diff --git a/backend/internal/repository/gateway_cache.go b/backend/internal/repository/gateway_cache.go
index 9365252a..46ae0c16 100644
--- a/backend/internal/repository/gateway_cache.go
+++ b/backend/internal/repository/gateway_cache.go
@@ -238,3 +238,41 @@ func (c *gatewayCache) SaveGeminiSession(ctx context.Context, groupID int64, pre
 
 	return c.rdb.Eval(ctx, geminiTrieSaveScript, []string{trieKey}, digestChain, value, ttlSeconds).Err()
 }
+
+// ============ Anthropic 会话 Fallback 方法 (复用 Trie 实现) ============
+
+// FindAnthropicSession 查找 Anthropic 会话（复用 Gemini Trie Lua 脚本）
+func (c *gatewayCache) FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	if digestChain == "" {
+		return "", 0, false
+	}
+
+	trieKey := service.BuildAnthropicTrieKey(groupID, prefixHash)
+	ttlSeconds := int(service.AnthropicSessionTTL().Seconds())
+
+	result, err := c.rdb.Eval(ctx, geminiTrieFindScript, []string{trieKey}, digestChain, ttlSeconds).Result()
+	if err != nil || result == nil {
+		return "", 0, false
+	}
+
+	value, ok := result.(string)
+	if !ok || value == "" {
+		return "", 0, false
+	}
+
+	uuid, accountID, ok = service.ParseGeminiSessionValue(value)
+	return uuid, accountID, ok
+}
+
+// SaveAnthropicSession 保存 Anthropic 会话（复用 Gemini Trie Lua 脚本）
+func (c *gatewayCache) SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	if digestChain == "" {
+		return nil
+	}
+
+	trieKey := service.BuildAnthropicTrieKey(groupID, prefixHash)
+	value := service.FormatGeminiSessionValue(uuid, accountID)
+	ttlSeconds := int(service.AnthropicSessionTTL().Seconds())
+
+	return c.rdb.Eval(ctx, geminiTrieSaveScript, []string{trieKey}, digestChain, value, ttlSeconds).Err()
+}
diff --git a/backend/internal/service/anthropic_session.go b/backend/internal/service/anthropic_session.go
new file mode 100644
index 00000000..2d86ed35
--- /dev/null
+++ b/backend/internal/service/anthropic_session.go
@@ -0,0 +1,89 @@
+package service
+
+import (
+	"encoding/json"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Anthropic 会话 Fallback 相关常量
+const (
+	// anthropicSessionTTLSeconds Anthropic 会话缓存 TTL（5 分钟）
+	anthropicSessionTTLSeconds = 300
+
+	// anthropicTrieKeyPrefix Anthropic Trie 会话 key 前缀
+	anthropicTrieKeyPrefix = "anthropic:trie:"
+
+	// anthropicDigestSessionKeyPrefix Anthropic 摘要 fallback 会话 key 前缀
+	anthropicDigestSessionKeyPrefix = "anthropic:digest:"
+)
+
+// AnthropicSessionTTL 返回 Anthropic 会话缓存 TTL
+func AnthropicSessionTTL() time.Duration {
+	return anthropicSessionTTLSeconds * time.Second
+}
+
+// BuildAnthropicDigestChain 根据 Anthropic 请求生成摘要链
+// 格式: s:<hash>-u:<hash>-a:<hash>-u:<hash>-...
+// s = system, u = user, a = assistant
+func BuildAnthropicDigestChain(parsed *ParsedRequest) string {
+	if parsed == nil {
+		return ""
+	}
+
+	var parts []string
+
+	// 1. system prompt
+	if parsed.System != nil {
+		systemData, _ := json.Marshal(parsed.System)
+		if len(systemData) > 0 && string(systemData) != "null" {
+			parts = append(parts, "s:"+shortHash(systemData))
+		}
+	}
+
+	// 2. messages
+	for _, msg := range parsed.Messages {
+		msgMap, ok := msg.(map[string]any)
+		if !ok {
+			continue
+		}
+		role, _ := msgMap["role"].(string)
+		prefix := rolePrefix(role)
+		content := msgMap["content"]
+		contentData, _ := json.Marshal(content)
+		parts = append(parts, prefix+":"+shortHash(contentData))
+	}
+
+	return strings.Join(parts, "-")
+}
+
+// rolePrefix 将 Anthropic 的 role 映射为单字符前缀
+func rolePrefix(role string) string {
+	switch role {
+	case "assistant":
+		return "a"
+	default:
+		return "u"
+	}
+}
+
+// BuildAnthropicTrieKey 构建 Anthropic Trie Redis key
+// 格式: anthropic:trie:{groupID}:{prefixHash}
+func BuildAnthropicTrieKey(groupID int64, prefixHash string) string {
+	return anthropicTrieKeyPrefix + strconv.FormatInt(groupID, 10) + ":" + prefixHash
+}
+
+// GenerateAnthropicDigestSessionKey 生成 Anthropic 摘要 fallback 的 sessionKey
+// 组合 prefixHash 前 8 位 + uuid 前 8 位，确保不同会话产生不同的 sessionKey
+func GenerateAnthropicDigestSessionKey(prefixHash, uuid string) string {
+	prefix := prefixHash
+	if len(prefixHash) >= 8 {
+		prefix = prefixHash[:8]
+	}
+	uuidPart := uuid
+	if len(uuid) >= 8 {
+		uuidPart = uuid[:8]
+	}
+	return anthropicDigestSessionKeyPrefix + prefix + ":" + uuidPart
+}
diff --git a/backend/internal/service/anthropic_session_test.go b/backend/internal/service/anthropic_session_test.go
new file mode 100644
index 00000000..e2f873e7
--- /dev/null
+++ b/backend/internal/service/anthropic_session_test.go
@@ -0,0 +1,357 @@
+package service
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestBuildAnthropicDigestChain_NilRequest(t *testing.T) {
+	result := BuildAnthropicDigestChain(nil)
+	if result != "" {
+		t.Errorf("expected empty string for nil request, got: %s", result)
+	}
+}
+
+func TestBuildAnthropicDigestChain_EmptyMessages(t *testing.T) {
+	parsed := &ParsedRequest{
+		Messages: []any{},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	if result != "" {
+		t.Errorf("expected empty string for empty messages, got: %s", result)
+	}
+}
+
+func TestBuildAnthropicDigestChain_SingleUserMessage(t *testing.T) {
+	parsed := &ParsedRequest{
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	parts := splitChain(result)
+	if len(parts) != 1 {
+		t.Fatalf("expected 1 part, got %d: %s", len(parts), result)
+	}
+	if !strings.HasPrefix(parts[0], "u:") {
+		t.Errorf("expected prefix 'u:', got: %s", parts[0])
+	}
+}
+
+func TestBuildAnthropicDigestChain_UserAndAssistant(t *testing.T) {
+	parsed := &ParsedRequest{
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "hi there"},
+		},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	parts := splitChain(result)
+	if len(parts) != 2 {
+		t.Fatalf("expected 2 parts, got %d: %s", len(parts), result)
+	}
+	if !strings.HasPrefix(parts[0], "u:") {
+		t.Errorf("part[0] expected prefix 'u:', got: %s", parts[0])
+	}
+	if !strings.HasPrefix(parts[1], "a:") {
+		t.Errorf("part[1] expected prefix 'a:', got: %s", parts[1])
+	}
+}
+
+func TestBuildAnthropicDigestChain_WithSystemString(t *testing.T) {
+	parsed := &ParsedRequest{
+		System: "You are a helpful assistant",
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	parts := splitChain(result)
+	if len(parts) != 2 {
+		t.Fatalf("expected 2 parts (s + u), got %d: %s", len(parts), result)
+	}
+	if !strings.HasPrefix(parts[0], "s:") {
+		t.Errorf("part[0] expected prefix 's:', got: %s", parts[0])
+	}
+	if !strings.HasPrefix(parts[1], "u:") {
+		t.Errorf("part[1] expected prefix 'u:', got: %s", parts[1])
+	}
+}
+
+func TestBuildAnthropicDigestChain_WithSystemContentBlocks(t *testing.T) {
+	parsed := &ParsedRequest{
+		System: []any{
+			map[string]any{"type": "text", "text": "You are a helpful assistant"},
+		},
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	parts := splitChain(result)
+	if len(parts) != 2 {
+		t.Fatalf("expected 2 parts (s + u), got %d: %s", len(parts), result)
+	}
+	if !strings.HasPrefix(parts[0], "s:") {
+		t.Errorf("part[0] expected prefix 's:', got: %s", parts[0])
+	}
+}
+
+func TestBuildAnthropicDigestChain_ConversationPrefixRelationship(t *testing.T) {
+	// 核心测试：验证对话增长时链的前缀关系
+	// 上一轮的完整链一定是下一轮链的前缀
+	system := "You are a helpful assistant"
+
+	// 第 1 轮: system + user
+	round1 := &ParsedRequest{
+		System: system,
