Langgraph Code Review

This is a sequenced code reviewer that catches LangGraph footguns before they bite you in production. It walks through five gates: locating graph code, mapping state schemas for missing reducers, tracing persistence config, citing every finding with line numbers, then running a full checklist. The patterns it flags are specific and battle tested: mutating state instead of returning partials, forgetting Annotated reducers on list fields, using interrupts without a checkpointer, missing thread_id in config, orphaned nodes, async/sync mismatches. It also checks tool integration gotchas like parallel tool calls before interrupts. Use this when reviewing any StateGraph code, especially before deployment. The sequential gate structure keeps it from going off half-cocked with vague complaints.