DeepSeek Harness for VS Code

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An independent, pre-release VS Code client for DeepSeek Harness. It opens an official SDK runtime in the current workspace, streams the durable session log into a sidebar, shows tool activity, and opens file-tool results in VS Code's native diff editor.

This community project is not maintained or endorsed by DeepSeek.

Real model demonstration

The recording uses the released extension architecture, official VS Code 1.133.0 arm64, the bundled official DSH SDK runtime, deepseek-official / deepseek-v4-flash, and a real bash tool call. No fixture or mock transport is involved.

Features

• Reusable, bundled dsh-jsonrpc-agent subprocess managed by @deepseek-ai/dsh-sdk-client.
• Streaming root-session assistant messages and collapsible tool cards.
• Native before/after diff editors from durable tool/result.data.meta.diffs.
• Session state and input/output token totals.
• New-session, runtime-restart, and diagnostic-output commands.
• Fixed workspace-write sandbox policy; operations that require interactive approval fail closed.

Prerequisites

• VS Code 1.100 or newer with a trusted local folder open.
• Node.js 22.19 or newer on PATH. The runtime is a separate Node process because signed macOS editors cannot load third-party native modules into their Electron executable.
• A VSIX built for the current operating system and CPU. The embedded runtime contains native subprocess dependencies, so release artifacts are platform-specific.
• DEEPSEEK_API_KEY in the environment that launches VS Code. DEEPSEEK_BASE_URL is optional. The extension deliberately has no secret-valued setting.

On macOS, a VS Code process started from the Dock may not inherit shell variables. Launching code . from a configured shell is the simplest development setup.

Install

Download and install the tested macOS arm64 VSIX:

curl -fLO https://github.com/lonelymoon87/dsh-vscode/releases/download/v0.1.1/dsh-vscode-darwin-arm64-0.1.1.vsix
code --install-extension dsh-vscode-darwin-arm64-0.1.1.vsix

The first release provides a tested macOS arm64 build only. Other platforms are not yet available.

To build the extension from source instead:

pnpm install
pnpm run check
code --install-extension dsh-vscode-*-0.1.1.vsix

Open the DeepSeek Harness Activity Bar view and submit a prompt. Cmd+Enter or Ctrl+Enter also sends the prompt.

Settings

Setting	Default	Meaning
deepseekHarness.nodePath	node	Node 22.19+ executable for the bundled runtime; set an absolute path when the editor does not inherit the shell PATH.
deepseekHarness.runtimeCommand	empty	Optional external dsh-jsonrpc-agent executable that replaces nodePath and the bundled entrypoint.
deepseekHarness.runtimeArgs	[]	Arguments appended to the resolved runtime executable.
deepseekHarness.provider	deepseek-official	Provider route sent during initialize.
deepseekHarness.model	deepseek-v4-flash	Model id sent during initialize.
deepseekHarness.maxTokens	49152	Positive output-token cap for each root-agent request.

The extension passes its bundled runtime/launcher/cordis.yml through DSH_CORDIS_CONFIG, the first workspace folder through DSH_CWD, and extension-private storage through DSH_SESSION_ROOT. The VSIX includes the matching official runtime packages. runtimeArgs follow the bundled entrypoint or the configured external runtime command.

Security and failure behavior

Untrusted and virtual workspaces are unsupported. The runtime receives the first local workspace folder as its writable root, and the extension never sends webview HTML through innerHTML. SDK transport errors remain visible in the transcript and the DeepSeek Harness output channel; restarting replaces the failed process and re-reads settings.

The current SDK wire has no server-to-client approval request or client approval response. The included runtime therefore uses a fixed workspace-write policy, and the official approval service rejects operations that require an answerer. The extension does not silently broaden permissions.

Known limitations

• No mid-turn cancel, approval UI, session list, or session resume because the rc.6 SDK protocol does not expose those operations.
• One active root session and one workspace folder are shown at a time; descendant notifications are not mixed into the root transcript.
• Markdown, image attachments, and structured non-diff tool presentations fall back to plain text.
• VS Marketplace publication and signed release artifacts remain pending; GitHub Release VSIX files are unsigned community builds.

Development

pnpm run test covers notification projection and the official SDK against a real scripted JSON-RPC subprocess. pnpm run package builds a VSIX. Product-visible pull requests must include a GIF captured from the branch's real extension, runtime, and model flow; fixtures are test inputs, not release evidence.

See CONTRIBUTING.md and SECURITY.md.

Release evidence

• pnpm run check covers type checking, unit tests, production build, and VSIX packaging.
• CI runs on Node 22.19 and Node 24.
• The v0.1.1 VSIX was installed into a fresh official VS Code profile and completed a real model round, tool card, and token-usage projection.
• Bugs and compatibility reports are tracked in GitHub Issues.