fix(trading): K线Y轴动态缩放 + 价格显示格式统一 + 首日涨幅修复

- K线图Y轴改为只基于可见K线计算范围，实现动态缩放（类似TradingView）
- 价格显示统一使用 0.0{n}xxx 格式替代科学计数法，覆盖全局 formatPrice、
  K线图、交易记录页、挖矿记录页
- 修复"较上线首日"百分比始终显示 +0.00% 的问题：getFirstSnapshot 过滤
  price=0 的早期快照

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/services/trading-service/src/infrastructure/persistence/repositories/price-snapshot.repository.ts

@@ -29,10 +29,11 @@ export class PriceSnapshotRepository {
   }
 
   /**
-   * 获取最早的价格快照（上线首日价格）
+   * 获取最早的非零价格快照（上线首日价格）
    */
   async getFirstSnapshot(): Promise<PriceSnapshotEntity | null> {
     const record = await this.prisma.priceSnapshot.findFirst({
+      where: { price: { gt: 0 } },
       orderBy: { snapshotTime: 'asc' },
     });
     if (!record) {

frontend/mining-app/lib/core/utils/format_utils.dart

@@ -44,7 +44,30 @@ String formatPercent(String? value, [int precision = 2]) {
 }
 
 String formatPrice(String? value) {
-  return formatDecimal(value, 8);
+  if (value == null || value.isEmpty) return '0';
+  try {
+    final decimal = Decimal.parse(value);
+    if (decimal >= Decimal.one) return decimal.toStringAsFixed(4);
+    if (decimal >= Decimal.parse('0.0001')) return decimal.toStringAsFixed(6);
+    if (decimal <= Decimal.zero) return '0';
+    // 0.00000980 → 0.0{5}980
+    final str = decimal.toStringAsFixed(18);
+    final dotIndex = str.indexOf('.');
+    int zeroCount = 0;
+    for (int i = dotIndex + 1; i < str.length; i++) {
+      if (str[i] == '0') {
+        zeroCount++;
+      } else {
+        break;
+      }
+    }
+    final sigStart = dotIndex + 1 + zeroCount;
+    final sigEnd = sigStart + 3 > str.length ? str.length : sigStart + 3;
+    final significant = str.substring(sigStart, sigEnd);
+    return '0.0{$zeroCount}$significant';
+  } catch (e) {
+    return '0';
+  }
 }
 
 String formatAmount(String? value) {

frontend/mining-app/lib/presentation/pages/profile/mining_records_page.dart

@@ -302,7 +302,24 @@ class _MiningRecordsListPageState extends ConsumerState<MiningRecordsListPage> {
   String _formatPrice(String price) {
     try {
       final value = double.parse(price);
-      return value.toStringAsFixed(8);
+      if (value >= 1) return value.toStringAsFixed(4);
+      if (value >= 0.0001) return value.toStringAsFixed(6);
+      if (value <= 0) return '0';
+      // 0.00000980 → 0.0{5}980
+      final str = value.toStringAsFixed(18);
+      final dotIndex = str.indexOf('.');
+      int zeroCount = 0;
+      for (int i = dotIndex + 1; i < str.length; i++) {
+        if (str[i] == '0') {
+          zeroCount++;
+        } else {
+          break;
+        }
+      }
+      final sigStart = dotIndex + 1 + zeroCount;
+      final sigEnd = sigStart + 3 > str.length ? str.length : sigStart + 3;
+      final significant = str.substring(sigStart, sigEnd);
+      return '0.0{$zeroCount}$significant';
     } catch (e) {
       return price;
     }

