diff --git a/backend/internal/ai/tts/mimo.go b/backend/internal/ai/tts/mimo.go
index 208d301..5e80cbb 100644
--- a/backend/internal/ai/tts/mimo.go
+++ b/backend/internal/ai/tts/mimo.go
@@ -27,20 +27,16 @@ type MiMoService struct {
 }
 
 // NewMiMoService 创建 MiMo TTS 服务。
-func NewMiMoService(apiKey, model, voice, endpoint string, timeoutSec int, logger *zap.SugaredLogger) *MiMoService {
-	if model == "" {
-		model = "mimo-v2.5-tts"
-	}
-	if voice == "" {
-		voice = "冰糖"
-	}
-	if endpoint == "" {
-		endpoint = "https://api.xiaomimimo.com/v1"
-	}
+// model、voice、endpoint 由 config 层保证非空。
+func NewMiMoService(apiKey, model, voice, endpoint string, timeoutSec, httpClientTimeoutSec int, logger *zap.SugaredLogger) *MiMoService {
 	timeout := time.Duration(timeoutSec) * time.Second
 	if timeout <= 0 {
 		timeout = 5 * time.Second
 	}
+	httpClientTimeout := time.Duration(httpClientTimeoutSec) * time.Second
+	if httpClientTimeout <= 0 {
+		httpClientTimeout = 30 * time.Second
+	}
 	return &MiMoService{
 		apiKey:   apiKey,
 		model:    model,
@@ -48,7 +44,7 @@ func NewMiMoService(apiKey, model, voice, endpoint string, timeoutSec int, logge
 		endpoint: endpoint,
 		timeout:  timeout,
 		logger:   logger,
-		client:   &http.Client{Timeout: 30 * time.Second},
+		client:   &http.Client{Timeout: httpClientTimeout},
 	}
 }
 
diff --git a/backend/internal/ai/tts/openai.go b/backend/internal/ai/tts/openai.go
index 6e0123e..8741ce6 100644
--- a/backend/internal/ai/tts/openai.go
+++ b/backend/internal/ai/tts/openai.go
@@ -25,23 +25,19 @@ type OpenAIService struct {
 }
 
 // NewOpenAIService 创建 OpenAI TTS 服务。
-func NewOpenAIService(apiKey, model, voice, endpoint string, speed float64, timeoutSec int, logger *zap.SugaredLogger) *OpenAIService {
-	if model == "" {
-		model = "tts-1"
-	}
-	if voice == "" {
-		voice = "alloy"
-	}
+// model、voice、endpoint 由 config 层保证非空。
+func NewOpenAIService(apiKey, model, voice, endpoint string, speed float64, timeoutSec, httpClientTimeoutSec int, logger *zap.SugaredLogger) *OpenAIService {
 	if speed <= 0 {
 		speed = 1.0
 	}
-	if endpoint == "" {
-		endpoint = "https://api.openai.com/v1"
-	}
 	timeout := time.Duration(timeoutSec) * time.Second
 	if timeout <= 0 {
 		timeout = 5 * time.Second
 	}
+	httpClientTimeout := time.Duration(httpClientTimeoutSec) * time.Second
+	if httpClientTimeout <= 0 {
+		httpClientTimeout = 30 * time.Second
+	}
 	return &OpenAIService{
 		apiKey:   apiKey,
 		model:    model,
@@ -50,7 +46,7 @@ func NewOpenAIService(apiKey, model, voice, endpoint string, speed float64, time
 		endpoint: endpoint,
 		timeout:  timeout,
 		logger:   logger,
-		client:   &http.Client{Timeout: 30 * time.Second},
+		client:   &http.Client{Timeout: httpClientTimeout},
 	}
 }