feat(agents): migrate createReactAgent to core LangChain project

.github/workflows/compatibility.yml

@@ -57,6 +57,10 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: ${{ env.NODE_VERSION }}
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      - name: Build required workspace packages
+        run: pnpm build --filter=@langchain/openai --filter=@langchain/anthropic --filter=@langchain/cohere --filter=@langchain/textsplitters
       - name: Test LangChain with latest deps
         run: docker compose -f dependency_range_tests/docker-compose.yml run langchain-latest-deps
 
@@ -72,6 +76,10 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: ${{ env.NODE_VERSION }}
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      - name: Build required workspace packages
+        run: pnpm build --filter=@langchain/openai --filter=@langchain/anthropic --filter=@langchain/cohere --filter=@langchain/textsplitters
       - name: Test LangChain with lowest deps
         run: docker compose -f dependency_range_tests/docker-compose.yml run langchain-lowest-deps
 

.github/workflows/standard-tests.yml

@@ -20,6 +20,7 @@ jobs:
             mistralai,
             aws,
             google-vertexai-web,
+            agents,
           ]
     steps:
       - uses: actions/checkout@v4

.gitignore

@@ -50,3 +50,6 @@ credentials.json
 .vercel
 
 bun.lock
+coverage/
+
+examples/src/createReactAgent/*.png

dependency_range_tests/docker-compose.yml

@@ -1,4 +1,3 @@
-
 services:
   # LangChain
   langchain-latest-deps:
@@ -10,6 +9,10 @@ services:
     working_dir: /app
     volumes:
       - ../libs/langchain:/langchain
+      - ../libs/langchain-textsplitters:/libs/langchain-textsplitters
+      - ../libs/providers/langchain-openai:/libs/langchain-openai
+      - ../libs/providers/langchain-anthropic:/libs/langchain-anthropic
+      - ../libs/providers/langchain-cohere:/libs/langchain-cohere
       - ./scripts:/scripts
     command: bash /scripts/langchain/test-with-latest-deps.sh
   langchain-lowest-deps:
@@ -21,6 +24,11 @@ services:
     working_dir: /app
     volumes:
       - ../libs/langchain:/langchain
+      - ../libs/langchain-core:/libs/langchain-core
+      - ../libs/langchain-textsplitters:/libs/langchain-textsplitters
+      - ../libs/providers/langchain-openai:/libs/langchain-openai
+      - ../libs/providers/langchain-anthropic:/libs/langchain-anthropic
+      - ../libs/providers/langchain-cohere:/libs/langchain-cohere
       - ./scripts:/scripts
     command: bash /scripts/langchain/test-with-lowest-deps.sh
 

dependency_range_tests/scripts/langchain/node/update_resolutions_latest.js

@@ -4,44 +4,52 @@ const communityPackageJsonPath = "package.json";
 const currentPackageJson = JSON.parse(
   fs.readFileSync(communityPackageJsonPath)
 );
+currentPackageJson.pnpm = { overrides: {} };
 
-// Convert workspace dependencies to peer dependencies since they don't exist in the test environment
-if (currentPackageJson.devDependencies) {
-  for (const [depName, depVersion] of Object.entries(
-    currentPackageJson.devDependencies
-  )) {
-    if (depVersion.includes("workspace:")) {
-      delete currentPackageJson.devDependencies[depName];
-    }
-  }
+if (
+  currentPackageJson.peerDependencies?.["@langchain/core"] &&
+  !currentPackageJson.peerDependencies["@langchain/core"].includes("rc")
+) {
+  currentPackageJson.peerDependencies = {
+    ...currentPackageJson.peerDependencies,
+    "@langchain/core": "*",
+  };
 }
 
-if (currentPackageJson.dependencies) {
-  for (const [depName, depVersion] of Object.entries(
-    currentPackageJson.dependencies
-  )) {
-    if (depVersion.includes("workspace:")) {
-      // Convert workspace dependencies to peer dependencies
-      if (!currentPackageJson.peerDependencies) {
-        currentPackageJson.peerDependencies = {};
-      }
-      currentPackageJson.peerDependencies[depName] = "*";
-      delete currentPackageJson.dependencies[depName];
-    }
+/**
+ * Link workspace dependencies via file path
+ */
+const workspaceDependencies = [
+  ...Object.entries(currentPackageJson.devDependencies),
+  ...Object.entries(currentPackageJson.dependencies),
+].filter(([, depVersion]) => depVersion.includes("workspace:"));
+
+for (const [depName, depVersion] of workspaceDependencies) {
+  /**
+   * for the peer dependency @langchain/core, we want to make sure to install max version
+   * defined above
+   */
+  if (depName === "@langchain/core") {
+    delete currentPackageJson.devDependencies[depName];
+    continue;
   }
-}
 
