docs: remove C# Implementation Considerations sections, clean up temp scripts, reorganize test files

- Remove 'C# Implementation Considerations' sections from 34 indicator .md files
- Delete 29 temp PowerShell scripts (_fix_mojibake.ps1, _hex_scan.ps1, etc.)
- Move test files into tests/ subdirectories for consistent project structure
- Add trader-focused bullet points to indicator documentation

lib/reversals/psar/tests/Psar.Quantower.Tests.cs

@@ -0,0 +1,133 @@
+using TradingPlatform.BusinessLayer;
+using QuanTAlib;
+
+namespace QuanTAlib.Tests;
+
+public sealed class PsarIndicatorTests
+{
+    [Fact]
+    public void PsarIndicator_Constructor_SetsDefaults()
+    {
+        var indicator = new PsarIndicator();
+
+        Assert.Equal(0.02, indicator.AfStart);
+        Assert.Equal(0.02, indicator.AfIncrement);
+        Assert.Equal(0.20, indicator.AfMax);
+        Assert.True(indicator.ShowColdValues);
+        Assert.Contains("PSAR", indicator.Name, StringComparison.Ordinal);
+        Assert.False(indicator.SeparateWindow);
+        Assert.True(indicator.OnBackGround);
+    }
+
+    [Fact]
+    public void PsarIndicator_MinHistoryDepths_EqualsZero()
+    {
+        var indicator = new PsarIndicator();
+
+        Assert.Equal(0, PsarIndicator.MinHistoryDepths);
+        IWatchlistIndicator watchlistIndicator = indicator;
+        Assert.Equal(0, watchlistIndicator.MinHistoryDepths);
+    }
+
+    [Fact]
+    public void PsarIndicator_ShortName_IncludesParameters()
+    {
+        var indicator = new PsarIndicator { AfStart = 0.02, AfMax = 0.20 };
+        indicator.Initialize();
+
+        Assert.Contains("PSAR", indicator.ShortName, StringComparison.Ordinal);
+        Assert.Contains("0.02", indicator.ShortName, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void PsarIndicator_SourceCodeLink_IsValid()
+    {
+        var indicator = new PsarIndicator();
+
+        Assert.Contains("github.com", indicator.SourceCodeLink, StringComparison.Ordinal);
+        Assert.Contains("Psar", indicator.SourceCodeLink, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void PsarIndicator_Initialize_CreatesInternalIndicator()
+    {
+        var indicator = new PsarIndicator();
+
+        indicator.Initialize();
+
+        // After init, line series should exist (SAR only)
+        Assert.Single(indicator.LinesSeries);
+    }
+
+    [Fact]
+    public void PsarIndicator_ProcessUpdate_HistoricalBar_ComputesValue()
+    {
+        var indicator = new PsarIndicator { AfStart = 0.02, AfIncrement = 0.02, AfMax = 0.20 };
+        indicator.Initialize();
+
+        var now = DateTime.UtcNow;
+        for (int i = 0; i < 20; i++)
+        {
+            indicator.HistoricalData.AddBar(now.AddMinutes(i), 100 + i, 110 + i, 90 + i, 105 + i);
+
+            var args = new UpdateArgs(UpdateReason.HistoricalBar);
+            indicator.ProcessUpdate(args);
+        }
+
+        double sar = indicator.LinesSeries[0].GetValue(0);
+
+        Assert.True(double.IsFinite(sar));
+    }
+
+    [Fact]
+    public void PsarIndicator_ProcessUpdate_NewBar_ComputesValue()
+    {
+        var indicator = new PsarIndicator { AfStart = 0.02, AfIncrement = 0.02, AfMax = 0.20 };
+        indicator.Initialize();
+
+        var now = DateTime.UtcNow;
+        for (int i = 0; i < 10; i++)
+        {
+            indicator.HistoricalData.AddBar(now.AddMinutes(i), 100 + i, 110 + i, 90 + i, 105 + i);
+            var args = new UpdateArgs(UpdateReason.HistoricalBar);
+            indicator.ProcessUpdate(args);
+        }
+
+        // Simulate a new bar
+        indicator.HistoricalData.AddBar(now.AddMinutes(10), 110, 120, 100, 115);
+        var newArgs = new UpdateArgs(UpdateReason.NewBar);
+        indicator.ProcessUpdate(newArgs);
+
+        double sar = indicator.LinesSeries[0].GetValue(0);
+
+        Assert.True(double.IsFinite(sar));
+    }
+
+    [Fact]
+    public void PsarIndicator_SingleLineSeries_IsPresent()
+    {
+        var indicator = new PsarIndicator();
+        indicator.Initialize();
+
+        var now = DateTime.UtcNow;
+        for (int i = 0; i < 20; i++)
+        {
+            indicator.HistoricalData.AddBar(now.AddMinutes(i), 100 + i, 110 + i, 90 + i, 105 + i);
+            var args = new UpdateArgs(UpdateReason.HistoricalBar);
+            indicator.ProcessUpdate(args);
+        }
+
+        Assert.Single(indicator.LinesSeries);
+        Assert.True(double.IsFinite(indicator.LinesSeries[0].GetValue(0)));
+    }
+
+    [Fact]
+    public void PsarIndicator_Description_IsSet()
+    {
+        var indicator = new PsarIndicator();
+
+        Assert.NotNull(indicator.Description);
+        Assert.NotEmpty(indicator.Description);
+        Assert.Contains("stop", indicator.Description, StringComparison.OrdinalIgnoreCase);
+    }
+}

