📖Glossary

Your decoder ring for the x402 protocol and autonomous crypto payments. No gatekeeping—just straight definitions that make sense.

🌐 x402 Protocol Terms

x402 The open protocol that makes autonomous payments possible. Built around HTTP 402 Payment Required, x402 lets machines pay other machines instantly on-chain. It's the backbone of the entire machine economy.

HTTP 402 Payment Required The forgotten HTTP status code that's about to change everything. When an API responds with 402, it's saying "pay me and I'll give you the goods." Yuki intercepts these responses and handles payment automatically. Zero manual intervention.

Facilitator The middleman (but trustless). A service or smart contract that coordinates x402 payments between payers and service providers. Yuki402 acts as your personal facilitator.

Payment Proof Cryptographic receipts that prove you paid. Transaction hashes and on-chain confirmations that service providers verify before granting access. No proof = no access. It's trustless by design.

Service Provider Anyone offering x402-compatible APIs, data, or services. Could be weather APIs, AI models, premium datasets—anything that speaks x402.

x402 Registry The on-chain directory of verified x402-compatible services. Think of it as the "whitelist" of legit services that play by the rules.

❄️ Yuki402 Terms

Yuki402 Your autonomous AI payment agent. She intercepts HTTP 402 responses, processes payment details, executes blockchain transactions, and delivers your data—all through natural language chat. No clicking, no manual approvals (within your limits).

Autonomous Payment Payments that happen without you clicking "Approve" every single time. Set your spending limits once, then Yuki handles everything automatically. It's like autopay, but for the entire internet.

Spending Limit Your safety net. Daily, weekly, and monthly caps on how much Yuki can spend autonomously. Start conservative (0.01 SOL/day), scale up as you get comfortable. Always in control.

Payment Gateway Smart contracts that temporarily hold funds during x402 transactions. Money flows through the gateway, gets verified on-chain, then releases to service providers. Trustless and transparent.

$YUKI Token The native token that powers fee-free access. Hold $YUKI, pay zero platform fees. Don't hold it? Pay a small fee that goes straight into automatic buybacks. More payments = more buybacks = more value.

⛓️ Blockchain Terms

Gas Fee The cost of doing business on-chain. Every blockchain transaction requires gas to compensate validators. On Solana it's pennies. On Ethereum it can be... less fun. Yuki optimizes for the cheapest chain available.

Settlement Time How fast your payment confirms on-chain. Yuki on Solana? 2 seconds. Ethereum? 12-15 seconds. Bitcoin? We don't talk about Bitcoin settlement times.

Chain Agnostic Works on multiple blockchains—Solana, Ethereum, Polygon, you name it. Yuki doesn't care which chain you use; she picks the fastest and cheapest option for each payment.

Non-Custodial You hold the keys, you hold the crypto. Yuki never touches your funds directly—she just facilitates signatures and transactions. Your wallet, your control.

Smart Contract Code that lives on the blockchain and automatically enforces rules. No lawyers, no middlemen, no "trust me bro." Just pure, verifiable logic.

Transaction Hash (TxHash) The unique ID for every blockchain transaction. Think of it as your payment receipt that's permanently etched into the blockchain. Use it to track, verify, and flex your on-chain activity.

Wallet Your blockchain identity. MetaMask, Phantom, Coinbase Wallet—whatever you use to sign transactions and hold crypto. Connect it to Yuki and you're ready to roll.

RPC Endpoint The gateway between your app and the blockchain. Free public RPCs work but can be slow and rate-limited. Premium RPCs (Helius, QuickNode, Alchemy) are faster, more reliable, and worth every penny for production use.

Devnet The blockchain sandbox where everything's free and nothing matters. Perfect for testing Yuki without risking real funds. Get free devnet SOL from the faucet and go wild.

Mainnet The real deal. Real money, real transactions, real consequences. Once you're comfortable on devnet, graduate to mainnet and join the machine economy for real.

🤖 AI & Chat Terms

Natural Language Processing (NLP) The tech that lets you talk to Yuki like a human instead of typing cryptic commands. "Get me weather data for London" instead of curl -X POST https://api.weather.com/v1/...

Streaming Response Real-time text generation where Yuki's response appears word-by-word as she "thinks." Feels more like conversation, less like waiting for a loading spinner.

