diff --git a/backend/internal/handler/gateway_handler_warmup_intercept_unit_test.go b/backend/internal/handler/gateway_handler_warmup_intercept_unit_test.go
new file mode 100644
index 00000000..15d85949
--- /dev/null
+++ b/backend/internal/handler/gateway_handler_warmup_intercept_unit_test.go
@@ -0,0 +1,340 @@
+//go:build unit
+
+package handler
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/config"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ctxkey"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/pagination"
+	middleware "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"
+)
+
+// 目标：严格验证“antigravity 账号通过 /v1/messages 提供 Claude 服务时”，
+// 当账号 credentials.intercept_warmup_requests=true 且请求为 Warmup 时，
+// 后端会在转发上游前直接拦截并返回 mock 响应（不依赖上游）。
+
+type fakeSchedulerCache struct {
+	accounts []*service.Account
+}
+
+func (f *fakeSchedulerCache) GetSnapshot(_ context.Context, _ service.SchedulerBucket) ([]*service.Account, bool, error) {
+	return f.accounts, true, nil
+}
+func (f *fakeSchedulerCache) SetSnapshot(_ context.Context, _ service.SchedulerBucket, _ []service.Account) error {
+	return nil
+}
+func (f *fakeSchedulerCache) GetAccount(_ context.Context, _ int64) (*service.Account, error) {
+	return nil, nil
+}
+func (f *fakeSchedulerCache) SetAccount(_ context.Context, _ *service.Account) error { return nil }
+func (f *fakeSchedulerCache) DeleteAccount(_ context.Context, _ int64) error         { return nil }
+func (f *fakeSchedulerCache) UpdateLastUsed(_ context.Context, _ map[int64]time.Time) error {
+	return nil
+}
+func (f *fakeSchedulerCache) TryLockBucket(_ context.Context, _ service.SchedulerBucket, _ time.Duration) (bool, error) {
+	return true, nil
+}
+func (f *fakeSchedulerCache) ListBuckets(_ context.Context) ([]service.SchedulerBucket, error) {
+	return nil, nil
+}
+func (f *fakeSchedulerCache) GetOutboxWatermark(_ context.Context) (int64, error) { return 0, nil }
+func (f *fakeSchedulerCache) SetOutboxWatermark(_ context.Context, _ int64) error { return nil }
+
+type fakeGroupRepo struct {
+	group *service.Group
+}
+
+func (f *fakeGroupRepo) Create(context.Context, *service.Group) error { return nil }
+func (f *fakeGroupRepo) GetByID(context.Context, int64) (*service.Group, error) {
+	return f.group, nil
+}
+func (f *fakeGroupRepo) GetByIDLite(context.Context, int64) (*service.Group, error) {
+	return f.group, nil
+}
+func (f *fakeGroupRepo) Update(context.Context, *service.Group) error          { return nil }
+func (f *fakeGroupRepo) Delete(context.Context, int64) error                   { return nil }
+func (f *fakeGroupRepo) DeleteCascade(context.Context, int64) ([]int64, error) { return nil, nil }
+func (f *fakeGroupRepo) List(context.Context, pagination.PaginationParams) ([]service.Group, *pagination.PaginationResult, error) {
+	return nil, nil, nil
+}
+func (f *fakeGroupRepo) ListWithFilters(context.Context, pagination.PaginationParams, string, string, string, *bool) ([]service.Group, *pagination.PaginationResult, error) {
+	return nil, nil, nil
+}
+func (f *fakeGroupRepo) ListActive(context.Context) ([]service.Group, error) { return nil, nil }
+func (f *fakeGroupRepo) ListActiveByPlatform(context.Context, string) ([]service.Group, error) {
+	return nil, nil
+}
+func (f *fakeGroupRepo) ExistsByName(context.Context, string) (bool, error)    { return false, nil }
+func (f *fakeGroupRepo) GetAccountCount(context.Context, int64) (int64, error) { return 0, nil }
+func (f *fakeGroupRepo) DeleteAccountGroupsByGroupID(context.Context, int64) (int64, error) {
+	return 0, nil
+}
+func (f *fakeGroupRepo) GetAccountIDsByGroupIDs(context.Context, []int64) ([]int64, error) {
+	return nil, nil
+}
+func (f *fakeGroupRepo) BindAccountsToGroup(context.Context, int64, []int64) error { return nil }
+func (f *fakeGroupRepo) UpdateSortOrders(context.Context, []service.GroupSortOrderUpdate) error {
+	return nil
+}
+
+type fakeConcurrencyCache struct{}
+
+func (f *fakeConcurrencyCache) AcquireAccountSlot(context.Context, int64, int, string) (bool, error) {
