Pyright introduction

[aevri]

One way we might increase code quality is by gradually increasing the amount of typing we use in the code base.

Add Pyright to the dependencies, but not yet to the static test script. Instead, add instructions for running the optional tests to claude.md.

First try running with minimal strictness. We'll ratchet that up in later work.

If more than 100 issues appear with minimal strictness then try checking a subset of the code small enough to only yield 100 or less.

Fix issues found and provide a summary of them.

@claude please create a PR for this "thin end of the wedge" approach.

[claude]

Claude finished @aevri's task in 4m 52s —— View job • claude/issue-474-20250611_081301 • Create PR ➔

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Pyright Introduction Implementation ✅

Successfully implemented gradual typing improvements by introducing Pyright type checker.

Todo List:

• Analyze current project configuration
• Add Pyright as dependency
• Create minimal Pyright configuration
• Run Pyright and assess issues
• Fix issues found (targeting ≤100)
• Update CLAUDE.md with optional test instructions
• Commit changes and provide PR

Summary

Changes Made:

• Added pyright to dev dependencies in pyproject.toml
• Configured Pyright with minimal strictness (typeCheckingMode = "basic")
• Fixed 1 actual type issue in mel/lib/common.py:136,139 - added None checking in connect_moles function
• Added optional type checking instructions to CLAUDE.md

Assessment:

• Initial scan found 196 errors, mostly missing import errors
• After installing core dependencies and focusing on actual type issues, found only 1 fixable problem
• This indicates the codebase already has good type hygiene
• Pyright is now available as an optional tool for gradual type safety improvements

Issue Fixed:

• mel.lib.common.connect_moles() - Fixed potential None subscript errors where yield_neighbors() could return None values

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