fix(billing): add kimi-for-coding fallback pricing

backend/internal/service/billing_service.go

@@ -420,6 +420,13 @@ func (s *BillingService) initFallbackPricing() {
 		CacheReadPricePerToken: 0.15e-6, // $0.15 per MTok (cache hit, ¥1.10)
 		SupportsCacheBreakdown: false,
 	}
+	// kimi-for-coding 走 Kimi Coding endpoint，按当前 K2.6 coding 档位兜底计费。
+	s.fallbackPrices["kimi-for-coding"] = &ModelPricing{
+		InputPricePerToken:     0.95e-6,
+		OutputPricePerToken:    4e-6,
+		CacheReadPricePerToken: 0.15e-6,
+		SupportsCacheBreakdown: false,
+	}
 	s.fallbackPrices["kimi-k2.5"] = &ModelPricing{
 		InputPricePerToken:     0.60e-6, // $0.60 per MTok
 		OutputPricePerToken:    3e-6,    // $3.00 per MTok
@@ -576,8 +583,11 @@ func (s *BillingService) getFallbackPricing(model string) *ModelPricing {
 		return s.fallbackPrices["glm-4-32b-0414-128k"]
 	}
 
-	// 月之暗面 Kimi（kimi-k2.6 / kimi-k2.5 / kimi-k2-thinking / kimi-k2）
+	// 月之暗面 Kimi（kimi-k2.6 / kimi-for-coding / kimi-k2.5 / kimi-k2-thinking / kimi-k2）
 	// K2-0905 / K2-0711 官方未保留定价，不进入 fallback。
+	if strings.Contains(modelLower, "kimi-for-coding") {
+		return s.fallbackPrices["kimi-for-coding"]
+	}
 	if strings.Contains(modelLower, "kimi-k2.6") || strings.Contains(modelLower, "kimi-k2-6") {
 		return s.fallbackPrices["kimi-k2.6"]
 	}

backend/internal/service/billing_service_test.go

@@ -494,6 +494,13 @@ func TestGetFallbackPricing_FamilyMatching(t *testing.T) {
 			expectedOutput:    floatPtr(4e-6),
 			expectedCacheRead: floatPtr(0.15e-6),
 		},
+		{
+			name:              "kimi for coding explicit alias",
+			model:             "kimi-for-coding",
+			expectedInput:     0.95e-6,
+			expectedOutput:    floatPtr(4e-6),
+			expectedCacheRead: floatPtr(0.15e-6),
+		},
 		{
 			name:              "kimi k2.5",
 			model:             "kimi-k2.5",