# @langchain/core

## 1.2.3

### Patch Changes

- [#11200](https://github.com/langchain-ai/langchainjs/pull/11200) [`08e5888`](https://github.com/langchain-ai/langchainjs/commit/08e588865927c3bf0eb2ec418cfb3fba527e14bb) Thanks [@hntrl](https://github.com/hntrl)! - fix(aws): normalize and safely replay Bedrock reasoning blocks

  Emit standard reasoning blocks with preserved signatures, omit incomplete signature-only reasoning during replay, and retain compatibility with legacy and redacted Bedrock reasoning.

## 1.2.2

### Patch Changes

- [#11171](https://github.com/langchain-ai/langchainjs/pull/11171) [`82bef01`](https://github.com/langchain-ai/langchainjs/commit/82bef01ad3dd5e0317e48da40707be6bccc52f94) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): coerce string v1 AIMessage content to text blocks

  Prevent `contentBlocks.push is not a function` when constructing an
  `AIMessage` with `response_metadata.output_version === "v1"` and string
  `content` (common in serialized LangGraph stream payloads).

## 1.2.1

### Patch Changes

- [#10674](https://github.com/langchain-ai/langchainjs/pull/10674) [`f017708`](https://github.com/langchain-ai/langchainjs/commit/f01770895c06621b469a6c6b5244747f6efdfbf7) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix: classify provider 429s before retrying

- [#11092](https://github.com/langchain-ai/langchainjs/pull/11092) [`7918bbd`](https://github.com/langchain-ai/langchainjs/commit/7918bbdd2eaf8d9aff736b122f359a555267e1e7) Thanks [@aolsenjazz](https://github.com/aolsenjazz)! - fix(core): only treat arrays of content blocks as ToolMessage content

  Fix tool outputs that are arrays of plain objects being forwarded as malformed message content. An array is now only treated as message content blocks when every element is an object with a `type`; otherwise it is JSON-stringified.

## 1.2.0

### Minor Changes

- [#10924](https://github.com/langchain-ai/langchainjs/pull/10924) [`2e28115`](https://github.com/langchain-ai/langchainjs/commit/2e2811509d75af94f57cedcc3842f178f4c020d1) Thanks [@christian-bromann](https://github.com/christian-bromann)! - feat(core): add OpenAI-compatible stream event conversion

### Patch Changes

- [#11047](https://github.com/langchain-ai/langchainjs/pull/11047) [`ac0f71d`](https://github.com/langchain-ai/langchainjs/commit/ac0f71d03994664cfee98e71a584d4aa3321746f) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): preserve AIMessage content blocks

  Keep existing v1 contentBlocks when constructing AIMessage instances so serialized messages do not lose block content during deserialization.

## 1.1.49

### Patch Changes

- [#10679](https://github.com/langchain-ai/langchainjs/pull/10679) [`1f7b495`](https://github.com/langchain-ai/langchainjs/commit/1f7b4952ea1d7cebd572453877b670a7740a397b) Thanks [@hnustwjj](https://github.com/hnustwjj)! - fix(core): make `RemoveMessage` type-compatible across `MessageStructure` variants

  Remove unnecessary `TStructure` generic from `RemoveMessage` — its content is always `[]`, so the type parameter only caused incompatibilities when passing `RemoveMessage` into APIs expecting a different `MessageStructure` (e.g. `@langchain/langgraph-sdk`'s `Message<DefaultToolCall>`). Also add `{ type: "remove"; id: string }` to `BaseMessageLike` so the serialized format is accepted by TypeScript, matching the existing runtime behavior in `coerceMessageLikeToMessage`.

## 1.1.48

### Patch Changes

- [#10832](https://github.com/langchain-ai/langchainjs/pull/10832) [`1b24369`](https://github.com/langchain-ai/langchainjs/commit/1b24369a970ad6f56f1f428027f48601f87e62eb) Thanks [@info-arnav](https://github.com/info-arnav)! - fix(core, openrouter): make CJS default re-exports callable

- [#10666](https://github.com/langchain-ai/langchainjs/pull/10666) [`2bb55b0`](https://github.com/langchain-ai/langchainjs/commit/2bb55b053f49f89e81e3252a7af08e86d71ddd95) Thanks [@hnustwjj](https://github.com/hnustwjj)! - feat(openrouter): surface reasoning content as v1 standard content blocks

  `convertOpenRouterResponseToBaseMessage` and
  `convertOpenRouterDeltaToBaseMessageChunk` now copy OpenRouter's
  `reasoning` (flat string) and `reasoning_details` (structured array) fields
  onto `additional_kwargs.reasoning_content` / `additional_kwargs.reasoning_details`.
  A new `ChatOpenRouterTranslator` is registered in `@langchain/core` under
  the `"openrouter"` provider key so `AIMessage.contentBlocks` emits standard
  `{type: "reasoning"}` blocks alongside text and tool calls.

  Previously, reasoning text returned by reasoning-capable models routed
  through OpenRouter (DeepSeek R1, Minimax M2, Claude extended thinking,
  o-series, etc.) was silently dropped: only the `reasoning_tokens` count
  was preserved via `usage_metadata`. Consumers using standard content blocks
  (including the frontend agent UI patterns shown in the docs) could not
  display the model's chain of thought.

- [#10918](https://github.com/langchain-ai/langchainjs/pull/10918) [`3999fab`](https://github.com/langchain-ai/langchainjs/commit/3999fab55870c6eea22d6d90c08aa472f9b2fac3) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(openai): stream custom tool calls through Responses API chunks

## 1.1.47

### Patch Changes

- [#10906](https://github.com/langchain-ai/langchainjs/pull/10906) [`f61b345`](https://github.com/langchain-ai/langchainjs/commit/f61b3450f275831e47e69c08899b4a2b67b4bdb3) Thanks [@hntrl](https://github.com/hntrl)! - feat(core): add uuid v6 utility support

  Add `v6` UUID generation support to `@langchain/core/utils/uuid` by vendoring the upstream uuidjs `v6` implementation and its `v1ToV6` helper, exporting `v6` from the UUID utils index, and adding tests for deterministic generation, buffer/offset behavior, validation/versioning, and ordering.

- [#10872](https://github.com/langchain-ai/langchainjs/pull/10872) [`a640079`](https://github.com/langchain-ai/langchainjs/commit/a64007997a4940f51bba3c1c83dae89d1ccfb692) Thanks [@hntrl](https://github.com/hntrl)! - chore(deps): remove redundant @types/uuid declarations

  Remove `@types/uuid` from package manifests that rely on `@langchain/core/utils/uuid` or do not require uuid type stubs directly, and refresh the lockfile entries accordingly.

