Merge pull request #627 from touwaeriol/pr/bugfixes-and-enhancements

feat: 反重力（Antigravity）增强、Failover 重构及新模型支持

backend/internal/config/config.go

@@ -1158,6 +1158,7 @@ func setDefaults() {
 	viper.SetDefault("gateway.force_codex_cli", false)
 	viper.SetDefault("gateway.openai_passthrough_allow_timeout_headers", false)
 	viper.SetDefault("gateway.antigravity_fallback_cooldown_minutes", 1)
+	viper.SetDefault("gateway.antigravity_extra_retries", 10)
 	viper.SetDefault("gateway.max_body_size", int64(100*1024*1024))
 	viper.SetDefault("gateway.upstream_response_read_max_bytes", int64(8*1024*1024))
 	viper.SetDefault("gateway.proxy_probe_response_read_max_bytes", int64(1024*1024))

backend/internal/domain/constants.go

@@ -74,6 +74,7 @@ var DefaultAntigravityModelMapping = map[string]string{
 	"claude-opus-4-6-thinking":   "claude-opus-4-6-thinking", // 官方模型
 	"claude-opus-4-6":            "claude-opus-4-6-thinking", // 简称映射
 	"claude-opus-4-5-thinking":   "claude-opus-4-6-thinking", // 迁移旧模型
+	"claude-sonnet-4-6":          "claude-sonnet-4-6",
 	"claude-sonnet-4-5":          "claude-sonnet-4-5",
 	"claude-sonnet-4-5-thinking": "claude-sonnet-4-5-thinking",
 	// Claude 详细版本 ID 映射
@@ -89,16 +90,18 @@ var DefaultAntigravityModelMapping = map[string]string{
 	"gemini-2.5-pro":            "gemini-2.5-pro",
 	// Gemini 3 白名单
 	"gemini-3-flash":     "gemini-3-flash",
-	"gemini-3-pro-high":  "gemini-3.1-pro-high",
-	"gemini-3-pro-low":   "gemini-3.1-pro-low",
+	"gemini-3-pro-high":  "gemini-3-pro-high",
+	"gemini-3-pro-low":   "gemini-3-pro-low",
 	"gemini-3-pro-image": "gemini-3-pro-image",
-	// Gemini 3.1 透传
-	"gemini-3.1-pro-high": "gemini-3.1-pro-high",
-	"gemini-3.1-pro-low":  "gemini-3.1-pro-low",
 	// Gemini 3 preview 映射
 	"gemini-3-flash-preview":     "gemini-3-flash",
-	"gemini-3-pro-preview":       "gemini-3.1-pro-high",
+	"gemini-3-pro-preview":       "gemini-3-pro-high",
 	"gemini-3-pro-image-preview": "gemini-3-pro-image",
+	// Gemini 3.1 白名单
+	"gemini-3.1-pro-high": "gemini-3.1-pro-high",
+	"gemini-3.1-pro-low":  "gemini-3.1-pro-low",
+	// Gemini 3.1 preview 映射
+	"gemini-3.1-pro-preview": "gemini-3.1-pro-high",
 	// 其他官方模型
 	"gpt-oss-120b-medium":    "gpt-oss-120b-medium",
 	"tab_flash_lite_preview": "tab_flash_lite_preview",

backend/internal/handler/admin/account_handler.go

@@ -139,6 +139,13 @@ type BulkUpdateAccountsRequest struct {
 	ConfirmMixedChannelRisk *bool          `json:"confirm_mixed_channel_risk"` // 用户确认混合渠道风险
 }
 
+// CheckMixedChannelRequest represents check mixed channel risk request
+type CheckMixedChannelRequest struct {
+	Platform  string  `json:"platform" binding:"required"`
+	GroupIDs  []int64 `json:"group_ids"`
+	AccountID *int64  `json:"account_id"`
+}
+
 // AccountWithConcurrency extends Account with real-time concurrency info
 type AccountWithConcurrency struct {
 	*dto.Account
@@ -389,6 +396,50 @@ func (h *AccountHandler) GetByID(c *gin.Context) {
 	response.Success(c, h.buildAccountResponseWithRuntime(c.Request.Context(), account))
 }
 
+// CheckMixedChannel handles checking mixed channel risk for account-group binding.
+// POST /api/v1/admin/accounts/check-mixed-channel
+func (h *AccountHandler) CheckMixedChannel(c *gin.Context) {
+	var req CheckMixedChannelRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "Invalid request: "+err.Error())
+		return
+	}
+
+	if len(req.GroupIDs) == 0 {
+		response.Success(c, gin.H{"has_risk": false})
+		return
+	}
+
+	accountID := int64(0)
+	if req.AccountID != nil {
+		accountID = *req.AccountID
+	}
+
+	err := h.adminService.CheckMixedChannelRisk(c.Request.Context(), accountID, req.Platform, req.GroupIDs)
+	if err != nil {
+		var mixedErr *service.MixedChannelError
+		if errors.As(err, &mixedErr) {
+			response.Success(c, gin.H{
+				"has_risk": true,
+				"error":    "mixed_channel_warning",
+				"message":  mixedErr.Error(),
+				"details": gin.H{
+					"group_id":         mixedErr.GroupID,
+					"group_name":       mixedErr.GroupName,
+					"current_platform": mixedErr.CurrentPlatform,
+					"other_platform":   mixedErr.OtherPlatform,
+				},
+			})
+			return
+		}
+
+		response.ErrorFrom(c, err)
+		return
+	}
+
+	response.Success(c, gin.H{"has_risk": false})
+}
+
 // Create handles creating a new account
 // POST /api/v1/admin/accounts
 func (h *AccountHandler) Create(c *gin.Context) {
@@ -431,17 +482,10 @@ func (h *AccountHandler) Create(c *gin.Context) {
 		// 检查是否为混合渠道错误
 		var mixedErr *service.MixedChannelError
 		if errors.As(err, &mixedErr) {
-			// 返回特殊错误码要求确认
+			// 创建接口仅返回最小必要字段，详细信息由专门检查接口提供
 			c.JSON(409, gin.H{
 				"error":   "mixed_channel_warning",
 				"message": mixedErr.Error(),
-				"details": gin.H{
-					"group_id":         mixedErr.GroupID,
-					"group_name":       mixedErr.GroupName,
-					"current_platform": mixedErr.CurrentPlatform,
-					"other_platform":   mixedErr.OtherPlatform,
-				},
-				"require_confirmation": true,
 			})
 			return
 		}
@@ -501,17 +545,10 @@ func (h *AccountHandler) Update(c *gin.Context) {
 		// 检查是否为混合渠道错误
 		var mixedErr *service.MixedChannelError
 		if errors.As(err, &mixedErr) {
-			// 返回特殊错误码要求确认
+			// 更新接口仅返回最小必要字段，详细信息由专门检查接口提供
 			c.JSON(409, gin.H{
 				"error":   "mixed_channel_warning",
 				"message": mixedErr.Error(),
-				"details": gin.H{
-					"group_id":         mixedErr.GroupID,
-					"group_name":       mixedErr.GroupName,
-					"current_platform": mixedErr.CurrentPlatform,
-					"other_platform":   mixedErr.OtherPlatform,
-				},
-				"require_confirmation": true,
 			})
 			return
 		}

backend/internal/handler/admin/account_handler_mixed_channel_test.go

+package admin
+
+import (
+	"bytes"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+)
+
+func setupAccountMixedChannelRouter(adminSvc *stubAdminService) *gin.Engine {
+	gin.SetMode(gin.TestMode)
+	router := gin.New()
+	accountHandler := NewAccountHandler(adminSvc, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil)
+	router.POST("/api/v1/admin/accounts/check-mixed-channel", accountHandler.CheckMixedChannel)
+	router.POST("/api/v1/admin/accounts", accountHandler.Create)
+	router.PUT("/api/v1/admin/accounts/:id", accountHandler.Update)
+	return router
+}
+
+func TestAccountHandlerCheckMixedChannelNoRisk(t *testing.T) {
+	adminSvc := newStubAdminService()
+	router := setupAccountMixedChannelRouter(adminSvc)
+
+	body, _ := json.Marshal(map[string]any{
+		"platform":  "antigravity",
+		"group_ids": []int64{27},
+	})
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/admin/accounts/check-mixed-channel", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	router.ServeHTTP(rec, req)
+
+	require.Equal(t, http.StatusOK, rec.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, float64(0), resp["code"])
+	data, ok := resp["data"].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, false, data["has_risk"])
+	require.Equal(t, int64(0), adminSvc.lastMixedCheck.accountID)
+	require.Equal(t, "antigravity", adminSvc.lastMixedCheck.platform)
+	require.Equal(t, []int64{27}, adminSvc.lastMixedCheck.groupIDs)
+}
+
+func TestAccountHandlerCheckMixedChannelWithRisk(t *testing.T) {
+	adminSvc := newStubAdminService()
+	adminSvc.checkMixedErr = &service.MixedChannelError{
+		GroupID:         27,
+		GroupName:       "claude-max",
+		CurrentPlatform: "Antigravity",
+		OtherPlatform:   "Anthropic",
+	}
+	router := setupAccountMixedChannelRouter(adminSvc)
+
+	body, _ := json.Marshal(map[string]any{
+		"platform":   "antigravity",
+		"group_ids":  []int64{27},
+		"account_id": 99,
+	})
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/admin/accounts/check-mixed-channel", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	router.ServeHTTP(rec, req)
+
+	require.Equal(t, http.StatusOK, rec.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, float64(0), resp["code"])
+	data, ok := resp["data"].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, true, data["has_risk"])
+	require.Equal(t, "mixed_channel_warning", data["error"])
+	details, ok := data["details"].(map[string]any)
+	require.True(t, ok)
+	require.Equal(t, float64(27), details["group_id"])
+	require.Equal(t, "claude-max", details["group_name"])
+	require.Equal(t, "Antigravity", details["current_platform"])
+	require.Equal(t, "Anthropic", details["other_platform"])
+	require.Equal(t, int64(99), adminSvc.lastMixedCheck.accountID)
+}
+
+func TestAccountHandlerCreateMixedChannelConflictSimplifiedResponse(t *testing.T) {
+	adminSvc := newStubAdminService()
+	adminSvc.createAccountErr = &service.MixedChannelError{
+		GroupID:         27,
+		GroupName:       "claude-max",
+		CurrentPlatform: "Antigravity",
+		OtherPlatform:   "Anthropic",
+	}
+	router := setupAccountMixedChannelRouter(adminSvc)
+
+	body, _ := json.Marshal(map[string]any{
+		"name":        "ag-oauth-1",
+		"platform":    "antigravity",
+		"type":        "oauth",
+		"credentials": map[string]any{"refresh_token": "rt"},
+		"group_ids":   []int64{27},
+	})
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/admin/accounts", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	router.ServeHTTP(rec, req)
+
+	require.Equal(t, http.StatusConflict, rec.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, "mixed_channel_warning", resp["error"])
+	require.Contains(t, resp["message"], "mixed_channel_warning")
+	_, hasDetails := resp["details"]
+	_, hasRequireConfirmation := resp["require_confirmation"]
+	require.False(t, hasDetails)
+	require.False(t, hasRequireConfirmation)
+}
+
+func TestAccountHandlerUpdateMixedChannelConflictSimplifiedResponse(t *testing.T) {
+	adminSvc := newStubAdminService()
+	adminSvc.updateAccountErr = &service.MixedChannelError{
+		GroupID:         27,
+		GroupName:       "claude-max",
+		CurrentPlatform: "Antigravity",
+		OtherPlatform:   "Anthropic",
+	}
+	router := setupAccountMixedChannelRouter(adminSvc)
+
+	body, _ := json.Marshal(map[string]any{
+		"group_ids": []int64{27},
+	})
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPut, "/api/v1/admin/accounts/3", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	router.ServeHTTP(rec, req)
+
+	require.Equal(t, http.StatusConflict, rec.Code)
+	var resp map[string]any
+	require.NoError(t, json.Unmarshal(rec.Body.Bytes(), &resp))
+	require.Equal(t, "mixed_channel_warning", resp["error"])
+	require.Contains(t, resp["message"], "mixed_channel_warning")
+	_, hasDetails := resp["details"]
+	_, hasRequireConfirmation := resp["require_confirmation"]
+	require.False(t, hasDetails)
+	require.False(t, hasRequireConfirmation)
+}

