Agent Host Protocol

A synchronized, multi-client state protocol for AI agent sessions.

Read the documentation →

Overview

The Agent Host Protocol (AHP) defines how a portable, standalone sessions server communicates with its clients. Multiple clients can connect to the server and see a synchronized view of AI agent sessions through immutable state, pure reducers, and write-ahead reconciliation.

Client libraries

Language	Package	Version	Source
Rust	ahp · ahp-types · ahp-ws		clients/rust/ · CHANGELOG
TypeScript	@microsoft/agent-host-protocol		clients/typescript/ · CHANGELOG
Kotlin	com.microsoft.agenthostprotocol:agent-host-protocol		clients/kotlin/ · CHANGELOG
Go	github.com/microsoft/agent-host-protocol/clients/go		clients/go/ · CHANGELOG
Swift	SwiftPM: microsoft/agent-host-protocol		package README · CHANGELOG
.NET	Microsoft.VisualStudioCode.AgentHostProtocol · Microsoft.VisualStudioCode.AgentHostProtocol.Abstractions		clients/dotnet/ · CHANGELOG

Other clients: AHPX (CLI + Node.js client), VS Code (built-in Agent Sessions client), ahpc (terminal client) and WeChat AHP (VS Code extension connecting WeChat to an existing local Agent Host chat).

The Rust, Swift, Go, and .NET SDKs ship a MultiHostClient for talking to two or more hosts at once (single-host consumers use the same API via MultiHostClient::single / .single(...) / hosts.Single(...) / MultiHostClient.SingleAsync(...)). See Connecting to Multiple Hosts.

Servers

• VS Code agent host — The reference AHP server implementation (src/vs/platform/agentHost/node/).
• pi-ahp — An open-source AHP host for the pi coding agent, exposing pi sessions to AHP clients over WebSocket.
• ahpd — An open-source AHP host over WebSocket, that runs plugins: the agent, the ports and the server tools are all installed rather than built in, and @ahpd/sdk is the library to build a host of your own.

Versioning and releases

Each language client and the spec itself release independently on their own SemVer tracks. See docs/specification/versioning.md for the protocol-level rules and RELEASING.md for the release mechanics (tag conventions, CHANGELOG / metadata enforcement, required CI environments).

Development

# Install dependencies
npm install

# Start local dev server
npm run docs:dev

# Build for production
npm run docs:build

# Preview production build
npm run docs:preview

License

MIT