- [#10792](https://github.com/langchain-ai/langchainjs/pull/10792) [`3682268`](https://github.com/langchain-ai/langchainjs/commit/3682268cd1844b2573b01f07bee367e21cb7bdc7) Thanks [@Genmin](https://github.com/Genmin)! - fix(core): apply v1 message casting after implicit streaming aggregation

- [#10901](https://github.com/langchain-ai/langchainjs/pull/10901) [`f26fc4a`](https://github.com/langchain-ai/langchainjs/commit/f26fc4a6f461d6d0f86d59bd00197ad510432c4a) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(testing): share fakeModel invocation state across bindTools instances

## 1.1.46

### Patch Changes

- [#10847](https://github.com/langchain-ai/langchainjs/pull/10847) [`1659e7d`](https://github.com/langchain-ai/langchainjs/commit/1659e7d36e31e315c890fa98f43db887f7a2d52b) Thanks [@hntrl](https://github.com/hntrl)! - chore(core): reduce transitive dependency exposure and tighten release hygiene

  Remove direct runtime dependencies on `ansi-styles`, `camelcase`, and `decamelize`
  by inlining equivalent logic in core internals, and enable npm provenance in the
  release workflow.

- [#10790](https://github.com/langchain-ai/langchainjs/pull/10790) [`ef78bc6`](https://github.com/langchain-ai/langchainjs/commit/ef78bc6a21f9a8808ba95c98db2023f0a6b51bcc) Thanks [@Genmin](https://github.com/Genmin)! - fix(core): keep different content block types separate when merging chunks

## 1.1.45

### Patch Changes

- [#10833](https://github.com/langchain-ai/langchainjs/pull/10833) [`6cf39fe`](https://github.com/langchain-ai/langchainjs/commit/6cf39fe9636804f6280db0b98c4a4c72d5b103a0) Thanks [@colifran](https://github.com/colifran)! - chore(core): deprecate streamLog, streamEvents v1, RunnableWithMessageHistory and improve threat model verbiage for loads

- [#10835](https://github.com/langchain-ai/langchainjs/pull/10835) [`0aebe50`](https://github.com/langchain-ai/langchainjs/commit/0aebe5054cfb982f09d9775b017317a731b6576f) Thanks [@colifran](https://github.com/colifran)! - fix(core): deno re-declaration in LangSmith is causing unit test failures

## 1.1.44

### Patch Changes

- [#10822](https://github.com/langchain-ai/langchainjs/pull/10822) [`922a040`](https://github.com/langchain-ai/langchainjs/commit/922a040421391700fd92e04e6f44a37e3f24710b) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): translate content block delta for other models

## 1.1.43

### Patch Changes

- [#10814](https://github.com/langchain-ai/langchainjs/pull/10814) [`dfec1b7`](https://github.com/langchain-ai/langchainjs/commit/dfec1b7f8b2c530a43f639dc79d4965a80ea4b79) Thanks [@hntrl](https://github.com/hntrl)! - fix(google): restore structured output parsing with includeRaw and reasoning blocks

  Ensure structured output parsers read `BaseMessage` text content when `includeRaw: true`, so responses that include reasoning/thought blocks plus JSON text continue to parse correctly.

- [#10772](https://github.com/langchain-ai/langchainjs/pull/10772) [`1ba7131`](https://github.com/langchain-ai/langchainjs/commit/1ba71319150847438fa517fe612f65cfed85ffab) Thanks [@christian-bromann](https://github.com/christian-bromann)! - chore(core): new stream primitives

## 1.1.42

### Patch Changes

- [#10776](https://github.com/langchain-ai/langchainjs/pull/10776) [`20a9abe`](https://github.com/langchain-ai/langchainjs/commit/20a9abea23ffacf4ae8dc9a7aeec217143bbdeb6) Thanks [@hntrl](https://github.com/hntrl)! - fix(deps): remediate uuid vulnerability by removing direct uuid usage

## 1.1.41

### Patch Changes

- [#10733](https://github.com/langchain-ai/langchainjs/pull/10733) [`589f29c`](https://github.com/langchain-ai/langchainjs/commit/589f29ce844eb252c2d5e6b0f8d26de37763a0d7) Thanks [@jacoblee93](https://github.com/jacoblee93)! - fix(core): Update inheritance behavior for tracer metadata for special keys

- [#10711](https://github.com/langchain-ai/langchainjs/pull/10711) [`2e9e696`](https://github.com/langchain-ai/langchainjs/commit/2e9e6969e248a53ede0659a41d0ac8dbaf291ab4) Thanks [@jacoblee93](https://github.com/jacoblee93)! - feat(core): Add chat model and llm invocation params to traced metadata

## 1.1.40

### Patch Changes

- [#10694](https://github.com/langchain-ai/langchainjs/pull/10694) [`d3e0809`](https://github.com/langchain-ai/langchainjs/commit/d3e080995bb267bf3797067ab53c96bc2a6c8e3f) Thanks [@hntrl](https://github.com/hntrl)! - refactor(core): decouple tracer-only metadata defaults from runnable metadata
  - Add tracer-scoped inheritable metadata/tag options in callback manager while keeping backward-compatible aliases.
  - Move configurable-to-tracing metadata derivation into a tracer-only path and keep `ensureConfig` metadata mirroring limited to `model`.
  - Update `LangChainTracer` default metadata/tag handling and add regression tests for stream events metadata behavior.

## 1.1.39

### Patch Changes

- [#10430](https://github.com/langchain-ai/langchainjs/pull/10430) [`d3d0922`](https://github.com/langchain-ai/langchainjs/commit/d3d0922c24afcd3006fb94dcadd3ebe08fbf2383) Thanks [@christian-bromann](https://github.com/christian-bromann)! - feat(langchain): support for browser tools

## 1.1.38

### Patch Changes

- [#10552](https://github.com/langchain-ai/langchainjs/pull/10552) [`589ab9b`](https://github.com/langchain-ai/langchainjs/commit/589ab9be391a5d6c104f34877fc1b3e2a32fa449) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(langchain): accept cross-version runnable models in createAgent

## 1.1.37

### Patch Changes

- [#10511](https://github.com/langchain-ai/langchainjs/pull/10511) [`6933769`](https://github.com/langchain-ai/langchainjs/commit/6933769836fe3cec835588e5f8db9883200865f6) Thanks [@hntrl](https://github.com/hntrl)! - cache Zod-to-JSON-Schema conversions in toJsonSchema()

- [#10541](https://github.com/langchain-ai/langchainjs/pull/10541) [`50d5f32`](https://github.com/langchain-ai/langchainjs/commit/50d5f32fd30cabebf058b1c13255c1daadde6107) Thanks [@jacoblee93](https://github.com/jacoblee93)! - revert: Revert "feat(core): Add all chat model/llm invocation params to metadata"

