DeepSeek Harness Launcher

DeepSeek Harness Launcher

Start, open, and manage the DeepSeek Harness Web UI from VS Code with one click. The extension checks the environment, fetches DSH through npm, picks a safe port, waits for readiness, and cleans up the process on stop.

Features

• One-click access — start and open Harness from the status bar or Command Palette.
• Environment checks — validate Node.js, npx, the working directory, and launch settings.
• Server lifecycle — start, stop, restart, cancel, or connect to an existing server.
• Shared profile — reuse model settings and sessions across projects in the same environment.
• Remote access — support local, SSH, WSL, Dev Container, and Codespaces workspaces.
• Browser or editor — open Harness in the system browser or a VS Code webview.

Prerequisites

• VS Code 1.125 or newer.
• Node.js 22.19+ (22.x only) or 24+, with both node and npx in the same installation directory.
• A trusted local, SSH, WSL, Dev Container, or Codespaces workspace.
• An API key for a model you have access to (configured inside the Harness page; this extension does not read or store it).

Harness can read and write files and run commands: the extension does not start or connect services in Restricted Mode, and it asks for confirmation again when choosing a directory from an empty window.

Installation

Search for DeepSeek Harness Launcher in the Extensions view (Ctrl/Cmd+Shift+X), or visit Visual Studio Marketplace or Open VSX. You can also install a .vsix from GitHub Releases using Extensions: Install from VSIX….

Quick Start

1. Open and trust a project folder, then click DSH in the status bar or run DeepSeek Harness Launcher: Open.
2. The first run fetches DSH through npm. The status bar shows DSH Working…; click it to cancel or view the output.
3. Once the page opens, add your API key under Settings → Models in Harness, then confirm a directory in Choose workspace and start a session.

workingDirectory is DSH's launch directory and default workspace context, which affects AGENTS.md, CLAUDE.md, cwd .env, and similar files.

Commands

Settings

Usage

DeepSeek Harness Launcher: Open is the primary command: it starts the server when it is not running and opens it directly when it is.

Status Bar

The status bar shows: shield + DSH (untrusted), DSH (not running), DSH Working… (click to cancel or view output), DSH Stopping… (click for output), DSH: port (hosted by this window), link icon + DSH: port (external server), DSH: port* (settings changed; click to restart and apply), or error icon + DSH (hover for details and click for recovery actions).

Managed and External Servers

• A managed server is started by the extension. Its data lives in the extension's global storage, so model credentials, settings, and sessions are shared across projects. A single-writer lease keeps the profile safe; another VS Code window automatically connects to the running shared instance instead of starting a competing process. "Stop Server" waits for the session to clean up, then force-ends it and confirms the port was released.
• An external server can only be connected explicitly through an HTTP loopback address in this environment (for example http://127.0.0.1:3080). It supports open, copy, refresh, and disconnect only; the extension never stops it, and it keeps its own data directory.
• All projects in the same local or remote VS Code environment use one DSH application profile and reuse its running instance. Local, SSH, WSL, and container environments retain separate global storage because they run on different machines/filesystems.

Remote, WSL, and Containers

Node/npx, workingDirectory, relative paths, environment variables, and connection addresses are resolved in the environment where the workspace lives. The system browser is opened through openExternal, which resolves localhost forwarding; the built-in page and "Copy Access URL" use asExternalUri. With an automatic port, the exact non-loopback authority returned by VS Code is added to the DSH Host allow-list; if the forwarded authority cannot be determined, the extension fails safely.

DSH only listens on 127.0.0.1, but forwarding visibility is controlled by VS Code, Codespaces, or Dev Tunnels. Keep forwarded ports Private and do not share forwarded URLs.

Security and Privacy

• Use Harness only with projects you fully trust. workingDirectory and any added directories may be read, written, and executed by the agent. Workspace Trust is not a filesystem sandbox.
• The extension always passes --host 127.0.0.1, refuses to let users override the listen address, and does not support patches that would rewrite this boundary.
• The upstream Web service has no authentication or TLS suitable for the public internet. The first startup downloads a pinned top-level DSH version from npm; transitive dependencies may still change.
• API keys, model configuration, and sessions are written by DSH to the extension's global application profile and are shared across projects in the same environment. This extension does not read API keys and contains no telemetry.

Troubleshooting

Development

Use Node.js 24 and the pnpm version declared in package.json.

pnpm install --frozen-lockfile
pnpm compile
pnpm verify
pnpm ext:package

compile creates a development bundle; verify runs the available static checks and unit tests; build verifies and creates the production bundle. ext:package builds a VSIX through the same verification gate used in CI. Use watch during development.

See Architecture for module boundaries and lifecycle rules, and Contributing for validation and release conventions.

Feedback

• Report bugs or request features: GitHub Issues
• Harness usage questions: DeepSeek Harness Discussions

License

MIT

Maintained by Quincy Zhang.