deepseek-harness-acp

Use DeepSeek Harness from Agent Client Protocol clients such as Zed and Backchat.

The adapter composes the harness in-process and maps its session-event log onto the full ACP vocabulary: streamed text and reasoning, tool calls with diffs and display terminals, plans, permission requests, session modes, config options, slash commands, skills, and MCP servers. Credentials never touch your editor config — it reuses the key you saved in the dsh Web UI, or dsh-acp login saves one to the same store.

Two ways to plug it in

Both shapes share $DSH_HOME: the same credential store, settings, presets, and session logs as dsh web — conversations started in the Web UI can be listed and loaded from the editor.

A · Standalone server

npm install -g @openma/deepseek-harness-acp
dsh-acp login        # interactive; or save the key in the dsh Web UI

// Zed settings.json
{
  "agent_servers": {
    "DeepSeek Harness": { "command": "dsh-acp" }
  }
}

Self-contained: it finds your DeepSeek Harness via --dsh-path / DSH_PATH, its own tree, ./node_modules, dsh on PATH, or npm root -g — and ships a vendored harness runtime as the last candidate, so it works out of the box and always prefers the dsh you installed. When a real $DSH_HOME/profiles/acp exists, that profile owns the composition.

B · dsh profile plugin

npm install -g @deepseek-ai/dsh
dsh web                                                  # save your API key once
dsh plugin --profile acp add -w @openma/deepseek-harness-acp

// Zed settings.json
{
  "agent_servers": {
    "DeepSeek Harness": { "command": "dsh", "args": ["--profile", "acp"] }
  }
}

This creates $DSH_HOME/profiles/acp and registers the package's dsh.bundle patch: the bridge mounts over @deepseek-ai/dsh-base — the same product baseline as dsh web, with the module-reload watcher off. Extend the profile in $DSH_HOME/profiles/acp/cordis.patch.yml like any other dsh profile.

Authentication

No keys in editor config, no secrets pasted into chat. ACP clients follow the protocol: initialize advertises three Agent Auth methods.

1. API key — api-key, or api-key:<provider> when more than one route is live. The client may pass _meta["api-key"].apiKey.
2. Browser — browser. The adapter opens a localhost sign-in page; the secret never travels over ACP. Hidden when NO_BROWSER is set.
3. Custom gateway — gateway, only when the client opts in with clientCapabilities.auth._meta.gateway === true. The client sends _meta.gateway { baseUrl, headers, providerName? }.

The adapter writes credentials to the harness store. Missing credentials fail session/new and session/prompt with auth_required (-32000). Logout is the ACP logout method.

1. Harness credential store — $DSH_HOME/.credentials.yaml (mode 600), the file the dsh Web UI writes; hot-reloaded. Save a key with dsh-acp login [--provider <route>], or the Web UI (Settings → Models).
2. Process environment — DEEPSEEK_API_KEY / DEEPSEEK_BASE_URL (and the matching ANTHROPIC_API_KEY / OPENAI_API_KEY for those routes) in the environment that launches the agent.

The credential gate is the current provider route. An Anthropic-only store is enough for an Anthropic session; a DeepSeek key does not unlock another provider.

