refactor(usage): modularize UsagePage into separate section components

src/components/usage/ApiDetailsCard.tsx

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+import { useState } from 'react';
+import { useTranslation } from 'react-i18next';
+import { Card } from '@/components/ui/Card';
+import { formatTokensInMillions, formatUsd, type ApiStats } from '@/utils/usage';
+import styles from '@/pages/UsagePage.module.scss';
+
+export interface ApiDetailsCardProps {
+  apiStats: ApiStats[];
+  loading: boolean;
+  hasPrices: boolean;
+}
+
+export function ApiDetailsCard({ apiStats, loading, hasPrices }: ApiDetailsCardProps) {
+  const { t } = useTranslation();
+  const [expandedApis, setExpandedApis] = useState<Set<string>>(new Set());
+
+  const toggleExpand = (endpoint: string) => {
+    setExpandedApis((prev) => {
+      const newSet = new Set(prev);
+      if (newSet.has(endpoint)) {
+        newSet.delete(endpoint);
+      } else {
+        newSet.add(endpoint);
+      }
+      return newSet;
+    });
+  };
+
+  return (
+    <Card title={t('usage_stats.api_details')}>
+      {loading ? (
+        <div className={styles.hint}>{t('common.loading')}</div>
+      ) : apiStats.length > 0 ? (
+        <div className={styles.apiList}>
+          {apiStats.map((api) => (
+            <div key={api.endpoint} className={styles.apiItem}>
+              <div className={styles.apiHeader} onClick={() => toggleExpand(api.endpoint)}>
+                <div className={styles.apiInfo}>
+                  <span className={styles.apiEndpoint}>{api.endpoint}</span>
+                  <div className={styles.apiStats}>
+                    <span className={styles.apiBadge}>
+                      {t('usage_stats.requests_count')}: {api.totalRequests}
+                    </span>
+                    <span className={styles.apiBadge}>
+                      Tokens: {formatTokensInMillions(api.totalTokens)}
+                    </span>
+                    {hasPrices && api.totalCost > 0 && (
+                      <span className={styles.apiBadge}>
+                        {t('usage_stats.total_cost')}: {formatUsd(api.totalCost)}
+                      </span>
+                    )}
+                  </div>
+                </div>
+                <span className={styles.expandIcon}>
+                  {expandedApis.has(api.endpoint) ? '▼' : '▶'}
+                </span>
+              </div>
+              {expandedApis.has(api.endpoint) && (
+                <div className={styles.apiModels}>
+                  {Object.entries(api.models).map(([model, stats]) => (
+                    <div key={model} className={styles.modelRow}>
+                      <span className={styles.modelName}>{model}</span>
+                      <span className={styles.modelStat}>
+                        {stats.requests} {t('usage_stats.requests_count')}
+                      </span>
+                      <span className={styles.modelStat}>{formatTokensInMillions(stats.tokens)}</span>
+                    </div>
+                  ))}
+                </div>
+              )}
+            </div>
+          ))}
+        </div>
+      ) : (
+        <div className={styles.hint}>{t('usage_stats.no_data')}</div>
+      )}
+    </Card>
+  );
+}

src/components/usage/ChartLineSelector.tsx

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+import { useTranslation } from 'react-i18next';
+import { Card } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
+import styles from '@/pages/UsagePage.module.scss';
+
+export interface ChartLineSelectorProps {
+  chartLines: string[];
+  modelNames: string[];
+  maxLines?: number;
+  onChange: (lines: string[]) => void;
+}
+
+export function ChartLineSelector({
+  chartLines,
+  modelNames,
+  maxLines = 9,
+  onChange
+}: ChartLineSelectorProps) {
+  const { t } = useTranslation();
+
+  const handleAdd = () => {
+    if (chartLines.length >= maxLines) return;
+    const unusedModel = modelNames.find((m) => !chartLines.includes(m));
+    if (unusedModel) {
+      onChange([...chartLines, unusedModel]);
+    } else {
+      onChange([...chartLines, 'all']);
+    }
+  };
+
+  const handleRemove = (index: number) => {
+    if (chartLines.length <= 1) return;
+    const newLines = [...chartLines];
+    newLines.splice(index, 1);
+    onChange(newLines);
+  };
+
+  const handleChange = (index: number, value: string) => {
+    const newLines = [...chartLines];
+    newLines[index] = value;
+    onChange(newLines);
+  };
+
+  return (
+    <Card
+      title={t('usage_stats.chart_line_actions_label')}
+      extra={
+        <div className={styles.chartLineHeader}>
+          <span className={styles.chartLineCount}>
+            {chartLines.length}/{maxLines}
+          </span>
+          <Button
+            variant="secondary"
+            size="sm"
+            onClick={handleAdd}
+            disabled={chartLines.length >= maxLines}
+          >
+            {t('usage_stats.chart_line_add')}
+          </Button>
+        </div>
+      }
+    >
+      <div className={styles.chartLineList}>
+        {chartLines.map((line, index) => (
+          <div key={index} className={styles.chartLineItem}>
+            <span className={styles.chartLineLabel}>
+              {t(`usage_stats.chart_line_label_${index + 1}`)}
+            </span>
+            <select
+              value={line}
+              onChange={(e) => handleChange(index, e.target.value)}
+              className={styles.select}
+            >
+              <option value="all">{t('usage_stats.chart_line_all')}</option>
+              {modelNames.map((name) => (
+                <option key={name} value={name}>
+                  {name}
+                </option>
+              ))}
+            </select>
+            {chartLines.length > 1 && (
+              <Button variant="danger" size="sm" onClick={() => handleRemove(index)}>
+                {t('usage_stats.chart_line_delete')}
+              </Button>
+            )}
+          </div>
+        ))}
+      </div>
+      <p className={styles.chartLineHint}>{t('usage_stats.chart_line_hint')}</p>
+    </Card>
+  );
+}

