LLM Patterns

# LLM Patterns Skill


For AI-first applications where LLMs handle logical operations.

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## Core Principle

**LLM for logic, code for plumbing.**

Use LLMs for:
- Classification, extraction, summarization
- Decision-making with natural language reasoning
- Content generation and transformation
- Complex conditional logic that would be brittle in code

Use traditional code for:
- Data validation (Zod/Pydantic)
- API routing and HTTP handling
- Database operations
- Authentication/authorization
- Orchestration and error handling

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## Project Structure

```
project/
├── src/
│   ├── core/
│   │   ├── prompts/           # Prompt templates
│   │   │   ├── classify.ts
│   │   │   └── extract.ts
│   │   ├── llm/               # LLM client and utilities
│   │   │   ├── client.ts      # LLM client wrapper
│   │   │   ├── schemas.ts     # Response schemas (Zod)
│   │   │   └── index.ts
│   │   └── services/          # Business logic using LLM
│   ├── infra/
│   └── ...
├── tests/
│   ├── unit/
│   ├── integration/
│   └── llm/                   # LLM-specific tests
│       ├── fixtures/          # Saved responses for deterministic tests
│       ├── evals/             # Evaluation test suites
│       └── mocks/             # Mock LLM responses
└── _project_specs/