fix(@langchain/google) Fixes for ID in Vertex function calls (#10292)

Co-authored-by: Hunter Lovell <40191806+hntrl@users.noreply.github.com>
Co-authored-by: Hunter Lovell <hunter@hntrl.io>

Author: afirstenberg

.changeset/silver-deers-reply.md

@@ -0,0 +1,5 @@
+---
+"@langchain/google": patch
+---
+
+fixes for Vertex function calls

libs/providers/langchain-google/src/chat_models/tests/index.int.test.ts

@@ -567,15 +567,15 @@ describe.each(coreModelInfo)(
           tool_calls: [
             {
               type: "tool_call",
-              id: "test-id",
+              id: "lc-tool-call-test-id",
               name: "test",
               args: {
                 testName: "cobalt",
               },
             },
           ],
         }),
-        new ToolMessage(JSON.stringify(toolResult), "test-id"),
+        new ToolMessage(JSON.stringify(toolResult), "lc-tool-call-test-id"),
       ];
       const res = await llm.stream(messages);
       const resArray: BaseMessageChunk[] = [];

libs/providers/langchain-google/src/chat_models/tests/index.test.ts

@@ -135,7 +135,7 @@ class MockChunkStreamingResponse implements Response {
   readonly type: ResponseType = "basic";
   readonly url: string = "http://localhost";
   readonly bodyUsed: boolean = false;
-  readonly body: ReadableStream<Uint8Array>;
+  readonly body: ReadableStream<Uint8Array<ArrayBuffer>>;
 
   constructor(chunks: object[]) {
     const encoder = new TextEncoder();
@@ -165,7 +165,7 @@ class MockChunkStreamingResponse implements Response {
   async text(): Promise<string> {
     throw new Error("Not implemented");
   }
-  async bytes(): Promise<Uint8Array> {
+  async bytes(): Promise<Uint8Array<ArrayBuffer>> {
     throw new Error("Not implemented");
   }
   clone(): Response {
@@ -983,11 +983,11 @@ describe("Google Mock", () => {
         {
           handleLLMNewToken(
             token: string,
-            _idx: unknown,
-            _runId: unknown,
-            _parentRunId: unknown,
-            _tags: unknown,
-            fields: { chunk?: unknown }
+            _idx,
+            _runId,
+            _parentRunId,
+            _tags,
+            fields
           ) {
             newTokenCalls.push({ text: token, chunk: fields?.chunk });
           },
@@ -1100,11 +1100,11 @@ describe("Google Mock", () => {
         {
           handleLLMNewToken(
             token: string,
-            _idx: unknown,
-            _runId: unknown,
-            _parentRunId: unknown,
-            _tags: unknown,
-            fields: { chunk?: unknown }
+            _idx,
+            _runId,
+            _parentRunId,
+            _tags,
+            fields
           ) {
             newTokenCalls.push({ text: token, chunk: fields?.chunk });
           },

libs/providers/langchain-google/src/converters/messages.ts

@@ -465,9 +465,10 @@ function convertStandardContentMessageToGeminiContent(
     const matchedToolCall = aiMsg?.tool_calls?.find(
       (tc) => tc.id === message.tool_call_id
     );
+    const isGeneratedId = message.tool_call_id.startsWith("lc-tool-call-");
     parts.push({
       functionResponse: {
-        id: message.tool_call_id,
+        ...(isGeneratedId ? {} : { id: message.tool_call_id }),
         name: matchedToolCall?.name ?? message.name ?? "unknown",
         response: { result: responseContent },
       },
@@ -762,12 +763,13 @@ function convertLegacyContentMessageToGeminiContent(
     if (!aiMsg) {
       throw new ToolCallNotFoundError(message.tool_call_id);
     }
+    const isGeneratedId = message.tool_call_id.startsWith("lc-tool-call-");
     const matchedToolCall = aiMsg.tool_calls?.find(
       (tc) => tc.id === message.tool_call_id
     );
     parts.push({
       functionResponse: {
-        id: message.tool_call_id,
+        ...(isGeneratedId ? {} : { id: message.tool_call_id }),
         name: matchedToolCall?.name ?? message.name ?? "unknown",
         response: { result: responseContent },
       },
@@ -978,7 +980,9 @@ export const convertGeminiPartsToToolCalls: Converter<
       const functionCallPart = part as Gemini.Part.FunctionCall;
       toolCalls.push({
         type: "tool_call",
-        id: functionCallPart.functionCall.id ?? uuidv4().replace(/-/g, ""),
+        id:
+          functionCallPart.functionCall.id ??
+          `lc-tool-call-${uuidv4().replace(/-/g, "")}`,
         name: functionCallPart.functionCall.name,
         args: functionCallPart.functionCall.args ?? {},
         thoughtSignature: functionCallPart.thoughtSignature,

