DeepSeek Harness for VS Code

Your coding agent, with every change in view.
Bring DeepSeek Harness (DSH) into VS Code: work with your code, review native diffs, and follow each task with built-in Trace and usage insights.

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Install for VS Code · Open VSX · Download VSIX · Changelog

An independent community project. Issues welcome.

For JetBrains IDEs (IDEA, PyCharm, etc.), please see dsh-intellij-integration.

Why DSH?

• See what changed. Review tool edits in VS Code's native side-by-side diff, even outside a Git repository.
• Decide before execution. Approval cards show commands and target files, with proposed diffs for supported file writes.
• Start with context. Bring files, selections, Git diffs, or paused debugger state into a task without copying everything by hand.
• Pick up where you left off. Resume persistent sessions and follow tools, subagents, Todos, and token usage in the Activity panel.

Quick start

Requires VS Code 1.106.0 or later and a configured DSH model provider with credentials.

1. Install the extension from the Marketplace or Open VSX links above, or search for harcochen.dsh-vsc-integration in Extensions.
2. Open chat. Open and trust your project folder, then run DSH: Open Chat from the Command Palette. The extension automatically starts or connects to a Runtime; by default, it attempts a managed Runtime download when no usable environment is available.
3. Set up your provider. Run DSH: Configure API Key for DeepSeek credentials. For other providers, use DSH: Open dsh Web UI in Browser. Select or register a DSH Workspace, then choose a model.
4. Give it a task. Type @ to reference a file, or right-click a selection for DSH actions. Follow the task, respond to approval requests, and open diffs from tool cards to review the result.

A DSH Workspace groups sessions in Harness and can be associated with a project path. When using the same Runtime, you can continue sessions created in the Web UI.

Try it on real work

Your task	A place to start
Understand unfamiliar code	Select code and use the DSH explain action: “Walk through the execution flow and edge cases.”
Review a change	Use the DSH review action on a Git diff in Source Control: “Check these changes for regressions and point to the relevant lines.”
Investigate a breakpoint	While paused, run DSH: Explain Current Debug State to attach context including the call stack and local variables.
Continue earlier work	Switch to a previous session and use the conversation outline to revisit the discussion.

Features

Native diff for every edit, no Git required

After a write/edit tool call, open the target file to see VS Code's native side-by-side diff. The before-image is reconstructed by replaying hunks backwards from the Session log, so it also works in non-Git repositories and Git-ignored files.

Preview before approval

The approval card shows the actual command line, working directory, and target files that will be written. For supported file-writing tools, open a native diff of the proposed change before approving it.

A write whose target file still has unsaved editor changes is not released: approval is refused, the card names the files and stays pending, and you can save or revert them and approve again.

Slash commands enumerated live from the Runtime

The slash menu dynamically fetches commands registered by the Runtime for the current session (/plan, /compact, /goal, etc.) and merges them with the extension's own IDE commands.

Editor and Git context

• Right-click the current file, selection, or Git diff to explain, fix, review, or generate documentation.
• Right-click Ask about resource in Explorer to ask about a file or folder.
• The @ menu autocompletes project files and previous Sessions.
• DSH: Capture AppShot (macOS only) captures a window screenshot and inserts it into the conversation as a draft.

Sessions, Trace, and Activity at a glance

The sidebar provides a native conversation-outline TreeView. Trace, token usage, Todo lists, and subagents are gathered in the Activity panel. The UI supports VS Code's dark and light themes.

DSH: Open Chat in Editor Tab mirrors the same conversation in an editor tab, so the chat can sit next to the file you are editing. Both surfaces show one session and one stream — switching between them does not restart or fork anything.

Autonomous debugging (off by default)

With dsh.autonomousDebugging enabled, the extension exposes a loopback MCP endpoint inside this window and the agent can drive the VS Code debugger: debug_start launches a launch configuration that already exists in the workspace, debug_breakpoint adds, removes and lists breakpoints, debug_control continues, steps and waits for the next pause, and debug_context reads the paused stack, variables and source. Variables whose names look like secrets are replaced with [redacted by dsh-ide] before they leave the window. The endpoint binds 127.0.0.1 only, checks the Host header and a per-launch token, and never lets the model invent a launch configuration. It applies to a Runtime this window starts; switching the setting needs a Runtime restart, which the extension offers when you change it.

Credentials and balance

The bottom bar shows your current balance, including peak and off-peak pricing. Low balances are highlighted clearly.

FAQ

Do I need to install DSH manually? Usually no. The extension looks for a usable local environment and attempts to download a managed Runtime when needed. The first download requires network access; dsh.installWhenMissing controls automatic installation.

Can I connect to an existing Runtime? Yes. Set dsh.serverUrl to your running dsh web address and set dsh.serverToken to its launch token when the token is not already in the URL. This extension accepts valid SemVer versions at or above dsh 0.1.5-rc.1, including newer prereleases and stable versions. RC.2 is the default download and upgrade target. V3 history and opt-in Assistant streams remain required. Session migration preserves original logs, but older runtimes cannot read the upgraded V3 files.

