A2A Progressive Adoption Guide

A2A is introduced progressively after MCP baseline maturity.

Rollout stages

1. Internal-only mode: AEEF-native handoff artifacts, no A2A requirement.
2. Cross-runtime pilot: A2A profile for one workflow spanning two runtimes.
3. Inter-org mode: A2A required for partner or vendor agent interoperability.

Preconditions

• MCP-required baseline already enforced.
• Agent contracts and run-ledger schema active.
• Handoff artifacts validated in CI.

Required controls when A2A is enabled

• Contract identity mapping between AEEF agent_id and A2A party identity.
• Handoff payload validation against handoff-artifact.schema.json.
• Gate decision synchronization across runtime boundaries.
• Signed provenance records for external-facing exchanges.

Decision rule

If all agents execute within one runtime and one trust domain, A2A remains optional. If workflow crosses runtime/vendor boundaries, A2A profile is mandatory.