+	return true, nil
+}
+func (f *fakeConcurrencyCache) ReleaseAccountSlot(context.Context, int64, string) error { return nil }
+func (f *fakeConcurrencyCache) GetAccountConcurrency(context.Context, int64) (int, error) {
+	return 0, nil
+}
+func (f *fakeConcurrencyCache) IncrementAccountWaitCount(context.Context, int64, int) (bool, error) {
+	return true, nil
+}
+func (f *fakeConcurrencyCache) DecrementAccountWaitCount(context.Context, int64) error { return nil }
+func (f *fakeConcurrencyCache) GetAccountWaitingCount(context.Context, int64) (int, error) {
+	return 0, nil
+}
+func (f *fakeConcurrencyCache) AcquireUserSlot(context.Context, int64, int, string) (bool, error) {
+	return true, nil
+}
+func (f *fakeConcurrencyCache) ReleaseUserSlot(context.Context, int64, string) error   { return nil }
+func (f *fakeConcurrencyCache) GetUserConcurrency(context.Context, int64) (int, error) { return 0, nil }
+func (f *fakeConcurrencyCache) IncrementWaitCount(context.Context, int64, int) (bool, error) {
+	return true, nil
+}
+func (f *fakeConcurrencyCache) DecrementWaitCount(context.Context, int64) error { return nil }
+func (f *fakeConcurrencyCache) GetAccountsLoadBatch(context.Context, []service.AccountWithConcurrency) (map[int64]*service.AccountLoadInfo, error) {
+	return map[int64]*service.AccountLoadInfo{}, nil
+}
+func (f *fakeConcurrencyCache) GetUsersLoadBatch(context.Context, []service.UserWithConcurrency) (map[int64]*service.UserLoadInfo, error) {
+	return map[int64]*service.UserLoadInfo{}, nil
+}
+func (f *fakeConcurrencyCache) CleanupExpiredAccountSlots(context.Context, int64) error { return nil }
+
+func newTestGatewayHandler(t *testing.T, group *service.Group, accounts []*service.Account) (*GatewayHandler, func()) {
+	t.Helper()
+
+	schedulerCache := &fakeSchedulerCache{accounts: accounts}
+	schedulerSnapshot := service.NewSchedulerSnapshotService(schedulerCache, nil, nil, nil, nil)
+
+	gwSvc := service.NewGatewayService(
+		nil, // accountRepo (not used: scheduler snapshot hit)
+		&fakeGroupRepo{group: group},
+		nil, // usageLogRepo
+		nil, // userRepo
+		nil, // userSubRepo
+		nil, // userGroupRateRepo
+		nil, // cache (disable sticky)
+		nil, // cfg
+		schedulerSnapshot,
+		nil, // concurrencyService (disable load-aware; tryAcquire always acquired)
+		nil, // billingService
+		nil, // rateLimitService
+		nil, // billingCacheService
+		nil, // identityService
+		nil, // httpUpstream
+		nil, // deferredService
+		nil, // claudeTokenProvider
+		nil, // sessionLimitCache
+		nil, // digestStore
+	)
+
+	// RunModeSimple：跳过计费检查，避免引入 repo/cache 依赖。
+	cfg := &config.Config{RunMode: config.RunModeSimple}
+	billingCacheSvc := service.NewBillingCacheService(nil, nil, nil, cfg)
+
+	concurrencySvc := service.NewConcurrencyService(&fakeConcurrencyCache{})
+	concurrencyHelper := NewConcurrencyHelper(concurrencySvc, SSEPingFormatClaude, 0)
+
+	h := &GatewayHandler{
+		gatewayService:      gwSvc,
+		billingCacheService: billingCacheSvc,
+		concurrencyHelper:   concurrencyHelper,
+		// 这些字段对本测试不敏感，保持较小即可
+		maxAccountSwitches:       1,
+		maxAccountSwitchesGemini: 1,
+	}
+
+	cleanup := func() {
+		billingCacheSvc.Stop()
+	}
+	return h, cleanup
+}
+
+func TestGatewayHandlerMessages_InterceptWarmup_AntigravityAccount_MixedSchedulingV1(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	groupID := int64(2001)
+	accountID := int64(1001)
+
+	group := &service.Group{
+		ID:       groupID,
+		Hydrated: true,
+		Platform: service.PlatformAnthropic, // /v1/messages（Claude兼容）入口
+		Status:   service.StatusActive,
+	}
+
+	account := &service.Account{
+		ID:       accountID,
+		Name:     "ag-1",
+		Platform: service.PlatformAntigravity,
+		Type:     service.AccountTypeOAuth,
+		Credentials: map[string]any{
+			"access_token":              "tok_xxx",
+			"intercept_warmup_requests": true,
+		},
+		Extra: map[string]any{
+			"mixed_scheduling": true, // 关键：允许被 anthropic 分组混合调度选中
+		},
+		Concurrency:   1,
+		Priority:      1,
