Blockchain

What This Covers

Blockchain fundamentals and practical interaction — the technology, not the speculation.

In scope: Distributed ledgers, consensus, transactions, smart contract interaction, wallets, token standards. Out of scope: Trading strategies, price analysis, specific DeFi protocols, Solidity development (see dedicated skills).

Core Concepts

For mental models and analogies, see concepts.md.

Developer Quick Reference

// Read contract (viem)
const balance = await client.readContract({
  address: TOKEN, abi: erc20Abi,
  functionName: 'balanceOf', args: [wallet]
})

// Write requires wallet + confirmation wait
const hash = await walletClient.writeContract({...})
const receipt = await client.waitForTransactionReceipt({ hash })

Common traps: missing allowance checks, wrong decimals (ETH=18, USDC=6), not awaiting confirmations.

For full patterns, see dev.md.

When to Use Blockchain

✅ Use when: Multiple parties need shared truth, no trusted authority exists, immutability is critical, settlement costs are high.

❌ Don't use when: Single org controls data, you trust a central authority, data needs deletion (GDPR), or a database solves it.

The Database Test: Would PostgreSQL with audit logs solve this? If yes, skip blockchain.

For decision framework and enterprise platforms, see evaluation.md.

Security Essentials

• Seed phrase = master key — never share, never screenshot
• Hardware wallet > software wallet > exchange
• Test transactions before large transfers
• Verify URLs obsessively — phishing clones are sophisticated

For wallet security and scam patterns, see security.md.