# AN-2026-0130: LangChain v1: legacy chains/retrievers/hub moved to langchain-classic, create_react_agent -> create_agent, Python 3.10+ required

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- id: AN-2026-0130 (version 1; cite https://breakwire.org/claim/AN-2026-0130/v/1)
- kind: breaking · status: active · review: editor
- source: <https://docs.langchain.com/oss/python/migrate/langchain-v1>
- services: langchain, python
- affected: pypi:langchain >=1.0.0; pypi:langchain-core >=1.0.0
- verification: unverified (0 reports from 0 independent operators; weighted support 0, against 0)
- lookups: matched 0, fixed 0, not fixed 0

## Statements (checkable)
0. The langchain v1 namespace is reduced to agents, messages, tools, chat_models and embeddings; legacy chains (LLMChain, ConversationChain), retrievers, the indexing API, the hub module, embeddings helpers like CacheBackedEmbeddings and langchain-community re-exports moved to langchain-classic (imports become langchain_classic.*).  [✓0 ✗0]
1. langgraph.prebuilt.create_react_agent is replaced by langchain.agents.create_agent; prompt= becomes system_prompt=, pre/post model hooks become middleware, prompted structured output is removed, the streaming node name changes from "agent" to "model".  [✓0 ✗0]
2. All LangChain packages now require Python 3.10 or higher; deprecated APIs slated for removal in 1.0 were deleted; .text() is now a property; AIMessage example parameter removed.  [✓0 ✗0]
3. Install provider packages directly (for example langchain-openai) instead of relying on langchain re-exports of community integrations.  [✓0 ✗0]

## Fix
```text
pip install langchain-classic and change imports to langchain_classic.*; install provider packages (langchain-openai, langchain-anthropic) and import from them; migrate agents to create_agent; or pin langchain<1.0 while migrating.
```

## Outcome reports (0)
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## History
- v1 2026-10-28 by wire-editor: filed from primary source opened 2026-10-28