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	chain1 := BuildAnthropicDigestChain(round1)
+
+	// 第 2 轮: system + user + assistant + user
+	round2 := &ParsedRequest{
+		System: system,
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "hi there"},
+			map[string]any{"role": "user", "content": "how are you?"},
+		},
+	}
+	chain2 := BuildAnthropicDigestChain(round2)
+
+	// 第 3 轮: system + user + assistant + user + assistant + user
+	round3 := &ParsedRequest{
+		System: system,
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "hi there"},
+			map[string]any{"role": "user", "content": "how are you?"},
+			map[string]any{"role": "assistant", "content": "I'm doing well"},
+			map[string]any{"role": "user", "content": "great"},
+		},
+	}
+	chain3 := BuildAnthropicDigestChain(round3)
+
+	t.Logf("Chain1: %s", chain1)
+	t.Logf("Chain2: %s", chain2)
+	t.Logf("Chain3: %s", chain3)
+
+	// chain1 是 chain2 的前缀
+	if !strings.HasPrefix(chain2, chain1) {
+		t.Errorf("chain1 should be prefix of chain2:\n  chain1: %s\n  chain2: %s", chain1, chain2)
+	}
+
+	// chain2 是 chain3 的前缀
+	if !strings.HasPrefix(chain3, chain2) {
+		t.Errorf("chain2 should be prefix of chain3:\n  chain2: %s\n  chain3: %s", chain2, chain3)
+	}
+
+	// chain1 也是 chain3 的前缀（传递性）
+	if !strings.HasPrefix(chain3, chain1) {
+		t.Errorf("chain1 should be prefix of chain3:\n  chain1: %s\n  chain3: %s", chain1, chain3)
+	}
+}
+
+func TestBuildAnthropicDigestChain_DifferentSystemProducesDifferentChain(t *testing.T) {
+	parsed1 := &ParsedRequest{
+		System: "System A",
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+	parsed2 := &ParsedRequest{
+		System: "System B",
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+		},
+	}
+
+	chain1 := BuildAnthropicDigestChain(parsed1)
+	chain2 := BuildAnthropicDigestChain(parsed2)
+
+	if chain1 == chain2 {
+		t.Error("Different system prompts should produce different chains")
+	}
+
+	// 但 user 部分的 hash 应该相同
+	parts1 := splitChain(chain1)
+	parts2 := splitChain(chain2)
+	if parts1[1] != parts2[1] {
+		t.Error("Same user message should produce same hash regardless of system")
+	}
+}
+
+func TestBuildAnthropicDigestChain_DifferentContentProducesDifferentChain(t *testing.T) {
+	parsed1 := &ParsedRequest{
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "ORIGINAL reply"},
+			map[string]any{"role": "user", "content": "next"},
+		},
+	}
+	parsed2 := &ParsedRequest{
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "TAMPERED reply"},
+			map[string]any{"role": "user", "content": "next"},
+		},
+	}
+
+	chain1 := BuildAnthropicDigestChain(parsed1)
+	chain2 := BuildAnthropicDigestChain(parsed2)
+
+	if chain1 == chain2 {
+		t.Error("Different content should produce different chains")
+	}
+
+	parts1 := splitChain(chain1)
+	parts2 := splitChain(chain2)
+	// 第一个 user message hash 应该相同
+	if parts1[0] != parts2[0] {
+		t.Error("First user message hash should be the same")
+	}
+	// assistant reply hash 应该不同
+	if parts1[1] == parts2[1] {
+		t.Error("Assistant reply hash should differ")
+	}
+}
+
+func TestBuildAnthropicDigestChain_Deterministic(t *testing.T) {
+	parsed := &ParsedRequest{
+		System: "test system",
+		Messages: []any{
+			map[string]any{"role": "user", "content": "hello"},
+			map[string]any{"role": "assistant", "content": "hi"},
+		},
+	}
+
+	chain1 := BuildAnthropicDigestChain(parsed)
+	chain2 := BuildAnthropicDigestChain(parsed)
+
+	if chain1 != chain2 {
+		t.Errorf("BuildAnthropicDigestChain not deterministic: %s vs %s", chain1, chain2)
+	}
+}
+
+func TestBuildAnthropicTrieKey(t *testing.T) {
+	tests := []struct {
+		name       string
+		groupID    int64
+		prefixHash string
+		want       string
+	}{
+		{
+			name:       "normal",
+			groupID:    123,
+			prefixHash: "abcdef12",
+			want:       "anthropic:trie:123:abcdef12",
+		},
+		{
+			name:       "zero group",
+			groupID:    0,
+			prefixHash: "xyz",
+			want:       "anthropic:trie:0:xyz",
+		},
+		{
+			name:       "empty prefix",
+			groupID:    1,
+			prefixHash: "",
+			want:       "anthropic:trie:1:",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := BuildAnthropicTrieKey(tt.groupID, tt.prefixHash)
+			if got != tt.want {
+				t.Errorf("BuildAnthropicTrieKey(%d, %q) = %q, want %q", tt.groupID, tt.prefixHash, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestGenerateAnthropicDigestSessionKey(t *testing.T) {
+	tests := []struct {
+		name       string
+		prefixHash string
+		uuid       string
+		want       string
+	}{
+		{
+			name:       "normal 16 char hash with uuid",
+			prefixHash: "abcdefgh12345678",
+			uuid:       "550e8400-e29b-41d4-a716-446655440000",
+			want:       "anthropic:digest:abcdefgh:550e8400",
+		},
+		{
+			name:       "exactly 8 chars",
+			prefixHash: "12345678",
+			uuid:       "abcdefgh",
+			want:       "anthropic:digest:12345678:abcdefgh",
+		},
+		{
+			name:       "short values",
+			prefixHash: "abc",
+			uuid:       "xyz",
+			want:       "anthropic:digest:abc:xyz",
+		},
+		{
+			name:       "empty values",
+			prefixHash: "",
+			uuid:       "",
+			want:       "anthropic:digest::",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := GenerateAnthropicDigestSessionKey(tt.prefixHash, tt.uuid)
+			if got != tt.want {
+				t.Errorf("GenerateAnthropicDigestSessionKey(%q, %q) = %q, want %q", tt.prefixHash, tt.uuid, got, tt.want)
+			}
+		})
+	}
+
+	// 验证不同 uuid 产生不同 sessionKey
+	t.Run("different uuid different key", func(t *testing.T) {
+		hash := "sameprefix123456"
+		result1 := GenerateAnthropicDigestSessionKey(hash, "uuid0001-session-a")
+		result2 := GenerateAnthropicDigestSessionKey(hash, "uuid0002-session-b")
+		if result1 == result2 {
+			t.Errorf("Different UUIDs should produce different session keys: %s vs %s", result1, result2)
+		}
+	})
+}
+
+func TestAnthropicSessionTTL(t *testing.T) {
+	ttl := AnthropicSessionTTL()
+	if ttl.Seconds() != 300 {
+		t.Errorf("expected 300 seconds, got: %v", ttl.Seconds())
+	}
+}
+
+func TestBuildAnthropicDigestChain_ContentBlocks(t *testing.T) {
+	// 测试 content 为 content blocks 数组的情况
+	parsed := &ParsedRequest{
+		Messages: []any{
+			map[string]any{
+				"role": "user",
+				"content": []any{
+					map[string]any{"type": "text", "text": "describe this image"},
+					map[string]any{"type": "image", "source": map[string]any{"type": "base64"}},
+				},
+			},
+		},
+	}
+	result := BuildAnthropicDigestChain(parsed)
+	parts := splitChain(result)
+	if len(parts) != 1 {
+		t.Fatalf("expected 1 part, got %d: %s", len(parts), result)
+	}
+	if !strings.HasPrefix(parts[0], "u:") {
+		t.Errorf("expected prefix 'u:', got: %s", parts[0])
+	}
+}
diff --git a/backend/internal/service/antigravity_gateway_service.go b/backend/internal/service/antigravity_gateway_service.go
index 3d3c9cca..435cf0de 100644
--- a/backend/internal/service/antigravity_gateway_service.go
+++ b/backend/internal/service/antigravity_gateway_service.go
@@ -35,7 +35,7 @@ const (
 	// - 预检查：剩余限流时间 < 此阈值时等待，>= 此阈值时切换账号
 	antigravityRateLimitThreshold       = 7 * time.Second
 	antigravitySmartRetryMinWait        = 1 * time.Second  // 智能重试最小等待时间
-	antigravitySmartRetryMaxAttempts    = 3                // 智能重试最大次数
+	antigravitySmartRetryMaxAttempts    = 1                // 智能重试最大次数（仅重试 1 次，防止重复限流/长期等待）
 	antigravityDefaultRateLimitDuration = 30 * time.Second // 默认限流时间（无 retryDelay 时使用）
 
