Your coding agents deserve a protocol, not a PTY scraper

What it does

acpx acts as a command-line router for the Agent Client Protocol (ACP), giving orchestrators a single interface to dispatch work to Pi, Codex, Claude Code, or any ACP-compatible agent. It wraps the underlying tools in persistent, named, per-repo sessions that survive across invocations, queue prompts, and report back structured messages—thinking steps, tool calls, diffs—rather than raw ANSI streams. The client handles lifecycle details like cooperative cancel, crash recovery, and soft-close so the caller does not have to manage agent processes directly.

The interesting bit

The project treats the terminal as a control plane rather than a display surface: it intercepts ACP traffic and maintains session state on disk, which means you can queue a prompt, disconnect, and resume later, or run parallel named sessions for backend and frontend work in the same repository. There is also an experimental TypeScript flow runtime for multi-step workflows where deterministic shell actions and model turns alternate, complete with workspace isolation so agents can work in disposable directories.

Key highlights

• Persistent, repo-scoped sessions with named parallel workstreams (-s backend, -s frontend)
• Prompt queueing and cooperative cancel via IPC without tearing down session state
• Automatic crash detection and session resume when an agent process dies
• Structured output (thinking, tool calls, diffs) instead of parsing ANSI escape sequences
• Experimental TypeScript flow modules for multi-step agent workflows with shell-backed action steps

Caveats

• Explicitly alpha: the CLI and runtime interfaces are likely to change, so downstream integrations may break
• ACP spec coverage is incomplete; the project links to a coverage roadmap rather than claiming full compliance

Verdict Worth a look if you are building agent harnesses or CI pipelines that need to delegate coding tasks reliably. Skip it if you want a stable, end-user chat interface—this is plumbing for machines talking to machines.