diff --git a/langchain-core/src/language_models/chat_models.ts b/langchain-core/src/language_models/chat_models.ts
index 9239ff52c03b..a80776ff0ba3 100644
--- a/langchain-core/src/language_models/chat_models.ts
+++ b/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,
diff --git a/langchain-core/src/messages/base.ts b/langchain-core/src/messages/base.ts
index 8b74c7f158e1..639fcf226025 100644
--- a/langchain-core/src/messages/base.ts
+++ b/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();
diff --git a/langchain-core/src/runnables/tests/runnable_history.test.ts b/langchain-core/src/runnables/tests/runnable_history.test.ts
index 4efe19047e7a..0614f35c71ce 100644
--- a/langchain-core/src/runnables/tests/runnable_history.test.ts
+++ b/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!!",
+    }),
   ]);
 });
 
diff --git a/langchain-core/src/runnables/tests/runnable_stream_events.test.ts b/langchain-core/src/runnables/tests/runnable_stream_events.test.ts
index e9ab07a36fae..7f6bce337ce8 100644
--- a/langchain-core/src/runnables/tests/runnable_stream_events.test.ts
+++ b/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" }),
       },
     },
   ]);
diff --git a/langchain-core/src/runnables/tests/runnable_stream_events_v2.test.ts b/langchain-core/src/runnables/tests/runnable_stream_events_v2.test.ts
index d1fc1ea7fc65..1702d226aa4b 100644
--- a/langchain-core/src/runnables/tests/runnable_stream_events_v2.test.ts
+++ b/langchain-core/src/runnables/tests/runnable_stream_events_v2.test.ts
@@ -90,6 +90,10 @@ test("Runnable streamEvents method on a chat model", async () => {
   for await (const event of eventStream) {
     events.push(event);
   }
+
+  // used here to avoid casting every ID
+  const anyString = expect.any(String) as unknown as string;
+
   expect(events).toMatchObject([
     {
       data: { input: "hello" },
@@ -100,7 +104,7 @@ test("Runnable streamEvents method on a chat model", async () => {
       tags: [],
     },
     {
-      data: { chunk: new AIMessageChunk({ content: "a" }) },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "a" }) },
       event: "on_chat_model_stream",
       name: "FakeListChatModel",
       metadata: expect.any(Object),
@@ -108,7 +112,7 @@ test("Runnable streamEvents method on a chat model", async () => {
       tags: [],
     },
     {
-      data: { chunk: new AIMessageChunk({ content: "b" }) },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "b" }) },
       event: "on_chat_model_stream",
       name: "FakeListChatModel",
       metadata: expect.any(Object),
@@ -116,7 +120,7 @@ test("Runnable streamEvents method on a chat model", async () => {
       tags: [],
     },
     {
-      data: { chunk: new AIMessageChunk({ content: "c" }) },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "c" }) },
       event: "on_chat_model_stream",
       name: "FakeListChatModel",
       metadata: expect.any(Object),
@@ -124,7 +128,7 @@ test("Runnable streamEvents method on a chat model", async () => {
       tags: [],
     },
     {
-      data: { output: new AIMessageChunk({ content: "abc" }) },
+      data: { output: new AIMessageChunk({ id: anyString, content: "abc" }) },
       event: "on_chat_model_end",
       name: "FakeListChatModel",
       metadata: expect.any(Object),
@@ -748,6 +752,9 @@ test("Runnable streamEvents method with chat model chain", async () => {
   for await (const event of eventStream) {
     events.push(event);
   }
+
+  // used here to avoid casting every ID
+  const anyString = expect.any(String) as unknown as string;
   expect(events).toEqual([
     {
       run_id: expect.any(String),
@@ -816,7 +823,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ content: "R", id: anyString }) },
     },
     {
       event: "on_chain_stream",
@@ -826,7 +833,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ content: "R", id: anyString }) },
     },
     {
       event: "on_chat_model_stream",
@@ -839,7 +846,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("O") },
+      data: { chunk: new AIMessageChunk({ content: "O", id: anyString }) },
     },
     {
       event: "on_chain_stream",
@@ -849,7 +856,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("O") },
+      data: { chunk: new AIMessageChunk({ content: "O", id: anyString }) },
     },
     {
       event: "on_chat_model_stream",
@@ -862,7 +869,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("A") },
+      data: { chunk: new AIMessageChunk({ content: "A", id: anyString }) },
     },
     {
       event: "on_chain_stream",
@@ -872,7 +879,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("A") },
+      data: { chunk: new AIMessageChunk({ content: "A", id: anyString }) },
     },
     {
       event: "on_chat_model_stream",
@@ -885,7 +892,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ content: "R", id: anyString }) },
     },
     {
       event: "on_chain_stream",
@@ -895,7 +902,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ content: "R", id: anyString }) },
     },
     {
       event: "on_chat_model_end",
@@ -914,7 +921,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
             [new SystemMessage("You are Godzilla"), new HumanMessage("hello")],
           ],
         },
-        output: new AIMessageChunk("ROAR"),
+        output: new AIMessageChunk({ content: "ROAR", id: anyString }),
       },
     },
     {
@@ -925,9 +932,7 @@ test("Runnable streamEvents method with chat model chain", async () => {
       metadata: {
         foo: "bar",
       },
-      data: {
-        output: new AIMessageChunk("ROAR"),
-      },
+      data: { output: new AIMessageChunk({ content: "ROAR", id: anyString }) },
     },
   ]);
 });
@@ -965,6 +970,10 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
   for await (const event of eventStream) {
     events.push(event);
   }
+
+  // used here to avoid casting every ID
