How Does an AI Agent Check Whether It Should Pay Before It Spends? The /bin/bash.005 Spend Gate

Description and use

Spend Gate evaluates AI agent payments through four independent evidence paths and a coherence score before allowing a wallet to sign, preventing over‑cap or untrusted transactions.

Problem

An AI agent needs to decide whether to pay a payee before signing a transaction, avoiding unnecessary or risky spend.

Outcome

Spend Gate successfully passed a $0.001 USDC payment with coherence 1.0 and blocked a $5.00 over‑cap payment with coherence 1.0, costing $0.005 USDC per check.

Workflow

• 1. Intercept the 402 challenge before wallet signing.
• 2. Send payee, quoted amount, tool category, and optional manifest_url to Spend Gate via POST /x402/spend-gate.
• 3. Receive verdict: if gate_pass true and pay consensus, proceed to sign; if false, abort and review rejection reason.
• 4. If pass, optionally invoke Jev decision model for final judgment.
• 5. Sign or abort based on verdict and model output.

Evidence

The gate passes a $0.001 USDC call at coherence 1.0 and blocked a $5.00 over‑cap call at coherence 1.0 — consensus reject, Jev never fired, zero decision-model spend on the block.

Source

Four paths evaluate the payment independently — path independence is the point: a number computed from paths that copy each other would claim agreement that never happened.

Source