 	// Google RPC 状态和类型常量
@@ -247,6 +247,11 @@ func (s *AntigravityGatewayService) handleSmartRetry(p antigravityRetryLoopParam
 			}
 		}
 
+		// 清除粘性会话绑定，避免下次请求仍命中限流账号
+		if s.cache != nil && p.sessionHash != "" {
+			_ = s.cache.DeleteSessionAccountID(p.ctx, p.groupID, p.sessionHash)
+		}
+
 		// 返回账号切换信号，让上层切换账号重试
 		return &smartRetryResult{
 			action: smartRetryActionBreakWithResp,
@@ -264,27 +269,15 @@ func (s *AntigravityGatewayService) handleSmartRetry(p antigravityRetryLoopParam
 
 // antigravityRetryLoop 执行带 URL fallback 的重试循环
 func (s *AntigravityGatewayService) antigravityRetryLoop(p antigravityRetryLoopParams) (*antigravityRetryLoopResult, error) {
-	// 预检查：如果账号已限流，根据剩余时间决定等待或切换
+	// 预检查：如果账号已限流，直接返回切换信号
 	if p.requestedModel != "" {
 		if remaining := p.account.GetRateLimitRemainingTimeWithContext(p.ctx, p.requestedModel); remaining > 0 {
-			if remaining < antigravityRateLimitThreshold {
-				// 限流剩余时间较短，等待后继续
-				log.Printf("%s pre_check: rate_limit_wait remaining=%v model=%s account=%d",
-					p.prefix, remaining.Truncate(time.Millisecond), p.requestedModel, p.account.ID)
-				select {
-				case <-p.ctx.Done():
-					return nil, p.ctx.Err()
-				case <-time.After(remaining):
-				}
-			} else {
-				// 限流剩余时间较长，返回账号切换信号
-				log.Printf("%s pre_check: rate_limit_switch remaining=%v model=%s account=%d",
-					p.prefix, remaining.Truncate(time.Second), p.requestedModel, p.account.ID)
-				return nil, &AntigravityAccountSwitchError{
-					OriginalAccountID: p.account.ID,
-					RateLimitedModel:  p.requestedModel,
-					IsStickySession:   p.isStickySession,
-				}
+			log.Printf("%s pre_check: rate_limit_switch remaining=%v model=%s account=%d",
+				p.prefix, remaining.Truncate(time.Millisecond), p.requestedModel, p.account.ID)
+			return nil, &AntigravityAccountSwitchError{
+				OriginalAccountID: p.account.ID,
+				RateLimitedModel:  p.requestedModel,
+				IsStickySession:   p.isStickySession,
 			}
 		}
 	}
@@ -964,6 +957,16 @@ func isModelNotFoundError(statusCode int, body []byte) bool {
 }
 
 // Forward 转发 Claude 协议请求（Claude → Gemini 转换）
+//
+// 限流处理流程:
+//
+//	请求 → antigravityRetryLoop → 预检查(remaining>0? → 切换账号) → 发送上游
+//	  ├─ 成功 → 正常返回
+//	  └─ 429/503 → handleSmartRetry
+//	      ├─ retryDelay >= 7s → 设置模型限流 + 清除粘性绑定 → 切换账号
+//	      └─ retryDelay <  7s → 等待后重试 1 次
+//	          ├─ 成功 → 正常返回
+//	          └─ 失败 → 设置模型限流 + 清除粘性绑定 → 切换账号
 func (s *AntigravityGatewayService) Forward(ctx context.Context, c *gin.Context, account *Account, body []byte, isStickySession bool) (*ForwardResult, error) {
 	startTime := time.Now()
 	sessionID := getSessionID(c)
@@ -1583,6 +1586,16 @@ func stripSignatureSensitiveBlocksFromClaudeRequest(req *antigravity.ClaudeReque
 }
 
 // ForwardGemini 转发 Gemini 协议请求
+//
+// 限流处理流程:
+//
+//	请求 → antigravityRetryLoop → 预检查(remaining>0? → 切换账号) → 发送上游
+//	  ├─ 成功 → 正常返回
+//	  └─ 429/503 → handleSmartRetry
+//	      ├─ retryDelay >= 7s → 设置模型限流 + 清除粘性绑定 → 切换账号
+//	      └─ retryDelay <  7s → 等待后重试 1 次
+//	          ├─ 成功 → 正常返回
+//	          └─ 失败 → 设置模型限流 + 清除粘性绑定 → 切换账号
 func (s *AntigravityGatewayService) ForwardGemini(ctx context.Context, c *gin.Context, account *Account, originalModel string, action string, stream bool, body []byte, isStickySession bool) (*ForwardResult, error) {
 	startTime := time.Now()
 	sessionID := getSessionID(c)
diff --git a/backend/internal/service/antigravity_rate_limit_test.go b/backend/internal/service/antigravity_rate_limit_test.go
index 20936356..cd2a7a4a 100644
--- a/backend/internal/service/antigravity_rate_limit_test.go
+++ b/backend/internal/service/antigravity_rate_limit_test.go
@@ -803,7 +803,7 @@ func TestSetModelRateLimitByModelName_NotConvertToScope(t *testing.T) {
 	require.NotEqual(t, "claude_sonnet", call.modelKey, "should NOT be scope")
 }
 
