# description
Client-initiated handshake request to establish a KYA-OS session with nonce-based replay protection.

# properties.nonce.description
Base64url-encoded random value (minimum 16 bytes) for replay prevention. Each nonce MUST be unique per session.

# properties.audience.description
The intended recipient's DID (did:key or did:web). MUST match the server's DID for the request to be accepted.

# properties.timestamp.description
Unix timestamp in seconds. Server MAY reject requests with timestamps outside acceptable skew window (default: 120 seconds).

# properties.agentDid.description
The agent's DID if authenticated. Required for authenticated sessions.

# properties.clientInfo.description
Optional client metadata for session context.

# properties.clientInfo.properties.platform.description
Operating system or platform identifier.

# properties.clientInfo.properties.persistentId.description
Persistent client identifier across sessions.

# properties.clientProtocolVersion.description
Client's supported KYA-OS protocol version (e.g., '1.0').

# properties.clientCapabilities.description
Client capability flags for feature negotiation.