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.

One package, standalone or plugin

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.

Other dsh surfaces can mount the transport-independent @openma/deepseek-harness-acp/plugin on their Base Host tree and own the transport adapter. The TUI profile uses this path: it starts a separate TUI Client process and connects ACP over that process's standard stdin/stdout; it does not start dsh-acp or use an in-process Client stream.

The package is therefore not only a CLI wrapper. It is also the ACP surface plugin used by other dsh applications: one Host composition can expose the same sessions, tools, presets, skills, and persistence through a transport chosen by the surface.

DSH compatibility

The bundled runtime is DSH 0.1.5-rc.1, including the upstream cross-process session write lock. Your installed DSH still takes precedence; use an updated host or the bundled runtime to get the fix.

A competing load/resume returns a standard JSON-RPC error. Closing the session or exiting the owner process allows another process to resume it. Every process writing shared sessions must use a fixed backend; older hosts do not participate in this lock.

Restoring historical sessions uses the host's V3 migration, which preserves the original log. Upgraded sessions cannot be read by older hosts. Multi-root workspaces remain unsupported.

A · dsh profile plugin (recommended)

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

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

The plugin command creates $DSH_HOME/profiles/acp, installs or upgrades the adapter, and registers its 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. A global dsh-acp installation is not required for this path.

B · 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" }
  }
}

The standalone binary finds DeepSeek Harness via --dsh-path / DSH_PATH, ./node_modules, dsh on PATH, or npm root -g, then falls back to the exact runtime archived inside this package. DSH is only a wildcard optional peer for Host integration, never an npm-installed dependency: plugin mode uses the Host's tree, while standalone maps the same imports to the private runtime. When a real $DSH_HOME/profiles/acp exists, that profile owns the composition.

Plugin and extension model

There are two independent ways to extend an ACP-backed surface.

To use portable Agent Plugins, Codex plugins, Claude Code plugins, or Pi packages through an ACP client, add the Agent Plugins Bridge to the same profile:

dsh plugin --profile acp add @openma/dsh-agents-plugins-bridge@latest

The Bridge contributes ordinary Host rows. Imported commands, skills, tools, hooks, MCP connections, agents, and Pi extensions therefore reach ACP through this adapter's existing projections; there is no ACP-specific plugin import runtime. The Bridge's Web management panel and MCP Apps HTML renderer remain Web surfaces and are not sent over ACP.

For extensions that need a session-owned background lifecycle without an open terminal UI, use Martty owner. It is a generic ACP rpc client: this package remains the server/transport, while Martty owns the long-lived Session and explicit startup/shutdown slash commands.

Extend the Host composition

The ACP adapter rides the Cordis tree that the profile already owns. Add dsh plugins to that profile to change the agent composition instead of forking the ACP server: providers and models join the live catalog, commands and skills join the advertised session surface, tools and subagents appear through standard session/update, and the same session persistence remains available to every surface.

For applications embedding ACP, the public package entries are:

ctx.acpServer.connect(stream) creates a connection-owned bridge fiber over the existing Host composition. The transport owner retains process, stream, and TTY lifecycle; the ACP plugin retains session and agent semantics. This is the shape used by @openma/deepseek-harness-tui: ACP stays on the Base Host tree while a separate TUI Client process owns its own Cordis tree.

Adding a Cordis service does not automatically invent a wire method. Prefer a standard ACP capability or event projection whenever one exists; add an adapter only for behavior that must cross the client boundary.

Extend ACP without breaking ordinary clients

Optional wire behavior follows ACP's extension conventions:

1. Advertise support in initialize metadata, with a namespaced and versioned capability such as _meta.dsh.cordis.protocol.
2. Carry annotations on standard messages in namespaced _meta fields when no new request is needed.
3. Name custom JSON-RPC requests and notifications with a leading underscore, and send them only after both peers negotiated the matching capability.
4. Keep the standard ACP path complete. A client that does not advertise an extension must still get normal sessions, prompts, updates, cancellation, auth, and config options.

DSH tool result values

The ACP metadata registry is the authoritative list of every _meta field this adapter reads or emits. It records direction, carrier, shape, negotiation requirements, and replay behavior, including native DSH tool values at _meta.dsh.toolResult.value.

