0.10.16 — did the instance declare everything

A new feature brought a new string: the label under a comment shown in machine translation. The key was added to the engine; the counterpart in the English instance was not. The result: a Polish label under an English translation.

The worst thing about this fault is that **nothing breaks**. The build passes, the types agree, there is nothing for a test to catch. The engine simply takes the default set — which is Polish — and renders it without complaint.

Checking from the side of the built bundle does not help, and that was the trap I walked into personally. I searched the built file for the string, found it, and considered the matter closed. What I had found was the Polish default set, which is ALWAYS in the bundle because it is the fallback path. That was not a check; it was confirming to myself what I already believed.

The only reliable comparison is the list of keys from the strings type against what stands in the instance configuration. That is what the new script does. Deliberate omissions — plural categories a given language does not have, and a disabled engine credit — sit in an exception table with a reason, so they do not clutter the result. An instance with no strings of its own passes without objection, because it speaks the engine’s default language and is meant to.

Run across four deployments, it found twelve omissions, including the entire book-building button on the English side.