Debugging

Turns LangSmith observability documentation into a repeatable incident workflow for LLM and agent outages: start from a failing run ID or thread, use the UI or LangSmith MCP tools (`fetch_runs`, `get_thread_history`) to reconstruct prompts, tool calls, and errors, then narrow scope with documented filters (run_type, is_root, FQL `filter` / `trace_filter` / `tree_filter`) before proposing code or prompt changes. The playbook cites official pagination rules (character-budget pages with `page_number` and `total_pages`) so investigators do not assume single-shot dumps, and it reminds teams to separate Cloud OAuth Remote MCP paths from self-hosted `LANGSMITH_ENDPOINT` configurations when collecting evidence.

Diagnoses live production incidents using log triage, metric spike correlation, deploy window filtering, and safe reproduction steps without causing further disruption. Production debugging applies systematic debugging principles in a live environment where the cost of wrong actions is high and the ability to reproduce the issue is limited.