- [#10509](https://github.com/langchain-ai/langchainjs/pull/10509) [`5552999`](https://github.com/langchain-ai/langchainjs/commit/555299917c90322e25d7671bad2e20c9b104bad6) Thanks [@hntrl](https://github.com/hntrl)! - feat(openai): add support for phase parameter on Responses API messages
  - Extract `phase` from message output items and surface it on text content blocks
  - Support phase in streaming via `response.output_item.added` events
  - Round-trip phase through both raw provider and standard content paths
  - Move phase into `extras` dict in the core standard content translator

- [#10528](https://github.com/langchain-ai/langchainjs/pull/10528) [`8331833`](https://github.com/langchain-ai/langchainjs/commit/8331833c93ba907063c9fe28e9f935ed5dfec11c) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): normalize single-block content in mergeContent

## 1.1.36

### Patch Changes

- [#10512](https://github.com/langchain-ai/langchainjs/pull/10512) [`bbbfea1`](https://github.com/langchain-ai/langchainjs/commit/bbbfea185c0777ae06df2b24a1a84f941d499c2a) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): fix streaming chunk merge for providers without `index` on tool call deltas

  `_mergeLists` now falls back to `id`-based matching when items don't have an `index` field. Previously, providers routing through the OpenAI-compatible API without `index` on streaming tool call deltas (e.g. Anthropic models via `ChatOpenAI`) would accumulate hundreds of individual raw deltas in `tool_call_chunks` and `additional_kwargs.tool_calls` instead of merging them into a single entry per tool call. In a real trace with 3 concurrent subagents, this caused a single AI message to balloon from ~4KB to 146KB -- with 826 uncollapsed streaming fragments carrying a few bytes each.

  Also fixes `SystemMessage.concat()` which used `...this` to spread all instance properties (including `lc_kwargs`) into the new constructor, causing each chained `concat()` call to nest one level deeper. After 7 middleware `concat()` calls (typical in deepagents), a 7KB system prompt would serialize to 81KB due to content being duplicated at every nesting level.

## 1.1.35

### Patch Changes

- [#10327](https://github.com/langchain-ai/langchainjs/pull/10327) [`5dc11b5`](https://github.com/langchain-ai/langchainjs/commit/5dc11b55cccfe35e4dad910a33e904cf49b3088a) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): replace exported zod type references with structural duck-type interfaces to fix TypeScript OOM

  Replaces all exported Zod type references (`z3.ZodType`, `z4.$ZodType`, etc.) in `@langchain/core`'s public API with minimal structural ("duck-type") interfaces. This prevents TypeScript from performing expensive deep structural comparisons (~3,400+ lines of mutually recursive generics) when downstream packages resolve a different Zod version than `@langchain/core`, which was causing OOM crashes and unresponsive language servers in monorepo setups.

- [#10433](https://github.com/langchain-ai/langchainjs/pull/10433) [`7af0b65`](https://github.com/langchain-ai/langchainjs/commit/7af0b65d5ab9a173b528d6a821d269a79fbabdc6) Thanks [@tanushree-sharma](https://github.com/tanushree-sharma)! - feat: Add LangSmith integration metadata to createAgent and initChatModel

## 1.1.34

### Patch Changes

- [#10312](https://github.com/langchain-ai/langchainjs/pull/10312) [`bfb7944`](https://github.com/langchain-ai/langchainjs/commit/bfb7944a105470eee98fe4a0eef91e586600e1de) Thanks [@jacoblee93](https://github.com/jacoblee93)! - feat(core): Add all invocation params as part of metadata

## 1.1.33

### Patch Changes

- [#10412](https://github.com/langchain-ai/langchainjs/pull/10412) [`6db417b`](https://github.com/langchain-ai/langchainjs/commit/6db417b03ecb5e2ace413389d982294e0ac88433) Thanks [@pawel-twardziak](https://github.com/pawel-twardziak)! - fix(core): respect timeout option in streamEvents v2

- [#10424](https://github.com/langchain-ai/langchainjs/pull/10424) [`d69dfcc`](https://github.com/langchain-ai/langchainjs/commit/d69dfcca97503cf1c0b7e70ccf5fb7d507c60982) Thanks [@pawel-twardziak](https://github.com/pawel-twardziak)! - fix(core): preserve multimodal content in getBufferString as placeholders

## 1.1.32

### Patch Changes

- [#10330](https://github.com/langchain-ai/langchainjs/pull/10330) [`26488b5`](https://github.com/langchain-ai/langchainjs/commit/26488b596f01b7b7fe2f1d97d07164e52365ade5) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): treat empty string tool call chunk IDs as missing during merge

  Fixed `_mergeLists` in message base to treat empty string `""` IDs the same as `null`/`undefined` when merging tool call chunks. This fixes old completions-style streaming where follow-up chunks carry `id: ""` instead of `undefined`, which previously prevented chunks from being merged by index.

- [#10167](https://github.com/langchain-ai/langchainjs/pull/10167) [`ca826f6`](https://github.com/langchain-ai/langchainjs/commit/ca826f6fecae6087bf0dee7781ee80b587396ec1) Thanks [@colifran](https://github.com/colifran)! - feat: implement type inference for tool streams

- [#10334](https://github.com/langchain-ai/langchainjs/pull/10334) [`a602c42`](https://github.com/langchain-ai/langchainjs/commit/a602c42db75d7e7e01cab38b12e0b65b9c0cce95) Thanks [@maahir30](https://github.com/maahir30)! - fix(core): add JSDoc docstrings to fakeModel builder API and export FakeBuiltModel

- [#10254](https://github.com/langchain-ai/langchainjs/pull/10254) [`db7d017`](https://github.com/langchain-ai/langchainjs/commit/db7d017f7ce13cb937147aabcbfa3847d80bde9d) Thanks [@pawel-twardziak](https://github.com/pawel-twardziak)! - fix(core): preserve thoughtSignature in array content during streaming with thinking models

## 1.1.31

### Patch Changes

- [#10271](https://github.com/langchain-ai/langchainjs/pull/10271) [`7373b4c`](https://github.com/langchain-ai/langchainjs/commit/7373b4cd6a78bee105a952a11838c573fd1aafae) Thanks [@jacoblee93](https://github.com/jacoblee93)! - feat(core): Use uuid7 instead of v4 for generating run ids

