Importing a transponder model first (e.g. iso15693.type5, or iso14443a via the fuzzer) triggered pm3py.sim's __init__, which eagerly re-imported that same transponder before it finished initialising — ImportError on a partially-initialised module. Masked in the full suite by import order; failed whenever a transponder was the first import.
Move sim/__init__'s ~90 transponder re-exports into sim/_models.py and load them lazily via a PEP 562 __getattr__ (public API unchanged: attribute access, from-import, __all__, dir(), and 'import *' all still work). Defer fuzzer.py's iso14443a.base import into the one method that uses it. Add tests/test_import_hygiene.py — subprocess fresh-import guards per transponder family.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