+		Status:        service.StatusActive,
+		Schedulable:   true,
+		AccountGroups: []service.AccountGroup{{AccountID: accountID, GroupID: groupID}},
+	}
+
+	h, cleanup := newTestGatewayHandler(t, group, []*service.Account{account})
+	defer cleanup()
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+
+	body := []byte(`{
+		"model": "claude-sonnet-4-5",
+		"max_tokens": 256,
+		"messages": [{"role":"user","content":[{"type":"text","text":"Warmup"}]}]
+	}`)
+	req := httptest.NewRequest("POST", "/v1/messages", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	req = req.WithContext(context.WithValue(req.Context(), ctxkey.Group, group))
+	c.Request = req
+
+	apiKey := &service.APIKey{
+		ID:      3001,
+		UserID:  4001,
+		GroupID: &groupID,
+		Status:  service.StatusActive,
+		User: &service.User{
+			ID:          4001,
+			Concurrency: 10,
+			Balance:     100,
+		},
+		Group: group,
+	}
+
+	c.Set(string(middleware.ContextKeyAPIKey), apiKey)
+	c.Set(string(middleware.ContextKeyUser), middleware.AuthSubject{UserID: apiKey.UserID, Concurrency: 10})
+
+	h.Messages(c)
+
+	require.Equal(t, 200, rec.Code)
+
+	// 断言：确实选中了 antigravity 账号（不是纯函数测试，而是从 Handler 里验证调度结果）
+	selected, ok := c.Get(opsAccountIDKey)
+	require.True(t, ok)
+	require.Equal(t, accountID, selected)
+
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, "msg_mock_warmup", resp["id"])
+	require.Equal(t, "claude-sonnet-4-5", resp["model"])
+
+	content, ok := resp["content"].([]any)
+	require.True(t, ok)
+	require.Len(t, content, 1)
+	first, ok := content[0].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, "New Conversation", first["text"])
+}
+
+func TestGatewayHandlerMessages_InterceptWarmup_AntigravityAccount_ForcePlatform(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	groupID := int64(2002)
+	accountID := int64(1002)
+
+	group := &service.Group{
+		ID:       groupID,
+		Hydrated: true,
+		Platform: service.PlatformAntigravity,
+		Status:   service.StatusActive,
+	}
+
+	account := &service.Account{
+		ID:       accountID,
+		Name:     "ag-2",
+		Platform: service.PlatformAntigravity,
+		Type:     service.AccountTypeOAuth,
+		Credentials: map[string]any{
+			"access_token":              "tok_xxx",
+			"intercept_warmup_requests": true,
+		},
+		Concurrency:   1,
+		Priority:      1,
+		Status:        service.StatusActive,
+		Schedulable:   true,
+		AccountGroups: []service.AccountGroup{{AccountID: accountID, GroupID: groupID}},
+	}
+
+	h, cleanup := newTestGatewayHandler(t, group, []*service.Account{account})
+	defer cleanup()
+
+	rec := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(rec)
+
+	body := []byte(`{
+		"model": "claude-sonnet-4-5",
+		"max_tokens": 256,
+		"messages": [{"role":"user","content":[{"type":"text","text":"Warmup"}]}]
+	}`)
+	req := httptest.NewRequest("POST", "/antigravity/v1/messages", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+
+	// 模拟 routes/gateway.go 里的 ForcePlatform 中间件效果：
+	// - 写入 request.Context（Service读取）
+	// - 写入 gin.Context（Handler快速读取）
+	ctx := context.WithValue(req.Context(), ctxkey.Group, group)
+	ctx = context.WithValue(ctx, ctxkey.ForcePlatform, service.PlatformAntigravity)
+	req = req.WithContext(ctx)
+	c.Request = req
+	c.Set(string(middleware.ContextKeyForcePlatform), service.PlatformAntigravity)
+
+	apiKey := &service.APIKey{
+		ID:      3002,
+		UserID:  4002,
+		GroupID: &groupID,
+		Status:  service.StatusActive,
+		User: &service.User{
+			ID:          4002,
+			Concurrency: 10,
+			Balance:     100,
+		},
+		Group: group,
+	}
+
+	c.Set(string(middleware.ContextKeyAPIKey), apiKey)
+	c.Set(string(middleware.ContextKeyUser), middleware.AuthSubject{UserID: apiKey.UserID, Concurrency: 10})
+
+	h.Messages(c)
+
+	require.Equal(t, 200, rec.Code)
+
+	selected, ok := c.Get(opsAccountIDKey)
+	require.True(t, ok)
+	require.Equal(t, accountID, selected)
+
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, "msg_mock_warmup", resp["id"])
+	require.Equal(t, "claude-sonnet-4-5", resp["model"])
+}