libs/providers/langchain-google/src/converters/tests/messages.test.ts

@@ -40,7 +40,7 @@ describe("convertGeminiPartsToToolCalls", () => {
 
     expect(toolCalls).toHaveLength(1);
     expect(toolCalls[0].id).toBeDefined();
-    expect(toolCalls[0].id).not.toBe("call_0");
+    expect(toolCalls[0].id!.startsWith("lc-tool-call-")).toEqual(true);
   });
 
   test("generates unique IDs across multiple invocations", () => {
@@ -57,6 +57,8 @@ describe("convertGeminiPartsToToolCalls", () => {
     const secondCallToolCalls = convertGeminiPartsToToolCalls(parts);
 
     expect(firstCallToolCalls[0].id).not.toBe(secondCallToolCalls[0].id);
+    expect(firstCallToolCalls[0].id!.startsWith("lc-tool-call-"));
+    expect(secondCallToolCalls[0].id!.startsWith("lc-tool-call-"));
   });
 
   test("generates unique IDs for multiple tool calls in the same response", () => {
@@ -134,7 +136,7 @@ describe("convertMessagesToGeminiContents", () => {
     const toolResponseContent = contents.find((c) => c.role === "function");
     expect(toolResponseContent).toBeDefined();
 
-    const functionResponsePart = toolResponseContent!.parts.find(
+    const functionResponsePart = toolResponseContent!.parts!.find(
       (p) => "functionResponse" in p && p.functionResponse
     );
     expect(functionResponsePart).toBeDefined();
@@ -485,7 +487,7 @@ describe("convertMessagesToGeminiContents", () => {
     const toolResponseContent = contents.find((c) => c.role === "function");
     expect(toolResponseContent).toBeDefined();
 
-    const functionResponsePart = toolResponseContent!.parts.find(
+    const functionResponsePart = toolResponseContent!.parts!.find(
       (p) => "functionResponse" in p && p.functionResponse
     );
     expect(functionResponsePart).toBeDefined();
@@ -495,6 +497,79 @@ describe("convertMessagesToGeminiContents", () => {
     ).toBe("tool-call-xyz");
   });
 
+  test("omits generated tool_call_id from functionResponse.id (legacy path)", () => {
+    const messages = [
+      new HumanMessage("hello"),
+      new AIMessage({
+        content: "",
+        tool_calls: [
+          {
+            name: "my_tool",
+            args: { query: "test" },
+            id: "lc-tool-call-abc",
+            type: "tool_call",
+          },
+        ],
+      }),
+      new ToolMessage({
+        content: "result",
+        tool_call_id: "lc-tool-call-abc",
+        name: "my_tool",
+      }),
+    ];
+
+    const contents = convertMessagesToGeminiContents(messages);
+
+    const toolResponseContent = contents.find((c) => c.role === "function");
+    expect(toolResponseContent).toBeDefined();
+
+    const functionResponsePart = toolResponseContent!.parts!.find(
+      (p) => "functionResponse" in p && p.functionResponse
+    );
+    expect(functionResponsePart).toBeDefined();
+    expect(
+      (functionResponsePart as Gemini.Part.FunctionResponse).functionResponse!
+        .id
+    ).toBeUndefined();
+  });
+
+  test("omits generated tool_call_id from functionResponse.id (v1 standard path)", () => {
+    const messages = [
+      new HumanMessage("hello"),
+      new AIMessage({
+        content: "",
+        tool_calls: [
+          {
+            name: "my_tool",
+            args: { query: "test" },
+            id: "lc-tool-call-xyz",
+            type: "tool_call",
+          },
+        ],
+      }),
+      new ToolMessage({
+        content: "result",
+        tool_call_id: "lc-tool-call-xyz",
+        name: "my_tool",
+        response_metadata: { output_version: "v1" },
+      }),
+    ];
+
+    const contents = convertMessagesToGeminiContents(messages);
+
+    const toolResponseContent = contents.find((c) => c.role === "function");
+    expect(toolResponseContent).toBeDefined();
+
+    const functionResponsePart = toolResponseContent!.parts!.find(
+      (p) => "functionResponse" in p && p.functionResponse
+    );
+    expect(functionResponsePart).toBeDefined();
+    expect(
+      (functionResponsePart as Gemini.Part.FunctionResponse).functionResponse!
+        .id
+    ).toBeUndefined();
+  });
+
   test("v1 contentBlocks: text-plain block produces fileData part", () => {
     const messages = [
       new HumanMessage({