🛰️ export from upstream (31619fc)

README.md

@@ -66,6 +66,10 @@ sandcage claude --shell           # shell for debugging
 sandcage build                    # build/rebuild container image
 sandcage init                     # generate .sandcage.yml for your project
 sandcage setup ssh                # configure SSH key access for containers
+sandcage acp run claude           # ACP relay mode (bidirectional stdio)
+sandcage acp list                 # list agents in the ACP registry
+sandcage acp install <agent-id>   # install an agent from the registry
+sandcage acp installed            # list locally installed agents
 ```
 
 ## How It Works
@@ -80,6 +84,10 @@ sandcage setup ssh                # configure SSH key access for containers
 4. The agent runs as the container entrypoint, working in the mounted workspace
 5. All file changes are immediately visible on your host
 
+## ACP Support
+
+Sandcage includes built-in support for the Agent Control Protocol (ACP). Running `sandcage acp run <service>` starts the named agent container and establishes a bidirectional stdio relay, letting any ACP-compatible client communicate with the agent over standard I/O. Agents can be installed from the ACP registry with `sandcage acp install <agent-id>` and browsed with `sandcage acp list`.
+
 ## Configuration
 
 <p align="center">
@@ -122,7 +130,8 @@ See **[Configuration Reference](docs/configuration.md)** for all available optio
 
 - **Support for custom harnesses** — bring your own agent runtime beyond the built-in Claude Code, Codex, and Gemini CLI
 - **Full encapsulation hardening** — for worker and CI environments, ensuring complete sandboxing of file system, network, and credentials
-- **ACP integration** via [`dirigate`](https://github.com/dirigence/dirigate) — Agent Communication Protocol support for structured agent orchestration
+- **Full bollard integration** — replace docker compose with direct Docker API calls for faster startup and richer container control
+- **Interactive TTY mode** — full terminal emulation for agents that need a PTY
 
 ## Cross-Platform