ACP v2 Draft Drops With Major Breaking Changes, Overhauling Session States and Agent Interaction Patterns

ACP v2 draft releases with major breaking changes, overhauling session states to allow agents to send updates freely, introducing uniform message patching, redesigned file diff structures, and more flexible permissions — but implementers are warned to hold off on production deployment until the protocol is finalized.

• ACP v2 is now available in draft form, introducing major breaking changes focused on enabling more flexible session states, consistent patterns, and extensibility across the protocol.
• Key updates include a shift away from turn-based interaction to allow agents to send updates freely throughout a session, uniform message patching with stable IDs, overhauled file diff structures, and more flexible permission requests.
• The release is in draft status and open for community feedback before stabilization, with implementers advised to support both v1 and v2 simultaneously and avoid shipping v2 in production by default until it is finalized.