fix(deepseek): 模型名校验不再默认兜底，未配置映射时按官方名单校验

- 未配置 model_mapping 的 DeepSeek 账号不再放行任意模型名，改为官方名单精确匹配
  （deepseek-flash / deepseek-v4-pro / deepseek-v4-flash /
   deepseek-v4-flash-vision-exp / deepseek-v4-pro-0813）
- 校验前先归一化：剥离 Claude Code 客户端上下文后缀 [1m]（含重复形式）并统一小写，
  使官方 Claude Code 接入写法 deepseek-flash[1m] 继续可用
- 未知模型名在调度阶段即拒绝，返回 404 model_not_found，避免透传上游后触发
  per-(账号,模型) 冷却、并避免上游把不认识的模型名静默兜底成 deepseek-flash
- 出站前剥离泄漏的 [1m] 后缀，仅作用于 DeepSeek 平台
- 配置了 model_mapping 的账号语义不变（映射优先）

backend/internal/service/account.go

@@ -848,6 +848,10 @@ func resolveRequestedModelInMapping(mapping map[string]string, requestedModel st
 // 会把未知模型原样透传，Codex 上游对这类模型必然返回不可重试的 400，导致
 // 请求卡死在该账号上、无法 failover 到真正支持该模型的 API Key 账号（#3662）。
 // 未知/自定义别名仍保持允许（兼容渠道级映射），见 isOpenAIOAuthServableModel。
+//
+// 例外：DeepSeek 平台的空映射不再是「允许所有」，改按官方模型白名单判定
+// （isDeepseekServableModel）——未知模型名透传上游只会得到 404/400，并误触发
+// per-(账号,模型) 30 分钟冷却；带 [1m] 上下文后缀的写法先归一化再比对。
 func (a *Account) IsModelSupported(requestedModel string) bool {
 	// 透传模式仅替换认证、模型语义完全交由上游决定，因此放行所有模型。
 	// 该短路必须在 model_mapping 判定之前：账号从"白名单模式"切换到透传后，
@@ -861,6 +865,9 @@ func (a *Account) IsModelSupported(requestedModel string) bool {
 		if a.IsOpenAIOAuth() {
 			return isOpenAIOAuthServableModel(requestedModel)
 		}
+		if a.Platform == PlatformDeepseek {
+			return isDeepseekServableModel(requestedModel)
+		}
 		return true // 无映射 = 允许所有
 	}
 	if mappingSupportsRequestedModel(mapping, requestedModel) {

backend/internal/service/account_wildcard_test.go

@@ -231,6 +231,82 @@ func TestAccountIsModelSupported(t *testing.T) {
 			requestedModel: "gemini-3-flash",
 			expected:       false,
 		},
+
+		// DeepSeek 空映射：官方模型白名单（不再是「允许所有」）
+		{
+			name:           "deepseek empty mapping allows official flash",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-flash",
+			expected:       true,
+		},
+		{
+			name:           "deepseek empty mapping normalizes claude code long context suffix",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-flash[1m]",
+			expected:       true,
+		},
+		{
+			name:           "deepseek empty mapping matches case-insensitively",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-FLASH",
+			expected:       true,
+		},
+		{
+			name:           "deepseek empty mapping allows versioned pro name",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-v4-pro-0813",
+			expected:       true,
+		},
+		{
+			name:           "deepseek empty mapping rejects retired chat model",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-chat",
+			expected:       false,
+		},
+		{
+			name:           "deepseek empty mapping rejects foreign claude model",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "claude-sonnet-4-6",
+			expected:       false,
+		},
+		{
+			name:           "deepseek empty mapping rejects unknown gpt model",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "gpt-future-model",
+			expected:       false,
+		},
+		{
+			name:           "deepseek empty mapping rejects typo",
+			platform:       PlatformDeepseek,
+			credentials:    map[string]any{},
+			requestedModel: "deepseek-flas",
+			expected:       false,
+		},
+		{
+			name:     "deepseek explicit mapping wins over whitelist",
+			platform: PlatformDeepseek,
+			credentials: map[string]any{
+				"model_mapping": map[string]any{
+					"foo-bar": "deepseek-flash",
+				},
+			},
+			requestedModel: "foo-bar",
+			expected:       true,
+		},
+		{
+			name:           "non deepseek empty mapping still allows all",
+			platform:       PlatformAnthropic,
+			credentials:    map[string]any{},
+			requestedModel: "any-model",
+			expected:       true,
+		},
 	}
 
