feat(anthropic): 支持 API Key 自动透传并优化透传链路性能

- 新增 Anthropic API Key 自动透传开关与后端透传分支（仅替换认证）

- 账号编辑页新增自动透传开关，默认关闭

- 优化透传性能：SSE usage 解析 gjson 快路径、减少请求体重复拷贝、优化流式写回与非流式 usage 解析

- 补充单元测试与 benchmark，确保 Claude OAuth 路径不受影响

backend/internal/service/account.go

@@ -719,6 +719,17 @@ func (a *Account) IsOpenAIOAuthPassthroughEnabled() bool {
 	return a != nil && a.IsOpenAIOAuth() && a.IsOpenAIPassthroughEnabled()
 }
 
+// IsAnthropicAPIKeyPassthroughEnabled 返回 Anthropic API Key 账号是否启用“自动透传（仅替换认证）”。
+// 字段：accounts.extra.anthropic_passthrough。
+// 字段缺失或类型不正确时，按 false（关闭）处理。
+func (a *Account) IsAnthropicAPIKeyPassthroughEnabled() bool {
+	if a == nil || a.Platform != PlatformAnthropic || a.Type != AccountTypeAPIKey || a.Extra == nil {
+		return false
+	}
+	enabled, ok := a.Extra["anthropic_passthrough"].(bool)
+	return ok && enabled
+}
+
 // IsCodexCLIOnlyEnabled 返回 OpenAI OAuth 账号是否启用“仅允许 Codex 官方客户端”。
 // 字段：accounts.extra.codex_cli_only。
 // 字段缺失或类型不正确时，按 false（关闭）处理。

backend/internal/service/account_anthropic_passthrough_test.go

+package service
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAccount_IsAnthropicAPIKeyPassthroughEnabled(t *testing.T) {
+	t.Run("Anthropic API Key 开启", func(t *testing.T) {
+		account := &Account{
+			Platform: PlatformAnthropic,
+			Type:     AccountTypeAPIKey,
+			Extra: map[string]any{
+				"anthropic_passthrough": true,
+			},
+		}
+		require.True(t, account.IsAnthropicAPIKeyPassthroughEnabled())
+	})
+
+	t.Run("Anthropic API Key 关闭", func(t *testing.T) {
+		account := &Account{
+			Platform: PlatformAnthropic,
+			Type:     AccountTypeAPIKey,
+			Extra: map[string]any{
+				"anthropic_passthrough": false,
+			},
+		}
+		require.False(t, account.IsAnthropicAPIKeyPassthroughEnabled())
+	})
+
+	t.Run("字段类型非法默认关闭", func(t *testing.T) {
+		account := &Account{
+			Platform: PlatformAnthropic,
+			Type:     AccountTypeAPIKey,
+			Extra: map[string]any{
+				"anthropic_passthrough": "true",
+			},
+		}
+		require.False(t, account.IsAnthropicAPIKeyPassthroughEnabled())
+	})
+
+	t.Run("非 Anthropic API Key 账号始终关闭", func(t *testing.T) {
+		oauth := &Account{
+			Platform: PlatformAnthropic,
+			Type:     AccountTypeOAuth,
+			Extra: map[string]any{
+				"anthropic_passthrough": true,
+			},
+		}
+		require.False(t, oauth.IsAnthropicAPIKeyPassthroughEnabled())
+
+		openai := &Account{
+			Platform: PlatformOpenAI,
+			Type:     AccountTypeAPIKey,
+			Extra: map[string]any{
+				"anthropic_passthrough": true,
+			},
+		}
+		require.False(t, openai.IsAnthropicAPIKeyPassthroughEnabled())
+	})
+}