-func TestAntigravityRetryLoop_PreCheck_WaitsWhenRemainingBelowThreshold(t *testing.T) {
+func TestAntigravityRetryLoop_PreCheck_SwitchesWhenRateLimited(t *testing.T) {
 	upstream := &recordingOKUpstream{}
 	account := &Account{
 		ID:          1,
@@ -815,19 +815,15 @@ func TestAntigravityRetryLoop_PreCheck_WaitsWhenRemainingBelowThreshold(t *testi
 		Extra: map[string]any{
 			modelRateLimitsKey: map[string]any{
 				"claude-sonnet-4-5": map[string]any{
-					// RFC3339 here is second-precision; keep it safely in the future.
 					"rate_limit_reset_at": time.Now().Add(2 * time.Second).Format(time.RFC3339),
 				},
 			},
 		},
 	}
 
-	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Millisecond)
-	defer cancel()
-
 	svc := &AntigravityGatewayService{}
 	result, err := svc.antigravityRetryLoop(antigravityRetryLoopParams{
-		ctx:             ctx,
+		ctx:             context.Background(),
 		prefix:          "[test]",
 		account:         account,
 		accessToken:     "token",
@@ -841,12 +837,16 @@ func TestAntigravityRetryLoop_PreCheck_WaitsWhenRemainingBelowThreshold(t *testi
 		},
 	})
 
-	require.ErrorIs(t, err, context.DeadlineExceeded)
 	require.Nil(t, result)
-	require.Equal(t, 0, upstream.calls, "should not call upstream while waiting on pre-check")
+	var switchErr *AntigravityAccountSwitchError
+	require.ErrorAs(t, err, &switchErr)
+	require.Equal(t, account.ID, switchErr.OriginalAccountID)
+	require.Equal(t, "claude-sonnet-4-5", switchErr.RateLimitedModel)
+	require.True(t, switchErr.IsStickySession)
+	require.Equal(t, 0, upstream.calls, "should not call upstream when switching on pre-check")
 }
 
-func TestAntigravityRetryLoop_PreCheck_SwitchesWhenRemainingAtOrAboveThreshold(t *testing.T) {
+func TestAntigravityRetryLoop_PreCheck_SwitchesWhenRemainingLong(t *testing.T) {
 	upstream := &recordingOKUpstream{}
 	account := &Account{
 		ID:          2,
diff --git a/backend/internal/service/antigravity_smart_retry_test.go b/backend/internal/service/antigravity_smart_retry_test.go
index 623dfec5..999b408f 100644
--- a/backend/internal/service/antigravity_smart_retry_test.go
+++ b/backend/internal/service/antigravity_smart_retry_test.go
@@ -13,6 +13,23 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+// stubSmartRetryCache 用于 handleSmartRetry 测试的 GatewayCache mock
+// 仅关注 DeleteSessionAccountID 的调用记录
+type stubSmartRetryCache struct {
+	GatewayCache // 嵌入接口，未实现的方法 panic（确保只调用预期方法）
+	deleteCalls  []deleteSessionCall
+}
+
+type deleteSessionCall struct {
+	groupID     int64
+	sessionHash string
+}
+
+func (c *stubSmartRetryCache) DeleteSessionAccountID(_ context.Context, groupID int64, sessionHash string) error {
+	c.deleteCalls = append(c.deleteCalls, deleteSessionCall{groupID: groupID, sessionHash: sessionHash})
+	return nil
+}
+
 // mockSmartRetryUpstream 用于 handleSmartRetry 测试的 mock upstream
 type mockSmartRetryUpstream struct {
 	responses []*http.Response
@@ -198,7 +215,7 @@ func TestHandleSmartRetry_ShortDelay_SmartRetrySuccess(t *testing.T) {
 
 // TestHandleSmartRetry_ShortDelay_SmartRetryFailed_ReturnsSwitchError 测试智能重试失败后返回 switchError
 func TestHandleSmartRetry_ShortDelay_SmartRetryFailed_ReturnsSwitchError(t *testing.T) {
-	// 智能重试后仍然返回 429（需要提供 3 个响应，因为智能重试最多 3 次）
+	// 智能重试后仍然返回 429（需要提供 1 个响应，因为智能重试最多 1 次）
 	failRespBody := `{
 		"error": {
 			"status": "RESOURCE_EXHAUSTED",
@@ -213,19 +230,9 @@ func TestHandleSmartRetry_ShortDelay_SmartRetryFailed_ReturnsSwitchError(t *test
 		Header:     http.Header{},
 		Body:       io.NopCloser(strings.NewReader(failRespBody)),
 	}
-	failResp2 := &http.Response{
-		StatusCode: http.StatusTooManyRequests,
-		Header:     http.Header{},
-		Body:       io.NopCloser(strings.NewReader(failRespBody)),
-	}
-	failResp3 := &http.Response{
-		StatusCode: http.StatusTooManyRequests,
-		Header:     http.Header{},
-		Body:       io.NopCloser(strings.NewReader(failRespBody)),
-	}
 	upstream := &mockSmartRetryUpstream{
-		responses: []*http.Response{failResp1, failResp2, failResp3},
-		errors:    []error{nil, nil, nil},
+		responses: []*http.Response{failResp1},
+		errors:    []error{nil},
 	}
 
 	repo := &stubAntigravityAccountRepo{}
@@ -236,7 +243,7 @@ func TestHandleSmartRetry_ShortDelay_SmartRetryFailed_ReturnsSwitchError(t *test
 		Platform: PlatformAntigravity,
 	}
 
-	// 3s < 7s 阈值，应该触发智能重试（最多 3 次）
+	// 3s < 7s 阈值，应该触发智能重试（最多 1 次）
 	respBody := []byte(`{
 		"error": {
 			"status": "RESOURCE_EXHAUSTED",
@@ -284,7 +291,7 @@ func TestHandleSmartRetry_ShortDelay_SmartRetryFailed_ReturnsSwitchError(t *test
 	// 验证模型限流已设置
 	require.Len(t, repo.modelRateLimitCalls, 1)
 	require.Equal(t, "gemini-3-flash", repo.modelRateLimitCalls[0].modelKey)
-	require.Len(t, upstream.calls, 3, "should have made three retry calls (max attempts)")
+	require.Len(t, upstream.calls, 1, "should have made one retry call (max attempts)")
 }
 
 // TestHandleSmartRetry_503_ModelCapacityExhausted_ReturnsSwitchError 测试 503 MODEL_CAPACITY_EXHAUSTED 返回 switchError
@@ -556,19 +563,15 @@ func TestAntigravityRetryLoop_HandleSmartRetry_SwitchError_Propagates(t *testing
 	require.True(t, switchErr.IsStickySession)
 }
 
-// TestHandleSmartRetry_NetworkError_ContinuesRetry 测试网络错误时继续重试
-func TestHandleSmartRetry_NetworkError_ContinuesRetry(t *testing.T) {
-	// 第一次网络错误，第二次成功
-	successResp := &http.Response{
-		StatusCode: http.StatusOK,
-		Header:     http.Header{},
-		Body:       io.NopCloser(strings.NewReader(`{"result":"ok"}`)),
-	}
+// TestHandleSmartRetry_NetworkError_ExhaustsRetry 测试网络错误时（maxAttempts=1）直接耗尽重试并切换账号
+func TestHandleSmartRetry_NetworkError_ExhaustsRetry(t *testing.T) {
+	// 唯一一次重试遇到网络错误（nil response）
 	upstream := &mockSmartRetryUpstream{
-		responses: []*http.Response{nil, successResp}, // 第一次返回 nil（模拟网络错误）
-		errors:    []error{nil, nil},                  // mock 不返回 error，靠 nil response 触发
+		responses: []*http.Response{nil}, // 返回 nil（模拟网络错误）
+		errors:    []error{nil},          // mock 不返回 error，靠 nil response 触发
 	}
 