src/components/usage/ModelStatsCard.tsx

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+import { useTranslation } from 'react-i18next';
+import { Card } from '@/components/ui/Card';
+import { formatTokensInMillions, formatUsd } from '@/utils/usage';
+import styles from '@/pages/UsagePage.module.scss';
+
+export interface ModelStat {
+  model: string;
+  requests: number;
+  tokens: number;
+  cost: number;
+}
+
+export interface ModelStatsCardProps {
+  modelStats: ModelStat[];
+  loading: boolean;
+  hasPrices: boolean;
+}
+
+export function ModelStatsCard({ modelStats, loading, hasPrices }: ModelStatsCardProps) {
+  const { t } = useTranslation();
+
+  return (
+    <Card title={t('usage_stats.models')}>
+      {loading ? (
+        <div className={styles.hint}>{t('common.loading')}</div>
+      ) : modelStats.length > 0 ? (
+        <div className={styles.tableWrapper}>
+          <table className={styles.table}>
+            <thead>
+              <tr>
+                <th>{t('usage_stats.model_name')}</th>
+                <th>{t('usage_stats.requests_count')}</th>
+                <th>{t('usage_stats.tokens_count')}</th>
+                {hasPrices && <th>{t('usage_stats.total_cost')}</th>}
+              </tr>
+            </thead>
+            <tbody>
+              {modelStats.map((stat) => (
+                <tr key={stat.model}>
+                  <td className={styles.modelCell}>{stat.model}</td>
+                  <td>{stat.requests.toLocaleString()}</td>
+                  <td>{formatTokensInMillions(stat.tokens)}</td>
+                  {hasPrices && <td>{stat.cost > 0 ? formatUsd(stat.cost) : '--'}</td>}
+                </tr>
+              ))}
+            </tbody>
+          </table>
+        </div>
+      ) : (
+        <div className={styles.hint}>{t('usage_stats.no_data')}</div>
+      )}
+    </Card>
+  );
+}

src/components/usage/PriceSettingsCard.tsx

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+import { useState } from 'react';
+import { useTranslation } from 'react-i18next';
+import { Card } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
+import { Input } from '@/components/ui/Input';
+import type { ModelPrice } from '@/utils/usage';
+import styles from '@/pages/UsagePage.module.scss';
+
+export interface PriceSettingsCardProps {
+  modelNames: string[];
+  modelPrices: Record<string, ModelPrice>;
+  onPricesChange: (prices: Record<string, ModelPrice>) => void;
+}
+
+export function PriceSettingsCard({
+  modelNames,
+  modelPrices,
+  onPricesChange
+}: PriceSettingsCardProps) {
+  const { t } = useTranslation();
+
+  const [selectedModel, setSelectedModel] = useState('');
+  const [promptPrice, setPromptPrice] = useState('');
+  const [completionPrice, setCompletionPrice] = useState('');
+  const [cachePrice, setCachePrice] = useState('');
+
+  const handleSavePrice = () => {
+    if (!selectedModel) return;
+    const prompt = parseFloat(promptPrice) || 0;
+    const completion = parseFloat(completionPrice) || 0;
+    const cache = cachePrice.trim() === '' ? prompt : parseFloat(cachePrice) || 0;
+    const newPrices = { ...modelPrices, [selectedModel]: { prompt, completion, cache } };
+    onPricesChange(newPrices);
+    setSelectedModel('');
+    setPromptPrice('');
+    setCompletionPrice('');
+    setCachePrice('');
+  };
+
+  const handleDeletePrice = (model: string) => {
+    const newPrices = { ...modelPrices };
+    delete newPrices[model];
+    onPricesChange(newPrices);
+  };
+
+  const handleEditPrice = (model: string) => {
+    const price = modelPrices[model];
+    setSelectedModel(model);
+    setPromptPrice(price?.prompt?.toString() || '');
+    setCompletionPrice(price?.completion?.toString() || '');
+    setCachePrice(price?.cache?.toString() || '');
+  };
+
+  const handleModelSelect = (value: string) => {
+    setSelectedModel(value);
+    const price = modelPrices[value];
+    if (price) {
+      setPromptPrice(price.prompt.toString());
+      setCompletionPrice(price.completion.toString());
+      setCachePrice(price.cache.toString());
