Langfuse for tracing, prompt management, evals, cost and latency, and debugging.
You need traces across multi-step agent and tool runs.
Prompts should be versioned and managed outside the code.
You're running evals and tracking cost and latency.
Production behavior needs to be debuggable after the fact.
Build logs, agentic engineering decisions, agent failures, evals, and what survives real users. Sent weekly, never more.