CLAIM-2026-08-19-10

A2A extensions are declared as AgentExtension objects inside AgentCapabilities with a URI, description, required flag and params, negotiated via an A2A-Extensions HTTP header, and default to inactive; four extension scopes exist (data-only, profile, method and state machine).

Why it matters

The route to shipping a provenance field today, without waiting for the spec: declare a data-only extension, not required, so extension-unaware clients are unaffected.

Sources

• aaproject2026aa