Spec gap: anonymous-but-accountable agent participation in delegation chain

[asiridalugoda]

Summary

HDP hop records require agent_id: string but place no constraints on what that string represents. Ephemeral agents (serverless functions, short-lived containers, model instances with no stable identity) have no meaningful stable ID to provide. The spec gives no guidance, leading to random UUIDs that are useless for audit.

The gap

Two distinct sub-cases:

Case	Current workaround	Problem
Ephemeral agent with no stable identity	agent_id: "lambda-abc123" (random)	Not auditable, not correlatable
Anonymous-but-accountable agent	No mechanism	Accountability impossible

Proposed resolution (targeting §-01 of the IETF draft)

Add agent_id_type to hop records, mirroring principal.id_type:

agent_id_type: "stable" | "ephemeral" | "commitment"

• stable — persistent identifier, current default behavior
• ephemeral — declared transient; agent_id is a run-scoped nonce; verifiers MUST NOT use it for identity correlation
• commitment — agent_id is base64url(SHA-256(ephemeral_public_key || session_id)); the agent generates an Ed25519 keypair per session, signs its hop with the ephemeral private key, and includes agent_pub (the ephemeral public key) in the hop record

The commitment scheme provides anonymous-but-accountable participation: the hop is cryptographically bound to a key the agent controls, without revealing a stable identity across sessions.

Target

• IETF draft §-01 (update §5 hop record schema)
• v0.2 of @helixar_ai/hdp (additive, non-breaking — agent_id_type defaults to "stable")

Related

• Spec gap: key bootstrap mechanism for air-gapped environments #3 (air-gapped key bootstrap)
• CoAuthorizationRequest v0.2 preview — both are v0.2 scope items