home-assistant-custom-components.ha_mcp_tools: Install Python module via Nix instead of UV

[Masrepus]

Things done

HA-MCP refused to start on my system in its current form, with an error message about not being able to install the HA-MCP Python module using UV.

Adding this module to the custom component's dependencies explicitly and patching the _async_ensure_package function (https://github.com/homeassistant-ai/ha-mcp/blob/master/custom_components/ha_mcp_tools/embedded_server.py#L676) to bail out if the required version is already available makes it work.

While this behavior is necessary on NixOS, it may also be beneficial for other systems, so I will also open a PR for this upstream.

This PR also contains one additional patch that removes the auto update entity that prompts the user to install an update, since this is not possible in a Nix-managed setup anyway.

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.
• Follows the automation/AI policy.

[Masrepus]

@JamieMagee in case there is some other way you got this to work in its current form I'm happy to abandon the PR, but when investigating the failure on my machine, it looked like there simply was no way to bypass the UV installation attempt without code changes 🤔

[JamieMagee]

I wonder is this a flow that is only hit when you attempt to add ha_mcp as a new integration. I've been happily running (and using) ha_mcp for the last 6 months or so.

[JamieMagee]

I did some investigation and the UV path only runs for the in-process server entry introduced in 7.10. Older entries are treated as the tools entry, which explains why my setup kept working.

I've opened homeassistant-ai/ha-mcp#2272 to add support for externally managed packages through skip_pip. If that lands, nixpkgs should only need to add ha-mcp as a dependency and pass --skip-pip.

[Masrepus]

Ah, I didn't realize this was such a new feature, thanks for looking into it!

When reading through the code and docstrings some more, I was hesitant to create the upstream PR as-is, since it did seem that the installation path was something that their architecture requires. Let's see what comes out of the issue you created 🙏

[JamieMagee]

Looks like they fixed this upstream: homeassistant-ai/ha-mcp#2275. It should be available in 8.3.0.

[Masrepus]

Very nice, that was quick! I'm guessing we'd still need to add the Python module to the component's dependencies list, but I'll test it locally to see if that's necessary