- [#10262](https://github.com/langchain-ai/langchainjs/pull/10262) [`b0175a5`](https://github.com/langchain-ai/langchainjs/commit/b0175a5d3b68e8fba44a85bc23879bd06def2f52) Thanks [@maahir30](https://github.com/maahir30)! - fix: Move fakeModel from utils/testing to testing namespace
  move to updated namespace

- [#10185](https://github.com/langchain-ai/langchainjs/pull/10185) [`414f6ed`](https://github.com/langchain-ai/langchainjs/commit/414f6ed402ac6f1c0fd6cce4bed64fa3708eea3d) Thanks [@maahir30](https://github.com/maahir30)! - feat: add custom Vitest matchers for LangChain message and tool call assertions

  Adds a new `@langchain/core/testing/matchers` export containing custom Vitest matchers (`toBeHumanMessage`, `toBeAIMessage`, `toBeSystemMessage`, `toBeToolMessage`, `toHaveToolCalls`, `toHaveToolCallCount`, `toContainToolCall`, `toHaveToolMessages`, `toHaveBeenInterrupted`, `toHaveStructuredResponse`) that external users can register via `expect.extend(langchainMatchers)` in their Vitest setup files. Re-exported from `langchain` for convenience.

## 1.1.30

### Patch Changes

- [#10243](https://github.com/langchain-ai/langchainjs/pull/10243) [`96c630d`](https://github.com/langchain-ai/langchainjs/commit/96c630dfd009f2546d5bc36f5067ff868bb4067f) Thanks [@hntrl](https://github.com/hntrl)! - fix: add explicit `: symbol` type annotations to Symbol.for() declarations for cross-version compatibility

  TypeScript infers `unique symbol` type when Symbol.for() is used without an explicit type annotation, causing type incompatibility when multiple versions of the same package are present in a dependency tree. By adding explicit `: symbol` annotations, all declarations now use the general symbol type, making them compatible across versions while maintaining identical runtime behavior.

  Changes:
  - Added `: symbol` to `MESSAGE_SYMBOL` in messages/base.ts
  - Added `: symbol` to `MIDDLEWARE_BRAND` in agents/middleware/types.ts (also changed from Symbol() to Symbol.for() for cross-realm compatibility)

- [#10256](https://github.com/langchain-ai/langchainjs/pull/10256) [`a8b9ccc`](https://github.com/langchain-ai/langchainjs/commit/a8b9ccca5a85984a5a30008acd09f9991e591638) Thanks [@colifran](https://github.com/colifran)! - fix(core): standard schema type guards don't support callable schemas

- [#10204](https://github.com/langchain-ai/langchainjs/pull/10204) [`a1f22bb`](https://github.com/langchain-ai/langchainjs/commit/a1f22bba907731a18dca23c31cec5333444a3f55) Thanks [@colifran](https://github.com/colifran)! - feat(core): implement standard schema support for structured output

## 1.1.29

### Patch Changes

- [#10106](https://github.com/langchain-ai/langchainjs/pull/10106) [`9f30267`](https://github.com/langchain-ai/langchainjs/commit/9f30267e95a2a42fac71f1d3674b84c5a190dbbc) Thanks [@hntrl](https://github.com/hntrl)! - Add package version metadata to runnable traces. Each package now stamps its version in `this.metadata.versions` at construction time, making version info available in LangSmith trace metadata.

- [#10154](https://github.com/langchain-ai/langchainjs/pull/10154) [`403a99f`](https://github.com/langchain-ai/langchainjs/commit/403a99fd826383f30300809ae077e1c967023520) Thanks [@kanweiwei](https://github.com/kanweiwei)! - fix(core): add usage_metadata to AIMessage lc_aliases

- [#10169](https://github.com/langchain-ai/langchainjs/pull/10169) [`3b1fd54`](https://github.com/langchain-ai/langchainjs/commit/3b1fd5458a4aa29c398122829f383f21b5ac39da) Thanks [@hntrl](https://github.com/hntrl)! - fix(core, langchain): bump uuid dependency from ^10.0.0 to ^11.0.0 to fix Metro bundler error

  The `uuid` v10 package has ambiguous `exports` in its `package.json` which causes Metro (used by Expo/React Native) to resolve the wrong entry point, resulting in `Cannot read properties of undefined (reading 'v1')`. The `uuid` v11 package fixes its exports map to work correctly with Metro's package exports resolution.

- [#10044](https://github.com/langchain-ai/langchainjs/pull/10044) [`77bd982`](https://github.com/langchain-ai/langchainjs/commit/77bd98274a885e947d76f7a9c6dd0b3763453218) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): remove inherited LangChainTracer handlers when tracingEnabled is false

  When a RunTree explicitly disables tracing via `tracingEnabled: false`, `CallbackManager._configureSync` now strips any inherited `LangChainTracer` handlers so child runs don't produce traces.

## 1.1.28

### Patch Changes

- [#10140](https://github.com/langchain-ai/langchainjs/pull/10140) [`10a876c`](https://github.com/langchain-ai/langchainjs/commit/10a876c7d5ff27d8f2889761ee20e95f76a50518) Thanks [@hntrl](https://github.com/hntrl)! - Merge content blocks by string index during streaming.

- [#10102](https://github.com/langchain-ai/langchainjs/pull/10102) [`b46d96a`](https://github.com/langchain-ai/langchainjs/commit/b46d96a508a8bf212561dbb6f025e35c75f16257) Thanks [@colifran](https://github.com/colifran)! - feat: implement aynchronous generator tool calling for streaming partial tool results

## 1.1.27

### Patch Changes

- [#10104](https://github.com/langchain-ai/langchainjs/pull/10104) [`fb2226e`](https://github.com/langchain-ai/langchainjs/commit/fb2226e6decdaba21e78b3f01877b45fa1eed6d3) Thanks [@hntrl](https://github.com/hntrl)! - Revert "chore(deps): bump ansi-styles from 5.2.0 to 6.2.3"

## 1.1.26

### Patch Changes

- [#10085](https://github.com/langchain-ai/langchainjs/pull/10085) [`ed6ea53`](https://github.com/langchain-ai/langchainjs/commit/ed6ea53c38a004b65e30c0f5888a0ac7d8ee7028) Thanks [@colifran](https://github.com/colifran)! - fix(google): tool_calls are not preserved when concatenating AIMessageChunks

## 1.1.25

### Patch Changes

- [#10002](https://github.com/langchain-ai/langchainjs/pull/10002) [`27186c5`](https://github.com/langchain-ai/langchainjs/commit/27186c54884cfe7c2522fa50b42c3ca0ccaefdba) Thanks [@aditya-gg04](https://github.com/aditya-gg04)! - fix(core): support reasoning/thinking blocks in StringOutputParser