+    } else {
+      setPromptPrice('');
+      setCompletionPrice('');
+      setCachePrice('');
+    }
+  };
+
+  return (
+    <Card title={t('usage_stats.model_price_settings')}>
+      <div className={styles.pricingSection}>
+        {/* Price Form */}
+        <div className={styles.priceForm}>
+          <div className={styles.formRow}>
+            <div className={styles.formField}>
+              <label>{t('usage_stats.model_name')}</label>
+              <select
+                value={selectedModel}
+                onChange={(e) => handleModelSelect(e.target.value)}
+                className={styles.select}
+              >
+                <option value="">{t('usage_stats.model_price_select_placeholder')}</option>
+                {modelNames.map((name) => (
+                  <option key={name} value={name}>
+                    {name}
+                  </option>
+                ))}
+              </select>
+            </div>
+            <div className={styles.formField}>
+              <label>{t('usage_stats.model_price_prompt')} ($/1M)</label>
+              <Input
+                type="number"
+                value={promptPrice}
+                onChange={(e) => setPromptPrice(e.target.value)}
+                placeholder="0.00"
+                step="0.0001"
+              />
+            </div>
+            <div className={styles.formField}>
+              <label>{t('usage_stats.model_price_completion')} ($/1M)</label>
+              <Input
+                type="number"
+                value={completionPrice}
+                onChange={(e) => setCompletionPrice(e.target.value)}
+                placeholder="0.00"
+                step="0.0001"
+              />
+            </div>
+            <div className={styles.formField}>
+              <label>{t('usage_stats.model_price_cache')} ($/1M)</label>
+              <Input
+                type="number"
+                value={cachePrice}
+                onChange={(e) => setCachePrice(e.target.value)}
+                placeholder="0.00"
+                step="0.0001"
+              />
+            </div>
+            <Button variant="primary" onClick={handleSavePrice} disabled={!selectedModel}>
+              {t('common.save')}
+            </Button>
+          </div>
+        </div>
+
+        {/* Saved Prices List */}
+        <div className={styles.pricesList}>
+          <h4 className={styles.pricesTitle}>{t('usage_stats.saved_prices')}</h4>
+          {Object.keys(modelPrices).length > 0 ? (
+            <div className={styles.pricesGrid}>
+              {Object.entries(modelPrices).map(([model, price]) => (
+                <div key={model} className={styles.priceItem}>
+                  <div className={styles.priceInfo}>
+                    <span className={styles.priceModel}>{model}</span>
+                    <div className={styles.priceMeta}>
+                      <span>
+                        {t('usage_stats.model_price_prompt')}: ${price.prompt.toFixed(4)}/1M
+                      </span>
+                      <span>
+                        {t('usage_stats.model_price_completion')}: ${price.completion.toFixed(4)}/1M
+                      </span>
+                      <span>
+                        {t('usage_stats.model_price_cache')}: ${price.cache.toFixed(4)}/1M
+                      </span>
+                    </div>
+                  </div>
+                  <div className={styles.priceActions}>
+                    <Button variant="secondary" size="sm" onClick={() => handleEditPrice(model)}>
+                      {t('common.edit')}
+                    </Button>
+                    <Button variant="danger" size="sm" onClick={() => handleDeletePrice(model)}>
+                      {t('common.delete')}
+                    </Button>
+                  </div>
+                </div>
+              ))}
+            </div>
+          ) : (
+            <div className={styles.hint}>{t('usage_stats.model_price_empty')}</div>
+          )}
+        </div>
+      </div>
+    </Card>
+  );
+}

