Argon writes the MCP adapter under a frozen acceptance suite it cannot edit.
Gemini 4 Argon · recorded payment replay
Spend Theater
Argon turns a recorded payment log into a 3D replay, renders it, watches the result, and repairs it against frozen checks.
One-minute demo. Captions are available in the player.
01
What it proves
Argon renders the replay, reviews the evidence, and corrects failures over three retained iterations.
The replay shows a policy refusal and a confirmed 1.5 USDC Base Sepolia testnet settlement.
02
Frozen-check results
2first draft errors
2second draft errors
0final frozen-check errors
All three iterations remain in the record. Model visual scores are reported separately from factual checks. The final critic also logged two minor visual issues.
03
Evidence boundary
The replay is checked against a recorded event log, renderer observations, and page telemetry. It does not independently prove every chain fact.
04
Vaulted Checkout: the payment system
Spend Theater begins with this system. A Gemini buying agent shops through four fixed MCP calls. Its spend service can produce a signed intent, but it cannot sign a payment.
The wallet key stays inside a Basis Theory vault. Its Reactor independently checks the payee and amount before signing, so an upstream mistake or attack still stops at the vault. This recorded Base Sepolia testnet run includes a policy refusal and a confirmed 1.5 USDC settlement.
Spend Theater uses this payment log as its source material for the Argon build, watch, critique, and repair loop above.
Full Vaulted Checkout explainer. Captions are available in the player.