Type checking not catching invalid keys inside of loops

[2018kguo]

Type checking is not catching invalid key lookups within a for loop

Repro (Monty)

# repro_monty.py
from pydantic_monty import Monty, MontyTypingError

stubs = """
from typing import TypedDict

class SearchTag(TypedDict):
    id: str
"""

loop_code = """
def main() -> None:
    arr: list[SearchTag] = [{'id': 'u1'}]
    for result in arr:
        _x = result['uuid']  # expected invalid-key
main()
"""

direct_code = """
def main() -> None:
    arr: list[SearchTag] = [{'id': 'u1'}]
    _x = arr[0]['uuid']  # does raise invalid-key
main()
"""

for name, code in [('loop', loop_code), ('direct', direct_code)]:
    try:
        Monty(code, type_check=True, type_check_stubs=stubs)
        print(name, 'NO_TYPE_ERROR')
    except MontyTypingError as e:
        print(name, 'TYPE_ERROR')
        print(str(e).splitlines()[0])

Observed:

• loop NO_TYPE_ERROR
• direct TYPE_ERROR (error[invalid-key]: Unknown key "uuid" ...)

Repro (ty CLI)

# repro_ty.py
from typing import TypedDict

class SearchTag(TypedDict):
    id: str

def main() -> None:
    arr: list[SearchTag] = [{'id': 'u1'}]
    for result in arr:
        _x = result['uuid']  # should error

main()

Run:

ty check --python-version 3.14 repro_ty.py

Observed:

• error[invalid-key] is correctly reported.

Notes

• Isolated this with ty commit 6ded4bed1651e30b34dd04cdaa50c763036abb0d: it reports invalid-key with ty’s own/default typeshed, but shows the same missing loop check when --typeshed points to Monty’s vendored typesheds.

Version

pydantic-monty==0.0.7, macOS ARM64, Python 3.14