优化聊天框输入聚焦逻辑，增强网络错误处理

src/lib/chatStream.test.ts

@@ -97,4 +97,18 @@ describe("streamCopilotChat", () => {
       { type: "error", message: "Login expired. Please sign in again.", detail: undefined },
     ]);
   });
+
+  it("emits network error when fetch throws", async () => {
+    apiFetch.mockRejectedValue(new TypeError("Failed to fetch"));
+
+    const events: Array<{ type: string; message?: string; detail?: string }> = [];
+    await streamCopilotChat({
+      message: "hi",
+      onEvent: (event) => events.push(event),
+    });
+
+    expect(events).toEqual([
+      { type: "error", message: "network request failed", detail: "Failed to fetch" },
+    ]);
+  });
 });

src/lib/chatStream.ts

@@ -38,19 +38,30 @@ export const streamCopilotChat = async ({
   signal,
   onEvent,
 }: StreamOptions) => {
-  const response = await apiFetch(`${config.BACKEND_URL}/api/v1/copilot/chat/stream`, {
-    method: "POST",
-    signal,
-    headers: {
-      "Content-Type": "application/json",
-      Accept: "text/event-stream",
-    },
-    body: JSON.stringify({
-      message,
-      conversation_id: conversationId,
-    }),
-    skipAuthRedirect: true,
-  });
+  let response: Response;
+  try {
+    response = await apiFetch(`${config.BACKEND_URL}/api/v1/copilot/chat/stream`, {
+      method: "POST",
+      signal,
+      headers: {
+        "Content-Type": "application/json",
+        Accept: "text/event-stream",
+      },
+      body: JSON.stringify({
+        message,
+        conversation_id: conversationId,
+      }),
+      skipAuthRedirect: true,
+    });
+  } catch (error) {
+    const detail = error instanceof Error ? error.message : String(error);
+    onEvent({
+      type: "error",
+      message: "network request failed",
+      detail,
+    });
+    return;
+  }
 
   if (!response.ok || !response.body) {
     const detail = await response.text();