diff --git a/backend/internal/service/account.go b/backend/internal/service/account.go
index 1864eb54..fe6f432c 100644
--- a/backend/internal/service/account.go
+++ b/backend/internal/service/account.go
@@ -1137,6 +1137,77 @@ func (a *Account) GetSessionIdleTimeoutMinutes() int {
 	return 5
 }
 
+// GetBaseRPM 获取基础 RPM 限制
+// 返回 0 表示未启用
+func (a *Account) GetBaseRPM() int {
+	if a.Extra == nil {
+		return 0
+	}
+	if v, ok := a.Extra["base_rpm"]; ok {
+		return parseExtraInt(v)
+	}
+	return 0
+}
+
+// GetRPMStrategy 获取 RPM 策略
+// "tiered" = 三区模型（默认）, "sticky_exempt" = 粘性豁免
+func (a *Account) GetRPMStrategy() string {
+	if a.Extra == nil {
+		return "tiered"
+	}
+	if v, ok := a.Extra["rpm_strategy"]; ok {
+		if s, ok := v.(string); ok && s == "sticky_exempt" {
+			return "sticky_exempt"
+		}
+	}
+	return "tiered"
+}
+
+// GetRPMStickyBuffer 获取 RPM 粘性缓冲数量
+// tiered 模式下的黄区大小，默认为 base_rpm 的 20%（至少 1）
+func (a *Account) GetRPMStickyBuffer() int {
+	if a.Extra == nil {
+		return 0
+	}
+	if v, ok := a.Extra["rpm_sticky_buffer"]; ok {
+		val := parseExtraInt(v)
+		if val > 0 {
+			return val
+		}
+	}
+	base := a.GetBaseRPM()
+	buffer := base / 5
+	if buffer < 1 && base > 0 {
+		buffer = 1
+	}
+	return buffer
+}
+
+// CheckRPMSchedulability 根据当前 RPM 计数检查调度状态
+// 复用 WindowCostSchedulability 三态：Schedulable / StickyOnly / NotSchedulable
+func (a *Account) CheckRPMSchedulability(currentRPM int) WindowCostSchedulability {
+	baseRPM := a.GetBaseRPM()
+	if baseRPM <= 0 {
+		return WindowCostSchedulable
+	}
+
+	if currentRPM < baseRPM {
+		return WindowCostSchedulable
+	}
+
+	strategy := a.GetRPMStrategy()
+	if strategy == "sticky_exempt" {
+		return WindowCostStickyOnly // 粘性豁免无红区
+	}
+
+	// tiered: 黄区 + 红区
+	buffer := a.GetRPMStickyBuffer()
+	if currentRPM < baseRPM+buffer {
+		return WindowCostStickyOnly
+	}
+	return WindowCostNotSchedulable
+}
+
 // CheckWindowCostSchedulability 根据当前窗口费用检查调度状态
 // - 费用 < 阈值: WindowCostSchedulable（可正常调度）
 // - 费用 >= 阈值 且 < 阈值+预留: WindowCostStickyOnly（仅粘性会话）
diff --git a/backend/internal/service/account_rpm_test.go b/backend/internal/service/account_rpm_test.go
new file mode 100644
index 00000000..01797763
--- /dev/null
+++ b/backend/internal/service/account_rpm_test.go
@@ -0,0 +1,73 @@
+package service
+
+import "testing"
+
+func TestGetBaseRPM(t *testing.T) {
+	tests := []struct {
+		name     string
+		extra    map[string]any
+		expected int
+	}{
+		{"nil extra", nil, 0},
+		{"no key", map[string]any{}, 0},
+		{"zero", map[string]any{"base_rpm": 0}, 0},
+		{"int value", map[string]any{"base_rpm": 15}, 15},
+		{"float value", map[string]any{"base_rpm": 15.0}, 15},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := &Account{Extra: tt.extra}
+			if got := a.GetBaseRPM(); got != tt.expected {
+				t.Errorf("GetBaseRPM() = %d, want %d", got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestGetRPMStrategy(t *testing.T) {
+	tests := []struct {
+		name     string
+		extra    map[string]any
+		expected string
+	}{
+		{"nil extra", nil, "tiered"},
+		{"no key", map[string]any{}, "tiered"},
+		{"tiered", map[string]any{"rpm_strategy": "tiered"}, "tiered"},
+		{"sticky_exempt", map[string]any{"rpm_strategy": "sticky_exempt"}, "sticky_exempt"},
+		{"invalid", map[string]any{"rpm_strategy": "foobar"}, "tiered"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := &Account{Extra: tt.extra}
+			if got := a.GetRPMStrategy(); got != tt.expected {
+				t.Errorf("GetRPMStrategy() = %q, want %q", got, tt.expected)
+			}
+		})
+	}
+}
+
+func TestCheckRPMSchedulability(t *testing.T) {
+	tests := []struct {
+		name       string
+		extra      map[string]any
+		currentRPM int
+		expected   WindowCostSchedulability
+	}{
+		{"disabled", map[string]any{}, 100, WindowCostSchedulable},
+		{"green zone", map[string]any{"base_rpm": 15}, 10, WindowCostSchedulable},
+		{"yellow zone tiered", map[string]any{"base_rpm": 15}, 15, WindowCostStickyOnly},
+		{"red zone tiered", map[string]any{"base_rpm": 15}, 18, WindowCostNotSchedulable},
+		{"sticky_exempt at limit", map[string]any{"base_rpm": 15, "rpm_strategy": "sticky_exempt"}, 15, WindowCostStickyOnly},
+		{"sticky_exempt over limit", map[string]any{"base_rpm": 15, "rpm_strategy": "sticky_exempt"}, 100, WindowCostStickyOnly},
+		{"custom buffer", map[string]any{"base_rpm": 10, "rpm_sticky_buffer": 5}, 14, WindowCostStickyOnly},
+		{"custom buffer red", map[string]any{"base_rpm": 10, "rpm_sticky_buffer": 5}, 15, WindowCostNotSchedulable},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			a := &Account{Extra: tt.extra}
+			if got := a.CheckRPMSchedulability(tt.currentRPM); got != tt.expected {
+				t.Errorf("CheckRPMSchedulability(%d) = %d, want %d", tt.currentRPM, got, tt.expected)
+			}
+		})
+	}
+}