 	for _, tt := range tests {

backend/internal/service/openai_codex_transform.go

@@ -1228,7 +1228,15 @@ func normalizeOpenAIModelForUpstream(account *Account, model string) string {
 	if account == nil || account.UsesOpenAICodexProtocol() {
 		return normalizeCodexModel(model)
 	}
-	return strings.TrimSpace(model)
+	model = strings.TrimSpace(model)
+	if account.Platform == PlatformDeepseek {
+		// DeepSeek 走 OpenAI 兼容入口，不经 Anthropic 入站的 [1m] 后缀归一
+		// （parseGatewayRequestCurrentBody 仅处理 PlatformAnthropic 协议）。
+		// 官方 Claude Code 接入要求 ANTHROPIC_MODEL=deepseek-flash[1m] 写法，
+		// 出站前剥离泄漏的客户端上下文后缀，转发规范名给上游。
+		return normalizeClaudeCodeLongContextModel(model)
+	}
+	return model
 }
 
 func SupportsVerbosity(model string) bool {

backend/internal/service/openai_model_mapping.go

@@ -82,6 +82,43 @@ func isOpenAIOAuthServableModel(requestedModel string) bool {
 	return true
 }
 
+// deepseekServableModels 列出 DeepSeek 平台账号在「未配置 model_mapping」时
+// 可服务的官方模型名（精确匹配，小写比较）。deepseek-flash 与 deepseek-v4-pro
+// 为官方现行名；deepseek-v4-flash / deepseek-v4-flash-vision-exp 为处于兼容
+// 路由期的旧名（上游仍接受并按 flash 价计费）；deepseek-v4-pro-0813 为与
+// 计费 pro 档口径一致的版本化名。
+var deepseekServableModels = []string{
+	"deepseek-flash",
+	"deepseek-v4-pro",
+	"deepseek-v4-flash",
+	"deepseek-v4-flash-vision-exp",
+	"deepseek-v4-pro-0813",
+}
+
+// isDeepseekServableModel 报告 DeepSeek 平台账号在「未配置 model_mapping」时
+// 可服务的模型名。官方现行模型为 deepseek-flash 与 deepseek-v4-pro；旧名
+// deepseek-v4-flash / deepseek-v4-flash-vision-exp 处于兼容路由期（上游仍接受并
+// 按 flash 价计费），deepseek-v4-pro-0813 为版本化名。其余一律拒绝：既避免把
+// 未知模型透传给上游（上游 404/400 会触发 per-model 冷却并掩盖真实配置错误），
+// 也避免上游把不认识的模型名静默兜底成 deepseek-flash。
+// Source: https://api-docs.deepseek.com/quick_start/pricing
+//
+//	https://api-docs.deepseek.com/guides/anthropic_api
+func isDeepseekServableModel(requestedModel string) bool {
+	// 官方 Claude Code 接入文档要求 ANTHROPIC_MODEL=deepseek-flash[1m]：
+	// [1m] 是客户端上下文选择器，先按同一规则归一化再比对白名单。
+	model := strings.ToLower(normalizeClaudeCodeLongContextModel(strings.TrimSpace(requestedModel)))
+	if model == "" {
+		return true // 空模型交由上层必填校验处理
+	}
+	for _, servable := range deepseekServableModels {
+		if model == servable {
+			return true
+		}
+	}
+	return false
+}
+
 // resolveOpenAICompactForwardModel determines the compact-only upstream model
 // for /responses/compact requests. It never affects normal /responses traffic.
 // When no compact-specific mapping matches, the input model is returned as-is.

backend/internal/service/openai_model_mapping_test.go

@@ -429,6 +429,30 @@ func TestNormalizeOpenAIModelForUpstream(t *testing.T) {
 			model:   "gpt-4.1",
 			want:    "gpt-4.1",
 		},
+		{
+			name:    "deepseek strips claude code long context suffix",
+			account: &Account{Type: AccountTypeAPIKey, Platform: PlatformDeepseek},
+			model:   "deepseek-flash[1m]",
+			want:    "deepseek-flash",
+		},
+		{
+			name:    "deepseek strips duplicated long context suffix",
+			account: &Account{Type: AccountTypeAPIKey, Platform: PlatformDeepseek},
+			model:   "deepseek-flash[1M][1m]",
+			want:    "deepseek-flash",
+		},
+		{
+			name:    "deepseek preserves plain model",
+			account: &Account{Type: AccountTypeAPIKey, Platform: PlatformDeepseek},
+			model:   "deepseek-flash",
+			want:    "deepseek-flash",
+		},
+		{
+			name:    "non deepseek preserves long context suffix",
+			account: &Account{Type: AccountTypeAPIKey, Platform: PlatformOpenAI},
+			model:   "deepseek-flash[1m]",
+			want:    "deepseek-flash[1m]",
+		},
 	}
 
 	for _, tt := range tests {