latest otherwise;
5. creates a GitHub Release with the packed tgz attached.