mpp

# MPP - Machine Payments Protocol MPP is an open protocol (co-authored by Tempo and Stripe) that standardizes HTTP `402 Payment Required` for machine-to-machine payments. Clients pay in the same HTTP request - no accounts, API keys, or checkout flows needed. The core protocol spec is submitted to the IETF as the [Payment HTTP Authentication Scheme](https://datatracker.ietf.org/doc/draft-ryan-httpauth-payment/). ## Tempo token addresses Public Tempo token addresses referenced throughout this skill. Use the placeholder names in code; full addresses are in the [Tempo documentation](https://docs.tempo.finance). | Token | Network | Placeholder | |--------------------|----------|----------------------| | USDC.e (mainnet) | mainnet | `<USDC_TEMPO_MAINNET>` | | pathUSD (testnet) | testnet | `<PATHUSD_TESTNET>` | ## When to Use - Building a **paid API** that charges per request - Adding a **paywall** to endpoints or content - Enabling **AI agents** to pay for services autonomously - **MCP tool calls** that require payment - **Pay-per-token streaming** (LLM inference, content generation) - **Session-based metered billing** (pay-as-you-go) - Accepting **stablecoins** (Tempo), **cards** (Stripe), or **Bitcoin** (Lightning) for API access - Building a **payments proxy** to gate existing APIs (OpenAI, Anthropic, etc.) ## Core Architecture Three primitives power every MPP payment: 1. **Challenge** - server-issued payment requirement (in `WWW-Authentica...