+	repo := &stubAntigravityAccountRepo{}
 	account := &Account{
 		ID:       8,
 		Name:     "acc-8",
@@ -600,6 +603,7 @@ func TestHandleSmartRetry_NetworkError_ContinuesRetry(t *testing.T) {
 		action:       "generateContent",
 		body:         []byte(`{"input":"test"}`),
 		httpUpstream: upstream,
+		accountRepo:  repo,
 		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
 			return nil
 		},
@@ -612,10 +616,15 @@ func TestHandleSmartRetry_NetworkError_ContinuesRetry(t *testing.T) {
 
 	require.NotNil(t, result)
 	require.Equal(t, smartRetryActionBreakWithResp, result.action)
-	require.NotNil(t, result.resp, "should return successful response after network error recovery")
-	require.Equal(t, http.StatusOK, result.resp.StatusCode)
-	require.Nil(t, result.switchError, "should not return switchError on success")
-	require.Len(t, upstream.calls, 2, "should have made two retry calls")
+	require.Nil(t, result.resp, "should not return resp when switchError is set")
+	require.NotNil(t, result.switchError, "should return switchError after network error exhausted retry")
+	require.Equal(t, account.ID, result.switchError.OriginalAccountID)
+	require.Equal(t, "claude-sonnet-4-5", result.switchError.RateLimitedModel)
+	require.Len(t, upstream.calls, 1, "should have made one retry call")
+
+	// 验证模型限流已设置
+	require.Len(t, repo.modelRateLimitCalls, 1)
+	require.Equal(t, "claude-sonnet-4-5", repo.modelRateLimitCalls[0].modelKey)
 }
 
