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Agent2Agent Protocol

FabrCore 2.0 · Release and package availability

These guides track the current 2.0 source. Stable 2.0.0 publication is pending; package commands show the release target. Until it is published, follow the source quick start or use a matching available prerelease set. Release migration · Runtime modes

Connect agents across systems

A2A hosting is built into FabrCore.Host. Enable it when external agent systems or Copilot Studio need protocol access; ordinary internal messaging does not require it.

Set FabrCore:A2A:Enabled=true in application configuration, select published agents, and configure API-key or JWT authentication plus principal mapping. Agent cards, JSON-RPC/HTTP+JSON operations, streaming, task lookup and cancellation share the Host pipeline.

Choose principal isolation deliberately. Fixed principal mapping shares state among callers; per-caller mapping separates it. SQL ACL governs cross-principal agent access. Standalone remains a trusted workspace while transport authentication and task ownership checks still apply.

Durability follows the runtime mode

Standalone keeps tasks in process. SQL mode stores accepted, working and terminal snapshots in fabrOps, with ownership checks, cross-host reads/cancellation and leases that fence stale writers. Interrupted execution fails instead of automatically replaying effects. SSE streams remain local to the execution host and are not stored as replayable event history.

Terminal retention defaults to one hour. SQL failures do not fall back to memory. Custom task stores remain supported. Use FabrCore.Host.Testing for in-memory endpoint tests, then test SQL persistence and affected clients separately.

See the A2A skill for discovery, authentication, principal strategies and Copilot Studio interoperability.

Call Microsoft agents by handle

Inbound A2A hosting lets Studio call FabrCore. Outbound Work IQ uses its A2A adapter; outbound Copilot Studio uses the Studio client SDK. Both use the optional connection broker and remote-agent proxy. Read the integration guide.