diff --git a/internal/logic/admin/model.go b/internal/logic/admin/model.go
index b101769..5f683df 100644
--- a/internal/logic/admin/model.go
+++ b/internal/logic/admin/model.go
@@ -11,10 +11,12 @@ import (
 	"github.com/gogf/gf/v2/errors/gerror"
 	"github.com/gogf/gf/v2/frame/g"
 	"github.com/gogf/gf/v2/os/gtime"
+	"github.com/shopspring/decimal"
 
 	"github.com/qianfree/team-api/api/admin/v1"
 	"github.com/qianfree/team-api/internal/consts"
 	"github.com/qianfree/team-api/internal/dao"
+	"github.com/qianfree/team-api/internal/logic/billing"
 	"github.com/qianfree/team-api/internal/logic/common"
 	"github.com/qianfree/team-api/internal/logic/relay"
 	do "github.com/qianfree/team-api/internal/model/do"
@@ -506,10 +508,12 @@ func fetchLiteLLMSource(ctx context.Context, modelName string) *v1.OfficialPrici
 		return source
 	}
 
-	inputPrice := entry.InputCostPerToken * 1_000_000
-	outputPrice := entry.OutputCostPerToken * 1_000_000
-	cacheReadPrice := entry.CacheReadInputTokenCost * 1_000_000
-	cacheCreationPrice := entry.CacheCreationInputTokenCost * 1_000_000
+	// 修复定价单位转换：用 decimal 避免裸浮点乘法，将每 token 价格转换为每百万 token 价格
+	million := decimal.NewFromInt(1_000_000)
+	inputPrice := billing.RoundMoney(decimal.NewFromFloat(entry.InputCostPerToken).Mul(million))
+	outputPrice := billing.RoundMoney(decimal.NewFromFloat(entry.OutputCostPerToken).Mul(million))
+	cacheReadPrice := billing.RoundMoney(decimal.NewFromFloat(entry.CacheReadInputTokenCost).Mul(million))
+	cacheCreationPrice := billing.RoundMoney(decimal.NewFromFloat(entry.CacheCreationInputTokenCost).Mul(million))
 
 	billingMode := "token"
 	if entry.Mode == "image_generation" && entry.OutputCostPerImage > 0 && inputPrice == 0 && outputPrice == 0 {
@@ -522,10 +526,10 @@ func fetchLiteLLMSource(ctx context.Context, modelName string) *v1.OfficialPrici
 	source.MaxContext = entry.MaxInputTokens
 	source.MaxOutput = entry.MaxOutputTokens
 	source.Pricing = &v1.OfficialPricingItem{
-		InputPrice:         roundTo2(inputPrice),
-		OutputPrice:        roundTo2(outputPrice),
-		CacheReadPrice:     roundTo2(cacheReadPrice),
-		CacheCreationPrice: roundTo2(cacheCreationPrice),
+		InputPrice:         inputPrice,
+		OutputPrice:        outputPrice,
+		CacheReadPrice:     cacheReadPrice,
+		CacheCreationPrice: cacheCreationPrice,
 		BillingMode:        billingMode,
 	}
 
diff --git a/internal/logic/billing/money.go b/internal/logic/billing/money.go
index e1857b3..dd1d0cd 100644
--- a/internal/logic/billing/money.go
+++ b/internal/logic/billing/money.go
@@ -23,13 +23,19 @@ func dec(f float64) decimal.Decimal {
 	return decimal.NewFromFloat(f)
 }
 
-// roundMoney 将 decimal 金额四舍五入到 10 位小数（与 NUMERIC(20,10) 对齐）后返回 float64。
+// RoundMoney 将 decimal 金额四舍五入到 10 位小数（与 NUMERIC(20,10) 对齐）后返回 float64。
 // 用于把 decimal 精确计算的结果收敛到存储精度，作为 Go 层金额的统一出口。
-func roundMoney(d decimal.Decimal) float64 {
+// 导出给 admin/tenant 层调用（A8 Phase 1 扩展）。
+func RoundMoney(d decimal.Decimal) float64 {
 	f, _ := d.Round(moneyScale).Float64()
 	return f
 }
 
