Discovery Lifecycle Management

Within the SADAR Semantic Registry, the Discovery TTL(Time-to-Live) dictates exactly how long a consuming agent is permitted tocache a service discovery result before it must re-evaluate the service. It acts as a critical mechanism to ensure that autonomous agents always operate under valid, mutually verifiable terms.

Provider-Driven Expiration The Discovery TTL is explicitly declared by the serving entry within its manifest (via the discovery_ttl_seconds field). This means that the serving entry—not the registry or the requesting agent—defines the maximum lifetime of a cached candidate set.

When the Discovery TTL expires, the cached result is immediately invalidated. The next time the agent issues a discovery request, it triggers a full re-execution of the search against the current registrycontent, forming a new candidate list that the requester must evaluate and select from. The expired candidate list is retained strictly for audit purposes and cannot be used for routing. Ultimately, this TTL-scoping guarantees that discovery results never outlive the serving entry's own declared operational commitments.

Independence from Authentication The registry architecture maintains a strict separation between Discovery TTL and Authentication TTL. While Authentication TTL defines the time period for which the requesting agent’s identity is authenticated, the Discovery TTL strictly governs the validity period of the discovery results themselves. If an Authentication TTL expires, the agent can silently re-authenticate without restarting discovery or losing its cached results, provided those results are still within their Discovery TTL window.

Entity Updates and TTL Invalidation Signals Because services inherit critical context—such as payment methods and legal jurisdiction—directly from their owning entity, the validity of a service's Discovery TTL is structurally bound to the lifecycle of its owning entity. Ifan owning entity publishes a new ACTIVE version before a service's Discovery TTL expires, the registry emits TTL Invalidation Signals to handle the edge case:

• SOFT Signals (Advisory): Triggered by administrative or contact updates. The consumer can safely continue using its cached discovery results until the natural Discovery TTL expires, at which point it should re-resolve.
• HARD Signals (Mandatory): Triggered by material business changes, such as payment methodology updates, jurisdictional shifts, or status suspensions. When a HARD signal is emitted, the consumer must treat all cached discoveries for services under that entity as immediately stale, regardless of any remaining Discovery TTL, and must re-resolve the service before its next invocation.

To maintain compliance and trust, consumers are obligated to subscribe to or poll these entity invalidation signals for any entity whose services they actively hold in their discovery cache.

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