- [#10077](https://github.com/langchain-ai/langchainjs/pull/10077) [`05396f7`](https://github.com/langchain-ai/langchainjs/commit/05396f7ce0a91c49a3bae4bbcd3dbdd6cbd18089) Thanks [@christian-bromann](https://github.com/christian-bromann)! - feat(core): add ContextOverflowError, raise in anthropic and openai

- [#10081](https://github.com/langchain-ai/langchainjs/pull/10081) [`5a6f26b`](https://github.com/langchain-ai/langchainjs/commit/5a6f26bbaed80195dc538c538b96219a8b03f38f) Thanks [@hntrl](https://github.com/hntrl)! - feat(core): add namespace-based symbol branding for error class hierarchies

  Introduces `createNamespace` utility for hierarchical symbol-based branding of class hierarchies.
  All LangChain error classes now use this pattern, replacing hand-rolled duck-type `isInstance` checks
  with reliable cross-realm `Symbol.for`-based identity.
  - New `LangChainError` base class that all LangChain errors extend
  - New `createNamespace` / `Namespace` API in `@langchain/core/utils/namespace`
  - Refactored `ModelAbortError`, `ContextOverflowError` to use namespace branding
  - Added `ContextOverflowError.fromError()` static factory method
  - Deprecated `addLangChainErrorFields` in favor of `LangChainError` subclasses
  - Migrated Google provider errors (`GoogleError`, `ConfigurationError`, etc.) to namespace branding
  - Updated Anthropic and OpenAI providers to use `ContextOverflowError.fromError()`

## 1.1.24

### Patch Changes

- [#9978](https://github.com/langchain-ai/langchainjs/pull/9978) [`70a4400`](https://github.com/langchain-ai/langchainjs/commit/70a440085b4bc2d036726ed12d9dc7841e914061) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): fix web_search_call and file_search_call contentBlocks for OpenAI Responses API

## 1.1.23

### Patch Changes

- [#10000](https://github.com/langchain-ai/langchainjs/pull/10000) [`71d08c0`](https://github.com/langchain-ai/langchainjs/commit/71d08c0a3a2597bd5a084eb35a7830e5ea1a2b29) Thanks [@hntrl](https://github.com/hntrl)! - feat(google): add `@langchain/google` -- unified Google/Gemini integration

  New package that replaces the fragmented `@langchain/google-genai` / `@langchain/google-common` / Vertex AI package stack with a single integration.

  Published as 0.1.0 (early release). Existing Google packages will continue to receive maintenance updates.

## 1.1.22

### Patch Changes

- [#9995](https://github.com/langchain-ai/langchainjs/pull/9995) [`8f166b1`](https://github.com/langchain-ai/langchainjs/commit/8f166b159343ae6fd0d6d44c0835ab56c0b153f4) Thanks [@kaigritun](https://github.com/kaigritun)! - fix(core): skip empty text blocks in ChatOpenAI contentBlocks

## 1.1.21

### Patch Changes

- [#9990](https://github.com/langchain-ai/langchainjs/pull/9990) [`d5e3db0`](https://github.com/langchain-ai/langchainjs/commit/d5e3db0d01ab321ec70a875805b2f74aefdadf9d) Thanks [@hntrl](https://github.com/hntrl)! - feat(core): Add SSRF protection module (`@langchain/core/utils/ssrf`) with utilities for validating URLs against private IPs, cloud metadata endpoints, and localhost.

  fix(community): Harden `RecursiveUrlLoader` against SSRF attacks by integrating `validateSafeUrl` and replacing string-based URL comparison with origin-based `isSameOrigin` from the shared SSRF module.

## 1.1.20

### Patch Changes

- [#9957](https://github.com/langchain-ai/langchainjs/pull/9957) [`71c3cba`](https://github.com/langchain-ai/langchainjs/commit/71c3cba843ab16d877299d158a1de0c7d22f3fb9) Thanks [@jacoblee93](https://github.com/jacoblee93)! - feat(langchain,core): Update prompt pulling params, LangSmith version

## 1.1.19

### Patch Changes

- [#9905](https://github.com/langchain-ai/langchainjs/pull/9905) [`41bfea5`](https://github.com/langchain-ai/langchainjs/commit/41bfea51cf119573a3b956ee782d2731fe71c681) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(classic/community/core): avoid long lived abort signals

## 1.1.18

### Patch Changes

- [#9900](https://github.com/langchain-ai/langchainjs/pull/9900) [`a9b5059`](https://github.com/langchain-ai/langchainjs/commit/a9b50597186002221aaa4585246e569fa44c27c8) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): update method signatures to use `Partial<CallOptions>` for options parameters

  Updated `invoke`, `stream`, `generate`, and `generatePrompt` method signatures across `Runnable`, `BaseChatModel`, and `BaseLLM` to correctly accept `Partial<CallOptions>` instead of full `CallOptions`. This aligns the implementation with the `RunnableInterface` specification and allows users to pass partial options (e.g., `{ signal: abortedSignal }`) without TypeScript errors.

- [#9900](https://github.com/langchain-ai/langchainjs/pull/9900) [`a9b5059`](https://github.com/langchain-ai/langchainjs/commit/a9b50597186002221aaa4585246e569fa44c27c8) Thanks [@hntrl](https://github.com/hntrl)! - Improved abort signal handling for chat models:
  - Added `ModelAbortError` class in `@langchain/core/errors` that contains partial output when a model invocation is aborted mid-stream
  - `invoke()` now throws `ModelAbortError` with accumulated `partialOutput` when aborted during streaming (when using streaming callback handlers)
  - `stream()` throws a regular `AbortError` when aborted (since chunks are already yielded to the caller)
  - All provider implementations now properly check and propagate abort signals in both `_generate()` and `_streamResponseChunks()` methods
  - Added standard tests for abort signal behavior

## 1.1.17

### Patch Changes

- [#9842](https://github.com/langchain-ai/langchainjs/pull/9842) [`05a9733`](https://github.com/langchain-ai/langchainjs/commit/05a9733448a10764c0bfd070af859c33e623b998) Thanks [@encodedz](https://github.com/encodedz)! - Adding `on_tool_error` event into EventStreamCallbackHandler

## 1.1.16

### Patch Changes

- [#9830](https://github.com/langchain-ai/langchainjs/pull/9830) [`70387a1`](https://github.com/langchain-ai/langchainjs/commit/70387a144464539d65a546c8130cf51dfad025a1) Thanks [@bracesproul](https://github.com/bracesproul)! - fix: More undefined null errors and tests

- [#9679](https://github.com/langchain-ai/langchainjs/pull/9679) [`a7c6ec5`](https://github.com/langchain-ai/langchainjs/commit/a7c6ec51ab9baa186ab5ebf815599c08f5c7e8ab) Thanks [@christian-bromann](https://github.com/christian-bromann)! - feat(openai): elevate OpenAI image generation outputs to proper image content blocks