frontend/mining-app/lib/presentation/pages/profile/trading_records_page.dart

@@ -511,7 +511,24 @@ class _TradingRecordsPageState extends ConsumerState<TradingRecordsPage> with Si
   String _formatPrice(String price) {
     try {
       final value = double.parse(price);
-      return value.toStringAsFixed(4);
+      if (value >= 1) return value.toStringAsFixed(4);
+      if (value >= 0.0001) return value.toStringAsFixed(6);
+      if (value <= 0) return '0';
+      // 0.00000980 → 0.0{5}980
+      final str = value.toStringAsFixed(18);
+      final dotIndex = str.indexOf('.');
+      int zeroCount = 0;
+      for (int i = dotIndex + 1; i < str.length; i++) {
+        if (str[i] == '0') {
+          zeroCount++;
+        } else {
+          break;
+        }
+      }
+      final sigStart = dotIndex + 1 + zeroCount;
+      final sigEnd = sigStart + 3 > str.length ? str.length : sigStart + 3;
+      final significant = str.substring(sigStart, sigEnd);
+      return '0.0{$zeroCount}$significant';
     } catch (e) {
       return price;
     }

frontend/mining-app/lib/presentation/widgets/kline_chart/kline_chart_widget.dart

@@ -730,7 +730,22 @@ class _KlineChartWidgetState extends State<KlineChartWidget> {
   String _formatPrice(double price) {
     if (price >= 1) return price.toStringAsFixed(4);
     if (price >= 0.0001) return price.toStringAsFixed(6);
-    return price.toStringAsExponential(2);
+    if (price <= 0) return '0';
+    // 0.00000980 → 0.0{5}980
+    final str = price.toStringAsFixed(18);
+    final dotIndex = str.indexOf('.');
+    int zeroCount = 0;
+    for (int i = dotIndex + 1; i < str.length; i++) {
+      if (str[i] == '0') {
+        zeroCount++;
+      } else {
+        break;
+      }
+    }
+    final sigStart = dotIndex + 1 + zeroCount;
+    final sigEnd = math.min(sigStart + 3, str.length);
+    final significant = str.substring(sigStart, sigEnd);
+    return '0.0{$zeroCount}$significant';
   }
 
   String _formatVolume(double volume) {
@@ -746,17 +761,30 @@ class _KlineChartWidgetState extends State<KlineChartWidget> {
   }
 
   double _calcPriceY(double price, double chartHeight) {
-    if (widget.klines.isEmpty) return chartHeight / 2;
+    if (widget.klines.isEmpty || _chartWidth == 0) return chartHeight / 2;
+
+    // 与 KlinePainter 保持一致：只基于可见K线计算Y轴范围
+    const leftPadding = 8.0;
+    const rightPadding = 50.0;
+    final drawableWidth = _chartWidth - leftPadding - rightPadding;
+
+    final visibleStart = math.max(0, (_scrollX / _candleWidth - 2).floor());
+    final visibleEnd = math.min(widget.klines.length - 1, ((_scrollX + drawableWidth) / _candleWidth + 1).ceil());
 
     double minPrice = double.infinity;
     double maxPrice = double.negativeInfinity;
-    for (final kline in widget.klines) {
+    for (int i = visibleStart; i <= visibleEnd; i++) {
+      final kline = widget.klines[i];
       final low = double.tryParse(kline.low) ?? 0;
       final high = double.tryParse(kline.high) ?? 0;
       if (low < minPrice) minPrice = low;
       if (high > maxPrice) maxPrice = high;
     }
 
+    if (minPrice == double.infinity || maxPrice == double.negativeInfinity) {
+      return chartHeight / 2;
+    }
+
     final range = maxPrice - minPrice;
     // 防止 range 为 0 导致 NaN
     final safeRange = range > 0 ? range : (maxPrice > 0 ? maxPrice * 0.1 : 1.0);

frontend/mining-app/lib/presentation/widgets/kline_chart/kline_painter.dart

@@ -59,21 +59,31 @@ class KlinePainter extends CustomPainter {
     final chartWidth = size.width - leftPadding - rightPadding;
     final chartHeight = size.height - topPadding - bottomPadding;
 