src/components/usage/StatCards.tsx

@@ -0,0 +1,184 @@
+import type { CSSProperties, ReactNode } from 'react';
+import { useTranslation } from 'react-i18next';
+import { Line } from 'react-chartjs-2';
+import { IconDiamond, IconDollarSign, IconSatellite, IconTimer, IconTrendingUp } from '@/components/ui/icons';
+import {
+  formatTokensInMillions,
+  formatPerMinuteValue,
+  formatUsd,
+  calculateTokenBreakdown,
+  calculateRecentPerMinuteRates,
+  calculateTotalCost,
+  type ModelPrice
+} from '@/utils/usage';
+import { sparklineOptions } from '@/utils/usage/chartConfig';
+import type { UsagePayload } from './hooks/useUsageData';
+import type { SparklineBundle } from './hooks/useSparklines';
+import styles from '@/pages/UsagePage.module.scss';
+
+interface StatCardData {
+  key: string;
+  label: string;
+  icon: ReactNode;
+  accent: string;
+  accentSoft: string;
+  accentBorder: string;
+  value: string;
+  meta?: ReactNode;
+  trend: SparklineBundle | null;
+}
+
+export interface StatCardsProps {
+  usage: UsagePayload | null;
+  loading: boolean;
+  modelPrices: Record<string, ModelPrice>;
+  sparklines: {
+    requests: SparklineBundle | null;
+    tokens: SparklineBundle | null;
+    rpm: SparklineBundle | null;
+    tpm: SparklineBundle | null;
+    cost: SparklineBundle | null;
+  };
+}
+
+export function StatCards({ usage, loading, modelPrices, sparklines }: StatCardsProps) {
+  const { t } = useTranslation();
+
+  const tokenBreakdown = usage ? calculateTokenBreakdown(usage) : { cachedTokens: 0, reasoningTokens: 0 };
+  const rateStats = usage
+    ? calculateRecentPerMinuteRates(30, usage)
+    : { rpm: 0, tpm: 0, windowMinutes: 30, requestCount: 0, tokenCount: 0 };
+  const totalCost = usage ? calculateTotalCost(usage, modelPrices) : 0;
+  const hasPrices = Object.keys(modelPrices).length > 0;
+
+  const statsCards: StatCardData[] = [
+    {
+      key: 'requests',
+      label: t('usage_stats.total_requests'),
+      icon: <IconSatellite size={16} />,
+      accent: '#3b82f6',
+      accentSoft: 'rgba(59, 130, 246, 0.18)',
+      accentBorder: 'rgba(59, 130, 246, 0.35)',
+      value: loading ? '-' : (usage?.total_requests ?? 0).toLocaleString(),
+      meta: (
+        <>
+          <span className={styles.statMetaItem}>
+            <span className={styles.statMetaDot} style={{ backgroundColor: '#10b981' }} />
+            {t('usage_stats.success_requests')}: {loading ? '-' : (usage?.success_count ?? 0)}
+          </span>
+          <span className={styles.statMetaItem}>
+            <span className={styles.statMetaDot} style={{ backgroundColor: '#ef4444' }} />
+            {t('usage_stats.failed_requests')}: {loading ? '-' : (usage?.failure_count ?? 0)}
+          </span>
+        </>
+      ),
+      trend: sparklines.requests
+    },
+    {
+      key: 'tokens',
+      label: t('usage_stats.total_tokens'),
+      icon: <IconDiamond size={16} />,
+      accent: '#8b5cf6',
+      accentSoft: 'rgba(139, 92, 246, 0.18)',
+      accentBorder: 'rgba(139, 92, 246, 0.35)',
+      value: loading ? '-' : formatTokensInMillions(usage?.total_tokens ?? 0),
+      meta: (
+        <>
+          <span className={styles.statMetaItem}>
+            {t('usage_stats.cached_tokens')}: {loading ? '-' : formatTokensInMillions(tokenBreakdown.cachedTokens)}
+          </span>
+          <span className={styles.statMetaItem}>
+            {t('usage_stats.reasoning_tokens')}: {loading ? '-' : formatTokensInMillions(tokenBreakdown.reasoningTokens)}
+          </span>
+        </>
+      ),
+      trend: sparklines.tokens
+    },
+    {
+      key: 'rpm',
+      label: t('usage_stats.rpm_30m'),
+      icon: <IconTimer size={16} />,
+      accent: '#22c55e',
+      accentSoft: 'rgba(34, 197, 94, 0.18)',
+      accentBorder: 'rgba(34, 197, 94, 0.32)',
+      value: loading ? '-' : formatPerMinuteValue(rateStats.rpm),
+      meta: (
+        <span className={styles.statMetaItem}>
+          {t('usage_stats.total_requests')}: {loading ? '-' : rateStats.requestCount.toLocaleString()}
+        </span>
+      ),
+      trend: sparklines.rpm
+    },
+    {
+      key: 'tpm',
+      label: t('usage_stats.tpm_30m'),
+      icon: <IconTrendingUp size={16} />,
+      accent: '#f97316',
+      accentSoft: 'rgba(249, 115, 22, 0.18)',
+      accentBorder: 'rgba(249, 115, 22, 0.32)',
+      value: loading ? '-' : formatPerMinuteValue(rateStats.tpm),
+      meta: (
+        <span className={styles.statMetaItem}>
+          {t('usage_stats.total_tokens')}: {loading ? '-' : formatTokensInMillions(rateStats.tokenCount)}
+        </span>
+      ),
+      trend: sparklines.tpm
+    },
+    {
+      key: 'cost',
+      label: t('usage_stats.total_cost'),
+      icon: <IconDollarSign size={16} />,
+      accent: '#f59e0b',
+      accentSoft: 'rgba(245, 158, 11, 0.18)',
+      accentBorder: 'rgba(245, 158, 11, 0.32)',
+      value: loading ? '-' : hasPrices ? formatUsd(totalCost) : '--',
+      meta: (
+        <>
+          <span className={styles.statMetaItem}>
+            {t('usage_stats.total_tokens')}: {loading ? '-' : formatTokensInMillions(usage?.total_tokens ?? 0)}
+          </span>
+          {!hasPrices && (
+            <span className={`${styles.statMetaItem} ${styles.statSubtle}`}>
+              {t('usage_stats.cost_need_price')}
+            </span>
+          )}
+        </>
+      ),
+      trend: hasPrices ? sparklines.cost : null
+    }
+  ];
+
+  return (
+    <div className={styles.statsGrid}>
+      {statsCards.map((card) => (
+        <div
+          key={card.key}
+          className={styles.statCard}
+          style={
+            {
+              '--accent': card.accent,
+              '--accent-soft': card.accentSoft,
+              '--accent-border': card.accentBorder
+            } as CSSProperties
+          }
+        >
+          <div className={styles.statCardHeader}>
+            <div className={styles.statLabelGroup}>
+              <span className={styles.statLabel}>{card.label}</span>
+            </div>
+            <span className={styles.statIconBadge}>{card.icon}</span>
+          </div>
+          <div className={styles.statValue}>{card.value}</div>
+          {card.meta && <div className={styles.statMetaRow}>{card.meta}</div>}
+          <div className={styles.statTrend}>
+            {card.trend ? (
+              <Line className={styles.sparkline} data={card.trend.data} options={sparklineOptions} />
+            ) : (
+              <div className={styles.statTrendPlaceholder}></div>
+            )}
+          </div>
+        </div>
+      ))}
+    </div>
+  );
+}

