tool.Invocation.ResultSchema (JSON Schema, draft 2020-12): the executor
validates the single-loop final answer and, on violation, runs up to two
bounded corrective rounds on the same conversation (FinalGuard-style
extra rounds, but the round's text IS the new candidate); a conforming
answer is replaced by the bare validated JSON. Fail-open on compile
problems (host pre-dispatch compile is the authoritative gate) and
best-effort on persistent violations (last output stands, hosts keep
their fallback validator). External $refs fail closed — jsonschema/v6's
default loader resolves file:// from local disk, overridden with a deny
loader. Audit events: result_schema_round/_valid/_unmet/_skipped.
Multi-phase runs unvalidated (FinalGuard's single-loop-only scope).
Co-Authored-By: Claude Fable 5 <[email protected]>