 // TestHandleSmartRetry_NoRetryDelay_UsesDefaultRateLimit 测试无 retryDelay 时使用默认 1 分钟限流
@@ -674,3 +683,617 @@ func TestHandleSmartRetry_NoRetryDelay_UsesDefaultRateLimit(t *testing.T) {
 	require.Len(t, repo.modelRateLimitCalls, 1)
 	require.Equal(t, "claude-sonnet-4-5", repo.modelRateLimitCalls[0].modelKey)
 }
+
+// ---------------------------------------------------------------------------
+// 以下测试覆盖本次改动：
+// 1. antigravitySmartRetryMaxAttempts = 1（仅重试 1 次）
+// 2. 智能重试失败后清除粘性会话绑定（DeleteSessionAccountID）
+// ---------------------------------------------------------------------------
+
+// TestSmartRetryMaxAttempts_VerifyConstant 验证常量值为 1
+func TestSmartRetryMaxAttempts_VerifyConstant(t *testing.T) {
+	require.Equal(t, 1, antigravitySmartRetryMaxAttempts,
+		"antigravitySmartRetryMaxAttempts should be 1 to prevent repeated rate limiting")
+}
+
+// TestHandleSmartRetry_ShortDelay_StickySession_FailedRetry_ClearsSession
+// 核心场景：粘性会话 + 短延迟重试失败 → 必须清除粘性绑定
+func TestHandleSmartRetry_ShortDelay_StickySession_FailedRetry_ClearsSession(t *testing.T) {
+	failRespBody := `{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-sonnet-4-5"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`
+	failResp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(failRespBody)),
+	}
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{failResp},
+		errors:    []error{nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       10,
+		Name:     "acc-10",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-sonnet-4-5"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         42,
+		sessionHash:     "sticky-hash-abc",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	// 验证返回 switchError
+	require.NotNil(t, result)
+	require.Equal(t, smartRetryActionBreakWithResp, result.action)
+	require.NotNil(t, result.switchError)
+	require.True(t, result.switchError.IsStickySession, "switchError should carry IsStickySession=true")
+	require.Equal(t, account.ID, result.switchError.OriginalAccountID)
+
+	// 核心断言：DeleteSessionAccountID 被调用，且参数正确
+	require.Len(t, cache.deleteCalls, 1, "should call DeleteSessionAccountID exactly once")
+	require.Equal(t, int64(42), cache.deleteCalls[0].groupID)
+	require.Equal(t, "sticky-hash-abc", cache.deleteCalls[0].sessionHash)
+
+	// 验证仅重试 1 次
+	require.Len(t, upstream.calls, 1, "should make exactly 1 retry call (maxAttempts=1)")
+
+	// 验证模型限流已设置
+	require.Len(t, repo.modelRateLimitCalls, 1)
+	require.Equal(t, "claude-sonnet-4-5", repo.modelRateLimitCalls[0].modelKey)
+}
+
+// TestHandleSmartRetry_ShortDelay_NonStickySession_FailedRetry_NoDeleteSession
+// 非粘性会话 + 短延迟重试失败 → 不应调用 DeleteSessionAccountID（sessionHash 为空）
+func TestHandleSmartRetry_ShortDelay_NonStickySession_FailedRetry_NoDeleteSession(t *testing.T) {
+	failRespBody := `{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "gemini-3-flash"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`
+	failResp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(failRespBody)),
+	}
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{failResp},
+		errors:    []error{nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       11,
+		Name:     "acc-11",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "gemini-3-flash"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: false,
+		groupID:         42,
+		sessionHash:     "", // 非粘性会话，sessionHash 为空
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	require.NotNil(t, result)
+	require.Equal(t, smartRetryActionBreakWithResp, result.action)
+	require.NotNil(t, result.switchError)
+	require.False(t, result.switchError.IsStickySession)
+
+	// 核心断言：sessionHash 为空时不应调用 DeleteSessionAccountID
+	require.Len(t, cache.deleteCalls, 0, "should NOT call DeleteSessionAccountID when sessionHash is empty")
+}
+
+// TestHandleSmartRetry_ShortDelay_StickySession_FailedRetry_NilCache_NoPanic
+// 边界：cache 为 nil 时不应 panic
+func TestHandleSmartRetry_ShortDelay_StickySession_FailedRetry_NilCache_NoPanic(t *testing.T) {
+	failRespBody := `{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-sonnet-4-5"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`
+	failResp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(failRespBody)),
+	}
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{failResp},
+		errors:    []error{nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	account := &Account{
+		ID:       12,
+		Name:     "acc-12",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-sonnet-4-5"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         42,
+		sessionHash:     "sticky-hash-nil-cache",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	// cache 为 nil，不应 panic
+	svc := &AntigravityGatewayService{cache: nil}
+	require.NotPanics(t, func() {
+		result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+		require.NotNil(t, result)
+		require.Equal(t, smartRetryActionBreakWithResp, result.action)
+		require.NotNil(t, result.switchError)
+		require.True(t, result.switchError.IsStickySession)
+	})
+}
+
+// TestHandleSmartRetry_ShortDelay_StickySession_SuccessRetry_NoDeleteSession
+// 重试成功时不应清除粘性会话（只有失败才清除）
+func TestHandleSmartRetry_ShortDelay_StickySession_SuccessRetry_NoDeleteSession(t *testing.T) {
+	successResp := &http.Response{
+		StatusCode: http.StatusOK,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(`{"result":"ok"}`)),
+	}
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{successResp},
+		errors:    []error{nil},
+	}
+
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       13,
+		Name:     "acc-13",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-opus-4"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.5s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		isStickySession: true,
+		groupID:         42,
+		sessionHash:     "sticky-hash-success",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	require.NotNil(t, result)
+	require.Equal(t, smartRetryActionBreakWithResp, result.action)
+	require.NotNil(t, result.resp, "should return successful response")
+	require.Equal(t, http.StatusOK, result.resp.StatusCode)
+	require.Nil(t, result.switchError, "should not return switchError on success")
+
+	// 核心断言：重试成功时不应清除粘性会话
+	require.Len(t, cache.deleteCalls, 0, "should NOT call DeleteSessionAccountID on successful retry")
+}
+
+// TestHandleSmartRetry_LongDelay_StickySession_NoDeleteInHandleSmartRetry
+// 长延迟路径（情况1）在 handleSmartRetry 中不直接调用 DeleteSessionAccountID
+// （清除由 handler 层的 shouldClearStickySession 在下次请求时处理）
+func TestHandleSmartRetry_LongDelay_StickySession_NoDeleteInHandleSmartRetry(t *testing.T) {
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       14,
+		Name:     "acc-14",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	// 15s >= 7s 阈值 → 走长延迟路径
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-sonnet-4-5"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "15s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         42,
+		sessionHash:     "sticky-hash-long-delay",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	require.NotNil(t, result)
+	require.Equal(t, smartRetryActionBreakWithResp, result.action)
+	require.NotNil(t, result.switchError)
+	require.True(t, result.switchError.IsStickySession)
+
+	// 长延迟路径不在 handleSmartRetry 中调用 DeleteSessionAccountID
+	// （由上游 handler 的 shouldClearStickySession 处理）
+	require.Len(t, cache.deleteCalls, 0,
+		"long delay path should NOT call DeleteSessionAccountID in handleSmartRetry (handled by handler layer)")
+}
+
+// TestHandleSmartRetry_ShortDelay_NetworkError_StickySession_ClearsSession
+// 网络错误耗尽重试 + 粘性会话 → 也应清除粘性绑定
+func TestHandleSmartRetry_ShortDelay_NetworkError_StickySession_ClearsSession(t *testing.T) {
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{nil}, // 网络错误
+		errors:    []error{nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       15,
+		Name:     "acc-15",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "gemini-3-flash"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         99,
+		sessionHash:     "sticky-net-error",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	require.NotNil(t, result)
+	require.NotNil(t, result.switchError)
+	require.True(t, result.switchError.IsStickySession)
+
+	// 核心断言：网络错误耗尽重试后也应清除粘性绑定
+	require.Len(t, cache.deleteCalls, 1, "should call DeleteSessionAccountID after network error exhausts retry")
+	require.Equal(t, int64(99), cache.deleteCalls[0].groupID)
+	require.Equal(t, "sticky-net-error", cache.deleteCalls[0].sessionHash)
+}
+
+// TestHandleSmartRetry_ShortDelay_503_StickySession_FailedRetry_ClearsSession
+// 503 + 短延迟 + 粘性会话 + 重试失败 → 清除粘性绑定
+func TestHandleSmartRetry_ShortDelay_503_StickySession_FailedRetry_ClearsSession(t *testing.T) {
+	failRespBody := `{
+		"error": {
+			"code": 503,
+			"status": "UNAVAILABLE",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "gemini-3-pro"}, "reason": "MODEL_CAPACITY_EXHAUSTED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.5s"}
+			]
+		}
+	}`
+	failResp := &http.Response{
+		StatusCode: http.StatusServiceUnavailable,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(failRespBody)),
+	}
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{failResp},
+		errors:    []error{nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:       16,
+		Name:     "acc-16",
+		Type:     AccountTypeOAuth,
+		Platform: PlatformAntigravity,
+	}
+
+	respBody := []byte(`{
+		"error": {
+			"code": 503,
+			"status": "UNAVAILABLE",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "gemini-3-pro"}, "reason": "MODEL_CAPACITY_EXHAUSTED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.5s"}
+			]
+		}
+	}`)
+	resp := &http.Response{
+		StatusCode: http.StatusServiceUnavailable,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(respBody)),
+	}
+
+	params := antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         77,
+		sessionHash:     "sticky-503-short",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	}
+
+	availableURLs := []string{"https://ag-1.test"}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result := svc.handleSmartRetry(params, resp, respBody, "https://ag-1.test", 0, availableURLs)
+
+	require.NotNil(t, result)
+	require.NotNil(t, result.switchError)
+	require.True(t, result.switchError.IsStickySession)
+
+	// 验证粘性绑定被清除
+	require.Len(t, cache.deleteCalls, 1)
+	require.Equal(t, int64(77), cache.deleteCalls[0].groupID)
+	require.Equal(t, "sticky-503-short", cache.deleteCalls[0].sessionHash)
+
+	// 验证模型限流已设置
+	require.Len(t, repo.modelRateLimitCalls, 1)
+	require.Equal(t, "gemini-3-pro", repo.modelRateLimitCalls[0].modelKey)
+}
+
+// TestAntigravityRetryLoop_SmartRetryFailed_StickySession_SwitchErrorPropagates
+// 集成测试：antigravityRetryLoop → handleSmartRetry → switchError 传播
+// 验证 IsStickySession 正确传递到上层，且粘性绑定被清除
+func TestAntigravityRetryLoop_SmartRetryFailed_StickySession_SwitchErrorPropagates(t *testing.T) {
+	// 初始 429 响应
+	initialRespBody := []byte(`{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-opus-4-6"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`)
+	initialResp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(bytes.NewReader(initialRespBody)),
+	}
+
+	// 智能重试也返回 429
+	retryRespBody := `{
+		"error": {
+			"status": "RESOURCE_EXHAUSTED",
+			"details": [
+				{"@type": "type.googleapis.com/google.rpc.ErrorInfo", "metadata": {"model": "claude-opus-4-6"}, "reason": "RATE_LIMIT_EXCEEDED"},
+				{"@type": "type.googleapis.com/google.rpc.RetryInfo", "retryDelay": "0.1s"}
+			]
+		}
+	}`
+	retryResp := &http.Response{
+		StatusCode: http.StatusTooManyRequests,
+		Header:     http.Header{},
+		Body:       io.NopCloser(strings.NewReader(retryRespBody)),
+	}
+
+	upstream := &mockSmartRetryUpstream{
+		responses: []*http.Response{initialResp, retryResp},
+		errors:    []error{nil, nil},
+	}
+
+	repo := &stubAntigravityAccountRepo{}
+	cache := &stubSmartRetryCache{}
+	account := &Account{
+		ID:          17,
+		Name:        "acc-17",
+		Type:        AccountTypeOAuth,
+		Platform:    PlatformAntigravity,
+		Schedulable: true,
+		Status:      StatusActive,
+		Concurrency: 1,
+	}
+
+	svc := &AntigravityGatewayService{cache: cache}
+	result, err := svc.antigravityRetryLoop(antigravityRetryLoopParams{
+		ctx:             context.Background(),
+		prefix:          "[test]",
+		account:         account,
+		accessToken:     "token",
+		action:          "generateContent",
+		body:            []byte(`{"input":"test"}`),
+		httpUpstream:    upstream,
+		accountRepo:     repo,
+		isStickySession: true,
+		groupID:         55,
+		sessionHash:     "sticky-loop-test",
+		handleError: func(ctx context.Context, prefix string, account *Account, statusCode int, headers http.Header, body []byte, quotaScope AntigravityQuotaScope, groupID int64, sessionHash string, isStickySession bool) *handleModelRateLimitResult {
+			return nil
+		},
+	})
+
+	require.Nil(t, result, "should not return result when switchError")
+	require.NotNil(t, err, "should return error")
+
+	var switchErr *AntigravityAccountSwitchError
+	require.ErrorAs(t, err, &switchErr, "error should be AntigravityAccountSwitchError")
+	require.Equal(t, account.ID, switchErr.OriginalAccountID)
+	require.Equal(t, "claude-opus-4-6", switchErr.RateLimitedModel)
+	require.True(t, switchErr.IsStickySession, "IsStickySession must propagate through retryLoop")
+
+	// 验证粘性绑定被清除
+	require.Len(t, cache.deleteCalls, 1, "should clear sticky session in handleSmartRetry")
+	require.Equal(t, int64(55), cache.deleteCalls[0].groupID)
+	require.Equal(t, "sticky-loop-test", cache.deleteCalls[0].sessionHash)
+}
\ No newline at end of file
diff --git a/backend/internal/service/gateway_multiplatform_test.go b/backend/internal/service/gateway_multiplatform_test.go
index b3e60c21..d9c852e0 100644
--- a/backend/internal/service/gateway_multiplatform_test.go
+++ b/backend/internal/service/gateway_multiplatform_test.go
@@ -232,6 +232,14 @@ func (m *mockGatewayCacheForPlatform) SaveGeminiSession(ctx context.Context, gro
 	return nil
 }
 
