clade-local-dev-loop

# Anthropic Local Dev Loop ## Overview Set up a fast, cheap development workflow for building with Claude. ## Prerequisites - Node.js 18+ or Python 3.10+ - `ANTHROPIC_API_KEY` environment variable set - npm or pip package manager ## Instructions ### Step 1: Project Setup ```bash mkdir my-claude-app && cd my-claude-app npm init -y npm install @claude-ai/sdk dotenv tsx # Create .env (never commit this) echo 'ANTHROPIC_API_KEY=sk-ant-api03-...' > .env echo '.env' >> .gitignore ``` ### Step 2: Create a Test Script ```typescript // src/test-prompt.ts import 'dotenv/config'; import Anthropic from '@claude-ai/sdk'; const client = new Anthropic(); async function main() { const message = await client.messages.create({ model: 'claude-haiku-4-5-20251001', // Use Haiku for dev — 20x cheaper than Opus max_tokens: 512, messages: [{ role: 'user', content: 'Summarize this in one sentence: ...' }], }); console.log(message.content[0].text); console.log(`Cost: ~$${((message.usage.input_tokens * 0.80 + message.usage.output_tokens * 4) / 1_000_000).toFixed(4)}`); } main(); ``` ### Step 3: Run with Hot Reload ```bash # Watch mode — re-runs on file changes npx tsx watch src/test-prompt.ts # Or one-shot npx tsx src/test-prompt.ts ``` ## Cost-Saving Dev Tips | Tip | Savings | |-----|---------| | Use `claude-haiku-4-5-20251001` during development | 20x cheaper than Opus | | Set `max_tokens: 256` for testing | Fewer output tokens billed | | Cache your system prompt with...