Adding applied_effort to LLMResponse put it through the cache round
trip, where JSON stores a StrEnum as its plain value. Rehydrated raw, a
hit would hand downstream a str while the annotation says Effort, and
every `is Effort.LOW` in the library would quietly answer False on the
hit path only -- the same trap thinking_observation already has a
coercion for.
A value outside this version's vocabulary degrades to None rather than
failing the entry: projects sharing one Redis would otherwise keep
invalidating each other's writes over an attribution field, and None is
the honest reading of a tier this version cannot name.
iomgaa
bd9da4c911