+func (m *mockGatewayCacheForPlatform) FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	return "", 0, false
+}
+
+func (m *mockGatewayCacheForPlatform) SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	return nil
+}
+
 type mockGroupRepoForGateway struct {
 	groups           map[int64]*Group
 	getByIDCalls     int
diff --git a/backend/internal/service/gateway_service.go b/backend/internal/service/gateway_service.go
index 32646b11..480f5b67 100644
--- a/backend/internal/service/gateway_service.go
+++ b/backend/internal/service/gateway_service.go
@@ -313,6 +313,14 @@ type GatewayCache interface {
 	// SaveGeminiSession 保存 Gemini 会话
 	// Save Gemini session binding
 	SaveGeminiSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error
+
+	// FindAnthropicSession 查找 Anthropic 会话（Trie 匹配）
+	// Find Anthropic session using Trie matching
+	FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool)
+
+	// SaveAnthropicSession 保存 Anthropic 会话
+	// Save Anthropic session binding
+	SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error
 }
 
 // derefGroupID safely dereferences *int64 to int64, returning 0 if nil
@@ -323,21 +331,15 @@ func derefGroupID(groupID *int64) int64 {
 	return *groupID
 }
 
-// stickySessionRateLimitThreshold 定义清除粘性会话的限流时间阈值。
-// 当账号限流剩余时间超过此阈值时，清除粘性会话以便切换到其他账号。
-// 低于此阈值时保持粘性会话，等待短暂限流结束。
-const stickySessionRateLimitThreshold = 10 * time.Second
-
 // shouldClearStickySession 检查账号是否处于不可调度状态，需要清理粘性会话绑定。
 // 当账号状态为错误、禁用、不可调度、处于临时不可调度期间，
-// 或模型限流剩余时间超过 stickySessionRateLimitThreshold 时，返回 true。
+// 或请求的模型处于限流状态时，返回 true。
 // 这确保后续请求不会继续使用不可用的账号。
 //
 // shouldClearStickySession checks if an account is in an unschedulable state
 // and the sticky session binding should be cleared.
 // Returns true when account status is error/disabled, schedulable is false,
-// within temporary unschedulable period, or model rate limit remaining time
-// exceeds stickySessionRateLimitThreshold.
+// within temporary unschedulable period, or the requested model is rate-limited.
 // This ensures subsequent requests won't continue using unavailable accounts.
 func shouldClearStickySession(account *Account, requestedModel string) bool {
 	if account == nil {
@@ -349,8 +351,8 @@ func shouldClearStickySession(account *Account, requestedModel string) bool {
 	if account.TempUnschedulableUntil != nil && time.Now().Before(*account.TempUnschedulableUntil) {
 		return true
 	}
-	// 检查模型限流和 scope 限流，只在超过阈值时清除粘性会话
-	if remaining := account.GetRateLimitRemainingTimeWithContext(context.Background(), requestedModel); remaining > stickySessionRateLimitThreshold {
+	// 检查模型限流和 scope 限流，有限流即清除粘性会话
+	if remaining := account.GetRateLimitRemainingTimeWithContext(context.Background(), requestedModel); remaining > 0 {
 		return true
 	}
 	return false
@@ -488,23 +490,25 @@ func (s *GatewayService) GenerateSessionHash(parsed *ParsedRequest) string {
 		return s.hashContent(cacheableContent)
 	}
 
-	// 3. Fallback: 使用 system 内容
+	// 3. 最后 fallback: 使用 system + 所有消息的完整摘要串
+	var combined strings.Builder
 	if parsed.System != nil {
 		systemText := s.extractTextFromSystem(parsed.System)
 		if systemText != "" {
-			return s.hashContent(systemText)
+			_, _ = combined.WriteString(systemText)
 		}
 	}
-
-	// 4. 最后 fallback: 使用第一条消息
-	if len(parsed.Messages) > 0 {
-		if firstMsg, ok := parsed.Messages[0].(map[string]any); ok {
-			msgText := s.extractTextFromContent(firstMsg["content"])
+	for _, msg := range parsed.Messages {
+		if m, ok := msg.(map[string]any); ok {
+			msgText := s.extractTextFromContent(m["content"])
 			if msgText != "" {
-				return s.hashContent(msgText)
+				_, _ = combined.WriteString(msgText)
 			}
 		}
 	}
+	if combined.Len() > 0 {
+		return s.hashContent(combined.String())
+	}
 
 	return ""
 }
@@ -547,6 +551,22 @@ func (s *GatewayService) SaveGeminiSession(ctx context.Context, groupID int64, p
 	return s.cache.SaveGeminiSession(ctx, groupID, prefixHash, digestChain, uuid, accountID)
 }
 