-if (currentPackageJson.devDependencies?.["@langchain/core"]) {
-  delete currentPackageJson.devDependencies["@langchain/core"];
-  currentPackageJson.peerDependencies["@langchain/core"] = "*";
+  const libName = depName.split("/")[1];
+  /**
+   * reference the workspace dependency as a file path
+   */
+  currentPackageJson.devDependencies[
+    depName
+  ] = `file:/libs/langchain-${libName}`;
+  /**
+   * ensure that peer dependencies are also installed from the file path
+   * e.g. @langchain/openai depends on @langchain/core which should be resolved from the file path
+   */
+  currentPackageJson.pnpm.overrides[
+    depName
+  ] = `file:/libs/langchain-${libName}`;
 }
 
-// Stupid hack
-currentPackageJson.resolutions = {
-  ...currentPackageJson.resolutions,
-  jackspeak: "2.1.1",
-};
-
 fs.writeFileSync(
   communityPackageJsonPath,
   JSON.stringify(currentPackageJson, null, 2)

dependency_range_tests/scripts/langchain/node/update_resolutions_lowest.js

@@ -6,6 +6,7 @@ const communityPackageJsonPath = "package.json";
 const currentPackageJson = JSON.parse(
   fs.readFileSync(communityPackageJsonPath)
 );
+currentPackageJson.pnpm = { overrides: {} };
 
 if (
   currentPackageJson.peerDependencies?.["@langchain/core"] &&
@@ -20,68 +21,40 @@ if (
   };
 }
 
-// Convert workspace dependencies to peer dependencies since they don't exist in the test environment
-if (currentPackageJson.devDependencies) {
-  for (const [depName, depVersion] of Object.entries(
-    currentPackageJson.devDependencies
-  )) {
-    if (depVersion.includes("workspace:")) {
-      delete currentPackageJson.devDependencies[depName];
-    }
+/**
+ * Convert workspace dev dependencies to install latest as they are only used for testing
+ */
+const workspaceDependencies = [
+  ...Object.entries(currentPackageJson.devDependencies),
+  ...Object.entries(currentPackageJson.dependencies),
+].filter(([, depVersion]) => depVersion.includes("workspace:"));
+
+for (const [depName, depVersion] of workspaceDependencies) {
+  /**
+   * for the peer dependency @langchain/core, we want to make sure to install min version
+   * defined above
+   */
+  if (depName === "@langchain/core") {
+    delete currentPackageJson.devDependencies[depName];
+    continue;
   }
-}
-
-if (currentPackageJson.dependencies) {
-  for (const [depName, depVersion] of Object.entries(
-    currentPackageJson.dependencies
-  )) {
-    if (depVersion.includes("workspace:")) {
-      // Convert workspace dependencies to peer dependencies
-      if (!currentPackageJson.peerDependencies) {
-        currentPackageJson.peerDependencies = {};
-      }
-      currentPackageJson.peerDependencies[depName] = "*";
-      delete currentPackageJson.dependencies[depName];
-    }
-  }
-}
 
-if (
-  currentPackageJson.peerDependencies?.["@langchain/openai"] &&
-  !currentPackageJson.peerDependencies["@langchain/openai"].includes("rc") &&
-  currentPackageJson.peerDependencies["@langchain/openai"] !== "*"
-) {
-  const minVersion = semver.minVersion(
-    currentPackageJson.peerDependencies["@langchain/openai"]
-  ).version;
-  currentPackageJson.peerDependencies = {
-    ...currentPackageJson.peerDependencies,
-    "@langchain/openai": minVersion,
-  };
+  const libName = depName.split("/")[1];
+  /**
+   * reference the workspace dependency as a file path
+   */
+  currentPackageJson.devDependencies[
+    depName
+  ] = `file:/libs/langchain-${libName}`;
+  /**
+   * ensure that peer dependencies are also installed from the file path
+   * e.g. @langchain/openai depends on @langchain/core which should be resolved from the file path
+   */
+  currentPackageJson.pnpm.overrides[
+    depName
+  ] = `file:/libs/langchain-${libName}`;
 }
 
