Project Update: Announcing PayAgent -- Autonomous Agentic Commerce Protocol with PayPal Guardrails
We just published the first full release of PayAgent for the PayPal AI Hackathon: Build what's next with PayPal and AI!
### The Big Idea
Autonomous AI agents are increasingly capable of coding, provisioning infrastructure, and orchestrating cloud services. But granting them payment access has been
an unsolved risk: a single runaway loop or prompt injection exploit could drain financial accounts in minutes.
PayAgent solves this by establishing a hardened programmatic guardrail layer between LLMs and payment gateways.
### What's New & Included:
- **PayPal Orders v2 REST Integration**: Direct OAuth2 token exchange with https://api-m.sandbox.paypal.com to create digital goods orders with strict item
breakdown validation and automated capture.
- **Deterministic Budget Guardrails**: Real-time evaluation of single-transaction caps ($35 default), rolling 24h spend ceilings ($150), and merchant whitelist
categories.
- **AdversarialShield & Shadow Simulation Box**: Intercepts prompt injections (SYSTEM OVERRIDE), delimiter density attacks, and unverified wallet redirects with
a pre-flight dry run before financial execution.
- **Human-in-the-Loop Escalation**: Flagged purchases above authorization thresholds pause and stage live PayPal checkout approval links for operator sign-off.
- **Cryptographic SHA-256 Merkle Audit Chain**: Tamper-evident hash-chained transaction ledger with replay attack prevention.
- **Stock shadcn/ui Zinc Dashboard**: Real-time WebSocket telemetry stream and interactive scenario tester.
### Quality & Open Source
- 18 / 18 unit & integration tests passing (bun test).
- Zero external runtime bloat built on Bun + TypeScript.
- Released under the permissive MIT Open Source License.
Explore the code on GitHub: https://github.com/Codenuclei/payagent