feat(core): always provide message ID inferred from run ID if not present while streaming

langchain-core/src/language_models/chat_models.ts

@@ -264,6 +264,10 @@ export abstract class BaseChatModel<
           callOptions,
           runManagers?.[0]
         )) {
+          if (chunk.message.id == null) {
+            const runId = runManagers?.at(0)?.runId;
+            if (runId != null) chunk.message._updateId(`run-${runId}`);
+          }
           chunk.message.response_metadata = {
             ...chunk.generationInfo,
             ...chunk.message.response_metadata,
@@ -362,6 +366,10 @@ export abstract class BaseChatModel<
         );
         let aggregated;
         for await (const chunk of stream) {
+          if (chunk.message.id == null) {
+            const runId = runManagers?.at(0)?.runId;
+            if (runId != null) chunk.message._updateId(`run-${runId}`);
+          }
           if (aggregated === undefined) {
             aggregated = chunk;
           } else {
@@ -397,6 +405,10 @@ export abstract class BaseChatModel<
           if (pResult.status === "fulfilled") {
             const result = pResult.value;
             for (const generation of result.generations) {
+              if (generation.message.id == null) {
+                const runId = runManagers?.at(0)?.runId;
+                if (runId != null) generation.message._updateId(`run-${runId}`);
+              }
               generation.message.response_metadata = {
                 ...generation.generationInfo,
                 ...generation.message.response_metadata,

langchain-core/src/messages/base.ts

@@ -289,6 +289,16 @@ export abstract class BaseMessage
     };
   }
 
+  // this private method is used to update the ID for the runtime
+  // value as well as in lc_kwargs for serialisation
+  _updateId(value: string | undefined) {
+    this.id = value;
+
+    // lc_attributes wouldn't work here, because jest compares the
+    // whole object
+    this.lc_kwargs.id = value;
+  }
+
   get [Symbol.toStringTag]() {
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
     return (this.constructor as any).lc_name();

langchain-core/src/runnables/tests/runnable_history.test.ts

@@ -22,6 +22,8 @@ import {
 import { ChatPromptTemplate, MessagesPlaceholder } from "../../prompts/chat.js";
 import { StringOutputParser } from "../../output_parsers/string.js";
 
+const anyString = expect.any(String) as unknown as string;
+
 // For `BaseChatMessageHistory`
 async function getGetSessionHistory(): Promise<
   (sessionId: string) => Promise<BaseChatMessageHistory>
@@ -107,9 +109,15 @@ test("Runnable with message history with a chat model", async () => {
   const sessionHistory = await getMessageHistory("2");
   expect(await sessionHistory.getMessages()).toEqual([
     new HumanMessage("hello"),
-    new AIMessage("Hello world!"),
+    new AIMessage({
+      id: anyString,
+      content: "Hello world!",
+    }),
     new HumanMessage("good bye"),
-    new AIMessageChunk("Hello world!"),
+    new AIMessageChunk({
+      id: anyString,
+      content: "Hello world!",
+    }),
   ]);
 });
 
@@ -129,6 +137,7 @@ test("Runnable with message history with a messages in, messages out chain", asy
     config: {},
     getMessageHistory,
   });
+
   const config: RunnableConfig = { configurable: { sessionId: "2" } };
   const output = await withHistory.invoke([new HumanMessage("hello")], config);
   expect(output.content).toBe("So long and thanks for the fish!!");
@@ -147,9 +156,15 @@ test("Runnable with message history with a messages in, messages out chain", asy
   const sessionHistory = await getMessageHistory("2");
   expect(await sessionHistory.getMessages()).toEqual([
     new HumanMessage("hello"),
-    new AIMessage("So long and thanks for the fish!!"),
+    new AIMessage({
+      id: anyString,
+      content: "So long and thanks for the fish!!",
+    }),
     new HumanMessage("good bye"),
-    new AIMessageChunk("So long and thanks for the fish!!"),
+    new AIMessageChunk({
+      id: anyString,
+      content: "So long and thanks for the fish!!",
+    }),
   ]);
 });
 

langchain-core/src/runnables/tests/runnable_stream_events.test.ts

@@ -30,6 +30,8 @@ function reverse(s: string) {
   return s.split("").reverse().join("");
 }
 
+const anyString = expect.any(String) as unknown as string;
+
 const originalCallbackValue = process.env.LANGCHAIN_CALLBACKS_BACKGROUND;
 
 afterEach(() => {
@@ -733,7 +735,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_chain_stream",
@@ -743,7 +745,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_llm_stream",
@@ -756,7 +758,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("O") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "O" }) },
     },
     {
       event: "on_chain_stream",
@@ -766,7 +768,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("O") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "O" }) },
     },
     {
       event: "on_llm_stream",
@@ -779,7 +781,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("A") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "A" }) },
     },
     {
       event: "on_chain_stream",
@@ -789,7 +791,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("A") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "A" }) },
     },
     {
       event: "on_llm_stream",
@@ -802,7 +804,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_chain_stream",
@@ -812,7 +814,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_llm_end",
@@ -836,7 +838,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
             [
               new ChatGenerationChunk({
                 generationInfo: {},
-                message: new AIMessageChunk("ROAR"),
+                message: new AIMessageChunk({ id: anyString, content: "ROAR" }),
                 text: "ROAR",
               }),
             ],
@@ -853,7 +855,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       data: {
-        output: new AIMessageChunk("ROAR"),
+        output: new AIMessageChunk({ id: anyString, content: "ROAR" }),
       },
     },
   ]);