Apr 25, 2026 · Artificial Intelligence

LangGraph Day 2: Watching State Changes Like a TV Series with State + Reducer

This article explains LangGraph’s two state‑update modes—overwrite and merge—shows how to use Annotated with custom reducers such as operator.add or add_messages, demonstrates when reducers run, and provides full Python examples, including persistence with checkpointers and custom merge functions.

AI AgentsAnnotatedLangGraph

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LangGraph Day 2: Watching State Changes Like a TV Series with State + Reducer

Data STUDIO

Mar 16, 2026 · Backend Development

11 Essential Pydantic v2 Practices to Avoid Common Pitfalls

This article explains why rigorous data validation is crucial and presents eleven practical Pydantic v2 techniques—including strong typing, boundary validation, separating validation from conversion, composing small models, using Annotated and RootModel, enforcing immutability, handling circular references, writing clear errors, keeping business logic out of models, and validating all external data—to make Python code more robust and maintainable.

AnnotatedModel DesignPydantic

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11 Essential Pydantic v2 Practices to Avoid Common Pitfalls