# Agent Client Protocol ACP

[5 · Act](/category/act/)

| Agent Client Protocol |
| --- |
| Category | [Act](/category/act/) |
| Governed by | Zed Industries acts as BDFL/design-team lead over a public Request for Dialog (RFD) process; Sergey Ignatov (JetBrains) joined as a second Lead Maintainer on 2026-02-18, reflecting growing Zed/JetBrains collaboration |
| Status | v1 stable and shipping; v2 published in Draft form as of 2026-07-20 |
| Phase | stable |
| Implementation | multi-implementation |
| Adoption | unmeasured |
| Version | v1 (stable); v2 draft (2026-07-20) |
| Specification | [https://agentclientprotocol.com/get-started/introduction](https://agentclientprotocol.com/get-started/introduction) |
| Found at | none fixed; local agents are launched as sub-processes, remote agents connect over HTTP or WebSocket (remote support still a work in progress) |
| Acronym collisions | Agent Communication Protocol (IBM), Agentic Commerce Protocol (OpenAI/Stripe), Agent Connect Protocol (AGNTCY) |
| Last checked | 2026-09-06 |

[Act](/category/act/) The Agent Client Protocol (ACP) standardizes how a code editor or IDE talks to a coding agent, so that any ACP-compatible agent works with any ACP-compatible editor without bespoke integration work on either side [[1]](#ref-1). It targets the same M×N problem the Language Server Protocol solved for editor-to-language-server integration, but for agent-to-editor instead.

## Overview
ACP assumes the user's primary surface is the editor, which reaches out to agents for specific tasks. Local agents run as editor sub-processes and communicate over JSON-RPC via stdio; remote, cloud-hosted agents are supported over HTTP or WebSocket, though the project's own documentation states full remote support is still a work in progress [[1]](#ref-1). ACP deliberately reuses MCP's JSON representations where practical, and layers on coding-specific UX types (e.g. representing diffs) that MCP does not define; user-facing text defaults to Markdown.

ACP does not itself define agent discovery beyond the ACP Registry (stabilized 2026-03-09), which gives clients a standard way to find, install, and configure agents — it does not attempt to be a general web-scale discovery mechanism [[2]](#ref-2). It also does not (yet) fully specify remote-agent transport; a dedicated Transports Working Group (JetBrains and Block/Goose engineers) was formed on 2026-04-22 specifically to standardize WebSocket/HTTP transports for remote agents [[2]](#ref-2).

As of this check (September 2026), ACP v1 is stable and has shipped a steady cadence of "Completed" RFDs throughout 2026 (session resume, session list, logout, elicitation, boolean config options, request cancellation, and more), and ACP v2's protocol documentation and schema were published in Draft form on 2026-07-20 [[2]](#ref-2). Rust and TypeScript SDKs both reached 1.0 on 2026-06-25 [[2]](#ref-2). Governance is unambiguous and disclosed rather than disputed: Zed Industries is the explicit "BDFL" (benevolent dictator for life) design-team lead over a public Request-for-Dialog process modeled loosely on Rust's RFC process, and JetBrains' Sergey Ignatov joined as a second Lead Maintainer on 2026-02-18, formalizing what the project describes as "growing collaboration between Zed and JetBrains" [[3]](#ref-3)[[2]](#ref-2). What is not yet settled: how much of the remote-agent transport work lands in v1 versus v2, and whether governance broadens beyond the two-company core team the project says it currently anticipates expanding.

## Discovery and probe

ACP Registry (a standard way for ACP clients to discover, install, and configure compatible agents, stabilized 2026-03-09); locally, agents run as editor sub-processes over stdio JSON-RPC · none fixed; local agents are launched as sub-processes, remote agents connect over HTTP or WebSocket (remote support still a work in progress)

```
stdio spawn {agent-binary} and send a JSON-RPC 2.0 initialize request per the ACP schema over stdin/stdout
parse:     response result containing protocolVersion and agentCapabilities confirms an ACP-speaking agent
on absent: process exits, writes non-JSON-RPC output, or times out: the binary does not speak ACP
```

Not probed live: client-side. ACP runs between an editor and a local agent binary over stdio.

## History
- 2026-09-05 — seeded from Exa Agent research run
- 2026-09-06 — verified against agentclientprotocol.com/get-started/introduction, agentclientprotocol.com/updates, agentclientprotocol.com/rfds/about
- 2026-09-06 — collisions updated to add Agent Connect Protocol (Cisco/AGNTCY), verified against github.com/agntcy/acp-spec, spec.acp.agntcy.org

## Instances

- [Zed editor](https://agentclientprotocol.com/get-started/introduction) · Recorded 2026-09-06 · service
- [Gemini CLI (Google)](https://dreaming.press/posts/agent-client-protocol-acp-vs-mcp.html) · Observed 2026-07-03 · business
- [JetBrains IDEs](https://www.danilchenko.dev/posts/agent-client-protocol/) · Observed 2026-06-04 · business
- [Goose (Block)](https://agentclientprotocol.com/updates) · Observed 2026-04-22 · service
- [Zed](https://zed.dev/docs/ai/external-agents) · Observed 2026-04-01 · business
- [JetBrains IDEs](https://agentclientprotocol.com/updates) · Observed 2026-02-18 · service

Every instance with its source is listed on the [instances page](/instances/).

## See also

- [Agent Communication Protocol](/protocols/agent-communication-protocol/)
- [Agentic Commerce Protocol](/protocols/agentic-commerce-protocol/)
- [Agent Connect Protocol (AGNTCY)](/protocols/agent-connect-protocol/)

- [ACP (three protocols)](/terms/acp/)

- Not to be confused with: Agent Communication Protocol (IBM), Agentic Commerce Protocol (OpenAI/Stripe), Agent Connect Protocol (AGNTCY)

## References

- ACP standardizes communication between code editors/IDEs and coding agents for both local (stdio sub-process) and remote (HTTP/WebSocket, still in progress) scenarios; it reuses MCP's JSON representations where possible and adds coding-UX-specific types such as diffs. — [https://agentclientprotocol.com/get-started/introduction](https://agentclientprotocol.com/get-started/introduction) (2026) VERIFIED
- ACP v2 protocol documentation and schema were published in Draft form on 2026-07-20; governance is a Zed-led design team using a public RFD (Request for Dialog) process, with Sergey Ignatov of JetBrains joining as Lead Maintainer on 2026-02-18 and an ACP Registry stabilized 2026-03-09. — [https://agentclientprotocol.com/updates](https://agentclientprotocol.com/updates) (2026-07-20) VERIFIED
- Governance is explicitly a 'design team with the Zed team as the lead (BDFL)'; RFDs are ACP's RFC-equivalent process, licensed Apache 2.0, discussed on Zulip and via GitHub PRs. — [https://agentclientprotocol.com/rfds/about](https://agentclientprotocol.com/rfds/about) (2026) VERIFIED

[JSON](/data/protocols/agent-client-protocol.json) · [Markdown](/protocols/agent-client-protocol/index.md)