- [#9817](https://github.com/langchain-ai/langchainjs/pull/9817) [`5e04543`](https://github.com/langchain-ai/langchainjs/commit/5e045435a783fdae44bc9a43e01a8e5eb7100db2) Thanks [@Ashx098](https://github.com/Ashx098)! - read error.status when response.status is absent to avoid retrying OpenAI SDK 4xx

- [#9819](https://github.com/langchain-ai/langchainjs/pull/9819) [`40b4467`](https://github.com/langchain-ai/langchainjs/commit/40b446762445575844610ee528abc77c247b2c43) Thanks [@MrDockal](https://github.com/MrDockal)! - Tool call content returns compacted json

- [#9815](https://github.com/langchain-ai/langchainjs/pull/9815) [`17e30bd`](https://github.com/langchain-ai/langchainjs/commit/17e30bd7f4c7bdf87c9c30304b3b9e121cc1fbbc) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): respect tracingEnabled=false from RunTree when env tracing is enabled

## 1.1.15

### Patch Changes

- [#9781](https://github.com/langchain-ai/langchainjs/pull/9781) [`230462d`](https://github.com/langchain-ai/langchainjs/commit/230462d28c3a8b5ccadf433ea2f523eb6e658de6) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): preserve index and timestamp fields in \_mergeDicts

## 1.1.14

### Patch Changes

- [#9797](https://github.com/langchain-ai/langchainjs/pull/9797) [`bd1ab45`](https://github.com/langchain-ai/langchainjs/commit/bd1ab45364391f69ce93ecba36a4a15dafca2b76) Thanks [@christian-bromann](https://github.com/christian-bromann)! - handle undefined error objects in async-caller

## 1.1.13

### Patch Changes

- [#9777](https://github.com/langchain-ai/langchainjs/pull/9777) [`3efe79c`](https://github.com/langchain-ai/langchainjs/commit/3efe79c62ff2ffe0ada562f7eecd85be074b649a) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): properly elevate reasoning tokens

- [#9789](https://github.com/langchain-ai/langchainjs/pull/9789) [`b8561c1`](https://github.com/langchain-ai/langchainjs/commit/b8561c17556bdf7a3ff8d70bc307422642a9172e) Thanks [@hntrl](https://github.com/hntrl)! - source JsonOutputParser content from text accessor

## 1.1.12

### Patch Changes

- [#9517](https://github.com/langchain-ai/langchainjs/pull/9517) [`23be5af`](https://github.com/langchain-ai/langchainjs/commit/23be5afd59b5f4806edef11937ce5e2ba300f7ee) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(@langchain/core): add literal name type inference to tool()

## 1.1.11

### Patch Changes

- [#9753](https://github.com/langchain-ai/langchainjs/pull/9753) [`a46a249`](https://github.com/langchain-ai/langchainjs/commit/a46a24983fd0fea649d950725a2673b3c435275f) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): allow shared object references in serialization

## 1.1.10

### Patch Changes

- [#9746](https://github.com/langchain-ai/langchainjs/pull/9746) [`817fc9a`](https://github.com/langchain-ai/langchainjs/commit/817fc9a56d4699f3563a6e153b13eadf7bcc661b) Thanks [@bracesproul](https://github.com/bracesproul)! - fix: `_mergeDicts` error when merging undefined values

## 1.1.9

### Patch Changes

- [#9725](https://github.com/langchain-ai/langchainjs/pull/9725) [`56600b9`](https://github.com/langchain-ai/langchainjs/commit/56600b94f8e185f44d4288b7a9b66c55778938dd) Thanks [@Orenoid](https://github.com/Orenoid)! - fix(langchain): update merge logic for numeric values in `mergeDicts`

- [#9736](https://github.com/langchain-ai/langchainjs/pull/9736) [`dc5c2ac`](https://github.com/langchain-ai/langchainjs/commit/dc5c2ac00f86dd2feeba9843d708926a5f38202e) Thanks [@hntrl](https://github.com/hntrl)! - fix(core): handle circular references in `load`

- [#9739](https://github.com/langchain-ai/langchainjs/pull/9739) [`c28d24a`](https://github.com/langchain-ai/langchainjs/commit/c28d24a8770f6d0e543cde116b0e38b3baf21301) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): use getBufferString for message summarization

- [#9702](https://github.com/langchain-ai/langchainjs/pull/9702) [`bfcb87d`](https://github.com/langchain-ai/langchainjs/commit/bfcb87d23c580c7881f650960a448fe2e54a30b3) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): improve interop with Zod

## 1.1.8

### Patch Changes

- [#9707](https://github.com/langchain-ai/langchainjs/pull/9707) [`e5063f9`](https://github.com/langchain-ai/langchainjs/commit/e5063f9c6e9989ea067dfdff39262b9e7b6aba62) Thanks [@hntrl](https://github.com/hntrl)! - add security hardening for `load`

- [#9684](https://github.com/langchain-ai/langchainjs/pull/9684) [`8996647`](https://github.com/langchain-ai/langchainjs/commit/89966470e8c0b112ce4f9a326004af6a4173f9e6) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): document purpose of name in base message

## 1.1.7

### Patch Changes

- [#9686](https://github.com/langchain-ai/langchainjs/pull/9686) [`df9c42b`](https://github.com/langchain-ai/langchainjs/commit/df9c42b3ab61b85309ab47256e1d93c3188435ee) Thanks [@hntrl](https://github.com/hntrl)! - add usage_metadata to metadata in LangChainTracer

- [#9665](https://github.com/langchain-ai/langchainjs/pull/9665) [`8d2982b`](https://github.com/langchain-ai/langchainjs/commit/8d2982bb94c0f4e4314ace3cc98a1ae87571b1ed) Thanks [@jacoblee93](https://github.com/jacoblee93)! - feat(core): Make runnable transform trace in a single payload in LangChainTracer

- [#9675](https://github.com/langchain-ai/langchainjs/pull/9675) [`af664be`](https://github.com/langchain-ai/langchainjs/commit/af664becc0245b2315ea2f784c9a6c1d7622dbb4) Thanks [@jacoblee93](https://github.com/jacoblee93)! - Bump LangSmith dep to 0.4.0

- [#9673](https://github.com/langchain-ai/langchainjs/pull/9673) [`ffb2402`](https://github.com/langchain-ai/langchainjs/commit/ffb24026cd93e58219519ee24c6e23ea57cb5bde) Thanks [@hntrl](https://github.com/hntrl)! - add `context` utility