-    // 计算价格范围
+    // 计算K线宽度（提前计算，用于确定可见范围）
+    final actualCandleWidth = candleWidth ?? (chartWidth / klines.length);
+    final bodyWidth = math.max(actualCandleWidth * 0.7, 2.0);
+
+    // 计算可见K线的索引范围
+    final visibleStart = math.max(0, (scrollOffset / actualCandleWidth - 2).floor());
+    final visibleEnd = math.min(klines.length - 1, ((scrollOffset + chartWidth) / actualCandleWidth + 1).ceil());
+
+    // 计算价格范围（只基于可见K线，实现Y轴动态缩放）
     double minPrice = double.infinity;
     double maxPrice = double.negativeInfinity;
 
-    for (final kline in klines) {
+    for (int i = visibleStart; i <= visibleEnd; i++) {
+      final kline = klines[i];
       final low = double.tryParse(kline.low) ?? 0;
       final high = double.tryParse(kline.high) ?? 0;
       if (low < minPrice) minPrice = low;
       if (high > maxPrice) maxPrice = high;
     }
 
-    // 考虑MA/EMA/BOLL线的范围
+    // 考虑可见区域内MA/EMA/BOLL线的范围
     if (maData != null) {
       for (final values in maData!.values) {
-        for (final v in values) {
+        for (int i = visibleStart; i <= visibleEnd && i < values.length; i++) {
+          final v = values[i];
           if (v != null) {
             if (v < minPrice) minPrice = v;
             if (v > maxPrice) maxPrice = v;
@@ -84,7 +94,8 @@ class KlinePainter extends CustomPainter {
 
     if (emaData != null) {
       for (final values in emaData!.values) {
-        for (final v in values) {
+        for (int i = visibleStart; i <= visibleEnd && i < values.length; i++) {
+          final v = values[i];
           if (v != null) {
             if (v < minPrice) minPrice = v;
             if (v > maxPrice) maxPrice = v;
@@ -95,7 +106,8 @@ class KlinePainter extends CustomPainter {
 
     if (bollData != null) {
       for (final values in bollData!.values) {
-        for (final v in values) {
+        for (int i = visibleStart; i <= visibleEnd && i < values.length; i++) {
+          final v = values[i];
           if (v != null) {
             if (v < minPrice) minPrice = v;
             if (v > maxPrice) maxPrice = v;
@@ -104,6 +116,12 @@ class KlinePainter extends CustomPainter {
       }
     }
 
+    // 防止无可见数据时的异常
+    if (minPrice == double.infinity || maxPrice == double.negativeInfinity) {
+      minPrice = 0;
+      maxPrice = 1;
+    }
+
     // 添加上下留白
     final priceRange = maxPrice - minPrice;
     // 避免 priceRange 为 0 导致 NaN
@@ -122,10 +140,6 @@ class KlinePainter extends CustomPainter {
     // 绘制网格和价格标签
     _drawGrid(canvas, size, minPrice, maxPrice, leftPadding, rightPadding, topPadding, chartHeight);
 
-    // 计算K线宽度 - 使用传入的宽度或自动计算
-    final actualCandleWidth = candleWidth ?? (chartWidth / klines.length);
-    final bodyWidth = math.max(actualCandleWidth * 0.7, 2.0);
-
     // 裁剪绘图区域，防止K线超出边界
     canvas.save();
     canvas.clipRect(Rect.fromLTRB(leftPadding, 0, size.width - rightPadding, size.height));
@@ -540,7 +554,22 @@ class KlinePainter extends CustomPainter {
   String _formatPrice(double price) {
     if (price >= 1) return price.toStringAsFixed(4);
     if (price >= 0.0001) return price.toStringAsFixed(6);
-    return price.toStringAsExponential(2);
+    if (price <= 0) return '0';
+    // 0.00000980 → 0.0{5}980
+    final str = price.toStringAsFixed(18);
+    final dotIndex = str.indexOf('.');
+    int zeroCount = 0;
+    for (int i = dotIndex + 1; i < str.length; i++) {
+      if (str[i] == '0') {
+        zeroCount++;
+      } else {
+        break;
+      }
+    }
+    final sigStart = dotIndex + 1 + zeroCount;
+    final sigEnd = math.min(sigStart + 3, str.length);
+    final significant = str.substring(sigStart, sigEnd);
+    return '0.0{$zeroCount}$significant';
   }
 
   @override