Root cause analysis for development issues — error messages, build failures, config problems, test failures, plugin errors, unexpected behavior. Use when the user pastes an error message, stack trace, or log output, says "investigate", "why is this failing", "debug this", "what's wrong with", "root cause", "figure out why", or describes something broken. Also trigger when the user shares a problem and seems stuck or confused about the cause, even if they don't explicitly ask for investigation.