## 1.1.6

### Patch Changes

- [#9668](https://github.com/langchain-ai/langchainjs/pull/9668) [`a7b2a7d`](https://github.com/langchain-ai/langchainjs/commit/a7b2a7db5ef57df3731ae6c9931f4b663e909505) Thanks [@bracesproul](https://github.com/bracesproul)! - fix: Cannot merge two undefined objects error

- [#9657](https://github.com/langchain-ai/langchainjs/pull/9657) [`a496c5f`](https://github.com/langchain-ai/langchainjs/commit/a496c5fc64d94cc0809216325b0f1bfde3f92c45) Thanks [@dqbd](https://github.com/dqbd)! - fix(core): avoid writing to TransformStream in EventStreamCallbackHandler when underlying ReadableStream is closed

- [#9658](https://github.com/langchain-ai/langchainjs/pull/9658) [`1da1325`](https://github.com/langchain-ai/langchainjs/commit/1da1325aea044fb37af54a9de1f4ae0b9f47d4a2) Thanks [@dqbd](https://github.com/dqbd)! - fix(core): ensure streaming test chat models respect AbortSignal

## 1.1.5

### Patch Changes

- [#9641](https://github.com/langchain-ai/langchainjs/pull/9641) [`005c729`](https://github.com/langchain-ai/langchainjs/commit/005c72903bcdf090e0f4c58960c8c243481f9874) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(community/core): various security fixes

- [#7907](https://github.com/langchain-ai/langchainjs/pull/7907) [`ab78246`](https://github.com/langchain-ai/langchainjs/commit/ab782462753e6c3ae5d55c0c251f795af32929d5) Thanks [@jasonphillips](https://github.com/jasonphillips)! - fix(core): handle subgraph nesting better in graph_mermaid

- [#9589](https://github.com/langchain-ai/langchainjs/pull/9589) [`8cc81c7`](https://github.com/langchain-ai/langchainjs/commit/8cc81c7cee69530f7a6296c69123edbe227b2fce) Thanks [@nathannewyen](https://github.com/nathannewyen)! - test(core): add test for response_metadata in streamEvents

- [#9644](https://github.com/langchain-ai/langchainjs/pull/9644) [`f32e499`](https://github.com/langchain-ai/langchainjs/commit/f32e4991d0e707324e3f6af287a1ee87ab833b7e) Thanks [@hntrl](https://github.com/hntrl)! - add bindTools to FakeListChatModel

- [#9508](https://github.com/langchain-ai/langchainjs/pull/9508) [`a28d83d`](https://github.com/langchain-ai/langchainjs/commit/a28d83d49dd1fd31e67b52a44abc70f2cc2a2026) Thanks [@shubham-021](https://github.com/shubham-021)! - Fix toFormattedString() to properly display nested objects in tool call arguments instead of [object Object]

- [#9165](https://github.com/langchain-ai/langchainjs/pull/9165) [`2e5ad70`](https://github.com/langchain-ai/langchainjs/commit/2e5ad70d16c1f13eaaea95336bbe2ec4a4a4954a) Thanks [@pawel-twardziak](https://github.com/pawel-twardziak)! - fix(mcp-adapters): preserve timeout from RunnableConfig in MCP tool calls

- [#9647](https://github.com/langchain-ai/langchainjs/pull/9647) [`e456c66`](https://github.com/langchain-ai/langchainjs/commit/e456c661aa1ab8f1ed4a98c40616f5a13270e88e) Thanks [@hntrl](https://github.com/hntrl)! - handle missing parent runs in tracer to prevent LangSmith 400 errors

- [#9597](https://github.com/langchain-ai/langchainjs/pull/9597) [`1cfe603`](https://github.com/langchain-ai/langchainjs/commit/1cfe603e97d8711343ae5f1f5a75648e7bd2a16e) Thanks [@hntrl](https://github.com/hntrl)! - use uuid7 for run ids

## 1.1.4

### Patch Changes

- [#9575](https://github.com/langchain-ai/langchainjs/pull/9575) [`0bade90`](https://github.com/langchain-ai/langchainjs/commit/0bade90ed47c7988ed86f1e695a28273c7b3df50) Thanks [@hntrl](https://github.com/hntrl)! - bin p-retry

- [#9574](https://github.com/langchain-ai/langchainjs/pull/9574) [`6c40d00`](https://github.com/langchain-ai/langchainjs/commit/6c40d00e926f377d249c2919549381522eac8ed1) Thanks [@hntrl](https://github.com/hntrl)! - Revert "fix(@langchain/core): update and bundle dependencies (#9534)"

## 1.1.3

### Patch Changes

- [#9534](https://github.com/langchain-ai/langchainjs/pull/9534) [`bd2c46e`](https://github.com/langchain-ai/langchainjs/commit/bd2c46e09e661d9ac766c09e71bc6687d6fc811c) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(@langchain/core): update and bundle `p-retry`, `ansi-styles`, `camelcase` and `decamelize` dependencies

- [#9544](https://github.com/langchain-ai/langchainjs/pull/9544) [`487378b`](https://github.com/langchain-ai/langchainjs/commit/487378bf14277659c8ca0ef06ea0f9836b818ff4) Thanks [@hntrl](https://github.com/hntrl)! - fix tool chunk concat behavior (#9450)

- [#9505](https://github.com/langchain-ai/langchainjs/pull/9505) [`138e7fb`](https://github.com/langchain-ai/langchainjs/commit/138e7fb6280705457079863bedb238b16b322032) Thanks [@chosh-dev](https://github.com/chosh-dev)! - feat: replace btoa with toBase64Url for encoding in drawMermaidImage

## 1.1.2

### Patch Changes

- [#9511](https://github.com/langchain-ai/langchainjs/pull/9511) [`833f578`](https://github.com/langchain-ai/langchainjs/commit/833f57834dc3aa64e4cfdd7499f865b2ab41462a) Thanks [@dqbd](https://github.com/dqbd)! - allow parsing more partial JSON

## 1.1.1

### Patch Changes

- [#9495](https://github.com/langchain-ai/langchainjs/pull/9495) [`636b994`](https://github.com/langchain-ai/langchainjs/commit/636b99459bf843362298866211c63a7a15c2a319) Thanks [@gsriram24](https://github.com/gsriram24)! - fix: use dynamic import for p-retry to support CommonJS environments

- [#9531](https://github.com/langchain-ai/langchainjs/pull/9531) [`38f0162`](https://github.com/langchain-ai/langchainjs/commit/38f0162b7b2db2be2c3a75ae468728adcb49fdfb) Thanks [@hntrl](https://github.com/hntrl)! - add `extras` to tools

