diff --git a/src/lib/authToken.ts b/src/lib/authToken.ts
index ee0f15c..72bbff5 100644
--- a/src/lib/authToken.ts
+++ b/src/lib/authToken.ts
@@ -49,3 +49,30 @@ export const getAccessToken = async () => {
   }
   return null;
 };
+
+export const getUserId = async () => {
+  const session = await getSession();
+  const sessionUserId = typeof session?.user?.id === "string" ? session.user.id : null;
+  if (sessionUserId) {
+    return sessionUserId;
+  }
+
+  const accessToken = await getAccessToken();
+  if (!accessToken) {
+    return null;
+  }
+
+  const payload = decodeJwtPayload(accessToken);
+  if (!payload || typeof payload !== "object") {
+    return null;
+  }
+
+  const candidate =
+    typeof payload.sub === "string"
+      ? payload.sub
+      : typeof payload.user_id === "string"
+        ? payload.user_id
+        : null;
+
+  return candidate;
+};
diff --git a/src/lib/chatStream.ts b/src/lib/chatStream.ts
index f32a61b..2da5472 100644
--- a/src/lib/chatStream.ts
+++ b/src/lib/chatStream.ts
@@ -99,6 +99,7 @@ export const streamAgentChat = async ({
           session_id: sessionId,
         }),
         projectHeaderMode: "include",
+        userHeaderMode: "include",
         skipAuthRedirect: true,
       },
     );
@@ -229,6 +230,7 @@ export const abortAgentChat = async (sessionId?: string) => {
       session_id: sessionId,
     }),
     projectHeaderMode: "include",
+    userHeaderMode: "include",
     skipAuthRedirect: true,
   });
 
@@ -249,6 +251,7 @@ export const forkAgentChat = async (sessionId: string | undefined, keepMessageCo
       keep_message_count: keepMessageCount,
     }),
     projectHeaderMode: "include",
+    userHeaderMode: "include",
     skipAuthRedirect: true,
   });
 
diff --git a/src/lib/requestHeaders.ts b/src/lib/requestHeaders.ts
index 95e45ac..541ce4d 100644
--- a/src/lib/requestHeaders.ts
+++ b/src/lib/requestHeaders.ts
@@ -1,12 +1,14 @@
-import { getAccessToken } from "@/lib/authToken";
+import { getAccessToken, getUserId } from "@/lib/authToken";
 import { useProjectStore } from "@/store/projectStore";
 
 export type AuthHeaderMode = "include" | "omit";
 export type ProjectHeaderMode = "auto" | "include" | "omit";
+export type UserHeaderMode = "include" | "omit";
 
 export interface AuthContextHeaderOptions {
   authHeaderMode?: AuthHeaderMode;
   projectHeaderMode?: ProjectHeaderMode;
+  userHeaderMode?: UserHeaderMode;
 }
 
 const shouldIncludeProjectHeader = (
@@ -34,6 +36,13 @@ export const applyAuthContextHeaders = async (
     headers.set("Authorization", `Bearer ${accessToken}`);
   }
 
+  if (options.userHeaderMode === "include") {
+    const userId = await getUserId();
+    if (userId) {
+      headers.set("X-User-Id", userId);
+    }
+  }
+
   const projectId = useProjectStore.getState().currentProjectId;
   if (
     projectId &&