diff --git a/backend/internal/handler/gateway_handler.go b/backend/internal/handler/gateway_handler.go
index 65836a7e..4fe89615 100644
--- a/backend/internal/handler/gateway_handler.go
+++ b/backend/internal/handler/gateway_handler.go
@@ -18,6 +18,7 @@ import (
 	"github.com/Wei-Shaw/sub2api/internal/pkg/claude"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/ctxkey"
 	pkgerrors "github.com/Wei-Shaw/sub2api/internal/pkg/errors"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/geminicli"
 	pkghttputil "github.com/Wei-Shaw/sub2api/internal/pkg/httputil"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/ip"
 	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
@@ -946,8 +947,8 @@ func (h *GatewayHandler) Models(c *gin.Context) {
 		platform = forcedPlatform
 	}
 
-	// Get available models from account configurations (without platform filter)
-	availableModels := h.gatewayService.GetAvailableModels(c.Request.Context(), groupID, "")
+	// Get available models from account configurations for the selected group platform.
+	availableModels := h.gatewayService.GetAvailableModels(c.Request.Context(), groupID, platform)
 
 	if len(availableModels) > 0 {
 		// Build model list from whitelist
@@ -968,7 +969,7 @@ func (h *GatewayHandler) Models(c *gin.Context) {
 	}
 
 	// Fallback to default models
-	if platform == "openai" {
+	if platform == service.PlatformOpenAI {
 		c.JSON(http.StatusOK, gin.H{
 			"object": "list",
 			"data":   openai.DefaultModels,
@@ -976,6 +977,14 @@ func (h *GatewayHandler) Models(c *gin.Context) {
 		return
 	}
 
+	if platform == service.PlatformGemini {
+		c.JSON(http.StatusOK, gin.H{
+			"object": "list",
+			"data":   geminicli.DefaultModels,
+		})
+		return
+	}
+
 	c.JSON(http.StatusOK, gin.H{
 		"object": "list",
 		"data":   claude.DefaultModels,
diff --git a/backend/internal/handler/gateway_models_test.go b/backend/internal/handler/gateway_models_test.go
new file mode 100644
index 00000000..af52ae23
--- /dev/null
+++ b/backend/internal/handler/gateway_models_test.go
@@ -0,0 +1,136 @@
+package handler
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+)
+
+type gatewayModelsAccountRepoStub struct {
+	service.AccountRepository
+
+	byGroup map[int64][]service.Account
+}
+
+type gatewayModelsResponseForTest struct {
+	Object string                    `json:"object"`
+	Data   []gatewayModelItemForTest `json:"data"`
+}
+
+type gatewayModelItemForTest struct {
+	ID string `json:"id"`
+}
+
+func (s *gatewayModelsAccountRepoStub) ListSchedulableByGroupID(ctx context.Context, groupID int64) ([]service.Account, error) {
+	accounts, ok := s.byGroup[groupID]
+	if !ok {
+		return nil, nil
+	}
+	out := make([]service.Account, len(accounts))
+	copy(out, accounts)
+	return out, nil
+}
+
+func newGatewayModelsHandlerForTest(repo service.AccountRepository) *GatewayHandler {
+	return &GatewayHandler{
+		gatewayService: service.NewGatewayService(
+			repo,
+			nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil,
+			nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil,
+		),
+	}
+}
+
+func TestGatewayModels_GeminiGroupFallsBackToGeminiModels(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	groupID := int64(20)
+	h := newGatewayModelsHandlerForTest(
+		&gatewayModelsAccountRepoStub{
+			byGroup: map[int64][]service.Account{
+				groupID: {
+					{ID: 1, Platform: service.PlatformGemini},
+				},
+			},
+		},
+	)
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodGet, "/v1/models", nil)
+	c.Set(string(middleware2.ContextKeyAPIKey), &service.APIKey{
+		Group: &service.Group{ID: groupID, Platform: service.PlatformGemini},
+	})
+
+	h.Models(c)
+
+	require.Equal(t, http.StatusOK, rec.Code)
+
+	var got gatewayModelsResponseForTest
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &got))
+	require.Equal(t, "list", got.Object)
+	require.Contains(t, modelIDsForTest(got.Data), "gemini-2.5-flash")
+	require.NotContains(t, modelIDsForTest(got.Data), "claude-sonnet-4-6")
+}
+
+func TestGatewayModels_GeminiGroupFiltersMappedModelsByPlatform(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	groupID := int64(21)
+	h := newGatewayModelsHandlerForTest(
+		&gatewayModelsAccountRepoStub{
+			byGroup: map[int64][]service.Account{
+				groupID: {
+					{
+						ID:       1,
+						Platform: service.PlatformAnthropic,
+						Credentials: map[string]any{
+							"model_mapping": map[string]any{
+								"claude-sonnet-4-6": "claude-sonnet-4-6",
+							},
+						},
+					},
+					{
+						ID:       2,
+						Platform: service.PlatformGemini,
+						Credentials: map[string]any{
+							"model_mapping": map[string]any{
+								"gemini-2.5-flash": "gemini-2.5-flash",
+							},
+						},
+					},
+				},
+			},
+		},
+	)
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+	c.Request = httptest.NewRequest(http.MethodGet, "/v1/models", nil)
+	c.Set(string(middleware2.ContextKeyAPIKey), &service.APIKey{
+		Group: &service.Group{ID: groupID, Platform: service.PlatformGemini},
+	})
+
+	h.Models(c)
+
+	require.Equal(t, http.StatusOK, rec.Code)
+
+	var got gatewayModelsResponseForTest
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &got))
+	require.Equal(t, []string{"gemini-2.5-flash"}, modelIDsForTest(got.Data))
+}
+
+func modelIDsForTest(models []gatewayModelItemForTest) []string {
+	ids := make([]string, 0, len(models))
+	for _, model := range models {
+		ids = append(ids, model.ID)
+	}
+	return ids
+}