Guidance

This is a wrapper for Microsoft's Guidance library, which gives you programmatic control over LLM outputs using regex patterns and formal grammars. It's useful when you absolutely need valid JSON or structured data back and can't afford to parse garbage. The library has solid traction with 18k GitHub stars, and the approach genuinely reduces latency compared to prompt engineering your way to structured outputs. You write Python code with control flow instead of crossing your fingers with system prompts. The tradeoff is complexity: you're essentially writing parsers, so use it when format guarantees matter more than development speed.