Add mypy cache-fix skill documentation

[mdegat01]

Proposed change

Add a repository skill document at .github/skills/mypy-cache-fix/SKILL.md describing how to diagnose and fix intermittent mypy internal errors caused by cache corruption.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:
• Link to cli pull request:
• Link to client library pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Ruff (ruff format supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints or add-on configuration are added/changed:

• Documentation added/updated for developers.home-assistant.io
• CLI updated (if necessary)
• Client library updated (if necessary)

[agners]

I've never seen this, how often does this happen? Is it really worth a skill? 🤔

[mdegat01]

It's possible its just a devcontainer issue but I see it all the time. I think maybe it happens on rebases? I'm not sure why. But like after you asked me to push this to another PR when I came back to the other PR it immediately ran into it again. This time it fixed it itself instead of trying to resort to no-verify commits like it did before.

I didn't really think there was a significant cost to a skill so I had it write it up. If there is or this is just a me problem I can just leave it locally only.

[agners]

Hm, it appears mypy 2.0 and newer switched to SQLite (python/mypy#21041).

I've dived into possible causes a bit, and most likely this is related to how we call mypy from pre-commit hooks. python/mypy#13916 has some good hints how to call mypy best.

I've come up with a new PR to address this: #6977. I think with that this skill should not be required anymore.

[agners]

Hm, it appears mypy 2.0 and newer switched to SQLite (python/mypy#21041).

I've dived into possible causes a bit, and most likely this is related to how we call mypy from pre-commit hooks. python/mypy#13916 has some good hints how to call mypy best.

I've come up with a new PR to address this: #6977. I think with that this skill should not be required anymore.

[home-assistant]

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[mdegat01]

Ok. Lets just leave this in draft for a bit to see if that addresses it, if so we can close. Also I don't mind just having this as a local skill if this is something I have to deal with a bunch but no one else does. I just want copilot to stop doing so many no-verify commits 😆