Why does our FR5 test double accept a status query I misspelled?

That caught the typo immediately. I have the installed interface version's documentation, so I'll use its response shapes too. Our current true value doesn't resemble a status response.

What did the screen do when the query failed?

Kept the last green status without marking it old. The stored value stayed unchanged too. We were only checking that the screen didn't crash.

Try success followed by failure, then check the age label as well as the stored value.

Thanks Mei, that sequence exposed the stale display. Offline tests now cover it and reject unknown calls. I still need to compare the response examples against the real controller when it's available.