The source audit covers upstream master c291e7961a and release tag dsh-v0.1.5-rc.2 (fb2c4b9e698e30edb738bca4cf0618587db7d203). Message feedback preserves categories for both ratings, including edits and conflict responses. When a Runtime supplies master’s optional modeSelectionEnabled policy, disabling it hides the IDE mode choices, clears a staged mode, and restores blank sessions to the effective default before their first prompt; started sessions keep their composition. Skill completion tooltips show SKILL.md paths when supplied. Missing optional fields retain RC.2 behavior. Version acceptance follows the minimum-version rule, independently of this source audit.

At this audit, npm latest and next point to RC.2. The extension keeps 0.1.5-rc.2 as its default; a compatible local installation is reused without downgrading.

The default dsh.command: "auto" probes dsh --version on PATH, then in the npm global prefix. A compatible local CLI is used directly. An incompatible CLI gets an upgrade prompt before any plugin download: it shows the current version, target and installation path. Approval upgrades a verified older npm global installation to dsh.runtimeVersion, then probes that same CLI again. Declining or closing the prompt uses pinned pnpm, then npx, then the managed CNB Runtime; missing CLIs also use this fallback. Upgrade failure offers fallback or cancellation. Unknown versions and older installations outside the active npm prefix get manual guidance. Diagnostics never prompt or install. Explicit local paths follow the same upgrade flow; explicit pnpm/npx keeps package-manager startup. If you previously saved dsh.command: "pnpm", reset it or select auto to enable local-first discovery.

Default app arguments are web --no-open; pnpm/npx gets its required prefix automatically when no argument override is saved. Existing package-manager argument overrides are preserved, and auto mode strips their package prefix when selecting a local CLI. Shared Runtime discovery still runs before choosing a new launcher, so fallback reuses a healthy Runtime instead of starting a second one.

As of the adaptation check, the CNB standalone Runtime mirror returns 404 for 0.1.5-rc.2. Use a compatible local CLI, the pinned pnpm/npx fallback, or an existing instance until that mirror is published; a standalone download is not currently verified. After compilation, node scripts/verify-runtime-discovery.mjs checks selection and actual startup arguments in an isolated POSIX CLI environment without downloads or model requests.

Does DSH support multi-root workspaces? DSH supports multiple independent Workspaces, but each Session has one working directory (cwd). A VS Code multi-root workspace is therefore represented by the first workspace folder for Runtime startup; use separate DSH Workspaces or Sessions when roots need different working directories.

Does DSH automatically identify secrets or personal information? No. Context is based on files, selections, and attachments that you explicitly choose; DSH reports size/truncation but does not send workspace content to an additional secret/PII classifier.

What if startup fails? Run DSH: Diagnose Environment, then DSH: Show dsh Runtime Logs from the Command Palette. Include your extension version, OS, and redacted error details when opening an issue.

Does it support Chinese? Yes. Commands, chat, Activity, and Trace follow VS Code's display language, with English and Simplified Chinese available.

Architecture and runtime

The extension connects to the Runtime through RC Remote RPC, using HTTP calls and a multiplexed WebSocket for live session updates.

Multiple VS Code windows discover each other through Runtime advertisements, then fall back to port 3080 and any configured dsh.serverPort. Every candidate is health-checked before use: authentication and a successful session/list call establish a usable connection, and advertised versions below the minimum are excluded. External services remain externally owned and are not stopped on disconnect. If authentication credentials are missing, set dsh.serverUrl to the full launch URL, including its token.

Advertisements are discovery metadata only. No advertisement grants or denies permission to start, so a missing, stale, or unreadable one can never block startup — the worst case is one failed health probe followed by this window launching its own Runtime.

Each window publishes exactly one file, <ownerId>.json, under dsh-runtime-advertisements-<user> in the OS temporary directory, carrying its endpoint, launch URL, version, PIDs, and composition hash. A window writes only its own file and never reclaims another's; legacy dsh-runtime.lock files are still read as hints, never written or removed. Readers take the sixteen most recent entries, so an abandoned file cannot crowd out live ones.

Advertisement lifecycle:

• Only a ready endpoint is published. A launch that fails before producing a URL leaves nothing behind.
• Startup briefly coordinates through a loopback mutex — at most 250 ms waiting and 500 ms held — and rechecks for a shared Runtime before spawning. Losing that race never blocks a launch; it just means this window starts its own Runtime.
• Explicit stop, dispose, and failed launches withdraw the advertisement.
• An unexpected launcher exit drops ownership but keeps the advertisement while its endpoint still answers, because package-manager wrappers routinely exit while the Runtime they started keeps serving. Only an explicitly refused loopback connection withdraws it; a timeout or an ambiguous host keeps the record.
• Startup is pinned to --host 127.0.0.1 and, without dsh.serverPort, to an OS-assigned port. A pinned port that loses a bind race retries once on an OS-assigned port.
• Shutdown stops owned process trees before withdrawing the advertisement. POSIX uses separate process groups; Windows uses scoped taskkill /T while the root identity is known.