+  const anyString = expect.any(String) as unknown as string;
+
   expect(events).toEqual([
     {
       run_id: expect.any(String),
@@ -1043,7 +1052,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_chat_model_stream",
@@ -1056,7 +1065,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("O") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "O" }) },
     },
     {
       event: "on_chat_model_stream",
@@ -1069,7 +1078,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("A") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "A" }) },
     },
     {
       event: "on_chat_model_stream",
@@ -1082,7 +1091,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("R") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "R" }) },
     },
     {
       event: "on_chat_model_end",
@@ -1101,7 +1110,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
             [new SystemMessage("You are Godzilla"), new HumanMessage("hello")],
           ],
         },
-        output: new AIMessageChunk("ROAR"),
+        output: new AIMessageChunk({ id: anyString, content: "ROAR" }),
       },
     },
     {
@@ -1112,7 +1121,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         foo: "bar",
       },
       name: "RunnableLambda",
-      data: { chunk: new AIMessageChunk("ROAR") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "ROAR" }) },
     },
     {
       event: "on_chain_stream",
@@ -1122,7 +1131,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessageChunk("ROAR") },
+      data: { chunk: new AIMessageChunk({ id: anyString, content: "ROAR" }) },
     },
     {
       event: "on_chain_end",
@@ -1134,7 +1143,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
       },
       data: {
         input: await template.invoke({ question: "hello" }),
-        output: new AIMessageChunk("ROAR"),
+        output: new AIMessageChunk({ id: anyString, content: "ROAR" }),
       },
     },
     {
@@ -1146,7 +1155,7 @@ test("Chat model that supports streaming, but is invoked, should still emit on_s
         foo: "bar",
       },
       data: {
-        output: new AIMessageChunk("ROAR"),
+        output: new AIMessageChunk({ id: anyString, content: "ROAR" }),
       },
     },
   ]);
@@ -1183,6 +1192,8 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
   for await (const event of eventStream) {
     events.push(event);
   }
+
+  const anyString = expect.any(String) as unknown as string;
   expect(events).toEqual([
     {
       run_id: expect.any(String),
@@ -1261,7 +1272,12 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
         ls_stop: undefined,
       },
       name: "my_model",
-      data: { chunk: new AIMessageChunk("You are Godzilla\nhello") },
+      data: {
+        chunk: new AIMessageChunk({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
+      },
     },
     {
       event: "on_chat_model_end",
@@ -1280,7 +1296,10 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
             [new SystemMessage("You are Godzilla"), new HumanMessage("hello")],
           ],
         },
-        output: new AIMessage("You are Godzilla\nhello"),
+        output: new AIMessage({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
       },
     },
     {
@@ -1291,7 +1310,12 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
         foo: "bar",
       },
       name: "RunnableLambda",
-      data: { chunk: new AIMessage("You are Godzilla\nhello") },
+      data: {
+        chunk: new AIMessage({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
+      },
     },
     {
       event: "on_chain_stream",
@@ -1301,7 +1325,12 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
         foo: "bar",
       },
       name: "my_chain",
-      data: { chunk: new AIMessage("You are Godzilla\nhello") },
+      data: {
+        chunk: new AIMessage({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
+      },
     },
     {
       event: "on_chain_end",
@@ -1313,7 +1342,10 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
       },
       data: {
         input: await template.invoke({ question: "hello" }),
-        output: new AIMessage("You are Godzilla\nhello"),
+        output: new AIMessage({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
       },
     },
     {
@@ -1325,7 +1357,10 @@ test("Chat model that doesn't support streaming, but is invoked, should emit one
         foo: "bar",
       },
       data: {
-        output: new AIMessage("You are Godzilla\nhello"),
+        output: new AIMessage({
+          id: anyString,
+          content: "You are Godzilla\nhello",
+        }),
       },
     },
   ]);
diff --git a/langchain-core/src/tracers/event_stream.ts b/langchain-core/src/tracers/event_stream.ts
index cf9c148c5275..015faa20e5c8 100644
--- a/langchain-core/src/tracers/event_stream.ts
+++ b/langchain-core/src/tracers/event_stream.ts
@@ -370,7 +370,7 @@ export class EventStreamCallbackHandler extends BaseTracer {
     if (runInfo.runType === "chat_model") {
       eventName = "on_chat_model_stream";
       if (kwargs?.chunk === undefined) {
-        chunk = new AIMessageChunk({ content: token });
+        chunk = new AIMessageChunk({ content: token, id: `run-${run.id}` });
       } else {
         chunk = kwargs.chunk.message;
       }
diff --git a/langchain-core/src/tracers/log_stream.ts b/langchain-core/src/tracers/log_stream.ts
index 004a682dec1b..13b97349b04b 100644
--- a/langchain-core/src/tracers/log_stream.ts
+++ b/langchain-core/src/tracers/log_stream.ts
@@ -457,7 +457,10 @@ export class LogStreamCallbackHandler extends BaseTracer {
       if (isChatGenerationChunk(kwargs?.chunk)) {
         streamedOutputValue = kwargs?.chunk;
       } else {
-        streamedOutputValue = new AIMessageChunk(token);
+        streamedOutputValue = new AIMessageChunk({
+          id: `run-${run.id}`,
+          content: token,
+        });
       }
     } else {
       streamedOutputValue = token;