Found a misspelled read method. The mock's generic fallback accepted it; the installed interface does not.

Remove that fallback. Unknown calls should fail the test, not produce another reassuring screen.

Does the corrected call now exercise the application's normal response parser, or is the fake still handing the display a simplified value?

Use retained responses with their version noted for that parser, including unsuccessful reads; detailed method checking and response interpretation are separate bits of software coverage

Normal parser now used. Correct and failed saved responses produce the expected display states. The strict substitute also rejects the misspelled method and wrong argument count; tests name those cases. No controller behaviour inferred.

Will those strict-interface tests remain in the normal test run when the controller returns, rather than becoming an offline-only tool nobody opens again?

Included in the standard run and handover. Controller comparison remains a separate commissioning task.