backend/internal/handler/admin/admin_service_stub_test.go

@@ -10,19 +10,27 @@ import (
 )
 
 type stubAdminService struct {
-	users           []service.User
-	apiKeys         []service.APIKey
-	groups          []service.Group
-	accounts        []service.Account
-	proxies         []service.Proxy
-	proxyCounts     []service.ProxyWithAccountCount
-	redeems         []service.RedeemCode
-	createdAccounts []*service.CreateAccountInput
-	createdProxies  []*service.CreateProxyInput
-	updatedProxyIDs []int64
-	updatedProxies  []*service.UpdateProxyInput
-	testedProxyIDs  []int64
-	mu              sync.Mutex
+	users            []service.User
+	apiKeys          []service.APIKey
+	groups           []service.Group
+	accounts         []service.Account
+	proxies          []service.Proxy
+	proxyCounts      []service.ProxyWithAccountCount
+	redeems          []service.RedeemCode
+	createdAccounts  []*service.CreateAccountInput
+	createdProxies   []*service.CreateProxyInput
+	updatedProxyIDs  []int64
+	updatedProxies   []*service.UpdateProxyInput
+	testedProxyIDs   []int64
+	createAccountErr error
+	updateAccountErr error
+	checkMixedErr    error
+	lastMixedCheck   struct {
+		accountID int64
+		platform  string
+		groupIDs  []int64
+	}
+	mu sync.Mutex
 }
 
 func newStubAdminService() *stubAdminService {
@@ -188,11 +196,17 @@ func (s *stubAdminService) CreateAccount(ctx context.Context, input *service.Cre
 	s.mu.Lock()
 	s.createdAccounts = append(s.createdAccounts, input)
 	s.mu.Unlock()
+	if s.createAccountErr != nil {
+		return nil, s.createAccountErr
+	}
 	account := service.Account{ID: 300, Name: input.Name, Status: service.StatusActive}
 	return &account, nil
 }
 
 func (s *stubAdminService) UpdateAccount(ctx context.Context, id int64, input *service.UpdateAccountInput) (*service.Account, error) {
+	if s.updateAccountErr != nil {
+		return nil, s.updateAccountErr
+	}
 	account := service.Account{ID: id, Name: input.Name, Status: service.StatusActive}
 	return &account, nil
 }
@@ -224,6 +238,13 @@ func (s *stubAdminService) BulkUpdateAccounts(ctx context.Context, input *servic
 	return &service.BulkUpdateAccountsResult{Success: 1, Failed: 0, SuccessIDs: []int64{1}}, nil
 }
 
+func (s *stubAdminService) CheckMixedChannelRisk(ctx context.Context, currentAccountID int64, currentAccountPlatform string, groupIDs []int64) error {
+	s.lastMixedCheck.accountID = currentAccountID
+	s.lastMixedCheck.platform = currentAccountPlatform
+	s.lastMixedCheck.groupIDs = append([]int64(nil), groupIDs...)
+	return s.checkMixedErr
+}
+
 func (s *stubAdminService) ListProxies(ctx context.Context, page, pageSize int, protocol, status, search string) ([]service.Proxy, int64, error) {
 	search = strings.TrimSpace(strings.ToLower(search))
 	filtered := make([]service.Proxy, 0, len(s.proxies))

backend/internal/handler/failover_loop.go

+package handler
+
+import (
+	"context"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+)
+
+// TempUnscheduler 用于 HandleFailoverError 中同账号重试耗尽后的临时封禁。
+// GatewayService 隐式实现此接口。
+type TempUnscheduler interface {
+	TempUnscheduleRetryableError(ctx context.Context, accountID int64, failoverErr *service.UpstreamFailoverError)
+}
+
+// FailoverAction 表示 failover 错误处理后的下一步动作
+type FailoverAction int
+
+const (
+	// FailoverContinue 继续循环（同账号重试或切换账号，调用方统一 continue）
+	FailoverContinue FailoverAction = iota
+	// FailoverExhausted 切换次数耗尽（调用方应返回错误响应）
+	FailoverExhausted
+	// FailoverCanceled context 已取消（调用方应直接 return）
+	FailoverCanceled
+)
+
+const (
+	// maxSameAccountRetries 同账号重试次数上限（针对 RetryableOnSameAccount 错误）
+	maxSameAccountRetries = 2
+	// sameAccountRetryDelay 同账号重试间隔
+	sameAccountRetryDelay = 500 * time.Millisecond
+	// singleAccountBackoffDelay 单账号分组 503 退避重试固定延时。
+	// Service 层在 SingleAccountRetry 模式下已做充分原地重试（最多 3 次、总等待 30s），
+	// Handler 层只需短暂间隔后重新进入 Service 层即可。
+	singleAccountBackoffDelay = 2 * time.Second
+)
+
+// FailoverState 跨循环迭代共享的 failover 状态
+type FailoverState struct {
+	SwitchCount           int
+	MaxSwitches           int
+	FailedAccountIDs      map[int64]struct{}
+	SameAccountRetryCount map[int64]int
+	LastFailoverErr       *service.UpstreamFailoverError
+	ForceCacheBilling     bool
+	hasBoundSession       bool
+}
+
+// NewFailoverState 创建 failover 状态
+func NewFailoverState(maxSwitches int, hasBoundSession bool) *FailoverState {
+	return &FailoverState{
+		MaxSwitches:           maxSwitches,
+		FailedAccountIDs:      make(map[int64]struct{}),
+		SameAccountRetryCount: make(map[int64]int),
+		hasBoundSession:       hasBoundSession,
+	}
+}
+
+// HandleFailoverError 处理 UpstreamFailoverError，返回下一步动作。
+// 包含：缓存计费判断、同账号重试、临时封禁、切换计数、Antigravity 延时。
+func (s *FailoverState) HandleFailoverError(
+	ctx context.Context,
+	gatewayService TempUnscheduler,
+	accountID int64,
+	platform string,
+	failoverErr *service.UpstreamFailoverError,
+) FailoverAction {
+	s.LastFailoverErr = failoverErr
+
+	// 缓存计费判断
+	if needForceCacheBilling(s.hasBoundSession, failoverErr) {
+		s.ForceCacheBilling = true
+	}
+
+	// 同账号重试：对 RetryableOnSameAccount 的临时性错误，先在同一账号上重试
+	if failoverErr.RetryableOnSameAccount && s.SameAccountRetryCount[accountID] < maxSameAccountRetries {
+		s.SameAccountRetryCount[accountID]++
+		log.Printf("Account %d: retryable error %d, same-account retry %d/%d",
+			accountID, failoverErr.StatusCode, s.SameAccountRetryCount[accountID], maxSameAccountRetries)
+		if !sleepWithContext(ctx, sameAccountRetryDelay) {
+			return FailoverCanceled
+		}
+		return FailoverContinue
+	}
+
+	// 同账号重试用尽，执行临时封禁
+	if failoverErr.RetryableOnSameAccount {
+		gatewayService.TempUnscheduleRetryableError(ctx, accountID, failoverErr)
+	}
+
+	// 加入失败列表
+	s.FailedAccountIDs[accountID] = struct{}{}
+
+	// 检查是否耗尽
+	if s.SwitchCount >= s.MaxSwitches {
+		return FailoverExhausted
+	}
+
+	// 递增切换计数
+	s.SwitchCount++
+	log.Printf("Account %d: upstream error %d, switching account %d/%d",
+		accountID, failoverErr.StatusCode, s.SwitchCount, s.MaxSwitches)
+
+	// Antigravity 平台换号线性递增延时
+	if platform == service.PlatformAntigravity {
+		delay := time.Duration(s.SwitchCount-1) * time.Second
+		if !sleepWithContext(ctx, delay) {
+			return FailoverCanceled
+		}
+	}
+
+	return FailoverContinue
+}
+
+// HandleSelectionExhausted 处理选号失败（所有候选账号都在排除列表中）时的退避重试决策。
+// 针对 Antigravity 单账号分组的 503 (MODEL_CAPACITY_EXHAUSTED) 场景：
+// 清除排除列表、等待退避后重新选号。
+//
+// 返回 FailoverContinue 时，调用方应设置 SingleAccountRetry context 并 continue。
+// 返回 FailoverExhausted 时，调用方应返回错误响应。
+// 返回 FailoverCanceled 时，调用方应直接 return。
+func (s *FailoverState) HandleSelectionExhausted(ctx context.Context) FailoverAction {
+	if s.LastFailoverErr != nil &&
+		s.LastFailoverErr.StatusCode == http.StatusServiceUnavailable &&
+		s.SwitchCount <= s.MaxSwitches {
+
+		log.Printf("Antigravity single-account 503 backoff: waiting %v before retry (attempt %d)",
+			singleAccountBackoffDelay, s.SwitchCount)
+		if !sleepWithContext(ctx, singleAccountBackoffDelay) {
+			return FailoverCanceled
+		}
+		log.Printf("Antigravity single-account 503 retry: clearing failed accounts, retry %d/%d",
+			s.SwitchCount, s.MaxSwitches)
+		s.FailedAccountIDs = make(map[int64]struct{})
+		return FailoverContinue
+	}
+	return FailoverExhausted
+}
+
+// needForceCacheBilling 判断 failover 时是否需要强制缓存计费。
+// 粘性会话切换账号、或上游明确标记时，将 input_tokens 转为 cache_read 计费。
+func needForceCacheBilling(hasBoundSession bool, failoverErr *service.UpstreamFailoverError) bool {
+	return hasBoundSession || (failoverErr != nil && failoverErr.ForceCacheBilling)
+}
+
+// sleepWithContext 等待指定时长，返回 false 表示 context 已取消。
+func sleepWithContext(ctx context.Context, d time.Duration) bool {
+	if d <= 0 {
+		return true
+	}
+	select {
+	case <-ctx.Done():
+		return false
+	case <-time.After(d):
+		return true
+	}
+}

