Module lookup 

Cache::lookup per CACHE-014..CACHE-016, plus Cache::lookup_status for AUX-015 step 11.

Cache::lookup returns Some(Manifest) only if every check on the entry passes; any failure (manifest missing, manifest unparseable, schema-version mismatch, hash-function mismatch, output blob missing, output blob size mismatch, captured stream missing, captured stream size mismatch) yields None.

Cache::lookup_status is the introspecting variant haz why needs: it preserves the same miss conditions but discriminates them into the four AUX-015 step 11 sub-states (CacheLookupStatus::Hit, CacheLookupStatus::MissNoEntry, CacheLookupStatus::MissSchemaMismatch, CacheLookupStatus::MissCorruptEntry). Unlike Cache::lookup, filesystem errors that are NOT the spec’s “missing entry” shape surface as CacheLookupError::Io.

CACHE-016 is explicit that a miss “MUST NOT raise an error to the caller”, so Cache::lookup’s return type stays Option<Manifest> rather than Result<Option<_>, _>. The introspecting Cache::lookup_status obeys the same semantics for the enumerated misses; it lifts only the truly unexpected IO failures into CacheLookupError.

Enums

CacheLookupError

Failure modes for Cache::lookup_status.

CacheLookupStatus

Discriminated outcome of Cache::lookup_status per AUX-015 step 11.