+// roundMoney 内部别名，保持向后兼容
+func roundMoney(d decimal.Decimal) float64 {
+	return RoundMoney(d)
+}
+
 // ceilUSD 将 decimal 金额向上取整到 6 位小数（钱包 USD 精度）后返回 float64。
 // 用于 CNY→USD 充值入账：宁可多给用户零头也不少给，且与展示精度一致。
 func ceilUSD(d decimal.Decimal) float64 {
@@ -52,3 +58,27 @@ func fromMicro(micro int64) float64 {
 	f, _ := decimal.New(micro, -6).Float64()
 	return f
 }
+
+// MultiplyMoney 金额精确乘法（A8 Phase 1 扩展）。
+// 用于替代裸浮点乘法，避免链式运算累积误差（如 price × months、amount × discount）。
+func MultiplyMoney(a, b float64) float64 {
+	return roundMoney(dec(a).Mul(dec(b)))
+}
+
+// DivideMoney 金额精确除法（A8 Phase 1 扩展）。
+// 用于替代裸浮点除法（如 totalCost / requests）。
+func DivideMoney(a, b float64) float64 {
+	return roundMoney(dec(a).Div(dec(b)))
+}
+
+// AddMoney 金额精确加法（A8 Phase 1 扩展）。
+// 用于循环累加避免误差放大。
+func AddMoney(a, b float64) float64 {
+	return roundMoney(dec(a).Add(dec(b)))
+}
+
+// SubtractMoney 金额精确减法（A8 Phase 1 扩展）。
+// 用于差额计算（如 available = balance - frozen）。
+func SubtractMoney(a, b float64) float64 {
+	return roundMoney(dec(a).Sub(dec(b)))
+}
diff --git a/internal/logic/billing/pricing.go b/internal/logic/billing/pricing.go
index 66cc7fc..68cd81e 100644
--- a/internal/logic/billing/pricing.go
+++ b/internal/logic/billing/pricing.go
@@ -502,7 +502,9 @@ func calculateTieredCostFromTiers(tiers []pricingTierRow, tokens int, isInput bo
 		return 0
 	}
 
-	var totalCost float64
+	// 修复阶梯定价循环累加：用 decimal 精确计算避免每次 ÷1M × price 的误差累积
+	million := decimal.NewFromInt(1_000_000)
+	totalCostD := decimal.Zero
 	remaining := int64(tokens)
 
 	for _, tier := range tiers {
@@ -516,7 +518,10 @@ func calculateTieredCostFromTiers(tiers []pricingTierRow, tokens int, isInput bo
 		}
 
 		if tier.MaxTokens == nil {
-			totalCost += float64(remaining) / 1_000_000.0 * price
+			// 最后一档：消耗所有剩余 token
+			totalCostD = totalCostD.Add(
+				decimal.NewFromInt(remaining).Div(million).Mul(dec(price)),
+			)
 			remaining = 0
 		} else {
 			available := *tier.MaxTokens - tier.MinTokens
@@ -527,10 +532,12 @@ func calculateTieredCostFromTiers(tiers []pricingTierRow, tokens int, isInput bo
 			if useTokens > available {
 				useTokens = available
 			}
-			totalCost += float64(useTokens) / 1_000_000.0 * price
+			totalCostD = totalCostD.Add(
+				decimal.NewFromInt(useTokens).Div(million).Mul(dec(price)),
+			)
 			remaining -= useTokens
 		}
 	}
 
-	return totalCost
+	return roundMoney(totalCostD)
 }
diff --git a/internal/logic/billing/task_billing.go b/internal/logic/billing/task_billing.go
index 1bb50cf..1f81526 100644
--- a/internal/logic/billing/task_billing.go
+++ b/internal/logic/billing/task_billing.go
@@ -8,6 +8,7 @@ import (
 
 	"github.com/gogf/gf/v2/frame/g"
 	"github.com/gogf/gf/v2/os/gtime"
+	"github.com/shopspring/decimal"
 
 	"github.com/qianfree/team-api/internal/dao"
 	do "github.com/qianfree/team-api/internal/model/do"
@@ -69,7 +70,12 @@ func estimateTaskCost(pricing *PricingResult, ratios map[string]float64) float64
 		// 预估 tokens ≈ base_tokens_per_second × duration × resolution_multiplier
 		// 火山方舟视频生成约 10000 tokens/s (480p 基准)，用于预扣估算
 		estimatedTokens := 10000.0 * duration * resolutionMul
-		cost = estimatedTokens / 1_000_000.0 * pricing.OutputPrice * pricing.TenantMultiplier
+		// 修复视频预扣三连乘：用 decimal 避免 ÷1M × 单价 × 倍率 的链式误差
+		million := decimal.NewFromInt(1_000_000)
+		costD := dec(estimatedTokens).Div(million).
+			Mul(dec(pricing.OutputPrice)).
+			Mul(dec(pricing.TenantMultiplier))
+		cost = roundMoney(costD)
 	default:
 		// 无时长信号（图片等扁平计费任务）：优先按次单价；未配按次价时用占位预扣，
 		// 绝不走视频 token 估算。结算阶段再按上游真实 token 用量多退少补
@@ -398,11 +404,11 @@ func (b *TaskBillingProviderImpl) RecalculateByTokens(ctx context.Context, tenan
 		return 0, nil
 	}
 
-	// 基础费用 = tokens × 单价
-	cost := float64(totalTokens) / 1_000_000.0 * pricing.OutputPrice
-
-	// 应用租户倍率
-	cost *= pricing.TenantMultiplier
+	// 修复 token 重算循环累乘：用 decimal 避免 ÷1M × 单价 × 倍率 × 循环比率 的链式误差
+	million := decimal.NewFromInt(1_000_000)
+	costD := decimal.NewFromInt(int64(totalTokens)).Div(million).
+		Mul(dec(pricing.OutputPrice)).
+		Mul(dec(pricing.TenantMultiplier))
 
