ExperimentalOptional_The _meta property is reserved by ACP to allow clients and agents to attach additional metadata to their interactions. Implementations MUST NOT make assumptions about values at these keys.
See protocol docs: Extensibility
OptionalterminalWhether the client supports terminal authentication methods.
When true, the agent may include terminal entries in its authentication methods.
UNSTABLE
This capability is not part of the spec yet, and may be removed or changed at any point.
Authentication capabilities supported by the client.
Advertised during initialization to inform the agent which authentication method types the client can handle. This governs opt-in types that require additional client-side support.