backend/internal/handler/failover_loop_test.go

+package handler
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+
+	"github.com/stretchr/testify/require"
+)
+
+// ---------------------------------------------------------------------------
+// Mock
+// ---------------------------------------------------------------------------
+
+// mockTempUnscheduler 记录 TempUnscheduleRetryableError 的调用信息。
+type mockTempUnscheduler struct {
+	calls []tempUnscheduleCall
+}
+
+type tempUnscheduleCall struct {
+	accountID   int64
+	failoverErr *service.UpstreamFailoverError
+}
+
+func (m *mockTempUnscheduler) TempUnscheduleRetryableError(_ context.Context, accountID int64, failoverErr *service.UpstreamFailoverError) {
+	m.calls = append(m.calls, tempUnscheduleCall{accountID: accountID, failoverErr: failoverErr})
+}
+
+// ---------------------------------------------------------------------------
+// Helper
+// ---------------------------------------------------------------------------
+
+func newTestFailoverErr(statusCode int, retryable, forceBilling bool) *service.UpstreamFailoverError {
+	return &service.UpstreamFailoverError{
+		StatusCode:             statusCode,
+		RetryableOnSameAccount: retryable,
+		ForceCacheBilling:      forceBilling,
+	}
+}
+
+// ---------------------------------------------------------------------------
+// NewFailoverState 测试
+// ---------------------------------------------------------------------------
+
+func TestNewFailoverState(t *testing.T) {
+	t.Run("初始化字段正确", func(t *testing.T) {
+		fs := NewFailoverState(5, true)
+		require.Equal(t, 5, fs.MaxSwitches)
+		require.Equal(t, 0, fs.SwitchCount)
+		require.NotNil(t, fs.FailedAccountIDs)
+		require.Empty(t, fs.FailedAccountIDs)
+		require.NotNil(t, fs.SameAccountRetryCount)
+		require.Empty(t, fs.SameAccountRetryCount)
+		require.Nil(t, fs.LastFailoverErr)
+		require.False(t, fs.ForceCacheBilling)
+		require.True(t, fs.hasBoundSession)
+	})
+
+	t.Run("无绑定会话", func(t *testing.T) {
+		fs := NewFailoverState(3, false)
+		require.Equal(t, 3, fs.MaxSwitches)
+		require.False(t, fs.hasBoundSession)
+	})
+
+	t.Run("零最大切换次数", func(t *testing.T) {
+		fs := NewFailoverState(0, false)
+		require.Equal(t, 0, fs.MaxSwitches)
+	})
+}
+
+// ---------------------------------------------------------------------------
+// sleepWithContext 测试
+// ---------------------------------------------------------------------------
+
+func TestSleepWithContext(t *testing.T) {
+	t.Run("零时长立即返回true", func(t *testing.T) {
+		start := time.Now()
+		ok := sleepWithContext(context.Background(), 0)
+		require.True(t, ok)
+		require.Less(t, time.Since(start), 50*time.Millisecond)
+	})
+
+	t.Run("负时长立即返回true", func(t *testing.T) {
+		start := time.Now()
+		ok := sleepWithContext(context.Background(), -1*time.Second)
+		require.True(t, ok)
+		require.Less(t, time.Since(start), 50*time.Millisecond)
+	})
+
+	t.Run("正常等待后返回true", func(t *testing.T) {
+		start := time.Now()
+		ok := sleepWithContext(context.Background(), 50*time.Millisecond)
+		elapsed := time.Since(start)
+		require.True(t, ok)
+		require.GreaterOrEqual(t, elapsed, 40*time.Millisecond)
+		require.Less(t, elapsed, 500*time.Millisecond)
+	})
+
+	t.Run("已取消context立即返回false", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+
+		start := time.Now()
+		ok := sleepWithContext(ctx, 5*time.Second)
+		require.False(t, ok)
+		require.Less(t, time.Since(start), 50*time.Millisecond)
+	})
+
+	t.Run("等待期间context取消返回false", func(t *testing.T) {
+		ctx, cancel := context.WithCancel(context.Background())
+		go func() {
+			time.Sleep(30 * time.Millisecond)
+			cancel()
+		}()
+
+		start := time.Now()
+		ok := sleepWithContext(ctx, 5*time.Second)
+		elapsed := time.Since(start)
+		require.False(t, ok)
+		require.Less(t, elapsed, 500*time.Millisecond)
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — 基本切换流程
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_BasicSwitch(t *testing.T) {
+	t.Run("非重试错误_非Antigravity_直接切换", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, false, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SwitchCount)
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+		require.Equal(t, err, fs.LastFailoverErr)
+		require.False(t, fs.ForceCacheBilling)
+		require.Empty(t, mock.calls, "不应调用 TempUnschedule")
+	})
+
+	t.Run("非重试错误_Antigravity_第一次切换无延迟", func(t *testing.T) {
+		// switchCount 从 0→1 时，sleepFailoverDelay(ctx, 1) 的延时 = (1-1)*1s = 0
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, false, false)
+
+		start := time.Now()
+		action := fs.HandleFailoverError(context.Background(), mock, 100, service.PlatformAntigravity, err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SwitchCount)
+		require.Less(t, elapsed, 200*time.Millisecond, "第一次切换延迟应为 0")
+	})
+
+	t.Run("非重试错误_Antigravity_第二次切换有1秒延迟", func(t *testing.T) {
+		// switchCount 从 1→2 时，sleepFailoverDelay(ctx, 2) 的延时 = (2-1)*1s = 1s
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		fs.SwitchCount = 1 // 模拟已切换一次
+
+		err := newTestFailoverErr(500, false, false)
+		start := time.Now()
+		action := fs.HandleFailoverError(context.Background(), mock, 200, service.PlatformAntigravity, err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 2, fs.SwitchCount)
+		require.GreaterOrEqual(t, elapsed, 800*time.Millisecond, "第二次切换延迟应约 1s")
+		require.Less(t, elapsed, 3*time.Second)
+	})
+
+	t.Run("连续切换直到耗尽", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(2, false)
+
+		// 第一次切换：0→1
+		err1 := newTestFailoverErr(500, false, false)
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err1)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SwitchCount)
+
+		// 第二次切换：1→2
+		err2 := newTestFailoverErr(502, false, false)
+		action = fs.HandleFailoverError(context.Background(), mock, 200, "openai", err2)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 2, fs.SwitchCount)
+
+		// 第三次已耗尽：SwitchCount(2) >= MaxSwitches(2)
+		err3 := newTestFailoverErr(503, false, false)
+		action = fs.HandleFailoverError(context.Background(), mock, 300, "openai", err3)
+		require.Equal(t, FailoverExhausted, action)
+		require.Equal(t, 2, fs.SwitchCount, "耗尽时不应继续递增")
+
+		// 验证失败账号列表
+		require.Len(t, fs.FailedAccountIDs, 3)
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+		require.Contains(t, fs.FailedAccountIDs, int64(200))
+		require.Contains(t, fs.FailedAccountIDs, int64(300))
+
+		// LastFailoverErr 应为最后一次的错误
+		require.Equal(t, err3, fs.LastFailoverErr)
+	})
+
+	t.Run("MaxSwitches为0时首次即耗尽", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(0, false)
+		err := newTestFailoverErr(500, false, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverExhausted, action)
+		require.Equal(t, 0, fs.SwitchCount)
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — 缓存计费 (ForceCacheBilling)
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_CacheBilling(t *testing.T) {
+	t.Run("hasBoundSession为true时设置ForceCacheBilling", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, true) // hasBoundSession=true
+		err := newTestFailoverErr(500, false, false)
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.True(t, fs.ForceCacheBilling)
+	})
+
+	t.Run("failoverErr.ForceCacheBilling为true时设置", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, false, true) // ForceCacheBilling=true
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.True(t, fs.ForceCacheBilling)
+	})
+
+	t.Run("两者均为false时不设置", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, false, false)
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.False(t, fs.ForceCacheBilling)
+	})
+
+	t.Run("一旦设置不会被后续错误重置", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+
+		// 第一次：ForceCacheBilling=true → 设置
+		err1 := newTestFailoverErr(500, false, true)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err1)
+		require.True(t, fs.ForceCacheBilling)
+
+		// 第二次：ForceCacheBilling=false → 仍然保持 true
+		err2 := newTestFailoverErr(502, false, false)
+		fs.HandleFailoverError(context.Background(), mock, 200, "openai", err2)
+		require.True(t, fs.ForceCacheBilling, "ForceCacheBilling 一旦设置不应被重置")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — 同账号重试 (RetryableOnSameAccount)
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_SameAccountRetry(t *testing.T) {
+	t.Run("第一次重试返回FailoverContinue", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(400, true, false)
+
+		start := time.Now()
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[100])
+		require.Equal(t, 0, fs.SwitchCount, "同账号重试不应增加切换计数")
+		require.NotContains(t, fs.FailedAccountIDs, int64(100), "同账号重试不应加入失败列表")
+		require.Empty(t, mock.calls, "同账号重试期间不应调用 TempUnschedule")
+		// 验证等待了 sameAccountRetryDelay (500ms)
+		require.GreaterOrEqual(t, elapsed, 400*time.Millisecond)
+		require.Less(t, elapsed, 2*time.Second)
+	})
+
+	t.Run("第二次重试仍返回FailoverContinue", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(400, true, false)
+
+		// 第一次
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[100])
+
+		// 第二次
+		action = fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 2, fs.SameAccountRetryCount[100])
+
+		require.Empty(t, mock.calls, "两次重试期间均不应调用 TempUnschedule")
+	})
+
+	t.Run("第三次重试耗尽_触发TempUnschedule并切换", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(400, true, false)
+
+		// 第一次、第二次重试
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, 2, fs.SameAccountRetryCount[100])
+
+		// 第三次：重试已达到 maxSameAccountRetries(2)，应切换账号
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SwitchCount)
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+
+		// 验证 TempUnschedule 被调用
+		require.Len(t, mock.calls, 1)
+		require.Equal(t, int64(100), mock.calls[0].accountID)
+		require.Equal(t, err, mock.calls[0].failoverErr)
+	})
+
+	t.Run("不同账号独立跟踪重试次数", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(5, false)
+		err := newTestFailoverErr(400, true, false)
+
+		// 账号 100 第一次重试
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[100])
+
+		// 账号 200 第一次重试（独立计数）
+		action = fs.HandleFailoverError(context.Background(), mock, 200, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[200])
+		require.Equal(t, 1, fs.SameAccountRetryCount[100], "账号 100 的计数不应受影响")
+	})
+
+	t.Run("重试耗尽后再次遇到同账号_直接切换", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(5, false)
+		err := newTestFailoverErr(400, true, false)
+
+		// 耗尽账号 100 的重试
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		// 第三次: 重试耗尽 → 切换
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+
+		// 再次遇到账号 100，计数仍为 2，条件不满足 → 直接切换
+		action = fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Len(t, mock.calls, 2, "第二次耗尽也应调用 TempUnschedule")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — TempUnschedule 调用验证
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_TempUnschedule(t *testing.T) {
+	t.Run("非重试错误不调用TempUnschedule", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, false, false) // RetryableOnSameAccount=false
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Empty(t, mock.calls)
+	})
+
+	t.Run("重试错误耗尽后调用TempUnschedule_传入正确参数", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(502, true, false)
+
+		// 耗尽重试
+		fs.HandleFailoverError(context.Background(), mock, 42, "openai", err)
