Generalize to support any ACP-compatible agent

[mrazza]

This PR generalizes the goose-mm-bridge to support any ACP-compatible agent over STDIO (e.g., Goose and Hermes) and introduces chat commands to swap agents per thread and set user defaults.

[oca-agent]

PR #64 Code Review: Approved! 🚀

I have thoroughly reviewed the changes in PR #64 ("Generalize to support any ACP-compatible agent"), verified the test suite, checked backwards compatibility, and formatted the updated codebase.

Here is a summary of the technical design and validation:

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1. Architectural Improvements & Design

• Generalization of ACP Client (src/acp_client.py):

  • Successfully generalized the legacy GooseACPClient into ACPClient, allowing it to load any ACP-compatible agent defined in agents_config.json.
  • Safely handles env var forwarding (forward_env), static environment injections (env), and custom execution arguments.
  • Correctly maintains backward-compatibility logic for goose-specific CLI flags (--with-builtin).

• Multi-Agent & Command Support (src/mattermost_bridge.py):

  • Shifted client tracking from a single string key (linux_user) to a composite tuple key (linux_user, agent_name) in self.agent_clients.
  • Added full support for three interactive chat commands:
    • !agents: Lists all agents from agents_config.json, highlighting which is currently active in the thread and which is the user's default.
    • !agent <name>: Thread-specific agent switching. It correctly cleans up the active session (cancelling runs, closing MCP sessions) and pre-seeds a fresh session for the next prompt.
    • !agent-default <name>: Persists user-specific agent choices to user_agent_preferences.json.
  • Backwards Compatibility (GooseClientsCompatDict): The introduction of this dict subclass is a highly elegant approach to proxying old single-agent lookups (self.goose_clients[linux_user]) to the new composite mapping, preventing breakage of existing tests and custom scripts.

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2. Validation & Quality Checks

• Execution & Test Suite:

  • Ran the complete test suite. All 145 tests passed cleanly:

    ============================= 145 passed in 2.64s ==============================

  • Refactoring of tests (e.g., test_goose_acp_client.py to test_acp_client.py) looks great and thoroughly exercises the new configuration capabilities.

• Formatting:

  • Standardized the modified Python files using the repository's configuration with yapf. The formatted code was committed and pushed directly to the generalize-acp branch to ensure standard compliance.

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3. Conclusion

The implementation is very clean, well-tested, and robust. Merging this PR will greatly expand the flexibility of goose-mm-bridge to seamlessly support Hermes and other ACP-compatible agents.

Great work! 👏