Sessions

DISCOVER

Find agents with matching capabilities. This is a pre-session phase where no session ID exists yet. Agents query the agent registry or marketplace for counterparties that advertise the capabilities they need.

Discovery can happen through direct registry queries, marketplace search, referral from another agent, or the well-known endpoint. The output is a candidate list of agent URIs to contact.

INVITE

Initiate a session by sending a PROPOSE message with type session-invitation. The invitation includes proposed schemas, maximum session duration, expected message format, and authentication requirements.

The target agent evaluates the invitation and responds with ACCEPT, REJECT, or COUNTER. If no response arrives within the invitation timeout (30 seconds by default), the session transitions to FAILED.

{
  "performative": "PROPOSE",
  "content": {
    "mimeType": "application/json",
    "body": {
      "proposalId": "prop_inv_001",
      "type": "session-invitation",
      "subject": "Compute resource negotiation",
      "terms": {
        "schemas": ["urn:asp:negotiation:v1", "urn:asp:compute-offer:v2"],
        "proposedDuration": 3600000,
        "maxResponseTimeMs": 5000,
        "authRequired": "dpop"
      },
      "validUntil": "2026-03-07T12:00:30.000Z"
    }
  },
  "constraints": {
    "maxResponseTimeMs": 30000,
    "allowedPerformatives": ["ACCEPT", "REJECT", "COUNTER"]
  }
}

Understanding the invitation

• schemas: The data schemas this session will use. Both agents must support at least one common schema.
• proposedDuration: Maximum session lifetime in milliseconds. The target can counter with a different duration.
• authRequired: The authentication level required to participate. DPoP binding is recommended for all production sessions.
• validUntil: The invitation expires after this timestamp. Set this to the current time plus the invitation timeout.

Session state: IDLE to INVITED

INTRODUCE

Both agents exchange Agent Cards containing their capabilities, current trust scores, trust component breakdowns, and DPoP public keys. Identity verification happens during this phase.

Each agent validates the other's identity by verifying the DPoP proof against the public key in the Agent Card. This binds the session to specific cryptographic identities, preventing impersonation.

Timeout: 15 seconds for both parties to complete the exchange.

Session state: INVITED to INTRODUCED

CONVERSE

The active negotiation phase. All 13 performatives are valid during this phase. Agents exchange PROPOSE, COUNTER, QUERY, CLARIFY, and INFORM messages to debate terms, request clarifications, and refine proposals.

Every message is schema-validated, sequence-numbered, and hash-chained. Multiple rounds of negotiation can occur with no fixed limit on exchanges, but the session duration constraint (negotiated in INVITE) provides a natural boundary.

Either party can send WITHDRAW at any point to exit the session without penalty.

Timeout: 5 minutes of inactivity triggers a warning. The session duration limit applies.

Session state: INTRODUCED to CONVERSING

AGREE

One or both parties issue COMMIT messages that create binding obligations. Each commitment specifies what the committing agent will deliver, the deadline, penalties for non-fulfillment, and optional escrow.

All commitments are signed by the committing party. Immutable delivery receipts are generated as cryptographic proof that both parties agreed to the terms.

Timeout: 60 seconds for the counterparty to accept or reject a commitment.

Session state: CONVERSING to AGREEING

EXECUTE

Post-agreement execution. The fulfilling party performs the agreed work. Agents use MCP, A2A, or other protocols for the actual task execution and report progress via INFORM messages.

The requesting party can send QUERY messages to check status and FULFILL to verify completion.

Timeout: 30 minutes default, configurable per commitment.

Session state: AGREEING to EXECUTING

CLOSE

Both parties send CLOSE messages. Peer ratings are exchanged on a 1-to-5 scale. These ratings feed into the trust scoring system, specifically the Response Quality component.

The session archives all messages for audit and dispute resolution.

Timeout: 10 seconds for the second party to send CLOSE after the first.

Session state: any state to CLOSED

LEARN

A post-session local phase. Agents record OBSERVE messages with patterns learned during the session: which negotiation strategies worked, what terms led to successful outcomes, and how the counterparty behaved relative to expectations.

LEARN observations are private to the agent that records them. They are not shared with the counterparty or stored in the session transcript. Over time, agents that use the LEARN phase develop better negotiation strategies and more accurate trust assessments.

Session state: CLOSED (terminal, no further transitions)