langgraph-code-review
Reviews LangGraph code for bugs, anti-patterns, and improvements. Use when reviewing code that uses StateGraph, nodes, edges, checkpointing, or other LangGraph features. Catches common mistakes in state management, graph structure, and async patterns.
npx skills add majiayu000/claude-skill-registry --skill langgraph-code-review --agent claude-code
Same command for any agent — swap --agent for codex, cursor, copilot.
Weekly change comes from our own snapshots, not the repository page — it measures attention, not adoption.
# LangGraph Code Review When reviewing LangGraph code, check for these categories of issues. ## Critical Issues ### 1. State Mutation Instead of Return ```python # BAD - mutates state directly def my_node(state: State) -> None: state["messages"].append(new_message) # Mutation! # GOOD - returns partial update def my_node(state: State) -> dict: return {"messages": [new_message]} # Let reducer handle it ``` ### 2. Missing Reducer for List Fields ```python # BAD - no reducer, each node overwrites class State(TypedDict): messages: list # Will be overwritten, not appended! # GOOD - reducer appends class State(TypedDict): messages: Annotated[list, operator.add] # Or use add_messages for chat: messages: Annotated[list, add_messages] ``` ### 3. Wrong Return Type from Conditional Edge ```python # BAD - returns invalid node name def router(state) -> str: return "nonexistent_node" # Runtime error! # GOOD - use Literal type hint for safety def router(state) -> Literal["agent", "tools", "__end__"]: if condition: return "agent" return END # Use constant, not string ``` ### 4. Missing Checkpointer for Interrupts ```python # BAD - interrupt without checkpointer def my_node(state): answer = interrup
- Critical Issues
- 1. State Mutation Instead of Return
- 2. Missing Reducer for List Fields
- 3. Wrong Return Type from Conditional Edge
- 4. Missing Checkpointer for Interrupts
- 5. Forgetting Thread ID with Checkpointer
- State Schema Issues
- 6. Using addmessages Without Message Types
- 7. Returning Full State Instead of Partial
- 8. Pydantic State Without Annotations
- Graph Structure Issues
- 9. Missing Entry Point
- 10. Unreachable Nodes
- 11. Conditional Edge Without All Paths
What does the langgraph-code-review skill do?
Reviews LangGraph code for bugs, anti-patterns, and improvements. Use when reviewing code that uses StateGraph, nodes, edges, checkpointing, or other LangGraph features. Catches common mistakes in state management, graph structure, and async patterns.
How do I install it?
Run `npx skills add majiayu000/claude-skill-registry --skill langgraph-code-review --agent claude-code` — it drops the skill into your project so the agent can pick it up. Swap the --agent value for codex, cursor or copilot if you use one of those.
Where does this skill come from?
From majiayu000/claude-skill-registry, a repository with 534 stars. We read it straight from the repository tree rather than a submitted listing, so what you see here is what is actually published.
Is a popular skill a good skill?
Not necessarily. Stars measure attention, not adoption — a repository can trend for a week and be abandoned. That is why we show the weekly change from our own snapshots next to the total, instead of a single flattering number.