DSH File Viewer

A universal file preview layer for DeepSeek Harness: open and inspect files right inside the web UI — no external application needed.

Preview ≠ Execute. The viewer is strictly read-only: previewing a file never runs shell commands, scripts, macros, or HTML. SVG is rendered through <img>, and Markdown is sanitized before display.

Supported file types

Type	Renderer
PNG / JPG / GIF / WEBP / SVG / BMP	Image (fit, zoom, pan, dimensions)
PDF	PDF.js (page nav, page input, zoom, fit width/page)
CSV / TSV	Data table (delimiter auto-detect, sticky header, row numbers, search, sort, column resize, windowed rows, chunked loading)
TXT / LOG / OUT / INI / CONF	Text (line numbers, wrap, search, font size, chunk navigation)
JS / TS / Python / Go / Rust / Java / C/C++ / C# / Shell / HTML / CSS / SQL / …	Code (highlight.js, read-only)
Markdown	Preview (sanitized) + Source
JSON / JSONL	Tree (expand/collapse, copy value/path) + Source
YAML	Source + parsed Tree
anything else	Fallback (metadata + Open externally / Reveal / Copy path / optional Open as text)

How it works

• Host half (dist/index.js) registers the /fileviewer loopback RPC channel: stat, readRange, readHead, list, openExternal, backed by ctx.fs. Every path is realpathed and boundary-checked against the allowed roots (workspace directories + host cwd + configured extraRoots), so traversal and symlink escapes are rejected.
• Client half (dist/client.js) provides the fileViewer service (ctx.get('fileViewer') → openFile(path, { line, renderer })) and renders a right-docked viewer column (styled like the Harness details panel) through the shell.overlay slot. It opens from:
  • produced-file chips in the conversation (conversation.chat.turnTail, priority -1 — clicking an agent-generated file previews it in-app), or
  • the "浏览文件 / Browse files" entry added to each workspace row's "…" menu (see the compatibility patch below).
• Workspace "…" menu patch (scripts/patch-workspace-menu.mjs): the workspace browser renders its row menu from a hardcoded list with no slot hook, so this script applies three guarded, idempotent edits to the installed @deepseek-ai/dsh-client-ui-workspace client bundle: a browseFiles menu item (zh/en labels), an onSelect branch calling window.__dsfvBrowseWorkspace(workspaceId), and the two dictionary keys. It aborts loudly on version drift and can be re-run safely after Harness updates (node scripts/patch-workspace-menu.mjs).
• Large-file strategy: < 5 MB whole-file, 5–50 MB chunked streaming, > 50 MB head-only with explicit "Load more / Go to end" navigation. Range reads are capped (8 MiB per call) and text/CSV rows are windowed, so a 500 MB log never lands in browser memory.
• Theming: styles use --dsw-alias-* tokens and match Harness's details panel proportions, so light/dark follow the Harness theme automatically.

Public API

// client side, any web plugin:
const fileViewer = ctx.get('fileViewer')
fileViewer.openFile('/workspace/output/report.csv')
fileViewer.openFile('/workspace/src/main.ts', { line: 125 })
fileViewer.openFile('/workspace/data.bin', { renderer: 'text' }) // force a renderer

Other plugins can extend the renderer registry:

// client side: register a custom renderer rule with priority
import { RendererRegistry } from 'dsh-file-viewer/core'
viewerRegistry.register({ id: 'nifti', priority: 500, extensions: ['nii', 'nii.gz'] })

Configuration

# cordis.patch.yml / settings
- id: dsh-file-viewer
  name: dsh-file-viewer
  config:
    enabled: true
    extraRoots:
      - /srv/data          # optional extra directories the viewer may read

Development

npm install            # (use a reachable registry if npmjs TLS is flaky)
npm run build          # esbuild → dist/index.js + dist/client.js
npm run check          # tsc (strict) over src and tests
npm test               # vitest: mime, renderer, paths, large-file, csv, json, file-service

Install into a DSH profile

# from the repo root (the profile resolves relative specs from your cwd)
dsh plugin --profile web add /path/to/dsh-file-viewer
# compatibility patch: add "浏览文件" to each workspace's "…" menu
node scripts/patch-workspace-menu.mjs
# then restart the web service (preflight on 43124 → 43123), see
# scripts/restart-dsh-web.sh for the safe pattern used in this repo.

Client-only changes hot-reload via dsh-client-hmr; node-half changes need a web restart. Re-run scripts/patch-workspace-menu.mjs after any Harness update that reinstalls @deepseek-ai/dsh-client-ui-workspace.

Security notes

• Path validation is enforced host-side on realpath'd targets against allowed roots (fs.contains); the client pre-check is defense-in-depth only.
• Markdown is rendered with html: false and sanitized with DOMPurify (scripts, iframes, event handlers and javascript: URLs removed).
• SVG is never injected as HTML — it is displayed through <img>.
• Binary detection: NUL scan + magic bytes; "Open as text" is always an explicit user action.
• Per-renderer error boundaries: a broken PDF/JSON can never crash the Harness UI.

License

MIT