Tighten Python Types

Tighten Python Types

Read the pinned upstream workflow at ../../vendor/tighten-types/tighten-types.md.txt before acting. Apply it in the current repository's context with these constraints:

• Default to Python files already changed for the user's task. Expand scope only when required by their interfaces or explicitly requested.
• Determine the supported Python version and configured type checker before choosing syntax or commands.
• Preserve runtime behavior and public compatibility. Avoid unrelated refactors, formatting churn, and blanket ignores.
• Replace broad Any, unparameterized containers, and ambiguous optionality with the narrowest honest types supported by evidence.
• Prefer natural narrowing, typed boundaries, protocols, and small helpers over cast; use cast only when runtime facts cannot be expressed otherwise.
• Do not invent types for dynamic or untrusted data. Validate it, model it explicitly, or keep the uncertainty visible at the boundary.
• Run the repository's formatter, linter, type checker, and focused tests. Report remaining errors and any annotations intentionally left broad.

For a disputed type-system rule, hand off to python-development:python-typing-reference.