## 1.1.0

### Minor Changes

- [#9475](https://github.com/langchain-ai/langchainjs/pull/9475) [`708d360`](https://github.com/langchain-ai/langchainjs/commit/708d360df1869def7e4caaa5995d6e907bbf54cd) Thanks [@christian-bromann](https://github.com/christian-bromann)! - allow to concat system messages

### Patch Changes

- [#9416](https://github.com/langchain-ai/langchainjs/pull/9416) [`0fe9beb`](https://github.com/langchain-ai/langchainjs/commit/0fe9bebee6710f719e47f913eec1ec4f638e4de4) Thanks [@hntrl](https://github.com/hntrl)! - fix 'moduleResultion: "node"' compatibility

- [#9463](https://github.com/langchain-ai/langchainjs/pull/9463) [`10fa2af`](https://github.com/langchain-ai/langchainjs/commit/10fa2afec0b81efd3467e61b59ba5c82e1043de5) Thanks [@christian-bromann](https://github.com/christian-bromann)! - fix(core): update p-retry to fix memory leak

## 1.0.6

### Patch Changes

- [#9431](https://github.com/langchain-ai/langchainjs/pull/9431) [`5709cb6`](https://github.com/langchain-ai/langchainjs/commit/5709cb64cc3e4eb300bde5ec8ae90686d2aa3d8e) Thanks [@dqbd](https://github.com/dqbd)! - fix(core): `store` should be accessible from tools

## 1.0.5

### Patch Changes

- [#9308](https://github.com/langchain-ai/langchainjs/pull/9308) [`04bd55c`](https://github.com/langchain-ai/langchainjs/commit/04bd55c63d8a0cb56f85da0b61a6bd6169b383f3) Thanks [@ro0sterjam](https://github.com/ro0sterjam)! - respect JSON schema references in interopZodTransformInputSchema

- [#9387](https://github.com/langchain-ai/langchainjs/pull/9387) [`ac0d4fe`](https://github.com/langchain-ai/langchainjs/commit/ac0d4fe3807e05eb2185ae8a36da69498e6163d4) Thanks [@hntrl](https://github.com/hntrl)! - Add `ModelProfile` and `.profile` properties to ChatModel

## 1.0.4

### Patch Changes

- 8319201: Export standard converter function utility

## 1.0.3

### Patch Changes

- 0a8a23b: feat(@langchain/core): support of ToolRuntime

## 1.0.2

### Patch Changes

- 6426eb6: fix chunks constructed with tool calls + chunks
- 619ae64: Add `BaseMessage.toFormattedString()`

## 1.0.1

### Patch changes

- cacc137: remove bad import map exports

## 1.0.0

🎉 **LangChain v1.0** is here! This release provides a focused, production-ready foundation for building agents with significant improvements to the core abstractions and APIs. See the [release notes](https://docs.langchain.com/oss/javascript/releases/langchain-v1) for more details.

### ✨ Major Features

#### Standard content blocks

A new unified API for accessing modern LLM features across all providers:

- **New `contentBlocks` property**: Provides provider-agnostic access to reasoning traces, citations, built-in tools (web search, code interpreters, etc.), and other advanced LLM features
- **Type-safe**: Full TypeScript support with type hints for all content block types
- **Backward compatible**: Content blocks can be loaded lazily with no breaking changes to existing code

Example:

```typescript
const response = await model.invoke([
  { role: "user", content: "What is the weather in Tokyo?" },
]);

// Access structured content blocks
for (const block of response.contentBlocks) {
  if (block.type === "thinking") {
    console.log("Model reasoning:", block.thinking);
  } else if (block.type === "text") {
    console.log("Response:", block.text);
  }
}
```

For more information, see our guide on [content blocks](https://docs.langchain.com/oss/javascript/langchain/messages#content).

#### Enhanced Message API

Improvements to the core message types:

- **Structured content**: Better support for multimodal content with the new content blocks API
- **Provider compatibility**: Consistent message format across all LLM providers
- **Rich metadata**: Enhanced metadata support for tracking message provenance and transformations

### 🔧 Improvements

- **Better structured output generation**: Core abstractions for generating structured outputs in the main agent loop
- **Improved type safety**: Enhanced TypeScript definitions across all core abstractions
- **Performance optimizations**: Reduced overhead in message processing and runnable composition
- **Better error handling**: More informative error messages and better error recovery

### 📦 Package Changes

The `@langchain/core` package remains focused on essential abstractions:

- Core message types and content blocks
- Base runnable abstractions
- Tool definitions and schemas
- Middleware infrastructure
- Callback system
- Output parsers
- Prompt templates

### 🔄 Migration Notes

**Backward Compatibility**: This release maintains backward compatibility with existing code. Content blocks are loaded lazily, so no changes are required to existing applications.

**New Features**: To take advantage of new features like content blocks and middleware:

1. Update to `@langchain/core@next`:

   ```bash
   npm install @langchain/core@1.0.0
   ```

2. Use the new `contentBlocks` property to access rich content:

   ```typescript
   const response = await model.invoke(messages);
   console.log(response.contentBlocks); // New API
   console.log(response.content); // Legacy API still works
   ```

3. For middleware and `createAgent`, install `langchain@next`:

   ```bash
   npm install langchain@1.0.0 @langchain/core@1.0.0
   ```

### 📚 Additional Resources

- [LangChain 1.0 Announcement](https://blog.langchain.com/langchain-langchain-1-0-alpha-releases/)
- [Migration Guide](https://docs.langchain.com/oss/javascript/migrate/langchain-v1)
- [Content Blocks Documentation](https://docs.langchain.com/oss/javascript/langchain/messages#content)
- [Agents Documentation](https://docs.langchain.com/oss/javascript/langchain/agents)

---

## 0.3.79

### Patch Changes

- 1063b43: fix chunks constructed with tool calls + chunks

## 0.3.78

### Patch Changes

- 1519a97: update chunk concat logic to match on missing ID fields
- 079e11d: omit tool call chunks without tool call id

## 0.3.76

### Patch Changes

- 41bd944: support base64 embeddings format
- e90bc0a: fix(core): prevent tool call chunks from merging incorrectly in AIMes…
- 3a99a40: Fix deserialization of RemoveMessage if represented as a plain object
- 58e9522: make mustache prompt with nested object working correctly
- e44dc1b: handle backticks in structured output

## 0.3.75

### Patch Changes

- d6d841f: fix(core): Fix deep nesting of runnables within traceables

## 0.3.74

### Patch Changes

- 4e53005: fix(core): Always inherit parent run id onto callback manager from context

## 0.3.73

### Patch Changes

- a5a2e10: add root export to satisfy bundler requirements