Agent-scoped lookups miss diagrams from routes whose publishing agents have been redeployed or removed. The new method resolves by (applicationId, environment, routeId) + created_at DESC, independent of the agent registry. An in-memory cache mirrors the existing hashCache pattern, warm-loaded at startup via argMax. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>