new·The score now tells you which way it movedA brain's exam only ever grows: its own material writes questions, and so does every question a real caller asked and did not get answered. The score is a percentage over that growing set, so a brain that learned more could post a smaller number — and this week three did. One of them answered two MORE questions than the week before and showed eighteen points less. Printed as a single percentage, that reads as decline to a reader and as punishment to anyone who contributes material.all news →
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explore / AI & agents / mozg / LangChain & LangGraph

LangChain · LangGraph

Answer questions about LangGraph exactly as documented: defining graphs with state, nodes and edges, persistence and checkpointing, human-in-the-loop, memory, streaming, subgraphs and deployment.

1,018 notes · updated 2026-08-14 · trained 80%

since last sitting: +33 newly passed — this brain is learning · the verified changelog →

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$ claude mcp add --transport http mozg \
https://mozg.sh/mcp --header "Authorization: Bearer …"
> use mozg/langgraph — …
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Ask it things like

answers 33/41 on its latest exam
What is the langgraph.json file and why is it required for deployment?Deployment & Observability✓
What is GRAPH_RECURSION_LIMIT and what is a common cause of this error?Error Handling & Fault Tolerance✓
What are the two main differences between stores and checkpointers?Memory & Store✓
How do you access the store and user_id from within any node in LangGraph?Memory & Store✓
How can you route execution between multiple nodes conditionally based on state values?Nodes & Edges✓
What does the Command primitive allow you to return from a node, and what are the two key parameters?Nodes & Edges✓
How do you create a ToolNode in JavaScript that can process tool calls from an LLM?Nodes & Edges✓
What is the function get_state_history used for?Persistence & Checkpointing✓

What it can answer

41 coverage checks
80%
Answers 33 of the exam's 41 questionsIt answers 33 questions, 33 more than last time, out of an exam that grew by 41.Nothing it used to answer has stopped working.
✓Memory & Store7 / 7
▲Nodes & Edges5 / 6
▲Error Handling & Fault Tolerance4 / 5
▲Persistence & Checkpointing4 / 5
✓Subgraphs4 / 4
▲State Definition & Management3 / 5
✓Deployment & Observability2 / 2
▲Human-in-the-Loop2 / 4
▲Streaming2 / 3
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Attacks survived

re-run weekly · 2026-08-10
✓gate-battery12/12 known hostile payloads caught by the ingest gate
✓injection-corpusevery active note scanned — no steering language
✓secret-corpusevery active note scanned — no keys or credentials

heuristic scans against known attack classes — measured and dated, not a promise of unpoisonability

Inside

  • Overwrite type for bypassing reducers · state definition
  • Runtime configuration in graphs · graph api and fundamentals
  • StateGraph API for graph creation · graph api and fundamentals
  • MessagesValue in JavaScript/TypeScript · memory/short-term
  • Private state between nodes · state definition
  • Alternative state definitions in JavaScript · state definition
  • State definition in LangGraph · state definition
  • Nodes as functions in LangGraph · nodes and edges
  • Reducers for state updates · state definition
  • add_messages reducer for message handling · memory/short-term
  • Multiple nodes cannot use Overwrite on same state key · state definition
  • Input and output schemas in StateGraph · graph api and fundamentals
  • Pydantic models for graph state · state definition
  • Retry policies for nodes · error handling and fault tolerance

Licence

CC BY-NC-SA 4.0

Use it, copy it, build on it, with credit. Selling it is not allowed.