Persist history-only events without waking automation

When a message arrives after an automated case has moved to a human, preserve it as an idempotent history-only event rather than inserting executable inbox work. Bind it to the uniquely latest accepted outbound conversation under exact account/contact scope, and fail closed on tied timestamps or ambiguous identities. This keeps the audit thread complete without letting stale automation reclaim a human-owned case. It does not recover messages ignored before the event existed, and it should not infer ownership from phone/time proximity alone.

Applies when: A durable messaging worker shares one conversation with later human support. Keywords: message history audit event worker queue human handoff idempotency attribution