+		fs.HandleFailoverError(context.Background(), mock, 42, "openai", err)
+		fs.HandleFailoverError(context.Background(), mock, 42, "openai", err)
+
+		require.Len(t, mock.calls, 1)
+		require.Equal(t, int64(42), mock.calls[0].accountID)
+		require.Equal(t, 502, mock.calls[0].failoverErr.StatusCode)
+		require.True(t, mock.calls[0].failoverErr.RetryableOnSameAccount)
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — Context 取消
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_ContextCanceled(t *testing.T) {
+	t.Run("同账号重试sleep期间context取消", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(400, true, false)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel() // 立即取消
+
+		start := time.Now()
+		action := fs.HandleFailoverError(ctx, mock, 100, "openai", err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverCanceled, action)
+		require.Less(t, elapsed, 100*time.Millisecond, "应立即返回")
+		// 重试计数仍应递增
+		require.Equal(t, 1, fs.SameAccountRetryCount[100])
+	})
+
+	t.Run("Antigravity延迟期间context取消", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		fs.SwitchCount = 1 // 下一次 switchCount=2 → delay = 1s
+		err := newTestFailoverErr(500, false, false)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel() // 立即取消
+
+		start := time.Now()
+		action := fs.HandleFailoverError(ctx, mock, 100, service.PlatformAntigravity, err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverCanceled, action)
+		require.Less(t, elapsed, 100*time.Millisecond, "应立即返回而非等待 1s")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — FailedAccountIDs 跟踪
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_FailedAccountIDs(t *testing.T) {
+	t.Run("切换时添加到失败列表", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", newTestFailoverErr(500, false, false))
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+
+		fs.HandleFailoverError(context.Background(), mock, 200, "openai", newTestFailoverErr(502, false, false))
+		require.Contains(t, fs.FailedAccountIDs, int64(200))
+		require.Len(t, fs.FailedAccountIDs, 2)
+	})
+
+	t.Run("耗尽时也添加到失败列表", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(0, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", newTestFailoverErr(500, false, false))
+		require.Equal(t, FailoverExhausted, action)
+		require.Contains(t, fs.FailedAccountIDs, int64(100))
+	})
+
+	t.Run("同账号重试期间不添加到失败列表", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", newTestFailoverErr(400, true, false))
+		require.Equal(t, FailoverContinue, action)
+		require.NotContains(t, fs.FailedAccountIDs, int64(100))
+	})
+
+	t.Run("同一账号多次切换不重复添加", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(5, false)
+
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", newTestFailoverErr(500, false, false))
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", newTestFailoverErr(500, false, false))
+		require.Len(t, fs.FailedAccountIDs, 1, "map 天然去重")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — LastFailoverErr 更新
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_LastFailoverErr(t *testing.T) {
+	t.Run("每次调用都更新LastFailoverErr", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+
+		err1 := newTestFailoverErr(500, false, false)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err1)
+		require.Equal(t, err1, fs.LastFailoverErr)
+
+		err2 := newTestFailoverErr(502, false, false)
+		fs.HandleFailoverError(context.Background(), mock, 200, "openai", err2)
+		require.Equal(t, err2, fs.LastFailoverErr)
+	})
+
+	t.Run("同账号重试时也更新LastFailoverErr", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+
+		err := newTestFailoverErr(400, true, false)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, err, fs.LastFailoverErr)
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — 综合集成场景
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_IntegrationScenario(t *testing.T) {
+	t.Run("模拟完整failover流程_多账号混合重试与切换", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, true) // hasBoundSession=true
+
+		// 1. 账号 100 遇到可重试错误，同账号重试 2 次
+		retryErr := newTestFailoverErr(400, true, false)
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", retryErr)
+		require.Equal(t, FailoverContinue, action)
+		require.True(t, fs.ForceCacheBilling, "hasBoundSession=true 应设置 ForceCacheBilling")
+
+		action = fs.HandleFailoverError(context.Background(), mock, 100, "openai", retryErr)
+		require.Equal(t, FailoverContinue, action)
+
+		// 2. 账号 100 重试耗尽 → TempUnschedule + 切换
+		action = fs.HandleFailoverError(context.Background(), mock, 100, "openai", retryErr)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SwitchCount)
+		require.Len(t, mock.calls, 1)
+
+		// 3. 账号 200 遇到不可重试错误 → 直接切换
+		switchErr := newTestFailoverErr(500, false, false)
+		action = fs.HandleFailoverError(context.Background(), mock, 200, "openai", switchErr)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 2, fs.SwitchCount)
+
+		// 4. 账号 300 遇到不可重试错误 → 再切换
+		action = fs.HandleFailoverError(context.Background(), mock, 300, "openai", switchErr)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 3, fs.SwitchCount)
+
+		// 5. 账号 400 → 已耗尽 (SwitchCount=3 >= MaxSwitches=3)
+		action = fs.HandleFailoverError(context.Background(), mock, 400, "openai", switchErr)
+		require.Equal(t, FailoverExhausted, action)
+
+		// 最终状态验证
+		require.Equal(t, 3, fs.SwitchCount, "耗尽时不再递增")
+		require.Len(t, fs.FailedAccountIDs, 4, "4个不同账号都在失败列表中")
+		require.True(t, fs.ForceCacheBilling)
+		require.Len(t, mock.calls, 1, "只有账号 100 触发了 TempUnschedule")
+	})
+
+	t.Run("模拟Antigravity平台完整流程", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(2, false)
+
+		err := newTestFailoverErr(500, false, false)
+
+		// 第一次切换：delay = 0s
+		start := time.Now()
+		action := fs.HandleFailoverError(context.Background(), mock, 100, service.PlatformAntigravity, err)
+		elapsed := time.Since(start)
+		require.Equal(t, FailoverContinue, action)
+		require.Less(t, elapsed, 200*time.Millisecond, "第一次切换延迟为 0")
+
+		// 第二次切换：delay = 1s
+		start = time.Now()
+		action = fs.HandleFailoverError(context.Background(), mock, 200, service.PlatformAntigravity, err)
+		elapsed = time.Since(start)
+		require.Equal(t, FailoverContinue, action)
+		require.GreaterOrEqual(t, elapsed, 800*time.Millisecond, "第二次切换延迟约 1s")
+
+		// 第三次：耗尽（无延迟，因为在检查延迟之前就返回了）
+		start = time.Now()
+		action = fs.HandleFailoverError(context.Background(), mock, 300, service.PlatformAntigravity, err)
+		elapsed = time.Since(start)
+		require.Equal(t, FailoverExhausted, action)
+		require.Less(t, elapsed, 200*time.Millisecond, "耗尽时不应有延迟")
+	})
+
+	t.Run("ForceCacheBilling通过错误标志设置", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false) // hasBoundSession=false
+
+		// 第一次：ForceCacheBilling=false
+		err1 := newTestFailoverErr(500, false, false)
+		fs.HandleFailoverError(context.Background(), mock, 100, "openai", err1)
+		require.False(t, fs.ForceCacheBilling)
+
+		// 第二次：ForceCacheBilling=true（Antigravity 粘性会话切换）
+		err2 := newTestFailoverErr(500, false, true)
+		fs.HandleFailoverError(context.Background(), mock, 200, "openai", err2)
+		require.True(t, fs.ForceCacheBilling, "错误标志应触发 ForceCacheBilling")
+
+		// 第三次：ForceCacheBilling=false，但状态仍保持 true
+		err3 := newTestFailoverErr(500, false, false)
+		fs.HandleFailoverError(context.Background(), mock, 300, "openai", err3)
+		require.True(t, fs.ForceCacheBilling, "不应重置")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleFailoverError — 边界条件
+// ---------------------------------------------------------------------------
+
+func TestHandleFailoverError_EdgeCases(t *testing.T) {
+	t.Run("StatusCode为0的错误也能正常处理", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(0, false, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+	})
+
+	t.Run("AccountID为0也能正常跟踪", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, true, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, 0, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[0])
+	})
+
+	t.Run("负AccountID也能正常跟踪", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		err := newTestFailoverErr(500, true, false)
+
+		action := fs.HandleFailoverError(context.Background(), mock, -1, "openai", err)
+		require.Equal(t, FailoverContinue, action)
+		require.Equal(t, 1, fs.SameAccountRetryCount[-1])
+	})
+
+	t.Run("空平台名称不触发Antigravity延迟", func(t *testing.T) {
+		mock := &mockTempUnscheduler{}
+		fs := NewFailoverState(3, false)
+		fs.SwitchCount = 1
+		err := newTestFailoverErr(500, false, false)
+
+		start := time.Now()
+		action := fs.HandleFailoverError(context.Background(), mock, 100, "", err)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Less(t, elapsed, 200*time.Millisecond, "空平台不应触发 Antigravity 延迟")
+	})
+}
+
+// ---------------------------------------------------------------------------
+// HandleSelectionExhausted 测试
+// ---------------------------------------------------------------------------
+
+func TestHandleSelectionExhausted(t *testing.T) {
+	t.Run("无LastFailoverErr时返回Exhausted", func(t *testing.T) {
+		fs := NewFailoverState(3, false)
+		// LastFailoverErr 为 nil
+
+		action := fs.HandleSelectionExhausted(context.Background())
+		require.Equal(t, FailoverExhausted, action)
+	})
+
+	t.Run("非503错误返回Exhausted", func(t *testing.T) {
+		fs := NewFailoverState(3, false)
+		fs.LastFailoverErr = newTestFailoverErr(500, false, false)
+
+		action := fs.HandleSelectionExhausted(context.Background())
+		require.Equal(t, FailoverExhausted, action)
+	})
+
+	t.Run("503且未耗尽_等待后返回Continue并清除失败列表", func(t *testing.T) {
+		fs := NewFailoverState(3, false)
+		fs.LastFailoverErr = newTestFailoverErr(503, false, false)
+		fs.FailedAccountIDs[100] = struct{}{}
+		fs.SwitchCount = 1
+
+		start := time.Now()
+		action := fs.HandleSelectionExhausted(context.Background())
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverContinue, action)
+		require.Empty(t, fs.FailedAccountIDs, "应清除失败账号列表")
+		require.GreaterOrEqual(t, elapsed, 1500*time.Millisecond, "应等待约 2s")
+		require.Less(t, elapsed, 5*time.Second)
+	})
+
+	t.Run("503但SwitchCount已超过MaxSwitches_返回Exhausted", func(t *testing.T) {
+		fs := NewFailoverState(2, false)
+		fs.LastFailoverErr = newTestFailoverErr(503, false, false)
+		fs.SwitchCount = 3 // > MaxSwitches(2)
+
+		start := time.Now()
+		action := fs.HandleSelectionExhausted(context.Background())
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverExhausted, action)
+		require.Less(t, elapsed, 100*time.Millisecond, "不应等待")
+	})
+
+	t.Run("503但context已取消_返回Canceled", func(t *testing.T) {
+		fs := NewFailoverState(3, false)
+		fs.LastFailoverErr = newTestFailoverErr(503, false, false)
+
+		ctx, cancel := context.WithCancel(context.Background())
+		cancel()
+
+		start := time.Now()
+		action := fs.HandleSelectionExhausted(ctx)
+		elapsed := time.Since(start)
+
+		require.Equal(t, FailoverCanceled, action)
+		require.Less(t, elapsed, 100*time.Millisecond, "应立即返回")
+	})
+
+	t.Run("503且SwitchCount等于MaxSwitches_仍可重试", func(t *testing.T) {
+		fs := NewFailoverState(2, false)
+		fs.LastFailoverErr = newTestFailoverErr(503, false, false)
+		fs.SwitchCount = 2 // == MaxSwitches，条件是 <=，仍可重试
+
+		action := fs.HandleSelectionExhausted(context.Background())
+		require.Equal(t, FailoverContinue, action)
+	})
+}

