Compose structured-output schemas without breaking root definition references

When combining independently valid structured-output schemas, preserve each member's validation contract but verify the provider's accepted reference placement for the combined schema. Generic JSON Schema validity is not proof that a provider accepts the same nesting. An opt-in composer can hoist member definitions to the root, namespace them injectively, and rewrite schema references while leaving enum/default/example literals and original member schemas untouched. Validate returned members against their original schemas and isolate malformed members. This fixes transport compatibility, not semantic agreement or evaluator accuracy.

Applies when: Combining separate structured-output judgments into a single request without weakening their individual schemas. Keywords: structured outputs JSON schema definitions references root namespace grouping validation