src/components/usage/UsageChart.tsx

@@ -0,0 +1,91 @@
+import { useTranslation } from 'react-i18next';
+import type { ChartOptions } from 'chart.js';
+import { Line } from 'react-chartjs-2';
+import { Card } from '@/components/ui/Card';
+import { Button } from '@/components/ui/Button';
+import type { ChartData } from '@/utils/usage';
+import { getHourChartMinWidth } from '@/utils/usage/chartConfig';
+import styles from '@/pages/UsagePage.module.scss';
+
+export interface UsageChartProps {
+  title: string;
+  period: 'hour' | 'day';
+  onPeriodChange: (period: 'hour' | 'day') => void;
+  chartData: ChartData;
+  chartOptions: ChartOptions<'line'>;
+  loading: boolean;
+  isMobile: boolean;
+  emptyText: string;
+}
+
+export function UsageChart({
+  title,
+  period,
+  onPeriodChange,
+  chartData,
+  chartOptions,
+  loading,
+  isMobile,
+  emptyText
+}: UsageChartProps) {
+  const { t } = useTranslation();
+
+  return (
+    <Card
+      title={title}
+      extra={
+        <div className={styles.periodButtons}>
+          <Button
+            variant={period === 'hour' ? 'primary' : 'secondary'}
+            size="sm"
+            onClick={() => onPeriodChange('hour')}
+          >
+            {t('usage_stats.by_hour')}
+          </Button>
+          <Button
+            variant={period === 'day' ? 'primary' : 'secondary'}
+            size="sm"
+            onClick={() => onPeriodChange('day')}
+          >
+            {t('usage_stats.by_day')}
+          </Button>
+        </div>
+      }
+    >
+      {loading ? (
+        <div className={styles.hint}>{t('common.loading')}</div>
+      ) : chartData.labels.length > 0 ? (
+        <div className={styles.chartWrapper}>
+          <div className={styles.chartLegend} aria-label="Chart legend">
+            {chartData.datasets.map((dataset, index) => (
+              <div
+                key={`${dataset.label}-${index}`}
+                className={styles.legendItem}
+                title={dataset.label}
+              >
+                <span className={styles.legendDot} style={{ backgroundColor: dataset.borderColor }} />
+                <span className={styles.legendLabel}>{dataset.label}</span>
+              </div>
+            ))}
+          </div>
+          <div className={styles.chartArea}>
+            <div className={styles.chartScroller}>
+              <div
+                className={styles.chartCanvas}
+                style={
+                  period === 'hour'
+                    ? { minWidth: getHourChartMinWidth(chartData.labels.length, isMobile) }
+                    : undefined
+                }
+              >
+                <Line data={chartData} options={chartOptions} />
+              </div>
+            </div>
+          </div>
+        </div>
+      ) : (
+        <div className={styles.hint}>{emptyText}</div>
+      )}
+    </Card>
+  );
+}

src/components/usage/hooks/index.ts

@@ -0,0 +1,8 @@
+export { useUsageData } from './useUsageData';
+export type { UsagePayload, UseUsageDataReturn } from './useUsageData';
+
+export { useSparklines } from './useSparklines';
+export type { SparklineData, SparklineBundle, UseSparklinesOptions, UseSparklinesReturn } from './useSparklines';
+
+export { useChartData } from './useChartData';
+export type { UseChartDataOptions, UseChartDataReturn } from './useChartData';

src/components/usage/hooks/useChartData.ts

@@ -0,0 +1,76 @@
+import { useState, useMemo } from 'react';
+import type { ChartOptions } from 'chart.js';
+import { buildChartData, type ChartData } from '@/utils/usage';
+import { buildChartOptions } from '@/utils/usage/chartConfig';
+import type { UsagePayload } from './useUsageData';
+
+export interface UseChartDataOptions {
+  usage: UsagePayload | null;
+  chartLines: string[];
+  isDark: boolean;
+  isMobile: boolean;
+}
+
+export interface UseChartDataReturn {
+  requestsPeriod: 'hour' | 'day';
+  setRequestsPeriod: (period: 'hour' | 'day') => void;
+  tokensPeriod: 'hour' | 'day';
+  setTokensPeriod: (period: 'hour' | 'day') => void;
+  requestsChartData: ChartData;
+  tokensChartData: ChartData;
+  requestsChartOptions: ChartOptions<'line'>;
+  tokensChartOptions: ChartOptions<'line'>;
+}
+
+export function useChartData({
+  usage,
+  chartLines,
+  isDark,
+  isMobile
+}: UseChartDataOptions): UseChartDataReturn {
+  const [requestsPeriod, setRequestsPeriod] = useState<'hour' | 'day'>('day');
+  const [tokensPeriod, setTokensPeriod] = useState<'hour' | 'day'>('day');
+
+  const requestsChartData = useMemo(() => {
+    if (!usage) return { labels: [], datasets: [] };
+    return buildChartData(usage, requestsPeriod, 'requests', chartLines);
+  }, [usage, requestsPeriod, chartLines]);
+
+  const tokensChartData = useMemo(() => {
+    if (!usage) return { labels: [], datasets: [] };
+    return buildChartData(usage, tokensPeriod, 'tokens', chartLines);
+  }, [usage, tokensPeriod, chartLines]);
+
+  const requestsChartOptions = useMemo(
+    () =>
+      buildChartOptions({
+        period: requestsPeriod,
+        labels: requestsChartData.labels,
+        isDark,
+        isMobile
+      }),
+    [requestsPeriod, requestsChartData.labels, isDark, isMobile]
+  );
+
+  const tokensChartOptions = useMemo(
+    () =>
+      buildChartOptions({
+        period: tokensPeriod,
+        labels: tokensChartData.labels,
+        isDark,
+        isMobile
+      }),
+    [tokensPeriod, tokensChartData.labels, isDark, isMobile]
+  );
+
+  return {
+    requestsPeriod,
+    setRequestsPeriod,
+    tokensPeriod,
+    setTokensPeriod,
+    requestsChartData,
+    tokensChartData,
+    requestsChartOptions,
+    tokensChartOptions
+  };
+}