backend/internal/handler/gateway_handler.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"log"
 	"net/http"
 	"strings"
 	"time"
@@ -257,12 +256,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 	hasBoundSession := sessionKey != "" && sessionBoundAccountID > 0
 
 	if platform == service.PlatformGemini {
-		maxAccountSwitches := h.maxAccountSwitchesGemini
-		switchCount := 0
-		failedAccountIDs := make(map[int64]struct{})
-		sameAccountRetryCount := make(map[int64]int) // 同账号重试计数
-		var lastFailoverErr *service.UpstreamFailoverError
-		var forceCacheBilling bool // 粘性会话切换时的缓存计费标记
+		fs := NewFailoverState(h.maxAccountSwitchesGemini, hasBoundSession)
 
 		// 单账号分组提前设置 SingleAccountRetry 标记，让 Service 层首次 503 就不设模型限流标记。
 		// 避免单账号分组收到 503 (MODEL_CAPACITY_EXHAUSTED) 时设 29s 限流，导致后续请求连续快速失败。
@@ -272,35 +266,28 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 		}
 
 		for {
-			selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), apiKey.GroupID, sessionKey, reqModel, failedAccountIDs, "") // Gemini 不使用会话限制
+			selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), apiKey.GroupID, sessionKey, reqModel, fs.FailedAccountIDs, "") // Gemini 不使用会话限制
 			if err != nil {
-				if len(failedAccountIDs) == 0 {
-					reqLog.Warn("gateway.account_select_failed", zap.Error(err), zap.Int("excluded_account_count", len(failedAccountIDs)))
-					h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "Service temporarily unavailable", streamStarted)
+				if len(fs.FailedAccountIDs) == 0 {
+					h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
 					return
 				}
-				// Antigravity 单账号退避重试：分组内没有其他可用账号时，
-				// 对 503 错误不直接返回，而是清除排除列表、等待退避后重试同一个账号。
-				// 谷歌上游 503 (MODEL_CAPACITY_EXHAUSTED) 通常是暂时性的，等几秒就能恢复。
-				if lastFailoverErr != nil && lastFailoverErr.StatusCode == http.StatusServiceUnavailable && switchCount <= maxAccountSwitches {
-					if sleepAntigravitySingleAccountBackoff(c.Request.Context(), switchCount) {
-						reqLog.Warn("gateway.single_account_retrying",
-							zap.Int("retry_count", switchCount),
-							zap.Int("max_retries", maxAccountSwitches),
-						)
-						failedAccountIDs = make(map[int64]struct{})
-						// 设置 context 标记，让 Service 层预检查等待限流过期而非直接切换
-						ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
-						c.Request = c.Request.WithContext(ctx)
-						continue
+				action := fs.HandleSelectionExhausted(c.Request.Context())
+				switch action {
+				case FailoverContinue:
+					ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
+					c.Request = c.Request.WithContext(ctx)
+					continue
+				case FailoverCanceled:
+					return
+				default: // FailoverExhausted
+					if fs.LastFailoverErr != nil {
+						h.handleFailoverExhausted(c, fs.LastFailoverErr, service.PlatformGemini, streamStarted)
+					} else {
+						h.handleFailoverExhaustedSimple(c, 502, streamStarted)
 					}
+					return
 				}
-				if lastFailoverErr != nil {
-					h.handleFailoverExhausted(c, lastFailoverErr, service.PlatformGemini, streamStarted)
-				} else {
-					h.handleFailoverExhaustedSimple(c, 502, streamStarted)
-				}
-				return
 			}
 			account := selection.Account
 			setOpsSelectedAccount(c, account.ID, account.Platform)
@@ -376,8 +363,8 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			// 转发请求 - 根据账号平台分流
 			var result *service.ForwardResult
 			requestCtx := c.Request.Context()
-			if switchCount > 0 {
-				requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, switchCount)
+			if fs.SwitchCount > 0 {
+				requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, fs.SwitchCount)
 			}
 			if account.Platform == service.PlatformAntigravity {
 				result, err = h.antigravityGatewayService.ForwardGemini(requestCtx, c, account, reqModel, "generateContent", reqStream, body, hasBoundSession)
@@ -390,45 +377,16 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			if err != nil {
 				var failoverErr *service.UpstreamFailoverError
 				if errors.As(err, &failoverErr) {
-					lastFailoverErr = failoverErr
-					if needForceCacheBilling(hasBoundSession, failoverErr) {
-						forceCacheBilling = true
-					}
-
-					// 同账号重试：对 RetryableOnSameAccount 的临时性错误，先在同一账号上重试
-					if failoverErr.RetryableOnSameAccount && sameAccountRetryCount[account.ID] < maxSameAccountRetries {
-						sameAccountRetryCount[account.ID]++
-						log.Printf("Account %d: retryable error %d, same-account retry %d/%d",
-							account.ID, failoverErr.StatusCode, sameAccountRetryCount[account.ID], maxSameAccountRetries)
-						if !sleepSameAccountRetryDelay(c.Request.Context()) {
-							return
-						}
+					action := fs.HandleFailoverError(c.Request.Context(), h.gatewayService, account.ID, account.Platform, failoverErr)
+					switch action {
+					case FailoverContinue:
 						continue
-					}
-
-					// 同账号重试用尽，执行临时封禁并切换账号
-					if failoverErr.RetryableOnSameAccount {
-						h.gatewayService.TempUnscheduleRetryableError(c.Request.Context(), account.ID, failoverErr)
-					}
-
-					failedAccountIDs[account.ID] = struct{}{}
-					if switchCount >= maxAccountSwitches {
-						h.handleFailoverExhausted(c, failoverErr, service.PlatformGemini, streamStarted)
+					case FailoverExhausted:
+						h.handleFailoverExhausted(c, fs.LastFailoverErr, service.PlatformGemini, streamStarted)
+						return
+					case FailoverCanceled:
 						return
 					}
-					switchCount++
-					reqLog.Warn("gateway.upstream_failover_switching",
-						zap.Int64("account_id", account.ID),
-						zap.Int("upstream_status", failoverErr.StatusCode),
-						zap.Int("switch_count", switchCount),
-						zap.Int("max_switches", maxAccountSwitches),
-					)
-					if account.Platform == service.PlatformAntigravity {
-						if !sleepFailoverDelay(c.Request.Context(), switchCount) {
-							return
-						}
-					}
-					continue
 				}
 				wroteFallback := h.ensureForwardErrorResponse(c, streamStarted)
 				reqLog.Error("gateway.forward_failed",
@@ -453,7 +411,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 					Subscription:      subscription,
 					UserAgent:         userAgent,
 					IPAddress:         clientIP,
-					ForceCacheBilling: forceCacheBilling,
+					ForceCacheBilling: fs.ForceCacheBilling,
 					APIKeyService:     h.apiKeyService,
 				}); err != nil {
 					logger.L().With(
@@ -486,45 +444,33 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 	}
 
 	for {
-		maxAccountSwitches := h.maxAccountSwitches
-		switchCount := 0
-		failedAccountIDs := make(map[int64]struct{})
-		sameAccountRetryCount := make(map[int64]int) // 同账号重试计数
-		var lastFailoverErr *service.UpstreamFailoverError
+		fs := NewFailoverState(h.maxAccountSwitches, hasBoundSession)
 		retryWithFallback := false
-		var forceCacheBilling bool // 粘性会话切换时的缓存计费标记
 
 		for {
 			// 选择支持该模型的账号
-			selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), currentAPIKey.GroupID, sessionKey, reqModel, failedAccountIDs, parsedReq.MetadataUserID)
+			selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), currentAPIKey.GroupID, sessionKey, reqModel, fs.FailedAccountIDs, parsedReq.MetadataUserID)
 			if err != nil {
-				if len(failedAccountIDs) == 0 {
-					reqLog.Warn("gateway.account_select_failed", zap.Error(err), zap.Int("excluded_account_count", len(failedAccountIDs)))
-					h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "Service temporarily unavailable", streamStarted)
+				if len(fs.FailedAccountIDs) == 0 {
+					h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts: "+err.Error(), streamStarted)
 					return
 				}
-				// Antigravity 单账号退避重试：分组内没有其他可用账号时，
-				// 对 503 错误不直接返回，而是清除排除列表、等待退避后重试同一个账号。
-				// 谷歌上游 503 (MODEL_CAPACITY_EXHAUSTED) 通常是暂时性的，等几秒就能恢复。
-				if lastFailoverErr != nil && lastFailoverErr.StatusCode == http.StatusServiceUnavailable && switchCount <= maxAccountSwitches {
-					if sleepAntigravitySingleAccountBackoff(c.Request.Context(), switchCount) {
-						reqLog.Warn("gateway.single_account_retrying",
-							zap.Int("retry_count", switchCount),
-							zap.Int("max_retries", maxAccountSwitches),
-						)
-						failedAccountIDs = make(map[int64]struct{})
-						// 设置 context 标记，让 Service 层预检查等待限流过期而非直接切换
-						ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
-						c.Request = c.Request.WithContext(ctx)
-						continue
+				action := fs.HandleSelectionExhausted(c.Request.Context())
+				switch action {
+				case FailoverContinue:
+					ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
+					c.Request = c.Request.WithContext(ctx)
+					continue
+				case FailoverCanceled:
+					return
+				default: // FailoverExhausted
+					if fs.LastFailoverErr != nil {
+						h.handleFailoverExhausted(c, fs.LastFailoverErr, platform, streamStarted)
+					} else {
+						h.handleFailoverExhaustedSimple(c, 502, streamStarted)
 					}
+					return
 				}
-				if lastFailoverErr != nil {
-					h.handleFailoverExhausted(c, lastFailoverErr, platform, streamStarted)
-				} else {
-					h.handleFailoverExhaustedSimple(c, 502, streamStarted)
-				}
-				return
 			}
 			account := selection.Account
 			setOpsSelectedAccount(c, account.ID, account.Platform)
@@ -600,8 +546,8 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 			// 转发请求 - 根据账号平台分流
 			var result *service.ForwardResult
 			requestCtx := c.Request.Context()
-			if switchCount > 0 {
-				requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, switchCount)
+			if fs.SwitchCount > 0 {
+				requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, fs.SwitchCount)
 			}
 			if account.Platform == service.PlatformAntigravity && account.Type != service.AccountTypeAPIKey {
 				result, err = h.antigravityGatewayService.Forward(requestCtx, c, account, body, hasBoundSession)
@@ -657,45 +603,16 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 				}
 				var failoverErr *service.UpstreamFailoverError
 				if errors.As(err, &failoverErr) {
-					lastFailoverErr = failoverErr
-					if needForceCacheBilling(hasBoundSession, failoverErr) {
-						forceCacheBilling = true
-					}
-
-					// 同账号重试：对 RetryableOnSameAccount 的临时性错误，先在同一账号上重试
-					if failoverErr.RetryableOnSameAccount && sameAccountRetryCount[account.ID] < maxSameAccountRetries {
-						sameAccountRetryCount[account.ID]++
-						log.Printf("Account %d: retryable error %d, same-account retry %d/%d",
-							account.ID, failoverErr.StatusCode, sameAccountRetryCount[account.ID], maxSameAccountRetries)
-						if !sleepSameAccountRetryDelay(c.Request.Context()) {
-							return
-						}
+					action := fs.HandleFailoverError(c.Request.Context(), h.gatewayService, account.ID, account.Platform, failoverErr)
+					switch action {
+					case FailoverContinue:
 						continue
-					}
-
-					// 同账号重试用尽，执行临时封禁并切换账号
-					if failoverErr.RetryableOnSameAccount {
-						h.gatewayService.TempUnscheduleRetryableError(c.Request.Context(), account.ID, failoverErr)
-					}
-
-					failedAccountIDs[account.ID] = struct{}{}
-					if switchCount >= maxAccountSwitches {
-						h.handleFailoverExhausted(c, failoverErr, account.Platform, streamStarted)
+					case FailoverExhausted:
+						h.handleFailoverExhausted(c, fs.LastFailoverErr, account.Platform, streamStarted)
+						return
+					case FailoverCanceled:
 						return
 					}
-					switchCount++
-					reqLog.Warn("gateway.upstream_failover_switching",
-						zap.Int64("account_id", account.ID),
-						zap.Int("upstream_status", failoverErr.StatusCode),
-						zap.Int("switch_count", switchCount),
-						zap.Int("max_switches", maxAccountSwitches),
-					)
-					if account.Platform == service.PlatformAntigravity {
-						if !sleepFailoverDelay(c.Request.Context(), switchCount) {
-							return
-						}
-					}
-					continue
 				}
 				wroteFallback := h.ensureForwardErrorResponse(c, streamStarted)
 				reqLog.Error("gateway.forward_failed",
@@ -720,7 +637,7 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 					Subscription:      currentSubscription,
 					UserAgent:         userAgent,
 					IPAddress:         clientIP,
-					ForceCacheBilling: forceCacheBilling,
+					ForceCacheBilling: fs.ForceCacheBilling,
 					APIKeyService:     h.apiKeyService,
 				}); err != nil {
 					logger.L().With(
@@ -733,11 +650,6 @@ func (h *GatewayHandler) Messages(c *gin.Context) {
 					).Error("gateway.record_usage_failed", zap.Error(err))
 				}
 			})
-			reqLog.Debug("gateway.request_completed",
-				zap.Int64("account_id", account.ID),
-				zap.Int("switch_count", switchCount),
-				zap.Bool("fallback_used", fallbackUsed),
-			)
 			return
 		}
 		if !retryWithFallback {
@@ -982,69 +894,6 @@ func (h *GatewayHandler) handleConcurrencyError(c *gin.Context, err error, slotT
 		fmt.Sprintf("Concurrency limit exceeded for %s, please retry later", slotType), streamStarted)
 }
 