 	// 应用附加比率（视频输入折扣等）
 	// 注意：跳过 duration/resolution，它们已体现在上游返回的 token 数中，不应再乘
@@ -410,9 +416,11 @@ func (b *TaskBillingProviderImpl) RecalculateByTokens(ctx context.Context, tenan
 		if k == "duration" || k == "resolution" {
 			continue
 		}
-		cost *= ratio
+		costD = costD.Mul(dec(ratio))
 	}
 
+	cost := roundMoney(costD)
+
 	// 最低消费
 	if cost < 0.01 {
 		cost = 0.01
diff --git a/internal/logic/tenant/billing.go b/internal/logic/tenant/billing.go
index 4050619..425af2a 100644
--- a/internal/logic/tenant/billing.go
+++ b/internal/logic/tenant/billing.go
@@ -66,7 +66,7 @@ func (s *sTenant) Wallet(ctx context.Context, req *v1.TenantWalletReq) (*v1.Tena
 	return &v1.TenantWalletRes{
 		Balance:          w.Balance,
 		FrozenBalance:    w.FrozenBalance,
-		AvailableBalance: w.Balance - w.FrozenBalance,
+		AvailableBalance: billing.SubtractMoney(w.Balance, w.FrozenBalance),
 		WarningThreshold: w.WarningThreshold,
 		Currency:         w.Currency,
 	}, nil
diff --git a/internal/logic/tenant/order.go b/internal/logic/tenant/order.go
index 27b08c3..b7ae7d0 100644
--- a/internal/logic/tenant/order.go
+++ b/internal/logic/tenant/order.go
@@ -14,6 +14,7 @@ import (
 	"github.com/qianfree/team-api/internal/dao"
 	do "github.com/qianfree/team-api/internal/model/do"
 
+	"github.com/qianfree/team-api/internal/logic/billing"
 	lcommon "github.com/qianfree/team-api/internal/logic/common"
 	"github.com/qianfree/team-api/internal/logic/payment"
 	"github.com/qianfree/team-api/internal/middleware"
@@ -111,7 +112,8 @@ func (s *sTenant) OrderCreate(ctx context.Context, req *v1.TenantOrderCreateReq)
 	if months >= 12 {
 		amount = plan.YearlyPrice
 	} else {
-		amount = plan.MonthlyPrice * float64(months)
+		// 修复订单金额连乘：用 decimal 避免 price × months 的浮点误差
+		amount = billing.MultiplyMoney(plan.MonthlyPrice, float64(months))
 	}
 
 	// 使用 crypto/rand 生成随机部分，避免碰撞
@@ -362,7 +364,8 @@ func (s *sTenant) RechargeCreate(ctx context.Context, req *v1.TenantRechargeCrea
 	finalAmount := req.Amount
 	if settings != nil {
 		if discount, ok := settings.AmountDiscount[int(req.Amount)]; ok && discount > 0 {
-			finalAmount = req.Amount * discount
+			// 修复充值折扣连乘：用 decimal 避免 amount × discount 的浮点误差
+			finalAmount = billing.MultiplyMoney(req.Amount, discount)
 		}
 	}
 
diff --git a/internal/logic/tenant/project.go b/internal/logic/tenant/project.go
index c79990e..3960736 100644
--- a/internal/logic/tenant/project.go
+++ b/internal/logic/tenant/project.go
@@ -167,7 +167,9 @@ func CheckProjectBudget(ctx context.Context, tenantID, projectID int64) error {
 	if err != nil {
 		return err
 	}
-	if totalCost < project.Budget {
+	// 修复预算超支浮点比较：加 epsilon 容差避免浮点误差导致误触发/漏触发
+	const epsilon = 0.000001 // 1 微美元容差
+	if totalCost < project.Budget-epsilon {
 		return nil
 	}
 
diff --git a/relay/channel/openai/audio.go b/relay/channel/openai/audio.go
index 728a1b4..6dca066 100644
--- a/relay/channel/openai/audio.go
+++ b/relay/channel/openai/audio.go
@@ -91,7 +91,8 @@ func extractAudioUsage(body []byte) *common.Usage {
 	var verboseResp dto.WhisperVerboseJSONResponse
 	if err := json.Unmarshal(body, &verboseResp); err == nil && verboseResp.Duration > 0 {
 		// 按音频时长估算：1 分钟 ≈ 150 tokens
-		estimatedTokens := int(verboseResp.Duration/60.0) * 150
+		// 修复浮点除法短扣：用整数运算 + 四舍五入避免 int(90/60.0)=1 丢失 0.5 分钟
+		estimatedTokens := (int(verboseResp.Duration)*150 + 30) / 60
 		if estimatedTokens == 0 {
 			estimatedTokens = 1
 		}