src/components/usage/hooks/useSparklines.ts

@@ -0,0 +1,138 @@
+import { useCallback, useMemo } from 'react';
+import { collectUsageDetails, extractTotalTokens } from '@/utils/usage';
+import type { UsagePayload } from './useUsageData';
+
+export interface SparklineData {
+  labels: string[];
+  datasets: [
+    {
+      data: number[];
+      borderColor: string;
+      backgroundColor: string;
+      fill: boolean;
+      tension: number;
+      pointRadius: number;
+      borderWidth: number;
+    }
+  ];
+}
+
+export interface SparklineBundle {
+  data: SparklineData;
+}
+
+export interface UseSparklinesOptions {
+  usage: UsagePayload | null;
+  loading: boolean;
+}
+
+export interface UseSparklinesReturn {
+  requestsSparkline: SparklineBundle | null;
+  tokensSparkline: SparklineBundle | null;
+  rpmSparkline: SparklineBundle | null;
+  tpmSparkline: SparklineBundle | null;
+  costSparkline: SparklineBundle | null;
+}
+
+export function useSparklines({ usage, loading }: UseSparklinesOptions): UseSparklinesReturn {
+  const buildLastHourSeries = useCallback(
+    (metric: 'requests' | 'tokens'): { labels: string[]; data: number[] } => {
+      if (!usage) return { labels: [], data: [] };
+      const details = collectUsageDetails(usage);
+      if (!details.length) return { labels: [], data: [] };
+
+      const windowMinutes = 60;
+      const now = Date.now();
+      const windowStart = now - windowMinutes * 60 * 1000;
+      const buckets = new Array(windowMinutes).fill(0);
+
+      details.forEach((detail) => {
+        const timestamp = Date.parse(detail.timestamp);
+        if (Number.isNaN(timestamp) || timestamp < windowStart) {
+          return;
+        }
+        const minuteIndex = Math.min(
+          windowMinutes - 1,
+          Math.floor((timestamp - windowStart) / 60000)
+        );
+        const increment = metric === 'tokens' ? extractTotalTokens(detail) : 1;
+        buckets[minuteIndex] += increment;
+      });
+
+      const labels = buckets.map((_, idx) => {
+        const date = new Date(windowStart + (idx + 1) * 60000);
+        const h = date.getHours().toString().padStart(2, '0');
+        const m = date.getMinutes().toString().padStart(2, '0');
+        return `${h}:${m}`;
+      });
+
+      return { labels, data: buckets };
+    },
+    [usage]
+  );
+
+  const buildSparkline = useCallback(
+    (
+      series: { labels: string[]; data: number[] },
+      color: string,
+      backgroundColor: string
+    ): SparklineBundle | null => {
+      if (loading || !series?.data?.length) {
+        return null;
+      }
+      const sliceStart = Math.max(series.data.length - 60, 0);
+      const labels = series.labels.slice(sliceStart);
+      const points = series.data.slice(sliceStart);
+      return {
+        data: {
+          labels,
+          datasets: [
+            {
+              data: points,
+              borderColor: color,
+              backgroundColor,
+              fill: true,
+              tension: 0.45,
+              pointRadius: 0,
+              borderWidth: 2
+            }
+          ]
+        }
+      };
+    },
+    [loading]
+  );
+
+  const requestsSparkline = useMemo(
+    () => buildSparkline(buildLastHourSeries('requests'), '#3b82f6', 'rgba(59, 130, 246, 0.18)'),
+    [buildLastHourSeries, buildSparkline]
+  );
+
+  const tokensSparkline = useMemo(
+    () => buildSparkline(buildLastHourSeries('tokens'), '#8b5cf6', 'rgba(139, 92, 246, 0.18)'),
+    [buildLastHourSeries, buildSparkline]
+  );
+
+  const rpmSparkline = useMemo(
+    () => buildSparkline(buildLastHourSeries('requests'), '#22c55e', 'rgba(34, 197, 94, 0.18)'),
+    [buildLastHourSeries, buildSparkline]
+  );
+
+  const tpmSparkline = useMemo(
+    () => buildSparkline(buildLastHourSeries('tokens'), '#f97316', 'rgba(249, 115, 22, 0.18)'),
+    [buildLastHourSeries, buildSparkline]
+  );
+
+  const costSparkline = useMemo(
+    () => buildSparkline(buildLastHourSeries('tokens'), '#f59e0b', 'rgba(245, 158, 11, 0.18)'),
+    [buildLastHourSeries, buildSparkline]
+  );
+
+  return {
+    requestsSparkline,
+    tokensSparkline,
+    rpmSparkline,
+    tpmSparkline,
+    costSparkline
+  };
+}