-// needForceCacheBilling 判断 failover 时是否需要强制缓存计费
-// 粘性会话切换账号、或上游明确标记时，将 input_tokens 转为 cache_read 计费
-func needForceCacheBilling(hasBoundSession bool, failoverErr *service.UpstreamFailoverError) bool {
-	return hasBoundSession || (failoverErr != nil && failoverErr.ForceCacheBilling)
-}
-
-const (
-	// maxSameAccountRetries 同账号重试次数上限（针对 RetryableOnSameAccount 错误）
-	maxSameAccountRetries = 2
-	// sameAccountRetryDelay 同账号重试间隔
-	sameAccountRetryDelay = 500 * time.Millisecond
-)
-
-// sleepSameAccountRetryDelay 同账号重试固定延时，返回 false 表示 context 已取消。
-func sleepSameAccountRetryDelay(ctx context.Context) bool {
-	select {
-	case <-ctx.Done():
-		return false
-	case <-time.After(sameAccountRetryDelay):
-		return true
-	}
-}
-
-// sleepFailoverDelay 账号切换线性递增延时：第1次0s、第2次1s、第3次2s…
-// 返回 false 表示 context 已取消。
-func sleepFailoverDelay(ctx context.Context, switchCount int) bool {
-	delay := time.Duration(switchCount-1) * time.Second
-	if delay <= 0 {
-		return true
-	}
-	select {
-	case <-ctx.Done():
-		return false
-	case <-time.After(delay):
-		return true
-	}
-}
-
-// sleepAntigravitySingleAccountBackoff Antigravity 平台单账号分组的 503 退避重试延时。
-// 当分组内只有一个可用账号且上游返回 503（MODEL_CAPACITY_EXHAUSTED）时使用，
-// 采用短固定延时策略。Service 层在 SingleAccountRetry 模式下已经做了充分的原地重试
-// （最多 3 次、总等待 30s），所以 Handler 层的退避只需短暂等待即可。
-// 返回 false 表示 context 已取消。
-func sleepAntigravitySingleAccountBackoff(ctx context.Context, retryCount int) bool {
-	// 固定短延时：2s
-	// Service 层已经在原地等待了足够长的时间（retryDelay × 重试次数），
-	// Handler 层只需短暂间隔后重新进入 Service 层即可。
-	const delay = 2 * time.Second
-
-	logger.L().With(
-		zap.String("component", "handler.gateway.failover"),
-		zap.Duration("delay", delay),
-		zap.Int("retry_count", retryCount),
-	).Info("gateway.single_account_backoff_waiting")
-
-	select {
-	case <-ctx.Done():
-		return false
-	case <-time.After(delay):
-		return true
-	}
-}
-
 func (h *GatewayHandler) handleFailoverExhausted(c *gin.Context, failoverErr *service.UpstreamFailoverError, platform string, streamStarted bool) {
 	statusCode := failoverErr.StatusCode
 	responseBody := failoverErr.ResponseBody

backend/internal/handler/gateway_handler_single_account_retry_test.go

-package handler
-
-import (
-	"context"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/require"
-)
-
-// ---------------------------------------------------------------------------
-// sleepAntigravitySingleAccountBackoff 测试
-// ---------------------------------------------------------------------------
-
-func TestSleepAntigravitySingleAccountBackoff_ReturnsTrue(t *testing.T) {
-	ctx := context.Background()
-	start := time.Now()
-	ok := sleepAntigravitySingleAccountBackoff(ctx, 1)
-	elapsed := time.Since(start)
-
-	require.True(t, ok, "should return true when context is not canceled")
-	// 固定延迟 2s
-	require.GreaterOrEqual(t, elapsed, 1500*time.Millisecond, "should wait approximately 2s")
-	require.Less(t, elapsed, 5*time.Second, "should not wait too long")
-}
-
-func TestSleepAntigravitySingleAccountBackoff_ContextCanceled(t *testing.T) {
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel() // 立即取消
-
-	start := time.Now()
-	ok := sleepAntigravitySingleAccountBackoff(ctx, 1)
-	elapsed := time.Since(start)
-
-	require.False(t, ok, "should return false when context is canceled")
-	require.Less(t, elapsed, 500*time.Millisecond, "should return immediately on cancel")
-}
-
-func TestSleepAntigravitySingleAccountBackoff_FixedDelay(t *testing.T) {
-	// 验证不同 retryCount 都使用固定 2s 延迟
-	ctx := context.Background()
-
-	start := time.Now()
-	ok := sleepAntigravitySingleAccountBackoff(ctx, 5)
-	elapsed := time.Since(start)
-
-	require.True(t, ok)
-	// 即使 retryCount=5，延迟仍然是固定的 2s
-	require.GreaterOrEqual(t, elapsed, 1500*time.Millisecond)
-	require.Less(t, elapsed, 5*time.Second)
-}

backend/internal/handler/gateway_handler_warmup_intercept_unit_test.go

+//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"])
+}

backend/internal/handler/gemini_v1beta_handler.go

@@ -344,11 +344,7 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 	hasBoundSession := sessionKey != "" && sessionBoundAccountID > 0
 	cleanedForUnknownBinding := false
 
-	maxAccountSwitches := h.maxAccountSwitchesGemini
-	switchCount := 0
-	failedAccountIDs := make(map[int64]struct{})
-	var lastFailoverErr *service.UpstreamFailoverError
-	var forceCacheBilling bool // 粘性会话切换时的缓存计费标记
+	fs := NewFailoverState(h.maxAccountSwitchesGemini, hasBoundSession)
 
 	// 单账号分组提前设置 SingleAccountRetry 标记，让 Service 层首次 503 就不设模型限流标记。
 	// 避免单账号分组收到 503 (MODEL_CAPACITY_EXHAUSTED) 时设 29s 限流，导致后续请求连续快速失败。
@@ -358,30 +354,24 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 	}
 
 	for {
-		selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), apiKey.GroupID, sessionKey, modelName, failedAccountIDs, "") // Gemini 不使用会话限制
+		selection, err := h.gatewayService.SelectAccountWithLoadAwareness(c.Request.Context(), apiKey.GroupID, sessionKey, modelName, fs.FailedAccountIDs, "") // Gemini 不使用会话限制
 		if err != nil {
-			if len(failedAccountIDs) == 0 {
+			if len(fs.FailedAccountIDs) == 0 {
 				googleError(c, http.StatusServiceUnavailable, "No available Gemini accounts: "+err.Error())
 				return
 			}
-			// Antigravity 单账号退避重试：分组内没有其他可用账号时，
-			// 对 503 错误不直接返回，而是清除排除列表、等待退避后重试同一个账号。
-			// 谷歌上游 503 (MODEL_CAPACITY_EXHAUSTED) 通常是暂时性的，等几秒就能恢复。
-			if lastFailoverErr != nil && lastFailoverErr.StatusCode == http.StatusServiceUnavailable && switchCount <= maxAccountSwitches {
-				if sleepAntigravitySingleAccountBackoff(c.Request.Context(), switchCount) {
-					reqLog.Warn("gemini.single_account_retrying",
-						zap.Int("retry_count", switchCount),
-						zap.Int("max_retries", maxAccountSwitches),
-					)
-					failedAccountIDs = make(map[int64]struct{})
-					// 设置 context 标记，让 Service 层预检查等待限流过期而非直接切换
-					ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
-					c.Request = c.Request.WithContext(ctx)
-					continue
-				}
+			action := fs.HandleSelectionExhausted(c.Request.Context())
+			switch action {
+			case FailoverContinue:
+				ctx := context.WithValue(c.Request.Context(), ctxkey.SingleAccountRetry, true)
+				c.Request = c.Request.WithContext(ctx)
+				continue
+			case FailoverCanceled:
+				return
+			default: // FailoverExhausted
+				h.handleGeminiFailoverExhausted(c, fs.LastFailoverErr)
+				return
 			}
-			h.handleGeminiFailoverExhausted(c, lastFailoverErr)
-			return
 		}
 		account := selection.Account
 		setOpsSelectedAccount(c, account.ID, account.Platform)
@@ -465,8 +455,8 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 		// 5) forward (根据平台分流)
 		var result *service.ForwardResult
 		requestCtx := c.Request.Context()
-		if switchCount > 0 {
-			requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, switchCount)
+		if fs.SwitchCount > 0 {
+			requestCtx = context.WithValue(requestCtx, ctxkey.AccountSwitchCount, fs.SwitchCount)
 		}
 		if account.Platform == service.PlatformAntigravity && account.Type != service.AccountTypeAPIKey {
 			result, err = h.antigravityGatewayService.ForwardGemini(requestCtx, c, account, modelName, action, stream, body, hasBoundSession)
@@ -479,29 +469,16 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 		if err != nil {
 			var failoverErr *service.UpstreamFailoverError
 			if errors.As(err, &failoverErr) {
-				failedAccountIDs[account.ID] = struct{}{}
-				if needForceCacheBilling(hasBoundSession, failoverErr) {
-					forceCacheBilling = true
-				}
-				if switchCount >= maxAccountSwitches {
-					lastFailoverErr = failoverErr
-					h.handleGeminiFailoverExhausted(c, lastFailoverErr)
+				failoverAction := fs.HandleFailoverError(c.Request.Context(), h.gatewayService, account.ID, account.Platform, failoverErr)
+				switch failoverAction {
+				case FailoverContinue:
+					continue
+				case FailoverExhausted:
+					h.handleGeminiFailoverExhausted(c, fs.LastFailoverErr)
+					return
+				case FailoverCanceled:
 					return
 				}
-				lastFailoverErr = failoverErr
-				switchCount++
-				reqLog.Warn("gemini.upstream_failover_switching",
-					zap.Int64("account_id", account.ID),
-					zap.Int("upstream_status", failoverErr.StatusCode),
-					zap.Int("switch_count", switchCount),
-					zap.Int("max_switches", maxAccountSwitches),
-				)
-				if account.Platform == service.PlatformAntigravity {
-					if !sleepFailoverDelay(c.Request.Context(), switchCount) {
-						return
-					}
-				}
-				continue
 			}
 			// ForwardNative already wrote the response
 			reqLog.Error("gemini.forward_failed", zap.Int64("account_id", account.ID), zap.Error(err))
@@ -539,7 +516,7 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 				IPAddress:             clientIP,
 				LongContextThreshold:  200000, // Gemini 200K 阈值
 				LongContextMultiplier: 2.0,    // 超出部分双倍计费
-				ForceCacheBilling:     forceCacheBilling,
+				ForceCacheBilling:     fs.ForceCacheBilling,
 				APIKeyService:         h.apiKeyService,
 			}); err != nil {
 				logger.L().With(
@@ -554,7 +531,7 @@ func (h *GatewayHandler) GeminiV1BetaModels(c *gin.Context) {
 		})
 		reqLog.Debug("gemini.request_completed",
 			zap.Int64("account_id", account.ID),
-			zap.Int("switch_count", switchCount),
+			zap.Int("switch_count", fs.SwitchCount),
 		)
 		return
 	}

backend/internal/pkg/antigravity/client_test.go

@@ -400,7 +400,9 @@ func TestShouldFallbackToNextURL_无错误且200(t *testing.T) {
 // ---------------------------------------------------------------------------
 
 func TestClient_ExchangeCode_成功(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		// 验证请求方法
@@ -493,7 +495,9 @@ func TestClient_ExchangeCode_成功(t *testing.T) {
 }
 
 func TestClient_ExchangeCode_无ClientSecret(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "")
+	old := defaultClientSecret
+	defaultClientSecret = ""
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	client := NewClient("")
 	_, err := client.ExchangeCode(context.Background(), "code", "verifier")
@@ -506,7 +510,9 @@ func TestClient_ExchangeCode_无ClientSecret(t *testing.T) {
 }
 
 func TestClient_ExchangeCode_服务器返回错误(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusBadRequest)
@@ -531,7 +537,9 @@ func TestClient_ExchangeCode_服务器返回错误(t *testing.T) {
 // ---------------------------------------------------------------------------
 
 func TestClient_RefreshToken_MockServer(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
@@ -590,7 +598,9 @@ func TestClient_RefreshToken_MockServer(t *testing.T) {
 }
 
 func TestClient_RefreshToken_无ClientSecret(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "")
+	old := defaultClientSecret
+	defaultClientSecret = ""
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	client := NewClient("")
 	_, err := client.RefreshToken(context.Background(), "refresh-tok")
@@ -784,7 +794,9 @@ func newTestClientWithRedirect(redirects map[string]string) *Client {
 // ---------------------------------------------------------------------------
 
 func TestClient_ExchangeCode_Success_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
@@ -853,7 +865,9 @@ func TestClient_ExchangeCode_Success_RealCall(t *testing.T) {
 }
 
 func TestClient_ExchangeCode_ServerError_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusBadRequest)
@@ -878,7 +892,9 @@ func TestClient_ExchangeCode_ServerError_RealCall(t *testing.T) {
 }
 
 func TestClient_ExchangeCode_InvalidJSON_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
@@ -901,7 +917,9 @@ func TestClient_ExchangeCode_InvalidJSON_RealCall(t *testing.T) {
 }
 
 func TestClient_ExchangeCode_ContextCanceled_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		time.Sleep(5 * time.Second) // 模拟慢响应
@@ -927,7 +945,9 @@ func TestClient_ExchangeCode_ContextCanceled_RealCall(t *testing.T) {
 // ---------------------------------------------------------------------------
 
 func TestClient_RefreshToken_Success_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != http.MethodPost {
@@ -976,7 +996,9 @@ func TestClient_RefreshToken_Success_RealCall(t *testing.T) {
 }
 
 func TestClient_RefreshToken_ServerError_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.WriteHeader(http.StatusUnauthorized)
@@ -998,7 +1020,9 @@ func TestClient_RefreshToken_ServerError_RealCall(t *testing.T) {
 }
 
 func TestClient_RefreshToken_InvalidJSON_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
@@ -1021,7 +1045,9 @@ func TestClient_RefreshToken_InvalidJSON_RealCall(t *testing.T) {
 }
 
 func TestClient_RefreshToken_ContextCanceled_RealCall(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "test-secret")
+	old := defaultClientSecret
+	defaultClientSecret = "test-secret"
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		time.Sleep(5 * time.Second)

backend/internal/pkg/antigravity/oauth.go

@@ -23,11 +23,9 @@ const (
 	UserInfoURL  = "https://www.googleapis.com/oauth2/v2/userinfo"
 
