three-dev-setup

Adds three.dev to a codebase so its LLM calls are recorded. Finds every LLM call site, groups the calls into use cases, and routes them through the three.dev proxy (gate.three.dev) with use case, session, and environment headers. Use when the user mentions three.dev, gate.three.dev, or X-Three headers, asks to record or monitor their LLM calls, or wants to set up or extend a three.dev integration. Covers OpenAI, Anthropic, Gemini, Azure OpenAI, OpenRouter, Bedrock, and LiteLLM clients. Read the docs before writing code; never guess header values or base URLs. Not for investigating failure modes or reading recorded conversations; that is the three-dev-failure-modes skill. Not for running or reading experiments; that is the three-dev-experiments skill. Not for defining or reporting quality metrics; that is the three-dev-quality-metrics-setup skill.