src/components/usage/hooks/useUsageData.ts

@@ -0,0 +1,153 @@
+import { useEffect, useState, useCallback, useRef } from 'react';
+import { useTranslation } from 'react-i18next';
+import { useNotificationStore } from '@/stores';
+import { usageApi } from '@/services/api/usage';
+import { loadModelPrices, saveModelPrices, type ModelPrice } from '@/utils/usage';
+
+export interface UsagePayload {
+  total_requests?: number;
+  success_count?: number;
+  failure_count?: number;
+  total_tokens?: number;
+  apis?: Record<string, unknown>;
+  [key: string]: unknown;
+}
+
+export interface UseUsageDataReturn {
+  usage: UsagePayload | null;
+  loading: boolean;
+  error: string;
+  modelPrices: Record<string, ModelPrice>;
+  setModelPrices: (prices: Record<string, ModelPrice>) => void;
+  loadUsage: () => Promise<void>;
+  handleExport: () => Promise<void>;
+  handleImport: () => void;
+  handleImportChange: (event: React.ChangeEvent<HTMLInputElement>) => Promise<void>;
+  importInputRef: React.RefObject<HTMLInputElement | null>;
+  exporting: boolean;
+  importing: boolean;
+}
+
+export function useUsageData(): UseUsageDataReturn {
+  const { t } = useTranslation();
+  const { showNotification } = useNotificationStore();
+
+  const [usage, setUsage] = useState<UsagePayload | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState('');
+  const [modelPrices, setModelPrices] = useState<Record<string, ModelPrice>>({});
+  const [exporting, setExporting] = useState(false);
+  const [importing, setImporting] = useState(false);
+  const importInputRef = useRef<HTMLInputElement | null>(null);
+
+  const loadUsage = useCallback(async () => {
+    setLoading(true);
+    setError('');
+    try {
+      const data = await usageApi.getUsage();
+      const payload = data?.usage ?? data;
+      setUsage(payload);
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : t('usage_stats.loading_error');
+      setError(message);
+    } finally {
+      setLoading(false);
+    }
+  }, [t]);
+
+  useEffect(() => {
+    loadUsage();
+    setModelPrices(loadModelPrices());
+  }, [loadUsage]);
+
+  const handleExport = async () => {
+    setExporting(true);
+    try {
+      const data = await usageApi.exportUsage();
+      const exportedAt =
+        typeof data?.exported_at === 'string' ? new Date(data.exported_at) : new Date();
+      const safeTimestamp = Number.isNaN(exportedAt.getTime())
+        ? new Date().toISOString()
+        : exportedAt.toISOString();
+      const filename = `usage-export-${safeTimestamp.replace(/[:.]/g, '-')}.json`;
+      const blob = new Blob([JSON.stringify(data ?? {}, null, 2)], { type: 'application/json' });
+      const url = window.URL.createObjectURL(blob);
+      const link = document.createElement('a');
+      link.href = url;
+      link.download = filename;
+      link.click();
+      window.URL.revokeObjectURL(url);
+      showNotification(t('usage_stats.export_success'), 'success');
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : '';
+      showNotification(
+        `${t('notification.download_failed')}${message ? `: ${message}` : ''}`,
+        'error'
+      );
+    } finally {
+      setExporting(false);
+    }
+  };
+
+  const handleImport = () => {
+    importInputRef.current?.click();
+  };
+
+  const handleImportChange = async (event: React.ChangeEvent<HTMLInputElement>) => {
+    const file = event.target.files?.[0];
+    event.target.value = '';
+    if (!file) return;
+
+    setImporting(true);
+    try {
+      const text = await file.text();
+      let payload: unknown;
+      try {
+        payload = JSON.parse(text);
+      } catch {
+        showNotification(t('usage_stats.import_invalid'), 'error');
+        return;
+      }
+
+      const result = await usageApi.importUsage(payload);
+      showNotification(
+        t('usage_stats.import_success', {
+          added: result?.added ?? 0,
+          skipped: result?.skipped ?? 0,
+          total: result?.total_requests ?? 0,
+          failed: result?.failed_requests ?? 0
+        }),
+        'success'
+      );
+      await loadUsage();
+    } catch (err: unknown) {
+      const message = err instanceof Error ? err.message : '';
+      showNotification(
+        `${t('notification.upload_failed')}${message ? `: ${message}` : ''}`,
+        'error'
+      );
+    } finally {
+      setImporting(false);
+    }
+  };
+
+  const handleSetModelPrices = useCallback((prices: Record<string, ModelPrice>) => {
+    setModelPrices(prices);
+    saveModelPrices(prices);
+  }, []);
+
+  return {
+    usage,
+    loading,
+    error,
+    modelPrices,
+    setModelPrices: handleSetModelPrices,
+    loadUsage,
+    handleExport,
+    handleImport,
+    handleImportChange,
+    importInputRef,
+    exporting,
+    importing
+  };
+}

src/components/usage/index.ts

@@ -0,0 +1,28 @@
+// Hooks
+export { useUsageData } from './hooks/useUsageData';
+export type { UsagePayload, UseUsageDataReturn } from './hooks/useUsageData';
+
+export { useSparklines } from './hooks/useSparklines';
+export type { SparklineData, SparklineBundle, UseSparklinesOptions, UseSparklinesReturn } from './hooks/useSparklines';
+
+export { useChartData } from './hooks/useChartData';
+export type { UseChartDataOptions, UseChartDataReturn } from './hooks/useChartData';
+
+// Components
+export { StatCards } from './StatCards';
+export type { StatCardsProps } from './StatCards';
+
+export { UsageChart } from './UsageChart';
+export type { UsageChartProps } from './UsageChart';
+
+export { ChartLineSelector } from './ChartLineSelector';
+export type { ChartLineSelectorProps } from './ChartLineSelector';
+
+export { ApiDetailsCard } from './ApiDetailsCard';
+export type { ApiDetailsCardProps } from './ApiDetailsCard';
+
+export { ModelStatsCard } from './ModelStatsCard';
+export type { ModelStatsCardProps, ModelStat } from './ModelStatsCard';
+
+export { PriceSettingsCard } from './PriceSettingsCard';
+export type { PriceSettingsCardProps } from './PriceSettingsCard';