-if (
-  currentPackageJson.peerDependencies?.["@langchain/textsplitters"] &&
-  !currentPackageJson.peerDependencies["@langchain/textsplitters"].includes(
-    "rc"
-  ) &&
-  currentPackageJson.peerDependencies["@langchain/textsplitters"] !== "*"
-) {
-  const minVersion = semver.minVersion(
-    currentPackageJson.peerDependencies["@langchain/textsplitters"]
-  ).version;
-  currentPackageJson.peerDependencies = {
-    ...currentPackageJson.peerDependencies,
-    "@langchain/textsplitters": minVersion,
-  };
-}
-
-// Stupid hack
-currentPackageJson.resolutions = {
-  ...currentPackageJson.resolutions,
-  jackspeak: "2.1.1",
-};
-
 fs.writeFileSync(
   communityPackageJsonPath,
   JSON.stringify(currentPackageJson, null, 2)

dependency_range_tests/scripts/langchain/test-with-latest-deps.sh

@@ -5,6 +5,7 @@ set -euxo pipefail
 corepack enable
 
 export CI=true
+export LC_DEPENDENCY_RANGE_TESTS=true
 
 # enable extended globbing for omitting build artifacts
 shopt -s extglob
@@ -16,16 +17,11 @@ mkdir -p /updater_script
 cp -r /scripts/langchain/node/!(node_modules|dist|dist-cjs|dist-esm|build|.next|.turbo) /updater_script/
 
 cd /updater_script
-
-pnpm install --prod
+npm install
 
 cd /app
-
-corepack enable
 node /updater_script/update_resolutions_latest.js
-
 pnpm install
-pnpm add @langchain/core
 
 # Check the test command completes successfully
 pnpm run test

dependency_range_tests/scripts/langchain/test-with-lowest-deps.sh

@@ -5,6 +5,7 @@ set -euxo pipefail
 corepack enable
 
 export CI=true
+export LC_DEPENDENCY_RANGE_TESTS=true
 
 # enable extended globbing for omitting build artifacts
 shopt -s extglob
@@ -16,18 +17,11 @@ mkdir -p /updater_script
 cp -r /scripts/langchain/node/!(node_modules|dist|dist-cjs|dist-esm|build|.next|.turbo) /updater_script/
 
 cd /updater_script
-
-pnpm install --prod
+npm install
 
 cd /app
-
 node /updater_script/update_resolutions_lowest.js
-
-# Read the @langchain/core version from peerDependencies
-core_version=$(node -p "require('./package.json').peerDependencies?.['@langchain/core']")
-
 pnpm install
-pnpm add @langchain/core@$core_version
 
 # Check the test command completes successfully
 pnpm run test

environment_tests/docker-compose.yml

@@ -12,6 +12,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -36,6 +37,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -60,6 +62,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -84,6 +87,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -108,6 +112,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -132,6 +137,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -156,6 +162,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai
@@ -177,6 +184,7 @@ services:
       - ../environment_tests/scripts:/scripts
       - ../libs/langchain:/langchain
       - ../libs/langchain-core:/langchain-core
+      - ../libs/langchain-agents:/langchain-agents
       - ../libs/langchain-community:/langchain-community
       - ../libs/providers/langchain-anthropic:/langchain-anthropic
       - ../libs/providers/langchain-openai:/langchain-openai

examples/package.json

@@ -62,6 +62,7 @@
     "@langchain/qdrant": "workspace:*",
     "@langchain/redis": "workspace:*",
     "@langchain/scripts": ">=0.1.0 <0.2.0",
+    "@langchain/tavily": "workspace:*",
     "@langchain/textsplitters": "workspace:*",
     "@langchain/weaviate": "workspace:*",
     "@langchain/xai": "workspace:*",

examples/src/chat/agent.ts

@@ -1,5 +1,4 @@
-// @ts-expect-error - createReactAgent is not yet available
-import { createReactAgent } from "langchain";
+import { createReactAgent, HumanMessage } from "langchain";
 import { pull } from "langchain/hub";
 import type { PromptTemplate } from "@langchain/core/prompts";
 
@@ -33,7 +32,7 @@ export const run = async () => {
   });
 
   const result = await agent.invoke({
-    input: "what is LangChain?",
+    messages: [new HumanMessage("what is LangChain?")],
   });
 
   console.log(result);