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Architecture

AI models are probabilistic. Execution systems must not be. Sigil Sign operates as a non-custodial, deterministic execution firewall. It ensures that high-stakes, agent-driven EVM actions physically cannot execute without mathematically proven authorization.

Core Primitives

The Sigil Open Framework separates autonomous capital deployment into three distinct layers:
LayerComponentRole
The FirewallSigil SignThe execution enforcement layer. Proxies RPC/Bundler requests and issues Intent Attestations.
The EngineOVEOpen Venture Engine. Orchestrates agent intelligence and formats EVM transactions.
The RulesFAFFiduciary Agent Framework. Defines the governance rules and legal parameters the agent must follow.

Intent Attestations

Intent Attestations are the cryptographic permission slips of the Sigil ecosystem. They are Ed25519-signed JWTs that are:
  • Short-lived: Expiring automatically in 60 seconds.
  • Tightly Bound: Cryptographically linked to a specific txCommit, userOpHash, and chainId.
If an agent attempts to submit an eth_sendRawTransaction or eth_sendUserOperation to the Sigil gateway without a valid, matching attestation, the request is instantly rejected at the network edge.

Execution Gateways

Sigil Sign exposes guarded gateways for both standard EOA and Account Abstraction flows.
  • JSON-RPC: POST /rpc/:chainId
  • ERC-4337 Bundler: POST /bundler/:chainId
Chain Selection Precedence:
The gateway routes transactions based on the following fallback logic:
  1. URL Path Parameter (/rpc/8453)
  2. Custom Header (Sigil-Chain-Id: 8453)
  3. Query Parameter (?chainId=8453)
  4. Default Fallback (Chain 1 - Mainnet)

Fiduciary Brakes

Fiduciary Brakes are deterministic execution controls. When an agent requests an attestation via POST /v1/authorize, Sigil Sign evaluates the payload against your predefined ASSURANCE.md policy. It deterministically prevents agents from:
  • Executing unauthorized transactions.
  • Bypassing governance constraints.
  • Exceeding treasury limits.
Private keys are never stored in Sigil infrastructure. Sigil signs the permission, not the transaction.