Context Window How much conversation history Yuki remembers. The bigger the window, the more coherent the conversation. Google Gemini 2.0 Flash has a massive context window—she won't forget what you said 10 messages ago.

Prompt Your input message. What you type to Yuki. "Generate an API key" = prompt. "Make me a sandwich" = also a prompt (but she probably can't help with that one).

Token (AI Context) Unit of text the AI processes. Roughly 4 characters per token. Not to be confused with $YUKI tokens—completely different thing. One's for AI math, the other's for holding.

Temperature Controls AI creativity. Low temperature (0.3) = deterministic, factual responses. High temperature (0.9) = creative, varied outputs. Yuki runs at 0.7 for balanced performance.

💸 Payment & Economic Terms

Micropayment Tiny payments ($0.01 - $1.00) that are only economically viable with low blockchain fees. Traditional payment processors charge 30¢+ per transaction—x402 makes micropayments possible.

Pay-Per-Use No subscriptions, no monthly fees. Pay only for what you consume. Used the API once? Pay once. Used it 1000 times? Pay 1000x. Simple, fair, transparent.

Zero Platform Fees The x402 promise: no middleman takes a cut. You pay gas fees (to validators) and service costs (to providers). That's it. Traditional platforms take 20-30%—x402 takes zero.

Settlement When payment moves from your wallet to the service provider's wallet and gets confirmed on-chain. After settlement, the payment is final and irreversible.

Refund Money back if the service fails to deliver. Smart contracts can enforce refunds programmatically if cryptographic proof isn't provided. Trustless consumer protection.

🛡️ Security Terms

Spending Cap Same as spending limit—maximum autonomous spending allowed. Your safety mechanism to prevent runaway costs.

Rate Limiting Cooldown periods between requests. Prevents spam, abuse, and accidental overspending. Yuki enforces a 50-second cooldown by default—adjust based on your needs.

Verification Process of confirming a service is legitimate and listed in the x402 registry. Yuki prioritizes verified services to protect you from scams.

Transaction Monitoring Real-time tracking of your spending against configured limits. Yuki logs every payment and blocks requests that would exceed your caps.

Private Key The master password to your wallet. Whoever holds it controls your crypto. NEVER share it. Not with Yuki. Not with anyone. Guard it like your life depends on it—because your funds do.

Seed Phrase 12-24 word backup phrase that regenerates your private key. Write it on paper, store it in a safe, never type it on a computer. Lose it = lose access to your wallet forever.

Hardware Wallet Physical device (Ledger, Trezor) that stores private keys offline. The gold standard for security. Costs $50-150 but worth it if you're holding serious amounts.

🔌 Service & API Terms

API (Application Programming Interface) How software talks to other software. x402-compatible APIs accept payment via blockchain before granting access. No API keys, no OAuth—just pay and go.

Endpoint Specific URL where an API service lives. For example: https://api.weather.com/v1/current is an endpoint for current weather data.

HTTP Request Your app asking a server for something. "Give me weather data for London" = HTTP request.

HTTP Response The server's answer. Could be data (200 OK), could be "pay me first" (402 Payment Required), could be "not found" (404).

JSON (JavaScript Object Notation) Standard data format for API responses. Structured text that both humans and machines can read. Most x402 services return data as JSON.

REST API Common type of web API that uses standard HTTP methods. Most x402-compatible services are REST APIs. Clean, simple, and widely supported.

🔐 Smart Contract Terms (OpenZeppelin)

ERC-20 The standard interface for fungible tokens on Ethereum. If you've held any Ethereum token, it was probably ERC-20. Ensures all tokens work with all wallets and exchanges.

Ownable Contract pattern where certain admin functions can only be called by the contract owner. Prevents random people from changing critical settings.

ReentrancyGuard Security pattern that prevents attackers from calling contract functions recursively to drain funds. Essential protection against one of the most common smart contract exploits.

Burnable Token feature that lets holders permanently destroy tokens. Reduces supply, potentially increasing value for remaining holders. $YUKI is burnable—automatic buybacks and burns.

📜 Solidity & Development Terms

Solidity Programming language for writing Ethereum smart contracts. Looks like JavaScript but compiles to bytecode that runs on the Ethereum Virtual Machine (EVM).