backend/internal/service/gateway_anthropic_apikey_passthrough_benchmark_test.go

+package service
+
+import "testing"
+
+func BenchmarkGatewayService_ParseSSEUsage_MessageStart(b *testing.B) {
+	svc := &GatewayService{}
+	data := `{"type":"message_start","message":{"usage":{"input_tokens":123,"cache_creation_input_tokens":45,"cache_read_input_tokens":6,"cached_tokens":6,"cache_creation":{"ephemeral_5m_input_tokens":20,"ephemeral_1h_input_tokens":25}}}}`
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		usage := &ClaudeUsage{}
+		svc.parseSSEUsage(data, usage)
+	}
+}
+
+func BenchmarkGatewayService_ParseSSEUsagePassthrough_MessageStart(b *testing.B) {
+	svc := &GatewayService{}
+	data := `{"type":"message_start","message":{"usage":{"input_tokens":123,"cache_creation_input_tokens":45,"cache_read_input_tokens":6,"cached_tokens":6,"cache_creation":{"ephemeral_5m_input_tokens":20,"ephemeral_1h_input_tokens":25}}}}`
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		usage := &ClaudeUsage{}
+		svc.parseSSEUsagePassthrough(data, usage)
+	}
+}
+
+func BenchmarkGatewayService_ParseSSEUsage_MessageDelta(b *testing.B) {
+	svc := &GatewayService{}
+	data := `{"type":"message_delta","usage":{"output_tokens":456,"cache_creation_input_tokens":30,"cache_read_input_tokens":7,"cached_tokens":7,"cache_creation":{"ephemeral_5m_input_tokens":10,"ephemeral_1h_input_tokens":20}}}`
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		usage := &ClaudeUsage{}
+		svc.parseSSEUsage(data, usage)
+	}
+}
+
+func BenchmarkGatewayService_ParseSSEUsagePassthrough_MessageDelta(b *testing.B) {
+	svc := &GatewayService{}
+	data := `{"type":"message_delta","usage":{"output_tokens":456,"cache_creation_input_tokens":30,"cache_read_input_tokens":7,"cached_tokens":7,"cache_creation":{"ephemeral_5m_input_tokens":10,"ephemeral_1h_input_tokens":20}}}`
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		usage := &ClaudeUsage{}
+		svc.parseSSEUsagePassthrough(data, usage)
+	}
+}
+
+func BenchmarkParseClaudeUsageFromResponseBody(b *testing.B) {
+	body := []byte(`{"id":"msg_123","type":"message","usage":{"input_tokens":123,"output_tokens":456,"cache_creation_input_tokens":45,"cache_read_input_tokens":6,"cached_tokens":6,"cache_creation":{"ephemeral_5m_input_tokens":20,"ephemeral_1h_input_tokens":25}}}`)
+	b.ReportAllocs()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = parseClaudeUsageFromResponseBody(body)
+	}
+}

frontend/src/components/account/EditAccountModal.vue

@@ -735,6 +735,36 @@
         </div>
       </div>
 
+      <!-- Anthropic API Key 自动透传开关 -->
+      <div
+        v-if="account?.platform === 'anthropic' && account?.type === 'apikey'"
+        class="border-t border-gray-200 pt-4 dark:border-dark-600"
+      >
+        <div class="flex items-center justify-between">
+          <div>
+            <label class="input-label mb-0">{{ t('admin.accounts.anthropic.apiKeyPassthrough') }}</label>
+            <p class="mt-1 text-xs text-gray-500 dark:text-gray-400">
+              {{ t('admin.accounts.anthropic.apiKeyPassthroughDesc') }}
+            </p>
+          </div>
+          <button
+            type="button"
+            @click="anthropicPassthroughEnabled = !anthropicPassthroughEnabled"
+            :class="[
+              'relative inline-flex h-6 w-11 flex-shrink-0 cursor-pointer rounded-full border-2 border-transparent transition-colors duration-200 ease-in-out focus:outline-none focus:ring-2 focus:ring-primary-500 focus:ring-offset-2',
+              anthropicPassthroughEnabled ? 'bg-primary-600' : 'bg-gray-200 dark:bg-dark-600'
+            ]"
+          >
+            <span
+              :class="[
+                'pointer-events-none inline-block h-5 w-5 transform rounded-full bg-white shadow ring-0 transition duration-200 ease-in-out',
+                anthropicPassthroughEnabled ? 'translate-x-5' : 'translate-x-0'
+              ]"
+            />
+          </button>
+        </div>
+      </div>
+
       <!-- OpenAI OAuth Codex 官方客户端限制开关 -->
       <div
         v-if="account?.platform === 'openai' && account?.type === 'oauth'"
@@ -1223,6 +1253,7 @@ const cacheTTLOverrideTarget = ref<string>('5m')
 // OpenAI 自动透传开关（OAuth/API Key）
 const openaiPassthroughEnabled = ref(false)
 const codexCLIOnlyEnabled = ref(false)
+const anthropicPassthroughEnabled = ref(false)
 const isOpenAIModelRestrictionDisabled = computed(() =>
   props.account?.platform === 'openai' && openaiPassthroughEnabled.value
 )
@@ -1317,12 +1348,16 @@ watch(
       // Load OpenAI passthrough toggle (OpenAI OAuth/API Key)
       openaiPassthroughEnabled.value = false
       codexCLIOnlyEnabled.value = false
+      anthropicPassthroughEnabled.value = false
       if (newAccount.platform === 'openai' && (newAccount.type === 'oauth' || newAccount.type === 'apikey')) {
         openaiPassthroughEnabled.value = extra?.openai_passthrough === true || extra?.openai_oauth_passthrough === true
         if (newAccount.type === 'oauth') {
           codexCLIOnlyEnabled.value = extra?.codex_cli_only === true
         }
       }
+      if (newAccount.platform === 'anthropic' && newAccount.type === 'apikey') {
+        anthropicPassthroughEnabled.value = extra?.anthropic_passthrough === true
+      }
 