Features

• Streaming — assistant text and reasoning deltas; assembled-message fallback.
• Images — promptCapabilities.image is advertised when the composition mounts ctx.attachments (dsh-base does). ACP image blocks are validated, stored with saveImage, and kept in wire order with surrounding text. resource_link stays a textual file pointer.
• Tool calls — ACP kinds, human titles, file locations, real diffs from fs-tool hunks, raw input/output; command output on a display terminal when the client supports one, fenced output otherwise.
• Permission presets as session modes — read-only / workspace-write / danger-full-access, each a named {sandbox, approval} pair recorded as a durable session fact (also exposed as a config option for clients that only render those).
• Agent composition — when the profile mounts agentPresets, an uncategorized config option id: "agent" lists the roster (standard / code / minimal / cordis, plus user copies). Switching rebuilds the agent live with history preserved. Authoring (copy/rm) stays on the Web settings page; there is no /preset slash.
• Live model catalog — providers × models from the running composition (third-party providers added in the Web UI appear immediately), plus reasoning-effort selection that follows your product default.
• Slash commands — adapter built-ins (/status, /model) plus the harness command registry (/compact, /goal, /permission, /plan, …) executed without a model turn, plus skills (/skill-name — the harness's own invocation gesture). Login and logout are ACP methods, not chat commands.
• Plans & usage — todo_write snapshots as ACP plans; token accounting as usage_update and per-turn usage.
• Sessions — session/load with full history replay, session/list, silent restore when a client prompts an old session after an agent restart, titles as session_info_update.
• MCP servers — per-session mcpServers mount @deepseek-ai/dsh-mcp-client instances (stdio + streamable HTTP); tools join as mcp__<server>__<tool>; a failing server never takes the session down.
• Real cancellation — session/cancel interrupts the live turn through the harness agent.

Configuration

Flags win over environment variables, which win over defaults. All optional — with no flags, sessions follow your product defaults (settings.yaml).

Subcommands: dsh-acp login [api-key] (interactive when omitted; input never echoes), dsh-acp update (self-update via npm).

Permissions and sandboxing

Sessions start in workspace-write: bash and file mutations are confined to the session's cwd (plus shared temp roots), and a model retry requesting wider access raises an ACP permission request. Always allow (this session) flips the approval policy to never for that session. danger-full-access disables both the sandbox and the prompts — use it only in disposable checkouts or containers. Each level is one durable preset (sandbox + approval together), the same three the Web UI offers.

Architecture

ACP client (Zed, …)
   │  ACP JSON-RPC over stdio
   ▼
dsh-acp
   ├─ src/profile-boot.ts     boots the harness's own profile machinery
   │                          (dsh-base + this bundle + $DSH_HOME layers)
   ├─ src/harness.ts          host discovery (DSH_PATH → cwd → PATH → npm -g → vendored)
   └─ src/bridge/             the ACP bridge (a cordis plugin)
        ├─ index.ts           sessions, prompts, cancel, modes, options,
        │                     commands, credentials, MCP mounts
        ├─ translate.ts       session-event → ACP update projection (pure)
        ├─ history.ts         stored-log replay for session/load (pure)
        └─ prompt.ts          ACP prompt blocks → harness content blocks (pure)
   ▼
your @deepseek-ai/dsh installation   (agent spine, llm, persistence, sandbox,
                                      tools, presets, skills, compaction, …)

The bridge consumes the harness session/event firehose — the same append-only log persistence stores — so live streaming, history replay, and session/list agree by construction. All harness modules, including cordis itself, load from one host tree: plugin and service identity is never split across copies.

Development

npm install         # dev deps include the harness packages (types + tests)
npm run typecheck   # tsc --noEmit
npm test            # vitest: unit + e2e smoke (boots the real composition; no model calls)
npm run build       # esbuild → dist/

To also run the e2e suite against a standalone host install:

npm install --prefix /tmp/dsh-host @deepseek-ai/dsh
DSH_ACP_TEST_HOST=/tmp/dsh-host npm test

Live iteration: paired profiles

Keep the profile your editor uses on the published package, and point a second profile at this worktree via a pnpm symlink:

dsh plugin --profile acp add -w @openma/deepseek-harness-acp   # stable
dsh plugin --profile acp-test add -w "link:$PWD"               # dev (symlink)

The dev loop is npm run build + restart — dist/ and cordis.patch.yml are read through the link. (pnpm treats file: as a copy install and caches same-version tarballs; link: avoids both.)

{
  "agent_servers": {
    "DeepSeek Harness": { "command": "dsh", "args": ["--profile", "acp"] },
    "DeepSeek Harness (dev)": { "command": "dsh", "args": ["--profile", "acp-test"] }
  }
}

License

Apache-2.0.