Complete participant conformance coverage, including identity boundaries (ASR-507) #220

Extend the existing conformance runner and published fixture corpus. Inventory current coverage before adding cases. The identity audit assigns semantic changes to #1338–#1341; this issue verifies them.

Done when

• Map participant contracts and feature claims to valid, invalid, cross-contract, and cross-stage cases.
• A composite participant remains one subject. Shared affiliation, implementation, or resources do not merge identities, histories, authority, or visibility.
• Objective ownership, assignment, and acting remain distinct. Participant-as-actor and participant-as-target cases traverse the approved address mappings.
• Reference-purpose rules agree across validation, composition, compilation, and editor suggestions; new referenceable kinds gain no unintended eligibility.
• Reject ambiguous imports, unknown or mismatched identities, stale configuration/digests, cross-episode records, and unauthorized resource/visibility joins. Preserve opaque identities where their contracts permit them.
• Separate schema acceptance, semantic conformance, and native execution evidence. Fixtures standing in for external systems have recorded provenance; coordinate with Audit the test suite for fixtures that assert shapes the real system never produces #1344.
• Update ASR-507 evidence and identify remaining unsupported cases.

Prerequisite: #1341. Reuse the manifest/provenance contracts delivered by #129/#433. No autonomy threshold or mandatory deployment/component model. #221 owns author scenarios; #257 owns the multi-role coverage summary.

Requirements

• ASR-507 — Participant Conformance Corpus