Untracked prompt changes cause hallucination rate surge from 2% to 15%

Without prompt version management, a prompt change caused hallucination rate to surge from 2% to 15% for inputs in a specific language (Japanese). With no prompt change history, rollback took 3 hours, during which hundreds of incorrect responses were served.

Implement prompt version management using LangFuse's Prompt Management feature with versions and labels (production, staging). Reference prompts by name and version using langfuse_prompt_name parameter. Each trace automatically records which prompt version was used, enabling rapid rollback and A/B testing.