# TODO P4.2: unit tests for the DeviceController license guard (plan §4.2,
#   docs/pending/license-gating-plan.md). Two cases:
#   1. license_lookup=lambda s: "" + fake _last_wafer_info → readMemoryAsync()
#      emits readResult {"error": ...} and spawns no thread.
#   2. lookup returning "02" → proceeds to _read_worker (mock DeviceService).
#   THINKING: guard is a trust boundary (plan §2.1); these fail if someone
#   reorders the busy/license checks or renames the "serialNumber" key.
#   Depends on P1.2 + P2.1 being implemented.