@deepseek-ai/dsh-acp

@deepseek-ai/dsh-acp

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Automation-only Agent Client Protocol server over JSON-RPC stdio. Programmatic clients create fresh harness agents, send text prompts, collect committed assistant text, resolve one-shot permission requests by policy, and cancel work. The primary in-repository client is dsh-subagent-acp.

This package is a transport adapter, not a UI integration or a capability seam. It does not expose editor navigation, transcript replay, commands, modes, configuration pickers, elicitation, reasoning, plans, titles, or tool presentation. Interactive rendering and human questions belong to the Web host and client modules.

Plugin

apply(ctx, config) opens an AgentSideConnection on stdin/stdout and drives ctx.agents. Stdout is reserved for protocol frames.

Config	Default	Meaning
provider	—	Initial provider route for every created agent.
model	—	Initial model for every created agent.

Both fields are optional so another agent/request listener may supply the target. The runnable ACP composition requires both.

Protocol contract

Method	Behavior
initialize	Negotiates the supported version and advertises baseline-only prompts (no image, audio, or embedded-context capability). No session, editor, terminal, filesystem, or MCP capability is advertised.
authenticate	No-op because the server advertises no authentication methods.
session/new	Creates a fresh agent with an absolute primary cwd; empty additionalDirectories and mcpServers are accepted, non-empty values reject.
session/prompt	Concatenates text blocks, renders baseline resource links as bracketed textual references, rejects empty or beyond-baseline input, permits one in-flight request per session, and waits for the whole agent to become idle. Normal quiescence reports end_turn; explicit ACP cancellation, disposal, or a prompt whose admission was discarded (a turnless slot) reports cancelled.
session/cancel	Cancels only the addressed agent and settles its pending prompt as cancelled; unknown ids are no-ops.
session/update	Emits one agent_message_chunk per non-empty text block in a committed assistant/message. Raw deltas and non-message events are omitted.
session/request_permission	Offers one-shot allow/reject choices for bridge-owned approval requests carrying a tool call id. Clients may answer automatically.

One connection may own several sessions. The bridge keys records by branded session id and checks exact agent identity before routing events or permission requests. Each session has an independent prompt slot, workspace, cancellation path, and disposer.

Committed-message output intentionally trades token-by-token latency for a clean automation result. Uncommitted provider chunks and retry attempts cannot leak partial text; reasoning and tool activity remain in the session log for observability through other interfaces.

Lifecycle

Client disconnect and Cordis disposal share one memoized teardown. The bridge first rejects new sessions and prompts, settles pending prompts, then drains continuable descendants only below this connection's exact owned Agents before disposing those handles in parallel and awaiting every result before reporting any failure. Other frontends sharing the Context retain their continuable forests and admission. An ACP-only plugin reload therefore leaves no orphan agent.

ACP requires each prompt response to carry a stopReason, but the bridge does not claim a prompt-specific turn outcome. Committed assistant messages stream across the owned activity, and steering or injected work may contribute before idle. Token-limit turn endings therefore do not become prompt-level ACP stop reasons (they settle as end_turn); a model error on the correlated turn rejects the prompt immediately.

Running

pnpm --dir /path/to/deepseek-harness run demo:acp boots the repository's automation server composition. A parent harness can spawn it through @deepseek-ai/dsh-subagent-acp; other ACP clients need only the core methods above.

Model Experience

Prompt text

What the model sees

session/prompt text blocks are concatenated verbatim into one user message; a baseline resource link appears in that message as a bracketed [resource_link name=… uri=…] reference the model may open with its own tools. Protocol metadata, client capabilities, permission choices, and session ids never enter the model request.

Token effect

Prompt tokens are data-dependent and remain in that session's history until compaction. Concurrent ACP sessions retain independent contexts.

KV Cache effect

Append-only; the new user message follows the reusable request prefix and does not invalidate prior cache entries.

Permission decisions

What the model sees

Nothing directly. The owning tool records its allowed, rejected, cancelled, or unavailable outcome through the normal tool-result path.

Token effect

Only the owning tool result contributes tokens.

KV Cache effect

Append-only through the owning tool result.

Known Limitations and Deferred Work

• Fresh sessions only — load, list, resume, delete, and fork are unsupported.
• Baseline prompts and one workspace only — images, audio, embedded resources, non-empty additional directories, and MCP servers reject; resource links flatten to textual references rather than fetched content.
• Committed answers only — live progress, reasoning, tool activity, plans, titles, and usage stay off the wire.
• Connection-owned lifetime — one connection releases all of its sessions; per-session close is not implemented.