LangChain Python (v1.3-focused)

Practical workflow for building reliable LangChain systems with correct 1.x APIs and strong multi-agent design.

When to activate

• Building or refactoring Python agents with create_agent
• Designing multi-agent systems (subagents, handoffs, router, skills)
• Implementing middleware/context engineering/stateful tools
• Integrating Tavily or provider-specific tools
• Migrating snippets from stale pre-1.0 docs to current semantics

Version baseline (important)

Assume LangChain 1.3.x semantics (langchain-core on the 1.4.x line) with LangGraph 1.2.x unless the user explicitly requests another version.