fix(@langchain/cerebras): recognize ToolMessage responses (#8925)

Co-authored-by: Hunter Lovell <[email protected]>

Author: christian-bromann

.changeset/kind-fireants-retire.md

@@ -0,0 +1,5 @@
+---
+"@langchain/cerebras": patch
+---
+
+recognize ToolMessage responses

libs/langchain-cerebras/src/tests/utils.test.ts

@@ -0,0 +1,112 @@
+import { test, expect, describe } from "@jest/globals";
+import {
+  HumanMessage,
+  AIMessage,
+  SystemMessage,
+  ToolMessage,
+} from "@langchain/core/messages";
+import { convertToCerebrasMessageParams } from "../utils.js";
+
+describe("convertToCerebrasMessageParams", () => {
+  test("should convert ToolMessage with content properly", () => {
+    const toolMessage = new ToolMessage({
+      content: "42",
+      tool_call_id: "139485753823DJDB#JXJX",
+      name: "count_globules",
+    });
+
+    const result = convertToCerebrasMessageParams([toolMessage]);
+
+    expect(result).toHaveLength(1);
+    expect(result[0]).toEqual({
+      role: "tool",
+      content: "42",
+      tool_call_id: "139485753823DJDB#JXJX",
+    });
+  });
+
+  test("should convert a full conversation with tool calls", () => {
+    const messages = [
+      new HumanMessage(
+        "Please tell me the current number of globules in the environment."
+      ),
+      new AIMessage({
+        content: "",
+        tool_calls: [
+          {
+            id: "139485753823DJDB#JXJX",
+            name: "count_globules",
+            args: {},
+            type: "tool_call",
+          },
+        ],
+      }),
+      new ToolMessage({
+        content: "42",
+        tool_call_id: "139485753823DJDB#JXJX",
+        name: "count_globules",
+      }),
+    ];
+
+    const result = convertToCerebrasMessageParams(messages);
+
+    expect(result).toHaveLength(3);
+
+    // Check human message
+    expect(result[0]).toEqual({
+      role: "user",
+      content:
+        "Please tell me the current number of globules in the environment.",
+    });
+
+    // Check AI message with tool calls
+    expect(result[1]).toEqual({
+      role: "assistant",
+      tool_calls: [
+        {
+          id: "139485753823DJDB#JXJX",
+          type: "function",
+          function: {
+            name: "count_globules",
+            arguments: "{}",
+          },
+        },
+      ],
+      content: "",
+    });
+
+    // Check tool message
+    expect(result[2]).toEqual({
+      role: "tool",
+      content: "42",
+      tool_call_id: "139485753823DJDB#JXJX",
+    });
+  });
+
+  test("should throw error for non-string tool message content", () => {
+    const toolMessage = new ToolMessage({
+      content: [
+        { type: "text", text: "array" },
+        { type: "text", text: "content" },
+      ],
+      tool_call_id: "test-id",
+      name: "test-tool",
+    });
+
+    expect(() => convertToCerebrasMessageParams([toolMessage])).toThrow(
+      "Non string tool message content is not supported"
+    );
+  });
+
+  test("should handle system messages", () => {
+    const systemMessage = new SystemMessage("You are a helpful assistant.");
+
+    const result = convertToCerebrasMessageParams([systemMessage]);
+
+    expect(result).toHaveLength(1);
+    expect(result[0]).toEqual({
+      role: "system",
+      content: "You are a helpful assistant.",
+    });
+  });
+});

libs/langchain-cerebras/src/utils.ts

@@ -62,6 +62,24 @@ function convertAIMessageToCerebras(
   );
 
   if (typeof messages.content === "string") {
+    // Check if there are tool calls even with string content
+    if (messages.tool_calls?.length) {
+      const toolCalls: CerebrasToolCall[] = messages.tool_calls.map((tc) => ({
+        id: tc.id!,
+        type: "function",
+        function: {
+          name: tc.name,
+          arguments: JSON.stringify(tc.args),
+        },
+      }));
+      return [
+        {
+          role: "assistant",
+          content: messages.content,
+          tool_calls: toolCalls,
+        },
+      ];
+    }
     return [
       {
         role: "assistant",
@@ -117,11 +135,11 @@ function convertHumanGenericMessagesToCerebras(
       },
     ];
   }
-  return message.content.map((c) => {
+  return message.content.map((c): CerebrasMessageParam => {
     if (c.type === "text") {
       return {
         role: "user",
-        content: c.text,
+        content: c.text as string,
       };
     } else if (c.type === "image_url") {
       if (typeof c.image_url === "string") {
@@ -130,7 +148,12 @@ function convertHumanGenericMessagesToCerebras(
           content: "",
           images: [extractBase64FromDataUrl(c.image_url)],
         };
-      } else if (c.image_url.url && typeof c.image_url.url === "string") {
+      } else if (
+        typeof c.image_url === "object" &&
+        c.image_url !== null &&
+        "url" in c.image_url &&
+        typeof c.image_url.url === "string"
+      ) {
         return {
           role: "user",
           content: "",
@@ -189,16 +212,16 @@ export function convertToCerebrasMessageParams(
   messages: BaseMessage[]
 ): CerebrasMessageParam[] {
   return messages.flatMap((msg) => {
-    if (["human", "generic"].includes(msg._getType())) {
-      return convertHumanGenericMessagesToCerebras(msg);
-    } else if (msg._getType() === "ai") {
-      return convertAIMessageToCerebras(msg);
-    } else if (msg._getType() === "system") {
-      return convertSystemMessageToCerebras(msg);
-    } else if (msg._getType() === "tool") {
+    if (["human", "generic"].includes(msg.getType())) {
+      return convertHumanGenericMessagesToCerebras(msg as HumanMessage);
+    } else if (msg.getType() === "ai") {
+      return convertAIMessageToCerebras(msg as AIMessage);
+    } else if (msg.getType() === "system") {
+      return convertSystemMessageToCerebras(msg as SystemMessage);
+    } else if (msg.getType() === "tool") {
       return convertToolMessageToCerebras(msg as ToolMessage);
     } else {
-      throw new Error(`Unsupported message type: ${msg._getType()}`);
+      throw new Error(`Unsupported message type: ${msg.getType()}`);
     }
   });
 }