 	// Antigravity OAuth 客户端凭证
-	ClientID     = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
-	ClientSecret = ""
+	ClientID = "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com"
 
 	// AntigravityOAuthClientSecretEnv 是 Antigravity OAuth client_secret 的环境变量名。
-	// 出于安全原因，该值不得硬编码入库。
 	AntigravityOAuthClientSecretEnv = "ANTIGRAVITY_OAUTH_CLIENT_SECRET"
 
 	// 固定的 redirect_uri（用户需手动复制 code）
@@ -51,14 +49,21 @@ const (
 	antigravityDailyBaseURL = "https://daily-cloudcode-pa.sandbox.googleapis.com"
 )
 
-// defaultUserAgentVersion 可通过环境变量 ANTIGRAVITY_USER_AGENT_VERSION 配置，默认 1.84.2
-var defaultUserAgentVersion = "1.84.2"
+// defaultUserAgentVersion 可通过环境变量 ANTIGRAVITY_USER_AGENT_VERSION 配置，默认 1.18.4
+var defaultUserAgentVersion = "1.18.4"
+
+// defaultClientSecret 可通过环境变量 ANTIGRAVITY_OAUTH_CLIENT_SECRET 配置
+var defaultClientSecret = "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"
 
 func init() {
 	// 从环境变量读取版本号，未设置则使用默认值
 	if version := os.Getenv("ANTIGRAVITY_USER_AGENT_VERSION"); version != "" {
 		defaultUserAgentVersion = version
 	}
+	// 从环境变量读取 client_secret，未设置则使用默认值
+	if secret := os.Getenv(AntigravityOAuthClientSecretEnv); secret != "" {
+		defaultClientSecret = secret
+	}
 }
 
 // GetUserAgent 返回当前配置的 User-Agent
@@ -67,14 +72,9 @@ func GetUserAgent() string {
 }
 
 func getClientSecret() (string, error) {
-	if v := strings.TrimSpace(ClientSecret); v != "" {
+	if v := strings.TrimSpace(defaultClientSecret); v != "" {
 		return v, nil
 	}
-	if v, ok := os.LookupEnv(AntigravityOAuthClientSecretEnv); ok {
-		if vv := strings.TrimSpace(v); vv != "" {
-			return vv, nil
-		}
-	}
 	return "", infraerrors.Newf(http.StatusBadRequest, "ANTIGRAVITY_OAUTH_CLIENT_SECRET_MISSING", "missing antigravity oauth client_secret; set %s", AntigravityOAuthClientSecretEnv)
 }
 

backend/internal/pkg/antigravity/oauth_test.go

@@ -7,6 +7,7 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"net/url"
+	"os"
 	"strings"
 	"testing"
 	"time"
@@ -17,8 +18,14 @@ import (
 // ---------------------------------------------------------------------------
 
 func TestGetClientSecret_环境变量设置(t *testing.T) {
+	old := defaultClientSecret
+	defaultClientSecret = ""
+	t.Cleanup(func() { defaultClientSecret = old })
 	t.Setenv(AntigravityOAuthClientSecretEnv, "my-secret-value")
 
+	// 需要重新触发 init 逻辑：手动从环境变量读取
+	defaultClientSecret = os.Getenv(AntigravityOAuthClientSecretEnv)
+
 	secret, err := getClientSecret()
 	if err != nil {
 		t.Fatalf("获取 client_secret 失败: %v", err)
@@ -29,11 +36,13 @@ func TestGetClientSecret_环境变量设置(t *testing.T) {
 }
 
 func TestGetClientSecret_环境变量为空(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "")
+	old := defaultClientSecret
+	defaultClientSecret = ""
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	_, err := getClientSecret()
 	if err == nil {
-		t.Fatal("环境变量为空时应返回错误")
+		t.Fatal("defaultClientSecret 为空时应返回错误")
 	}
 	if !strings.Contains(err.Error(), AntigravityOAuthClientSecretEnv) {
 		t.Errorf("错误信息应包含环境变量名: got %s", err.Error())
@@ -41,30 +50,31 @@ func TestGetClientSecret_环境变量为空(t *testing.T) {
 }
 
 func TestGetClientSecret_环境变量未设置(t *testing.T) {
-	// t.Setenv 会在测试结束时恢复，但我们需要确保它不存在
-	// 注意：如果 ClientSecret 常量非空，这个测试会直接返回常量值
-	// 当前代码中 ClientSecret = ""，所以会走环境变量逻辑
-
-	// 明确设置再取消，确保环境变量不存在
-	t.Setenv(AntigravityOAuthClientSecretEnv, "")
+	old := defaultClientSecret
+	defaultClientSecret = ""
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	_, err := getClientSecret()
 	if err == nil {
-		t.Fatal("环境变量未设置时应返回错误")
+		t.Fatal("defaultClientSecret 为空时应返回错误")
 	}
 }
 
 func TestGetClientSecret_环境变量含空格(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "   ")
+	old := defaultClientSecret
+	defaultClientSecret = "   "
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	_, err := getClientSecret()
 	if err == nil {
-		t.Fatal("环境变量仅含空格时应返回错误")
+		t.Fatal("defaultClientSecret 仅含空格时应返回错误")
 	}
 }
 
 func TestGetClientSecret_环境变量有前后空格(t *testing.T) {
-	t.Setenv(AntigravityOAuthClientSecretEnv, "  valid-secret  ")
+	old := defaultClientSecret
+	defaultClientSecret = "  valid-secret  "
+	t.Cleanup(func() { defaultClientSecret = old })
 
 	secret, err := getClientSecret()
 	if err != nil {
@@ -670,13 +680,17 @@ func TestConstants_值正确(t *testing.T) {
 	if ClientID != "1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com" {
 		t.Errorf("ClientID 不匹配: got %s", ClientID)
 	}
-	if ClientSecret != "" {
-		t.Error("ClientSecret 应为空字符串")
+	secret, err := getClientSecret()
+	if err != nil {
+		t.Fatalf("getClientSecret 应返回默认值，但报错: %v", err)
+	}
+	if secret != "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" {
+		t.Errorf("默认 client_secret 不匹配: got %s", secret)
 	}
 	if RedirectURI != "http://localhost:8085/callback" {
 		t.Errorf("RedirectURI 不匹配: got %s", RedirectURI)
 	}
-	if GetUserAgent() != "antigravity/1.84.2 windows/amd64" {
+	if GetUserAgent() != "antigravity/1.18.4 windows/amd64" {
 		t.Errorf("UserAgent 不匹配: got %s", GetUserAgent())
 	}
 	if SessionTTL != 30*time.Minute {

backend/internal/pkg/antigravity/request_transformer.go

@@ -206,6 +206,7 @@ type modelInfo struct {
 var modelInfoMap = map[string]modelInfo{
 	"claude-opus-4-5":   {DisplayName: "Claude Opus 4.5", CanonicalID: "claude-opus-4-5-20250929"},
 	"claude-opus-4-6":   {DisplayName: "Claude Opus 4.6", CanonicalID: "claude-opus-4-6"},
+	"claude-sonnet-4-6": {DisplayName: "Claude Sonnet 4.6", CanonicalID: "claude-sonnet-4-6"},
 	"claude-sonnet-4-5": {DisplayName: "Claude Sonnet 4.5", CanonicalID: "claude-sonnet-4-5-20250929"},
 	"claude-haiku-4-5":  {DisplayName: "Claude Haiku 4.5", CanonicalID: "claude-haiku-4-5-20251001"},
 }

backend/internal/server/routes/admin.go

@@ -219,6 +219,7 @@ func registerAccountRoutes(admin *gin.RouterGroup, h *handler.Handlers) {
 		accounts.GET("", h.Admin.Account.List)
 		accounts.GET("/:id", h.Admin.Account.GetByID)
 		accounts.POST("", h.Admin.Account.Create)
+		accounts.POST("/check-mixed-channel", h.Admin.Account.CheckMixedChannel)
 		accounts.POST("/sync/crs", h.Admin.Account.SyncFromCRS)
 		accounts.POST("/sync/crs/preview", h.Admin.Account.PreviewFromCRS)
 		accounts.PUT("/:id", h.Admin.Account.Update)

backend/internal/service/account_intercept_warmup_test.go

+//go:build unit
+
+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAccount_IsInterceptWarmupEnabled(t *testing.T) {
+	tests := []struct {
+		name        string
+		credentials map[string]any
+		expected    bool
+	}{
+		{
+			name:        "nil credentials",
+			credentials: nil,
+			expected:    false,
+		},
+		{
+			name:        "empty map",
+			credentials: map[string]any{},
+			expected:    false,
+		},
+		{
+			name:        "field not present",
+			credentials: map[string]any{"access_token": "tok"},
+			expected:    false,
+		},
+		{
+			name:        "field is true",
+			credentials: map[string]any{"intercept_warmup_requests": true},
+			expected:    true,
+		},
+		{
+			name:        "field is false",
+			credentials: map[string]any{"intercept_warmup_requests": false},
+			expected:    false,
+		},
+		{
+			name:        "field is string true",
+			credentials: map[string]any{"intercept_warmup_requests": "true"},
+			expected:    false,
+		},
+		{
+			name:        "field is int 1",
+			credentials: map[string]any{"intercept_warmup_requests": 1},
+			expected:    false,
+		},
+		{
+			name:        "field is nil",
+			credentials: map[string]any{"intercept_warmup_requests": nil},
+			expected:    false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := &Account{Credentials: tt.credentials}
+			result := a.IsInterceptWarmupEnabled()
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}

backend/internal/service/admin_service.go

@@ -54,6 +54,7 @@ type AdminService interface {
 	SetAccountError(ctx context.Context, id int64, errorMsg string) error
 	SetAccountSchedulable(ctx context.Context, id int64, schedulable bool) (*Account, error)
 	BulkUpdateAccounts(ctx context.Context, input *BulkUpdateAccountsInput) (*BulkUpdateAccountsResult, error)
+	CheckMixedChannelRisk(ctx context.Context, currentAccountID int64, currentAccountPlatform string, groupIDs []int64) error
 
 	// Proxy management
 	ListProxies(ctx context.Context, page, pageSize int, protocol, status, search string) ([]Proxy, int64, error)
@@ -2114,6 +2115,11 @@ func (s *adminServiceImpl) checkMixedChannelRisk(ctx context.Context, currentAcc
 	return nil
 }
 
+// CheckMixedChannelRisk checks whether target groups contain mixed channels for the current account platform.
+func (s *adminServiceImpl) CheckMixedChannelRisk(ctx context.Context, currentAccountID int64, currentAccountPlatform string, groupIDs []int64) error {
+	return s.checkMixedChannelRisk(ctx, currentAccountID, currentAccountPlatform, groupIDs)
+}
+
 func (s *adminServiceImpl) attachProxyLatency(ctx context.Context, proxies []ProxyWithAccountCount) {
 	if s.proxyLatencyCache == nil || len(proxies) == 0 {
 		return

backend/internal/service/antigravity_gateway_service.go

@@ -87,7 +87,6 @@ var (
 )
 
 const (
-	antigravityBillingModelEnv    = "GATEWAY_ANTIGRAVITY_BILL_WITH_MAPPED_MODEL"
 	antigravityForwardBaseURLEnv  = "GATEWAY_ANTIGRAVITY_FORWARD_BASE_URL"
 	antigravityFallbackSecondsEnv = "GATEWAY_ANTIGRAVITY_FALLBACK_COOLDOWN_SECONDS"
 )
@@ -1309,6 +1308,7 @@ func (s *AntigravityGatewayService) Forward(ctx context.Context, c *gin.Context,
 	// 应用 thinking 模式自动后缀：如果 thinking 开启且目标是 claude-sonnet-4-5，自动改为 thinking 版本
 	thinkingEnabled := claudeReq.Thinking != nil && (claudeReq.Thinking.Type == "enabled" || claudeReq.Thinking.Type == "adaptive")
 	mappedModel = applyThinkingModelSuffix(mappedModel, thinkingEnabled)
+	billingModel := mappedModel
 
