Agent Client Protocol (ACP) is a JSON-RPC-based protocol for talking to agent runtimes. dsh ships an automation-only ACP server (packages/acp/acp) 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 (see Subagents).

Package	Role
@deepseek-ai/dsh-acp	ACP server plugin over JSON-RPC stdio
@deepseek-ai/dsh-subagent-acp	ACP-backed subagent transport

What this package is (and is not)

From packages/acp/acp/README.md: 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. The server's surface is deliberately small: the automation contract only.

Plugin and configuration

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.
(task methods)	Fresh agents per task, text prompts in, committed assistant text out, one-shot permission requests resolved by policy, cancellation supported.

The implementation lives in packages/acp/acp/src/ — index.ts (the plugin, connection loop, method dispatch), codec.ts (JSON-RPC frame codec over stdio), and invariant.ts (its invariant companion, per the repo's per-package invariant convention).

The consumer: dsh-subagent-acp

The ACP server is not a standalone product surface; inside dsh it is the backend of the acp subagent transport. When an agent spawns a subagent through ctx.subagents with the ACP transport, dsh-subagent-acp launches the ACP server (a fresh harness agent inside a child process speaking ACP over stdio) and proxies the delegation through it — giving the subagent an isolated process boundary while keeping the uniform subagent API (see Subagents for the transport matrix: spawn, fork, acp, codex/claude-code/dsh-sdk).

The worked examples

Two runnable examples demonstrate the server surface:

• examples/acp-agent (acp-agent-example) — an ACP server composition over JSON-RPC stdio: boot the dsh-acp bundle, accept client sessions, run the agent loop, stream text back.
• packages/examples/acp-demo (@deepseek-ai/dsh-acp-demo) — the in-tree demo plugin that examples/acp-agent's cordis.yml wires into the server, providing the provider/model config that shows the server in action.

Key source files

Repo-relative path	What it provides
packages/acp/acp/src/index.ts	Plugin, AgentSideConnection, method dispatch
packages/acp/acp/src/codec.ts	JSON-RPC frame codec
packages/subagent/subagent-acp/src/	The ACP subagent transport
examples/acp-agent/	Server-side worked example
packages/examples/acp-demo/	The demo plugin the example boots

Further reading

• Subagents — the transport matrix and dsh-subagent-acp
• SDK Protocol — dsh's other JSON-RPC wire, for comparison
• Examples & Demos — how to run acp-agent and acp-demo
• Repo: packages/acp/acp/README.md, packages/subagent/subagent-acp/README.md