LangChain langchain==1.0.0a12 — Release Notes & Engineering Impact

Initial release release(langchain_v1): 1.0.0a12 (#33314) chore(langchain_v1): rename `model_request` node -> `model` (#33310) release(langchain_v1): 1.0.0a11 (#33307) chore(langchain_v1): remove support for `ToolNode` in `create_agent` (#33306) feat(langchain_v1): simplify to use ONE agent (#33302) chore(langchain_v1): remove text splitters from langchain v1 namespace (#33297) chore(langchain_v1): expose rate_limiters from langchain_core (#33305) fix(langchain_v1): tool selector should use last human message (#33294) feat(langchain_v1): `before_agent` and `after_agent` hooks (#33279) feat(langchain_v1): Implement Context Editing Middleware (#33267) feat(openai): enable stream_usage when using default base URL and client (#33205) chore(infra): pdm -> hatchling (#33289) feat(langchain_v1): Add retry_model_request middleware hook, add ModelFallbackMiddleware (#33275) fix(langchain_v1): linting fixes for llm tool selector (#33278) feat(langchain_v1): add llm selection middleware (#33272) feat(langchain_v1): represent server side tools in modifyModelRequest and update tool handling (#33274) feat(langchain_v1): Implement PIIMiddleware (#33271) fix(langchain_v1): dynamic response format (#33273) chore(langchain_v1): remove union return type in init_embeddings (#33062) feat(langchain_v1): Add ToolCallLimitMiddleware (#33269) chore(langchain_v1): change modifyModelRequest back to tools (#33270) fix(langchain_v1): handle switching resposne format strategy based on model identity (#33259) feat(langchain_v1): implement nicer devx for dynamic prompt (#33264) feat(langchain_v1): description generator for HITL middleware (#33195) chore(core,langchain,langchain_v1)!: remove globals from langchain-v1, update globals in langchain-classic, langchain-core (#33251) chore(langchain_v1)!: Remove ToolNode from agents (#33250) feat(langchain): model call limits (#33178) chore: delete deprecated items (#33192) chore(langchain_v1): uncomment some optional deps (#33244) docs: v1 docs updates (#33173) release: v1.0.0 (#32567) feat(langchain_v1): update messages namespace (#33207) feat(langchain): use decorators for jumps instead (#33179) feat(langchain_v1): add `async` support for `create_agent` (#33175) chore(langchain_v1): use list[str] for modifyModelRequest (#33166) feat(langchain): Using Structured Response as Key in Output Schema for Middleware Agent (#33159) chore(langchain_v1): expose middleware decorators and selected messages (#33163) feat(langchain): todo middleware (#33152) fix(langchain): handle `gpt-5` model name in `init_chat_model` (#33148) fix(langchain): add `context_management` to Anthropic chat model init (#33150) fix(langchain): fix response action for HITL (#33131) chore(langchain_v1): move tool node to tools namespace (#33132) docs: more standardization (#33124) docs: standardize `.. code-block` directive usage (#33122) docs: correct ported over directives (#33121) chore: bump ruff version to 0.13 (#33043) chore: bump locks (#33114) release(langchain): v1.0.0a9 (#33098) fix(langchain): extra arg for anthropic caching, `__end__` -> `end` for `jump_to` (#33097) fix(langchain_v1): version equality check (#33095) release(langchain): 1.0.0a8 (#33090) feat(langchain): improvements to anthropic prompt caching (#33058) style: repo linting pass (#33089) fix(langchain): need to inject all state for tools registered by middleware (#33087) chore(langchain): renaming for HITL (#33067) chore(langchain): simplifying HITL condition (#33065) fix(langchain_v1): only interrupt if at least one ToolConfig value is True (#33064) feat(langchain): new decorator pattern for dynamically generated middleware (#33053) fix(langchain): HITL bug causing dupe interrupt (#33052) chore: update `pyproject.toml` files, remove codespell (#33028) release(langchain): 1.0.0a6 (#33024) fix(langchain): use state schema as input schema to middleware nodes (#33023) feat(langchain): dynamic system prompt middleware (#33006) feat(langchain): improved HITL patterns (#32996) chore: restore commented out optional deps (#32971) chore: bump mypy version to 1.18 (#32914) release(langchain): v1.0.0a5 (#32917) fix(langchain): use messages from model request (#32908) fix(core): resolve mermaid node id collisions when special chars are used (#32857) revert: "chore: remove ruff target-version" (#32895) chore: remove ruff target-version (#32880) chore(docs): update package `README`s (#32869) feat(langchain): support PEP604 ( `|` union) in tool node error handlers (#32861) chore(langchain): add ruff rule E501 in `langchain_v1` (#32812) chore(langchain): add ruff rule UP007 in `langchain_v1` (#32811) chore(langchain): enable ruff docstring-code-format in langchain_v1 (#32855) chore(core): enable ruff docstring-code-format (#32834) feat(langchain): middleware support in `create_agent` (#32828) fix(langchain): fix mypy versions in `langchain_v1` (#32816) chore(langchain): cleanup `langchain_v1` mypy config (#32809) chore(langchain): add ruff rules D for `langchain_v1` (#32808) fix(langchain): update __init__ version (#32793) release(langchain): v1.0.0a3 (#32791) chore(langchain): rename `create_react_agent` -> `create_agent` (#32789) chore(langchain): remove upper bound at v1 for core (#32737) chore(langchain): also bump text splitters (#32722) chore(langchain): use latest core (#32720) chore(langchain): revert back to static versioning for now (#32719) release(langchain): v1.0.0a1 (#32718) feat(langchain): revamped `create_react_agent` (#32705) chore(langchain): remove untested chains for first alpha (#32710) chore(langchain): drop Python 3.9 to prep for v1 (#32704) chore: adress pytest-asyncio deprecation warnings + other nits (#32696) chore: update references to use the latest version of Claude-3.5 Sonnet (#32594) docs: update outdated `README.md` content (#32540) fix(tests): add `anthropic_proxy` to configurable test parameters (for v1) chore: formatting across codebase (#32466) feat(openai): `minimal` and `verbosity` (#32455) feat(langchain): add stuff and map reduce chains (#32333) fix: use new Google model names in examples (#32288) fix: update `bar_model` to use the correct model version `claude-3-7-sonnet-20250219` (#32284) refactor: remove references to unsupported model `claude-3-sonnet-20240229` (#32281) fix: formatting issues in docstrings (#32265) feat(docs): improve devx, fix `Makefile` targets (#32237) chore(langchain_v1): clean anything uncertain (#32228) feat(langchain): v1 scaffolding (#32166)