 	// 获取 access_token
 	if s.tokenProvider == nil {
@@ -1370,6 +1370,10 @@ func (s *AntigravityGatewayService) Forward(ctx context.Context, c *gin.Context,
 				ForceCacheBilling: switchErr.IsStickySession,
 			}
 		}
+		// 区分客户端取消和真正的上游失败，返回更准确的错误消息
+		if c.Request.Context().Err() != nil {
+			return nil, s.writeClaudeError(c, http.StatusBadGateway, "client_disconnected", "Client disconnected before upstream response")
+		}
 		return nil, s.writeClaudeError(c, http.StatusBadGateway, "upstream_error", "Upstream request failed after retries")
 	}
 	resp := result.resp
@@ -1618,7 +1622,7 @@ func (s *AntigravityGatewayService) Forward(ctx context.Context, c *gin.Context,
 	return &ForwardResult{
 		RequestID:        requestID,
 		Usage:            *usage,
-		Model:            originalModel, // 使用原始模型用于计费和日志
+		Model:            billingModel, // 使用映射模型用于计费和日志
 		Stream:           claudeReq.Stream,
 		Duration:         time.Since(startTime),
 		FirstTokenMs:     firstTokenMs,
@@ -1972,6 +1976,7 @@ func (s *AntigravityGatewayService) ForwardGemini(ctx context.Context, c *gin.Co
 	if mappedModel == "" {
 		return nil, s.writeGoogleError(c, http.StatusForbidden, fmt.Sprintf("model %s not in whitelist", originalModel))
 	}
+	billingModel := mappedModel
 
 	// 获取 access_token
 	if s.tokenProvider == nil {
@@ -2042,6 +2047,10 @@ func (s *AntigravityGatewayService) ForwardGemini(ctx context.Context, c *gin.Co
 				ForceCacheBilling: switchErr.IsStickySession,
 			}
 		}
+		// 区分客户端取消和真正的上游失败，返回更准确的错误消息
+		if c.Request.Context().Err() != nil {
+			return nil, s.writeGoogleError(c, http.StatusBadGateway, "Client disconnected before upstream response")
+		}
 		return nil, s.writeGoogleError(c, http.StatusBadGateway, "Upstream request failed after retries")
 	}
 	resp := result.resp
@@ -2197,7 +2206,7 @@ handleSuccess:
 	return &ForwardResult{
 		RequestID:        requestID,
 		Usage:            *usage,
-		Model:            originalModel,
+		Model:            billingModel,
 		Stream:           stream,
 		Duration:         time.Since(startTime),
 		FirstTokenMs:     firstTokenMs,
@@ -2642,7 +2651,16 @@ func (s *AntigravityGatewayService) handleUpstreamError(
 		defaultDur := s.getDefaultRateLimitDuration()
 
 		// 尝试解析模型 key 并设置模型级限流
-		modelKey := resolveAntigravityModelKey(requestedModel)
+		//
+		// 注意：requestedModel 可能是"映射前"的请求模型名（例如 claude-opus-4-6），
+		// 调度与限流判定使用的是 Antigravity 最终模型名（包含映射与 thinking 后缀）。
+		// 因此这里必须写入最终模型 key，确保后续调度能正确避开已限流模型。
+		modelKey := resolveFinalAntigravityModelKey(ctx, account, requestedModel)
+		if strings.TrimSpace(modelKey) == "" {
+			// 极少数情况下无法映射（理论上不应发生：能转发成功说明映射已通过），
+			// 保持旧行为作为兜底，避免完全丢失模型级限流记录。
+			modelKey = resolveAntigravityModelKey(requestedModel)
+		}
 		if modelKey != "" {
 			ra := s.resolveResetTime(resetAt, defaultDur)
 			if err := s.accountRepo.SetModelRateLimit(ctx, account.ID, modelKey, ra); err != nil {
@@ -3881,7 +3899,6 @@ func (s *AntigravityGatewayService) ForwardUpstream(ctx context.Context, c *gin.
 		return nil, fmt.Errorf("missing model")
 	}
 	originalModel := claudeReq.Model
-	billingModel := originalModel
 
 	// 构建上游请求 URL
 	upstreamURL := baseURL + "/v1/messages"
@@ -3934,7 +3951,7 @@ func (s *AntigravityGatewayService) ForwardUpstream(ctx context.Context, c *gin.
 		_, _ = c.Writer.Write(respBody)
 
 		return &ForwardResult{
-			Model: billingModel,
+			Model: originalModel,
 		}, nil
 	}
 
@@ -3975,7 +3992,7 @@ func (s *AntigravityGatewayService) ForwardUpstream(ctx context.Context, c *gin.
 	logger.LegacyPrintf("service.antigravity_gateway", "%s status=success duration_ms=%d", prefix, duration.Milliseconds())
 
 	return &ForwardResult{
-		Model:            billingModel,
+		Model:            originalModel,
 		Stream:           claudeReq.Stream,
 		Duration:         duration,
 		FirstTokenMs:     firstTokenMs,

backend/internal/service/antigravity_gateway_service_test.go

@@ -134,6 +134,36 @@ func (s *httpUpstreamStub) DoWithTLS(_ *http.Request, _ string, _ int64, _ int,
 	return s.resp, s.err
 }
 
+type antigravitySettingRepoStub struct{}
+
+func (s *antigravitySettingRepoStub) Get(ctx context.Context, key string) (*Setting, error) {
+	panic("unexpected Get call")
+}
+
+func (s *antigravitySettingRepoStub) GetValue(ctx context.Context, key string) (string, error) {
+	return "", ErrSettingNotFound
+}
+
+func (s *antigravitySettingRepoStub) Set(ctx context.Context, key, value string) error {
+	panic("unexpected Set call")
+}
+
+func (s *antigravitySettingRepoStub) GetMultiple(ctx context.Context, keys []string) (map[string]string, error) {
+	panic("unexpected GetMultiple call")
+}
+
+func (s *antigravitySettingRepoStub) SetMultiple(ctx context.Context, settings map[string]string) error {
+	panic("unexpected SetMultiple call")
+}
+
+func (s *antigravitySettingRepoStub) GetAll(ctx context.Context) (map[string]string, error) {
+	panic("unexpected GetAll call")
+}
+
+func (s *antigravitySettingRepoStub) Delete(ctx context.Context, key string) error {
+	panic("unexpected Delete call")
+}
+
 func TestAntigravityGatewayService_Forward_PromptTooLong(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	writer := httptest.NewRecorder()
@@ -160,8 +190,9 @@ func TestAntigravityGatewayService_Forward_PromptTooLong(t *testing.T) {
 	}
 
 	svc := &AntigravityGatewayService{
-		tokenProvider: &AntigravityTokenProvider{},
-		httpUpstream:  &httpUpstreamStub{resp: resp},
+		settingService: NewSettingService(&antigravitySettingRepoStub{}, &config.Config{Gateway: config.GatewayConfig{MaxLineSize: defaultMaxLineSize}}),
+		tokenProvider:  &AntigravityTokenProvider{},
+		httpUpstream:   &httpUpstreamStub{resp: resp},
 	}
 
 	account := &Account{
@@ -418,6 +449,113 @@ func TestAntigravityGatewayService_ForwardGemini_StickySessionForceCacheBilling(
 	require.True(t, failoverErr.ForceCacheBilling, "ForceCacheBilling should be true for sticky session switch")
 }
 
+// TestAntigravityGatewayService_Forward_BillsWithMappedModel
+// 验证：Antigravity Claude 转发返回的计费模型使用映射后的模型
+func TestAntigravityGatewayService_Forward_BillsWithMappedModel(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	writer := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(writer)
+
+	body, err := json.Marshal(map[string]any{
+		"model": "claude-sonnet-4-5",
+		"messages": []map[string]any{
+			{"role": "user", "content": "hello"},
+		},
+		"max_tokens": 16,
+		"stream":     true,
+	})
+	require.NoError(t, err)
+
+	req := httptest.NewRequest(http.MethodPost, "/v1/messages", bytes.NewReader(body))
+	c.Request = req
+
+	upstreamBody := []byte("data: {\"response\":{\"candidates\":[{\"content\":{\"parts\":[{\"text\":\"ok\"}]},\"finishReason\":\"STOP\"}],\"usageMetadata\":{\"promptTokenCount\":8,\"candidatesTokenCount\":3}}}\n\n")
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{"X-Request-Id": []string{"req-bill-1"}},
+		Body:       io.NopCloser(bytes.NewReader(upstreamBody)),
+	}
+
+	svc := &AntigravityGatewayService{
+		settingService: NewSettingService(&antigravitySettingRepoStub{}, &config.Config{Gateway: config.GatewayConfig{MaxLineSize: defaultMaxLineSize}}),
+		tokenProvider:  &AntigravityTokenProvider{},
+		httpUpstream:   &httpUpstreamStub{resp: resp},
+	}
+
+	const mappedModel = "gemini-3-pro-high"
+	account := &Account{
+		ID:          5,
+		Name:        "acc-forward-billing",
+		Platform:    PlatformAntigravity,
+		Type:        AccountTypeOAuth,
+		Status:      StatusActive,
+		Concurrency: 1,
+		Credentials: map[string]any{
+			"access_token": "token",
+			"model_mapping": map[string]any{
+				"claude-sonnet-4-5": mappedModel,
+			},
+		},
+	}
+
+	result, err := svc.Forward(context.Background(), c, account, body, false)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, mappedModel, result.Model)
+}
+
+// TestAntigravityGatewayService_ForwardGemini_BillsWithMappedModel
+// 验证：Antigravity Gemini 转发返回的计费模型使用映射后的模型
+func TestAntigravityGatewayService_ForwardGemini_BillsWithMappedModel(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	writer := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(writer)
+
+	body, err := json.Marshal(map[string]any{
+		"contents": []map[string]any{
+			{"role": "user", "parts": []map[string]any{{"text": "hello"}}},
+		},
+	})
+	require.NoError(t, err)
+
+	req := httptest.NewRequest(http.MethodPost, "/v1beta/models/gemini-2.5-flash:generateContent", bytes.NewReader(body))
+	c.Request = req
+
+	upstreamBody := []byte("data: {\"response\":{\"candidates\":[{\"content\":{\"parts\":[{\"text\":\"ok\"}]},\"finishReason\":\"STOP\"}],\"usageMetadata\":{\"promptTokenCount\":8,\"candidatesTokenCount\":3}}}\n\n")
+	resp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{"X-Request-Id": []string{"req-bill-2"}},
+		Body:       io.NopCloser(bytes.NewReader(upstreamBody)),
+	}
+
+	svc := &AntigravityGatewayService{
+		settingService: NewSettingService(&antigravitySettingRepoStub{}, &config.Config{Gateway: config.GatewayConfig{MaxLineSize: defaultMaxLineSize}}),
+		tokenProvider:  &AntigravityTokenProvider{},
+		httpUpstream:   &httpUpstreamStub{resp: resp},
+	}
+
+	const mappedModel = "gemini-3-pro-high"
+	account := &Account{
+		ID:          6,
+		Name:        "acc-gemini-billing",
+		Platform:    PlatformAntigravity,
+		Type:        AccountTypeOAuth,
+		Status:      StatusActive,
+		Concurrency: 1,
+		Credentials: map[string]any{
+			"access_token": "token",
+			"model_mapping": map[string]any{
+				"gemini-2.5-flash": mappedModel,
+			},
+		},
+	}
+
+	result, err := svc.ForwardGemini(context.Background(), c, account, "gemini-2.5-flash", "generateContent", true, body, false)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	require.Equal(t, mappedModel, result.Model)
+}
+
 // TestStreamUpstreamResponse_UsageAndFirstToken
 // 验证：usage 字段可被累积/覆盖更新，并且能记录首 token 时间
 func TestStreamUpstreamResponse_UsageAndFirstToken(t *testing.T) {