Summary

• restrict return simplification to adjacent assign; return name pairs in the same statement list
• remove simplified assignments by node identity instead of by variable name
• add a regression test covering the reported return path parameter crash

Why

The simplifier assumed any return <name> referred to a preceding assignment stored in a global name map. Returning a parameter or other local name with no matching assignment raised a KeyError, and deleting assignments by name was broader than the actual simplification target.

Validation

• .venv/bin/python -m pytest
• python3 -m py_compile pymini/pymini.py tests/test_api.py