+// FindAnthropicSession 查找 Anthropic 会话（基于内容摘要链的 Fallback 匹配）
+func (s *GatewayService) FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	if digestChain == "" || s.cache == nil {
+		return "", 0, false
+	}
+	return s.cache.FindAnthropicSession(ctx, groupID, prefixHash, digestChain)
+}
+
+// SaveAnthropicSession 保存 Anthropic 会话
+func (s *GatewayService) SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	if digestChain == "" || s.cache == nil {
+		return nil
+	}
+	return s.cache.SaveAnthropicSession(ctx, groupID, prefixHash, digestChain, uuid, accountID)
+}
+
 func (s *GatewayService) extractCacheableContent(parsed *ParsedRequest) string {
 	if parsed == nil {
 		return ""
@@ -1110,7 +1130,6 @@ func (s *GatewayService) SelectAccountWithLoadAwareness(ctx context.Context, gro
 									result.ReleaseFunc() // 释放槽位
 									// 继续到负载感知选择
 								} else {
-									_ = s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL)
 									if s.debugModelRoutingEnabled() {
 										log.Printf("[ModelRoutingDebug] routed sticky hit: group_id=%v model=%s session=%s account=%d", derefGroupID(groupID), requestedModel, shortSessionHash(sessionHash), stickyAccountID)
 									}
@@ -1264,7 +1283,6 @@ func (s *GatewayService) SelectAccountWithLoadAwareness(ctx context.Context, gro
 						if !s.checkAndRegisterSession(ctx, account, sessionHash) {
 							result.ReleaseFunc() // 释放槽位，继续到 Layer 2
 						} else {
-							_ = s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL)
 							return &AccountSelectionResult{
 								Account:     account,
 								Acquired:    true,
@@ -2169,9 +2187,6 @@ func (s *GatewayService) selectAccountForModelWithPlatform(ctx context.Context,
 							_ = s.cache.DeleteSessionAccountID(ctx, derefGroupID(groupID), sessionHash)
 						}
 						if !clearSticky && s.isAccountInGroup(account, groupID) && account.Platform == platform && (requestedModel == "" || s.isModelSupportedByAccountWithContext(ctx, account, requestedModel)) && account.IsSchedulableForModelWithContext(ctx, requestedModel) {
-							if err := s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL); err != nil {
-								log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
-							}
 							if s.debugModelRoutingEnabled() {
 								log.Printf("[ModelRoutingDebug] legacy routed sticky hit: group_id=%v model=%s session=%s account=%d", derefGroupID(groupID), requestedModel, shortSessionHash(sessionHash), accountID)
 							}
@@ -2272,9 +2287,6 @@ func (s *GatewayService) selectAccountForModelWithPlatform(ctx context.Context,
 						_ = s.cache.DeleteSessionAccountID(ctx, derefGroupID(groupID), sessionHash)
 					}
 					if !clearSticky && s.isAccountInGroup(account, groupID) && account.Platform == platform && (requestedModel == "" || s.isModelSupportedByAccountWithContext(ctx, account, requestedModel)) && account.IsSchedulableForModelWithContext(ctx, requestedModel) {
-						if err := s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL); err != nil {
-							log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
-						}
 						return account, nil
 					}
 				}
@@ -2383,9 +2395,6 @@ func (s *GatewayService) selectAccountWithMixedScheduling(ctx context.Context, g
 						}
 						if !clearSticky && s.isAccountInGroup(account, groupID) && (requestedModel == "" || s.isModelSupportedByAccountWithContext(ctx, account, requestedModel)) && account.IsSchedulableForModelWithContext(ctx, requestedModel) {
 							if account.Platform == nativePlatform || (account.Platform == PlatformAntigravity && account.IsMixedSchedulingEnabled()) {
-								if err := s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL); err != nil {
-									log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
-								}
 								if s.debugModelRoutingEnabled() {
 									log.Printf("[ModelRoutingDebug] legacy mixed routed sticky hit: group_id=%v model=%s session=%s account=%d", derefGroupID(groupID), requestedModel, shortSessionHash(sessionHash), accountID)
 								}
@@ -2488,9 +2497,6 @@ func (s *GatewayService) selectAccountWithMixedScheduling(ctx context.Context, g
 					}
 					if !clearSticky && s.isAccountInGroup(account, groupID) && (requestedModel == "" || s.isModelSupportedByAccountWithContext(ctx, account, requestedModel)) && account.IsSchedulableForModelWithContext(ctx, requestedModel) {
 						if account.Platform == nativePlatform || (account.Platform == PlatformAntigravity && account.IsMixedSchedulingEnabled()) {
-							if err := s.cache.RefreshSessionTTL(ctx, derefGroupID(groupID), sessionHash, stickySessionTTL); err != nil {
-								log.Printf("refresh session ttl failed: session=%s err=%v", sessionHash, err)
-							}
 							return account, nil
 						}
 					}
diff --git a/backend/internal/service/gemini_multiplatform_test.go b/backend/internal/service/gemini_multiplatform_test.go
index 601e7e2c..0c54dc39 100644
--- a/backend/internal/service/gemini_multiplatform_test.go
+++ b/backend/internal/service/gemini_multiplatform_test.go
@@ -281,6 +281,14 @@ func (m *mockGatewayCacheForGemini) SaveGeminiSession(ctx context.Context, group
 	return nil
 }
 
+func (m *mockGatewayCacheForGemini) FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	return "", 0, false
+}
+
+func (m *mockGatewayCacheForGemini) SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	return nil
+}
+
 // TestGeminiMessagesCompatService_SelectAccountForModelWithExclusions_GeminiPlatform 测试 Gemini 单平台选择
 func TestGeminiMessagesCompatService_SelectAccountForModelWithExclusions_GeminiPlatform(t *testing.T) {
 	ctx := context.Background()
diff --git a/backend/internal/service/openai_gateway_service_test.go b/backend/internal/service/openai_gateway_service_test.go
index 1c2c81ca..159b0afb 100644
--- a/backend/internal/service/openai_gateway_service_test.go
+++ b/backend/internal/service/openai_gateway_service_test.go
@@ -220,6 +220,14 @@ func (c *stubGatewayCache) SaveGeminiSession(ctx context.Context, groupID int64,
 	return nil
 }
 
+func (c *stubGatewayCache) FindAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain string) (uuid string, accountID int64, found bool) {
+	return "", 0, false
+}
+
+func (c *stubGatewayCache) SaveAnthropicSession(ctx context.Context, groupID int64, prefixHash, digestChain, uuid string, accountID int64) error {
+	return nil
+}
+
 func TestOpenAISelectAccountWithLoadAwareness_FiltersUnschedulable(t *testing.T) {
 	now := time.Now()
 	resetAt := now.Add(10 * time.Minute)
diff --git a/backend/internal/service/sticky_session_test.go b/backend/internal/service/sticky_session_test.go
index c70f12fe..e7ef8982 100644
--- a/backend/internal/service/sticky_session_test.go
+++ b/backend/internal/service/sticky_session_test.go
@@ -23,8 +23,7 @@ import (
 //   - 临时不可调度且未过期：清理
 //   - 临时不可调度已过期：不清理
 //   - 正常可调度状态：不清理
-//   - 模型限流超过阈值：清理
-//   - 模型限流未超过阈值：不清理
+//   - 模型限流（任意时长）：清理
 //
 // TestShouldClearStickySession tests the sticky session clearing logic.
 // Verifies correct behavior for various account states including:
@@ -35,9 +34,9 @@ func TestShouldClearStickySession(t *testing.T) {
 	future := now.Add(1 * time.Hour)
 	past := now.Add(-1 * time.Hour)
 
-	// 短限流时间（低于阈值，不应清除粘性会话）
+	// 短限流时间（有限流即清除粘性会话）
 	shortRateLimitReset := now.Add(5 * time.Second).Format(time.RFC3339)
-	// 长限流时间（超过阈值，应清除粘性会话）
+	// 长限流时间（有限流即清除粘性会话）
 	longRateLimitReset := now.Add(30 * time.Second).Format(time.RFC3339)
 
 	tests := []struct {
@@ -53,7 +52,7 @@ func TestShouldClearStickySession(t *testing.T) {
 		{name: "temp unschedulable", account: &Account{Status: StatusActive, Schedulable: true, TempUnschedulableUntil: &future}, requestedModel: "", want: true},
 		{name: "temp unschedulable expired", account: &Account{Status: StatusActive, Schedulable: true, TempUnschedulableUntil: &past}, requestedModel: "", want: false},
 		{name: "active schedulable", account: &Account{Status: StatusActive, Schedulable: true}, requestedModel: "", want: false},
-		// 模型限流测试
+		// 模型限流测试：有限流即清除
 		{
 			name: "model rate limited short duration",
 			account: &Account{
@@ -68,7 +67,7 @@ func TestShouldClearStickySession(t *testing.T) {
 				},
 			},
 			requestedModel: "claude-sonnet-4",
-			want:           false, // 低于阈值，不清除
+			want:           true, // 有限流即清除
 		},
 		{
 			name: "model rate limited long duration",
@@ -84,7 +83,7 @@ func TestShouldClearStickySession(t *testing.T) {
 				},
 			},
 			requestedModel: "claude-sonnet-4",
-			want:           true, // 超过阈值，清除
+			want:           true, // 有限流即清除
 		},
 		{
 			name: "model rate limited different model",