What's Changed

• chore(langchain): rebase main changes by @hntrl in #8811
• fix(langchain): port and export AgentRuntime by @christian-bromann in #8829

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/core==1.0.0-alpha.1...@langchain/core==1.0.0-alpha.2

What's Changed

• fix(openai): pass verbosity through by @hntrl in #8730

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/openai==0.6.8...@langchain/openai==0.6.9

What's Changed

• feat(langchain): new middleware concept for createAgent by @christian-bromann in #8851

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/aws==1.0.0-alpha.4...@langchain/aws==1.0.0-alpha.5

What's Changed

• chore(openai): minor cleanup in withStructuredOutput by @christian-bromann in #872
• test(openai): migrate to Vitest by @christian-bromann in #8758
• break(*): bump required Node.js version to v20 by @christian-bromann in #8773
• feat: content blocks with v0 messages by @hntrl in #8778
• chore(openai): rebase main changes by @hntrl in #8796

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/openai==0.6.9...@langchain/openai==1.0.0-alpha.1

This is an alpha release of @langchain/core 1.0.

Detailed documentation forthcoming.

@langchain/core 1.0 features standard, typed message content. This includes standard
types for reasoning, citations, server-side tool calls, and other modern LLM features.

There are no breaking changes associated with existing message content. The standard
content can be lazily-parsed off of existing v0 messages using the contentBlocks
property:

import { AIMessage } from "@langchain/core";

new AIMessage("Hello, world").contentBlocks

What's Changed

• chore(internal): add new package for tsdown build by @christian-bromann in #8599
• chore(internal): New LangChain Build System - tsdown-based Build Infrastructure by @christian-bromann in #8596
• chore(internal): migrate to pnpm by @christian-bromann in #8598
• chore: rearrange packages by @hntrl in #8608
• fix(build): change script name to avoid double compilation by @christian-bromann in #8613
• refactor: rewrite environment tests with TypeScript test runner and package verification by @christian-bromann in #8614
• chore(core): migrate to vitest by @hntrl in #8622
• chore(v1): remove unused babel.config.cjs files by @christian-bromann in #8629
• chore(v1): remove experimental files from langchain by @christian-bromann in #8672
• feat(core): basic chunk impl by @hntrl in #8744
• break(*): bump required Node.js version to v20 by @christian-bromann in #8773
• feat: content blocks with v0 messages by @hntrl in #8778

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/core==0.3.71...@langchain/core==1.0.0-alpha.1

What's Changed

• test(anthropic): migrate to Vitest by @christian-bromann in #8632
• chore(anthropic): remove experimental anthropic path by @hntrl in #8677
• break(*): bump required Node.js version to v20 by @christian-bromann in #8773
• feat: content blocks with v0 messages by @hntrl in #8778
• chore(anthropic): rebase main by @hntrl in #8799

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/anthropic==0.3.25...@langchain/anthropic==1.0.0.alpha-1

What's Changed

• openai/chat_models: remove console.log line by @haraldschilly in #8654
• fix(openai): make gpt-5-chat a non-reasoning model by @hntrl in #8715

New Contributors

• @haraldschilly made their first contribution in #8654

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/openai==0.6.6...@langchain/openai==0.6.8

What's Changed

• fix(openai): make gpt-5 family reasoning models by @hntrl in #8646
• feat(openai): custom tools by @hntrl in #8645
• feat(openai): add prompt cache key support by @hntrl in #8649
• chore(openai): add gpt-5 parameter tests by @hntrl in #8650

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/openai==0.6.5...@langchain/openai==0.6.6

What's Changed

• fix: enable handleLLMNewToken events for useResponsesApi=true by @ninjudd in #8578
• fix(openai): declarative defaultOptions by @hntrl in #8633
• feat(openai): bump sdk by @hntrl in #8639

New Contributors

• @ninjudd made their first contribution in #8578

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/openai==0.6.3...@langchain/openai==0.6.5

What's Changed

• fix(core): handle tool call chunks without IDs in streaming mode by @christian-bromann in #8581
• fix(core): extract variables from inside Mustache sections by @christian-bromann in #8580
• feat(core): add tool metadata by @hntrl in #8644

Full Changelog: https://github.com/langchain-ai/langchainjs/compare/@langchain/core==0.3.66...@langchain/core==0.3.68