After npm run compile, run node scripts/verify-runtime-discovery.mjs and node scripts/verify-runtime-shutdown.mjs to check launcher/port selection, advertisements, upgrade confirmation, and shutdown using isolated temporary directories, child processes, and loopback listeners.

graph TD
    A[VS Code Extension Host] <-->|RC Remote RPC| B[Standalone Harness Runtime]
    A <-->|Typed Full-State Bridge| C[React Webview UI]
    B <-->|CNB Distribution| D[Managed Local Engine]
    A <-->|Process Lock| E[Multi-Window Shared Runtime]

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Configuration

Search dsh in VS Code settings for the full list.

Setting	Default	What it does
dsh.serverUrl	""	URL of an already running dsh web Runtime; when set, the extension connects directly. Include ?token=... or set dsh.serverToken.
dsh.serverToken	""	Launch token for dsh.serverUrl; use it when the address and token are configured separately.
dsh.autoStart	true	Automatically start or connect to dsh web when the extension activates.
dsh.installWhenMissing	true	Automatically download and manage a standalone Runtime when no usable npm/dsh environment is available.
dsh.runtimeVersion	0.1.5-rc.2	Approved CLI upgrade and plugin download target; accepts any valid SemVer at or above RC.1 (CNB downloads require a published mirror).
dsh.npmRegistry	https://registry.npmmirror.com	Registry mirror used as a download fallback.
dsh.npxTimeoutMs	120000	Timeout while waiting for package-manager download and startup.
dsh.enableCompaction	true	Enable the official /compact command when the extension starts its own Runtime.
dsh.autonomousDebugging	false	Let the agent drive this window's debugger through a loopback MCP endpoint. Applies to a Runtime this window starts; needs a Runtime restart.
dsh.maxContextBytes	120000	Maximum UTF-8 bytes of <ide_context> included per prompt.
dsh.persistSession	true	Reuse the previous Session ID for the current workspace when possible.
dsh.agentStatusLabels	fat-whale messages	Random text shown during each streaming turn; customizable.
dsh.agentStatusLabel	""	Pins a single fixed status line when set.
dsh.enableEffortKnob	true	Use the runner sprite animation as the reasoning-effort slider button.

Other ways to install

From GitHub Releases — download the .vsix from Releases and run Extensions: Install from VSIX.... Pre-release builds go to Open VSX flagged as pre-release and to GitHub Releases; on Open VSX only users who switched that extension to its pre-release version receive them, and they never reach the VS Code Marketplace, which does not accept SemVer pre-release version numbers. From 0.8.0 on, stable releases use even minor versions (0.8.x) and pre-release builds use the next odd minor (0.9.x), so a stable release never supersedes a newer pre-release.

Build from source:

npm install
npm run check
npm run package

Then install the generated .vsix via Extensions: Install from VSIX....

Extension API

Other VS Code extensions can hook into the API DSH exports.

Conversation navigation API — register custom nodes

const registration = api.registerConversationNavigation([
    { seq: 42, label: "Review the PPO implementation", detail: "Training config" },
]);
context.subscriptions.push(registration);

Agent status label API — customize streaming status text

const dsh = vscode.extensions.getExtension<import("dsh-vsc-integration").DshExtensionApi>(
    "harcochen.dsh-vsc-integration",
);
const api = await dsh?.activate();
context.subscriptions.push(
    api?.registerAgentStatusPresentation({ label: "🐋 Diving" }),
);

Development and testing

npm install
npm run check      # TypeScript check (host + webview)
npm test           # Release gate: webview check + compile + test suite
npm run compile    # Build to dist/
npm run package    # Compile + vsce package
npm run release    # Test + version bump + CHANGELOG archive + tag

To check the Remote integration against an installed 0.1.5-rc.2 launcher:

npm run compile
node scripts/verify-remote-runtime.mjs --launcher /absolute/path/to/dsh

This smoke run uses a temporary DSH home/workspace and a loopback model stub. It does not use your sessions or external model credentials. The runner requires Node.js >=22.15.0 with node:zlib Zstandard support (zstdCompressSync; Node 23 users need >=23.8.0).

To verify the managed Runtime release logic:

node scripts/verify-managed-runtime.mjs              # remote contract only
node scripts/verify-managed-runtime.mjs --full       # install and smoke-test

More information

• Changelog
• Product TODO
• Third-party notices

Acknowledgments

Thanks to dsh-reasoning-effort for the chibi runner sprite reference. The conversation outline takes inspiration from the dsh-milestone project.

License

MIT