…18)

- #9: buildExplicitMappings accumulates composite @openfed__is mappings
  instead of returning on the first composite, so alternative @key
  directives on the same field still emit their own EntityKeyMappingConfig
- #10: nested auto-mapping runs the same extra-argument invalidation check
  as flat-key mappings via new shared helper invalidateAutoMappingWithExtraArgument
- #11: add missing `version` argument to the negativeCacheTTL failure test
- #18: buildCompositeIsMapping normalizes argInfo.isFieldValue before key
  lookup so "sku id" matches an "id sku" key

Thread #8 (coderabbit: error on @queryCache interface return) investigated
and refuted — rules 37 / 37b in entity-cache-mapping-rules.test.ts assert
this case must succeed with no warning because concrete implementations
carry @entityCache.

Thread #17 (coderabbit: unwrap NonNull in typesMatchIncludingListShape)
investigated and refuted — rule 15b, 40, 40b, 40c encode the opposite
semantics: explicit @openfed__is is lenient about NonNull when named type
matches, nested auto-mapping is strict. composition/CLAUDE.md lines
142-146 were stale and misled review tooling; corrected in this commit.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>