Gas price index on a 7-day cycle

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/Decentralized.Domain.Tests/Program.cs

@@ -824,6 +824,13 @@ internal static class Program
             Check(Math.Abs(TxRules.FeeCredits(FeeTier.Fast, true) - Tuning.TxFeeFast * Tuning.TxCongestedFeeMult) < 1e-9, "拥堵时手续费翻倍");
             Check(TxRules.Confirmations(100) == 3 && TxRules.Confirmations(5000) == 6 && TxRules.Confirmations(50000) == 12, "大额要更多确认");
             Check(TxRules.DropChance(FeeTier.Slow, true) > 0 && TxRules.DropChance(FeeTier.Slow, false) == 0 && TxRules.DropChance(FeeTier.Fast, true) == 0, "只有拥堵时的慢档会被丢");
+            double lo = 9, hi = 0;
+            for (int dd = 0; dd < 7; dd++) { double g = TxRules.GasCycle(dd, 2); lo = Math.Min(lo, g); hi = Math.Max(hi, g); }
+            Check(Math.Abs(TxRules.GasCycle(3, 2) - TxRules.GasCycle(10, 2)) < 1e-9 && lo < 0.6 && hi > 1.4, $"gas 7 天一个周期，0.5×–1.5×：{lo:0.00}–{hi:0.00}");
+            var gr = new Rng(4); bool inRange = true;
+            for (int dd = 0; dd < 200; dd++) { double g = TxRules.Gas(dd, 0, gr); if (g < 0.5 * 0.85 - 1e-9 || g > 1.5 * 1.15 + 1e-9) inRange = false; }
+            Check(inRange, "加上随机波动后仍在 0.425–1.725");
+            Check(Math.Abs(TxRules.FeeCredits(FeeTier.Normal, false, 1.5) - Tuning.TxFeeNormal * 1.5) < 1e-9, "手续费乘 gas");
             var h = new List<TxRecord>();
             for (int i = 0; i < 30; i++) TxRules.Record(h, new TxRecord { Day = i });
             Check(h.Count == TxRules.HistoryMax && h[0].Day == 29, "记录最新在前、有上限");