feat: implement tiered billing expression evaluation and related functionality

- Added support for tiered billing expressions in the billing system.
- Introduced new types and functions for handling billing expressions, including caching and execution.
- Updated existing billing logic to accommodate tiered billing scenarios.
- Enhanced request handling to support incoming billing expression requests.
- Added tests for tiered billing functionality to ensure correctness.

web/src/pages/Setting/Ratio/components/ModelPricingEditor.jsx

@@ -17,7 +17,7 @@ along with this program. If not, see <https://www.gnu.org/licenses/>.
 For commercial licensing, please contact support@quantumnous.com
 */
 
-import React, { useMemo, useState } from 'react';
+import React, { useCallback, useMemo, useState } from 'react';
 import {
   Banner,
   Button,
@@ -49,6 +49,7 @@ import {
   useModelPricingEditorState,
 } from '../hooks/useModelPricingEditorState';
 import { useIsMobile } from '../../../../hooks/common/useIsMobile';
+import TieredPricingEditor from './TieredPricingEditor';
 
 const { Text } = Typography;
 const EMPTY_CANDIDATE_MODEL_NAMES = [];
@@ -123,6 +124,8 @@ export default function ModelPricingEditor({
     handleOptionalFieldToggle,
     handleNumericFieldChange,
     handleBillingModeChange,
+    handleBillingExprChange,
+    handleRequestRuleExprChange,
     handleSubmit,
     addModel,
     deleteModel,
@@ -135,6 +138,15 @@ export default function ModelPricingEditor({
     filterMode,
   });
 
+  const getExprModeLabel = useCallback((model) => {
+    if (model?.billingMode !== 'tiered_expr') {
+      return '';
+    }
+    return (model.billingExpr || '').includes('tier(')
+      ? t('阶梯计费')
+      : t('表达式计费');
+  }, [t]);
+
   const columns = useMemo(
     () => [
       {
@@ -175,10 +187,20 @@ export default function ModelPricingEditor({
         dataIndex: 'billingMode',
         key: 'billingMode',
         render: (_, record) => (
-          <Tag color={record.billingMode === 'per-request' ? 'teal' : 'violet'}>
+          <Tag
+            color={
+              record.billingMode === 'per-request'
+                ? 'teal'
+                : record.billingMode === 'tiered_expr'
+                  ? 'amber'
+                  : 'violet'
+            }
+          >
             {record.billingMode === 'per-request'
               ? t('按次计费')
-              : t('按量计费')}
+              : record.billingMode === 'tiered_expr'
+                ? getExprModeLabel(record)
+                : t('按量计费')}
           </Tag>
         ),
       },
@@ -208,6 +230,7 @@ export default function ModelPricingEditor({
     [
       allowDeleteModel,
       deleteModel,
+      getExprModeLabel,
       selectedModelName,
       selectedModelNames,
       setSelectedModelName,
@@ -353,10 +376,20 @@ export default function ModelPricingEditor({
             title={selectedModel ? selectedModel.name : t('模型计费编辑器')}
             headerExtraContent={
               selectedModel ? (
-                <Tag color='blue'>
+                <Tag
+                  color={
+                    selectedModel.billingMode === 'per-request'
+                      ? 'teal'
+                      : selectedModel.billingMode === 'tiered_expr'
+                        ? 'amber'
+                        : 'blue'
+                  }
+                >
                   {selectedModel.billingMode === 'per-request'
                     ? t('按次计费')
-                    : t('按量计费')}
+                    : selectedModel.billingMode === 'tiered_expr'
+                      ? getExprModeLabel(selectedModel)
+                      : t('按量计费')}
                 </Tag>
               ) : null
             }
@@ -381,10 +414,11 @@ export default function ModelPricingEditor({
                   >
                     <Radio value='per-token'>{t('按量计费')}</Radio>
                     <Radio value='per-request'>{t('按次计费')}</Radio>
+                    <Radio value='tiered_expr'>{t('表达式/阶梯计费')}</Radio>
                   </RadioGroup>
                   <div className='mt-2 text-xs text-gray-500'>
                     {t(
-                      '这个界面默认按价格填写，保存时会自动换算回后端需要的倍率 JSON。',
+                      '普通按量/按次直接填价格就行；如果价格要跟请求参数或请求头联动，请切到表达式/阶梯计费。',
                     )}
                   </div>
                 </div>
@@ -415,6 +449,14 @@ export default function ModelPricingEditor({
                     onChange={(value) => handleNumericFieldChange('fixedPrice', value)}
                     extraText={t('适合 MJ / 任务类等按次收费模型。')}
                   />
+                ) : selectedModel.billingMode === 'tiered_expr' ? (
+                  <TieredPricingEditor
+                    model={selectedModel}
+                    onExprChange={handleBillingExprChange}
+                    requestRuleExpr={selectedModel.requestRuleExpr}
+                    onRequestRuleExprChange={handleRequestRuleExprChange}
+                    t={t}
+                  />
                 ) : (
                   <>
                     <Card