修复局域网连接出错问题

backend/internal/handler/http_test.go

@@ -134,6 +134,46 @@ func TestProtectedRoutesAcceptDeviceCredentialsFromCookies(t *testing.T) {
 	}
 }
 
+func TestRegisterDeviceDerivesNetworkGroupFromClientIP(t *testing.T) {
+	router, _ := newTestRouter()
+
+	alpha := registerDeviceWithRemoteAddr(t, router, map[string]any{
+		"device_id": "alpha",
+		"name":      "Alpha",
+		"type":      "desktop",
+	}, "192.168.1.10:1234")
+	bravo := registerDeviceWithRemoteAddr(t, router, map[string]any{
+		"device_id": "bravo",
+		"name":      "Bravo",
+		"type":      "phone",
+	}, "192.168.1.77:4567")
+	_ = registerDeviceWithRemoteAddr(t, router, map[string]any{
+		"device_id": "charlie",
+		"name":      "Charlie",
+		"type":      "phone",
+	}, "10.0.0.8:9999")
+
+	req := httptest.NewRequest(http.MethodGet, "/api/devices/candidates?deviceId="+alpha.ID, nil)
+	req.Header.Set("X-Device-ID", alpha.ID)
+	req.Header.Set("X-Device-Token", alpha.AuthToken)
+	resp := httptest.NewRecorder()
+	router.ServeHTTP(resp, req)
+
+	if resp.Code != http.StatusOK {
+		t.Fatalf("expected candidates request 200, got %d: %s", resp.Code, resp.Body.String())
+	}
+
+	var payload struct {
+		Data []registeredDevice `json:"data"`
+	}
+	if err := json.Unmarshal(resp.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("decode candidates response: %v", err)
+	}
+	if len(payload.Data) != 1 || payload.Data[0].ID != bravo.ID {
+		t.Fatalf("expected only same-network device %q, got %+v", bravo.ID, payload.Data)
+	}
+}
+
 func newTestRouter() (http.Handler, *store.MemoryStore) {
 	memStore := store.NewMemoryStore(model.RuntimeConfig{})
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
@@ -183,6 +223,33 @@ func registerDevice(t *testing.T, router http.Handler, payload map[string]any) r
 	return payloadWrapper.Data
 }
 
+func registerDeviceWithRemoteAddr(t *testing.T, router http.Handler, payload map[string]any, remoteAddr string) registeredDevice {
+	t.Helper()
+	body, err := json.Marshal(payload)
+	if err != nil {
+		t.Fatalf("marshal register body: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodPost, "/api/devices/register", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req.RemoteAddr = remoteAddr
+	resp := httptest.NewRecorder()
+	router.ServeHTTP(resp, req)
+
+	if resp.Code != http.StatusOK {
+		t.Fatalf("expected register 200, got %d: %s", resp.Code, resp.Body.String())
+	}
+
+	var payloadWrapper struct {
+		Data registeredDevice `json:"data"`
+	}
+	if err := json.Unmarshal(resp.Body.Bytes(), &payloadWrapper); err != nil {
+		t.Fatalf("decode register response: %v", err)
+	}
+
+	return payloadWrapper.Data
+}
+
 func createTransfer(t *testing.T, router http.Handler, device registeredDevice, payload map[string]any) transferRecord {
 	t.Helper()
 	body, err := json.Marshal(payload)