Mapping Solidity's version of a dictionary/hash table. Used for tracking balances, allowances, and other key-value data in smart contracts.

Event Blockchain log emitted by smart contracts. Used for tracking state changes and notifying external applications. Yuki listens for payment events to confirm transactions.

Modifier Reusable code snippet that adds conditions to functions. For example, onlyOwner modifier ensures only the contract owner can call a function.

Wei Smallest unit of Ether. 1 ETH = 10^18 wei. Like how 1 dollar = 100 cents, but with way more zeros. Used for precise calculations in smart contracts.

Lamport Smallest unit of SOL (Solana's native token). 1 SOL = 10^9 lamports. Named after Leslie Lamport, computer scientist and Turing Award winner.

🧪 Testing Terms

Hardhat Development environment for Ethereum smart contracts. Compile, test, deploy—all in one tool. Used for Yuki's smart contract development.

Chai Assertion library for writing contract tests. Makes tests readable: expect(balance).to.equal(1000) instead of cryptic assertions.

Test Fixture Reusable test setup that deploys contracts in a consistent state. Write setup once, reuse across multiple tests. Saves time and reduces errors.

Coverage Percentage of code executed by tests. 100% coverage = every line of code has a test. Yuki's contracts aim for 95%+ coverage.

Mock Contract Simplified contract used for testing. Instead of deploying real contracts with complex dependencies, use mocks to isolate and test specific functionality.

🔤 Common Abbreviations

AI - Artificial Intelligence (the tech behind Yuki's brain) API - Application Programming Interface (how services talk to apps) DYOR - Do Your Own Research (crypto mantra—never invest blindly) ETH - Ethereum (the blockchain and its native currency) HTTP - Hypertext Transfer Protocol (foundation of the web) IPFS - InterPlanetary File System (decentralized file storage) JSON - JavaScript Object Notation (standard data format) NLP - Natural Language Processing (how AI understands language) REST - Representational State Transfer (common API architecture) RPC - Remote Procedure Call (how apps talk to blockchains) SDK - Software Development Kit (tools for building integrations) SOL - Solana (the blockchain and its native currency) URL - Uniform Resource Locator (web addresses) UX - User Experience (how it feels to use something) Web3 - Decentralized internet built on blockchain technology

💡 Usage Examples

Using Terms in Context

"I set my daily spending limit to 0.1 SOL"

• Spending limit: Maximum autonomous spending Yuki can execute

• SOL: Solana's native cryptocurrency (~$25 at current prices)

• Daily: Resets every 24 hours automatically

"The transaction settled in 2 seconds on Solana"

• Transaction: Your blockchain payment from wallet to service provider

• Settled: Confirmed and irreversible on-chain

• 2 seconds: Solana's blazing-fast block time (Ethereum takes 12-15 seconds)

"Yuki found an x402-compatible weather API and paid 0.001 SOL for access"

• x402-compatible: Service accepts HTTP 402 Payment Required protocol

• API: Web service providing weather data

• 0.001 SOL: Micropayment (~$0.25) for single API request

"Check the transaction hash on Solscan to verify payment"

• Transaction hash: Unique identifier (like a receipt number) for your payment

• Solscan: Blockchain explorer for viewing Solana transactions

• Verify payment: Confirm the payment went through and can't be reversed

"Yuki uses Helius RPC for faster settlement times"

• Helius: Premium Solana RPC provider

• RPC: Remote Procedure Call—gateway between app and blockchain

• Settlement times: How fast transactions confirm (Helius is faster than free RPCs)

🔗 Related Resources

Want to dive deeper? Check these out:

• x402 Protocol: x402.org - Official protocol site

• x402 Technical Docs: x402.gitbook.io - Implementation guide

• Solana Documentation: docs.solana.com - Learn Solana development

• Ethereum Glossary: ethereum.org/en/glossary - Comprehensive Ethereum terms

• OpenZeppelin Docs: docs.openzeppelin.com - Smart contract library

• Solidity Documentation: docs.soliditylang.org - Learn Solidity programming

🤝 Contributing

Missing a term? Found a confusing definition? Let us know: 📧 Email: [email protected] 🐦 X: @yuki402xyz

This glossary evolves with the x402 ecosystem. As new concepts emerge, we update.

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Need more context? Check out the FAQ for common questions or the Resources page for external tools and guides.