       // Load antigravity model mapping (Antigravity 只支持映射模式)
       if (newAccount.platform === 'antigravity') {
@@ -1882,6 +1917,18 @@ const handleSubmit = async () => {
       updatePayload.extra = newExtra
     }
 
+    // For Anthropic API Key accounts, handle passthrough mode in extra
+    if (props.account.platform === 'anthropic' && props.account.type === 'apikey') {
+      const currentExtra = (props.account.extra as Record<string, unknown>) || {}
+      const newExtra: Record<string, unknown> = { ...currentExtra }
+      if (anthropicPassthroughEnabled.value) {
+        newExtra.anthropic_passthrough = true
+      } else {
+        delete newExtra.anthropic_passthrough
+      }
+      updatePayload.extra = newExtra
+    }
+
     // For OpenAI OAuth/API Key accounts, handle passthrough mode in extra
     if (props.account.platform === 'openai' && (props.account.type === 'oauth' || props.account.type === 'apikey')) {
       const currentExtra = (props.account.extra as Record<string, unknown>) || {}

frontend/src/i18n/locales/en.ts

@@ -1546,6 +1546,11 @@ export default {
         enableSora: 'Enable Sora simultaneously',
         enableSoraHint: 'Sora uses the same OpenAI account. Enable to create Sora account simultaneously.'
       },
+      anthropic: {
+        apiKeyPassthrough: 'Auto passthrough (auth only)',
+        apiKeyPassthroughDesc:
+          'Only applies to Anthropic API Key accounts. When enabled, messages/count_tokens are forwarded in passthrough mode with auth replacement only, while billing/concurrency/audit and safety filtering are preserved. Disable to roll back immediately.'
+      },
       modelRestriction: 'Model Restriction (Optional)',
       modelWhitelist: 'Model Whitelist',
       modelMapping: 'Model Mapping',

frontend/src/i18n/locales/zh.ts

@@ -1694,6 +1694,11 @@ export default {
         enableSora: '同时启用 Sora',
         enableSoraHint: 'Sora 使用相同的 OpenAI 账号，开启后将同时创建 Sora 平台账号'
       },
+      anthropic: {
+        apiKeyPassthrough: '自动透传（仅替换认证）',
+        apiKeyPassthroughDesc:
+          '仅对 Anthropic API Key 生效。开启后，messages/count_tokens 请求将透传上游并仅替换认证，保留计费/并发/审计及必要安全过滤；关闭即可回滚到现有兼容链路。'
+      },
       modelRestriction: '模型限制（可选）',
       modelWhitelist: '模型白名单',
       modelMapping: '模型映射',