The current package applies this pattern to the built-in _dsh/cordis/* family used by the TUI for Client capability discovery, dynamic Package lifecycle, and package-private Host/Client RPC. It is an explicit, versioned extension—not a synchronization of Cordis plugin ids, fibers, or inject across processes. The bridge's internal method registry is not currently a public arbitrary-extension API; new extension families should first define a stable capability, ownership, lifecycle, and fallback contract.

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. Model option ids are stable: bare model ids while one provider is registered, provider::model as soon as there are several — never keyed on the current default provider (which every switch rewrites), so an id a client cached keeps working. Bare ids are still accepted on input and resolve to the provider that serves them.
• 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/resume restores a durable session without replaying its transcript; session/load remains the full-history path. Also supports session/list, silent restore when a client prompts an old session after an agent restart, and titles as session_info_update. Multi-root sessions are not advertised: non-empty additionalDirectories on session/new, session/resume, session/load, or session/fork return Invalid params until dsh supports multiple workspace roots.
• Fork — initialize advertises sessionCapabilities.fork: {} and agentCapabilities._meta.jetbrains.air.fork = { version: 1, inclusive: true } (deep-merged next to dsh.cordis). session/fork creates a new session id and leaves the source session unchanged. Without _meta.jetbrains.air.fork, the new session copies the source's committed log. With that block, the copy keeps the selected assistant message and everything before it, and drops every later message. messageId is the ACP id <turn>:<step> (a <id>:segment:<n> id is also matched as <id>). An optional messageFingerprint (sha256: + SHA-256 of the assistant text) and 1-based messageOccurrence disambiguate. A bad version, a bad fingerprint, a missing id, or a point that is not in the log is JSON-RPC -32602 — the adapter does not silently copy the whole session. Unknown session ids and subagent child sessions are also -32602. Only persisted assistant messages are fork points; a running turn's live stream is ignored. If the selected message itself contains tool calls, those calls are removed from the copied message (their results are stored after the message, so keeping the calls would leave an illegal transcript and would make session/load replay continue past the message). Tool calls and results from earlier messages stay. session/load on the new session replays through that assistant message and no further; session/prompt continues from there. The fork response carries the same modes and configOptions shape as session/new.
• 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.
• Steering — the initialize response advertises _meta.steering.supported: true. Send _session/steering with { sessionId, prompt, _meta: { steering: { idleBehavior: "promptRequired" } } } to inject into an active turn; { outcome: "injected" } leaves its original prompt request and output stream in charge. If that turn ends before injection, the response is { outcome: "promptRequired", reason: "noRunningTurn" } and the client sends an ordinary session/prompt. Omitting idleBehavior uses the same behavior. Concurrent session/prompt steering remains supported.
• 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/bin.ts              selects one DSH tree before Host imports evaluate
   ├─ 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 → bundled runtime)
   └─ 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)
        ├─ fork.ts            session/fork meta, message lookup, inclusive cut (pure)
        └─ prompt.ts          ACP prompt blocks → harness content blocks (pure)
   ▼
external or package-bundled dsh     (agent spine, llm, persistence, sandbox,
                                     tools, presets, skills, compaction, …)

When embedded by another surface, only the transport edge changes:

dsh Base Host Cordis tree
   ├─ product plugins (agents, tools, skills, persistence, …)
   └─ @openma/deepseek-harness-acp/plugin
         └─ acpServer.connect(Stream)
                │ standard ACP + negotiated extensions
                ▼
          surface-owned Client process

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"] }
  }
}

Automated compatibility review

When .github/workflows/dsh-update.yml opens a new bundled-dsh upgrade PR, it automatically dispatches a Cursor cloud agent to review ACP compatibility with the new dsh version. The agent:

• Reads dsh release notes and API changes between versions
• Tests the ACP adapter with the new dsh version
• Pushes fixes directly to the PR branch if needed
• Posts a verdict comment on the PR (safe to merge / safe after fixes / not safe)

This requires the CURSOR_API_KEY organization or repository secret (a Cursor API key from the Cursor Dashboard). If the secret is not configured, the workflow skips the agent dispatch with a warning and leaves the PR open for manual review.

The agent uses the Cursor Cloud Agents API v1 with workOnCurrentBranch: true to push directly to the PR's head branch without creating a new branch or PR.

To manually test the review workflow on an existing PR, trigger the workflow via Actions → Update bundled dsh → Run workflow and provide the PR number. The dispatch logic lives in scripts/dispatch-cursor-review.sh.

License

Apache-2.0.