[SEP Draft] Hierarchical Mandate Tokens for Autonomous Agent Authority

[devfelipenunes]

[SEP Draft] Hierarchical Mandate Tokens for Autonomous Agent Authority

Author: Felipe Nunes Oliveira (@devfelipenunes)
Track: Standard
Status: Draft
Version: 0.3.0

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What this proposes

This draft defines a standard Soroban interface for Mandate tokens — non-transferable, revocable authority tokens that allow a sovereign identity (Root Anchor) to delegate programmable, scoped, and auditable power to AI agents or automated systems without sharing private keys.

The standard introduces a clean separation between:

• Immutable Scope: The "promise" of authority (TTL, budget limits, allowlists).
• Mutable MandateState: The runtime tracking (spent budget, revocation status).

Through a central Nexus registry, any third party can verify an agent's authority in a single, gas-efficient call.

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Why this matters for Stellar

As agentic systems scale, the "Identity Vacuum" and "Custody Risk" become existential threats. Giving an agent a private key is a binary choice between full access or zero access.

This SEP provides a Programmable Power of Attorney. By leveraging Stellar’s low fees and Soroban’s smart contract capabilities, we can enable a "Trustless Delegation" layer where agents can spend micro-budgets (via x402) or interact with DeFi, while the human retains absolute, atomic control.

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Key Mechanisms Defined

• Authority Epochs: A monotonic counter on the Root Anchor that allows for global, single-transaction revocation of entire delegation trees, solving the O(n) gas cost of individual revocations.
• DelegationPolicy: Granular sub-delegation rules, including budget_fraction, to prevent budget exhaustion through cascading sub-agents.
• Bounded Verification: A depth cap (MAX_DELEGATION_DEPTH) and an epoch-keyed VerificationCache that ensure verify_authority has a predictable, auditable gas cost.
• SEP-45 Remote Issuance: A flow allowing off-chain signers (hardware wallets) to issue Mandates via signed MandateRequest payloads without their keys ever touching the contract environment.

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Design decisions for feedback

1. Mandatory TTL: Is a time-to-live requirement enough of a baseline, or should the standard enforce a minimum transfer_limit to prevent "infinite" budget delegations by default?
2. Authority Epochs for Mass Revocation: We’ve implemented this to bound gas costs. Is this "nuclear option" too aggressive for complex enterprise setups where individual branch revocation is the norm?
3. MAX_DELEGATION_DEPTH = 8: Is a depth of 8 sufficient for high-orchestration agent swarms, or will this limit prevent valid use cases in recursive AI architectures?
4. ZKP for Confidential Delegation: The scope_commitment field allows for private verification. Should we push for a standardized ZK-Verifier interface now, or leave it for a companion SEP as ZK primitives (X-Ray) mature?

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Reference implementation

The reference implementation is maintained by the Zolvency protocol, where Mandates are implemented as Wills managed by the Nexus registry. This implementation demonstrates how a SoulID (Root Anchor) governs agents with high-performance authority checks.

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Full draft

The complete, technically detailed SEP-Mandate specification (v0.5.0) is available at:
[https://github.com/stellar/stellar-protocol/pull/1925](https://github.com/stellar/stellar-protocol/pull/1925)

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