feat: add new indicators (Decay, Edecay, MinusDi, MinusDm, PlusDi, PlusDm, Maxindex, Minindex, Sarext) and update pine scripts, core libs, validation tests, and python bindings

lib/feeds/gbm/Gbm.Tests.cs

@@ -664,6 +664,36 @@ public class GBMTests
         Assert.False(gbm.HasCurrentBar);
     }
 
+    [Fact]
+    public void GBM_FetchThenNext_PriceContinuity()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+        long startTime = new DateTime(2024, 1, 1, 9, 30, 0, DateTimeKind.Utc).Ticks;
+        var interval = TimeSpan.FromMinutes(1);
+
+        var series = gbm.Fetch(5, startTime, interval);
+        double lastBatchClose = series[4].Close;
+
+        // Next bar after Fetch must open at the last batch close (price continuity)
+        var nextBar = gbm.Next(isNew: true);
+        Assert.Equal(lastBatchClose, nextBar.Open, 1e-10);
+    }
+
+    [Fact]
+    public void GBM_NextThenFetch_PriceContinuity()
+    {
+        var gbm = new GBM(startPrice: 100.0, seed: 42);
+
+        _ = gbm.Next(isNew: true);
+        var bar2 = gbm.Next(isNew: true);  // _lastPrice = bar2.Close
+
+        long startTime = bar2.Time + TimeSpan.FromMinutes(1).Ticks;
+        var series = gbm.Fetch(3, startTime, TimeSpan.FromMinutes(1));
+
+        // First bar of Fetch must open at bar2.Close
+        Assert.Equal(bar2.Close, series[0].Open, 1e-10);
+    }
+
     #endregion
 
     #region IFeed Interface Tests

lib/feeds/gbm/gbm.cs

@@ -120,6 +120,10 @@ public sealed class GBM : IFeed
     /// <summary>
     /// Resets the generator to its initial state.
     /// </summary>
+    /// <remarks>
+    /// Sets the internal time anchor to <see cref="DateTime.UtcNow"/>. For deterministic
+    /// time sequences use <see cref="Reset(long)"/> with an explicit start time.
+    /// </remarks>
     public void Reset()
     {
         _lastPrice = StartPrice;
@@ -284,6 +288,15 @@ public sealed class GBM : IFeed
     /// <returns>A TBarSeries containing the generated bars</returns>
     /// <exception cref="ArgumentException">Thrown when count is not positive</exception>
     /// <exception cref="ArgumentOutOfRangeException">Thrown when interval is not positive</exception>
+    /// <remarks>
+    /// Price continuity: <c>batch[0].Open</c> equals <c>_lastPrice</c> at call time, so the
+    /// batch begins exactly where the previous <see cref="Next(bool)"/> call left off.
+    /// After the call, <c>_lastPrice</c> and <c>_lastTime</c> are updated to the end of the
+    /// generated batch, enabling seamless continuation via subsequent <see cref="Next(bool)"/>
+    /// calls. <paramref name="startTime"/> need not follow the previous <c>_lastTime</c> —
+    /// this allows replaying a window or generating a non-contiguous batch while preserving
+    /// price continuity.
+    /// </remarks>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public TBarSeries Fetch(int count, long startTime, TimeSpan interval)
     {