src/utils/usage/chartConfig.ts

@@ -0,0 +1,142 @@
+/**
+ * Chart.js configuration utilities for usage statistics
+ * Extracted from UsagePage.tsx for reusability
+ */
+
+import type { ChartOptions } from 'chart.js';
+
+/**
+ * Static sparkline chart options (no dependencies on theme/mobile)
+ */
+export const sparklineOptions: ChartOptions<'line'> = {
+  responsive: true,
+  maintainAspectRatio: false,
+  plugins: { legend: { display: false }, tooltip: { enabled: false } },
+  scales: { x: { display: false }, y: { display: false } },
+  elements: { line: { tension: 0.45 }, point: { radius: 0 } }
+};
+
+export interface ChartConfigOptions {
+  period: 'hour' | 'day';
+  labels: string[];
+  isDark: boolean;
+  isMobile: boolean;
+}
+
+/**
+ * Build chart options with theme and responsive awareness
+ */
+export function buildChartOptions({
+  period,
+  labels,
+  isDark,
+  isMobile
+}: ChartConfigOptions): ChartOptions<'line'> {
+  const pointRadius = isMobile && period === 'hour' ? 0 : isMobile ? 2 : 4;
+  const tickFontSize = isMobile ? 10 : 12;
+  const maxTickLabelCount = isMobile ? (period === 'hour' ? 8 : 6) : period === 'hour' ? 12 : 10;
+  const gridColor = isDark ? 'rgba(255, 255, 255, 0.06)' : 'rgba(17, 24, 39, 0.06)';
+  const axisBorderColor = isDark ? 'rgba(255, 255, 255, 0.10)' : 'rgba(17, 24, 39, 0.10)';
+  const tickColor = isDark ? 'rgba(255, 255, 255, 0.72)' : 'rgba(17, 24, 39, 0.72)';
+  const tooltipBg = isDark ? 'rgba(17, 24, 39, 0.92)' : 'rgba(255, 255, 255, 0.98)';
+  const tooltipTitle = isDark ? '#ffffff' : '#111827';
+  const tooltipBody = isDark ? 'rgba(255, 255, 255, 0.86)' : '#374151';
+  const tooltipBorder = isDark ? 'rgba(255, 255, 255, 0.10)' : 'rgba(17, 24, 39, 0.10)';
+
+  return {
+    responsive: true,
+    maintainAspectRatio: false,
+    interaction: {
+      mode: 'index',
+      intersect: false
+    },
+    plugins: {
+      legend: { display: false },
+      tooltip: {
+        backgroundColor: tooltipBg,
+        titleColor: tooltipTitle,
+        bodyColor: tooltipBody,
+        borderColor: tooltipBorder,
+        borderWidth: 1,
+        padding: 10,
+        displayColors: true,
+        usePointStyle: true
+      }
+    },
+    scales: {
+      x: {
+        grid: {
+          color: gridColor,
+          drawTicks: false
+        },
+        border: {
+          color: axisBorderColor
+        },
+        ticks: {
+          color: tickColor,
+          font: { size: tickFontSize },
+          maxRotation: isMobile ? 0 : 45,
+          minRotation: 0,
+          autoSkip: true,
+          maxTicksLimit: maxTickLabelCount,
+          callback: (value) => {
+            const index = typeof value === 'number' ? value : Number(value);
+            const raw =
+              Number.isFinite(index) && labels[index] ? labels[index] : typeof value === 'string' ? value : '';
+
+            if (period === 'hour') {
+              const [md, time] = raw.split(' ');
+              if (!time) return raw;
+              if (time.startsWith('00:')) {
+                return md ? [md, time] : time;
+              }
+              return time;
+            }
+
+            if (isMobile) {
+              const parts = raw.split('-');
+              if (parts.length === 3) {
+                return `${parts[1]}-${parts[2]}`;
+              }
+            }
+            return raw;
+          }
+        }
+      },
+      y: {
+        beginAtZero: true,
+        grid: {
+          color: gridColor
+        },
+        border: {
+          color: axisBorderColor
+        },
+        ticks: {
+          color: tickColor,
+          font: { size: tickFontSize }
+        }
+      }
+    },
+    elements: {
+      line: {
+        tension: 0.35,
+        borderWidth: isMobile ? 1.5 : 2
+      },
+      point: {
+        borderWidth: 2,
+        radius: pointRadius,
+        hoverRadius: 4
+      }
+    }
+  };
+}
+
+/**
+ * Calculate minimum chart width for hourly data on mobile devices
+ */
+export function getHourChartMinWidth(labelCount: number, isMobile: boolean): string | undefined {
+  if (!isMobile || labelCount <= 0) return undefined;
+  const perPoint = 56;
+  const minWidth = Math.min(labelCount * perPoint, 3000);
+  return `${minWidth}px`;
+}

src/utils/usage/index.ts

@@ -0,0 +1,6 @@
+// Chart configuration utilities
+export { sparklineOptions, buildChartOptions, getHourChartMinWidth } from './chartConfig';
+export type { ChartConfigOptions } from './chartConfig';
+
+// Re-export everything from the main usage.ts for backwards compatibility
+export * from '../usage';