goose and ACP as its primary client protocol

We're standardizing how clients talk to goose by adopting ACP (Agent Client Protocol) (https://agentclientprotocol.com) as the primary interface for all goose clients — desktop, CLI, and beyond.

Why

Today, goose has two different client paths:

• goose-cli communicates with the agent in-process
• goosed (the desktop backend) uses a custom REST + SSE streaming API

This split means every feature needs two implementations, and external clients have no stable contract to build against. As noted in our roadmap:

To support goose as a platform rather than a single app, we need a stable protocol boundary between clients, servers, and extensions. ACP is a strong contender for agent-to-client communication. A client–server architecture (even locally) gives us portability and experimentation without expanding the supported surface area endlessly.

What is ACP?

ACP is a standardized agent client protocol built on JSON-RPC 2.0. It defines a small, clear set of methods:

This gives us session management, streaming responses, tool execution with permission flows, and session resumption — all over a single POST /acp endpoint.

We've implemented an Streamable HTTP (and websocket upgrade) based transport for ACP in the goose-acp crate, and we will explore putting this forward as a standard.

The plan

We're rolling this out in four phases (tracked in #6642):

1. Stabilize ACP Server — Production-ready ACP-over-HTTP server with core goosed features, integration tests
2. TypeScript TUI Alpha — A new terminal UI built entirely on ACP, proving the protocol works as a daily driver
3. Desktop Migration — Migrate the Electron app from the custom goosed API to ACP (feature-flagged)
4. Consolidation — Remove goosed and goose-cli, leaving ACP as the single interface

What this means for you

• Extension authors: No change. MCP remains the protocol for extensions.
• Desktop/CLI users: The transition will be feature-flagged. No disruption expected.
• Building a custom client? ACP gives you a stable, documented contract to target. Any ACP-compatible client will work with goose. You can start looking at the goose-acp crate if you want to

Get involved

• 📋 Track progress: #6642 — goosed to ACP-over-HTTP
• 🗺️ Full roadmap context: goose OSS Roadmap (Feb–Apr 2026)
• 💬 Questions or feedback? Drop them in this discussion or talk to @alexhancock @jamadeo @jh-block on Discord.