lib/reversals/psar/tests/Psar.Tests.cs

@@ -0,0 +1,560 @@
+// PSAR Tests - Parabolic Stop And Reverse
+
+namespace QuanTAlib.Tests;
+
+// ── A) Constructor Validation ────────────────────────────────────────────
+public sealed class PsarConstructorTests
+{
+    [Fact]
+    public void Constructor_ZeroAfStart_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afStart: 0));
+        Assert.Equal("afStart", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_NegativeAfStart_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afStart: -0.01));
+        Assert.Equal("afStart", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_ZeroAfIncrement_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afIncrement: 0));
+        Assert.Equal("afIncrement", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_NegativeAfIncrement_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afIncrement: -0.01));
+        Assert.Equal("afIncrement", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_AfMaxEqualAfStart_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afStart: 0.02, afMax: 0.02));
+        Assert.Equal("afMax", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_AfMaxLessThanAfStart_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() => new Psar(afStart: 0.10, afMax: 0.05));
+        Assert.Equal("afStart", ex.ParamName);
+    }
+
+    [Fact]
+    public void Constructor_ValidDefaults_SetsProperties()
+    {
+        var psar = new Psar();
+
+        Assert.Equal(0.02, psar.AfStart);
+        Assert.Equal(0.02, psar.AfIncrement);
+        Assert.Equal(0.20, psar.AfMax);
+        Assert.Equal(1, psar.WarmupPeriod);
+        Assert.Contains("Psar", psar.Name, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void Constructor_CustomParams_SetsProperties()
+    {
+        var psar = new Psar(afStart: 0.01, afIncrement: 0.01, afMax: 0.10);
+
+        Assert.Equal(0.01, psar.AfStart);
+        Assert.Equal(0.01, psar.AfIncrement);
+        Assert.Equal(0.10, psar.AfMax);
+    }
+}
+
+// ── B) Basic Calculation ─────────────────────────────────────────────────
+public sealed class PsarBasicTests
+{
+    [Fact]
+    public void Update_ReturnsTValue()
+    {
+        var psar = new Psar();
+        var bar = new TBar(DateTime.UtcNow, 100, 95, 98, 97, 1000);
+
+        TValue result = psar.Update(bar);
+
+        Assert.IsType<TValue>(result);
+    }
+
+    [Fact]
+    public void Update_Last_IsAccessible()
+    {
+        var psar = new Psar();
+        var bar = new TBar(DateTime.UtcNow, 100, 95, 98, 97, 1000);
+
+        _ = psar.Update(bar);
+
+        Assert.True(double.IsFinite(psar.Last.Value) || double.IsNaN(psar.Last.Value));
+    }
+
+    [Fact]
+    public void Update_Sar_IsAccessible()
+    {
+        var psar = new Psar();
+
+        // Feed enough bars
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(i),
+                price + 2, price - 2, price + 1, price, 1000));
+        }
+
+        Assert.True(double.IsFinite(psar.Sar));
+    }
+
+    [Fact]
+    public void Name_ContainsParameters()
+    {
+        var psar = new Psar(afStart: 0.01, afIncrement: 0.02, afMax: 0.10);
+
+        Assert.Contains("0.01", psar.Name, StringComparison.Ordinal);
+        Assert.Contains("0.10", psar.Name, StringComparison.Ordinal);
+    }
+
+    [Fact]
+    public void FirstBar_Uptrend_SarEqualsLow()
+    {
+        var psar = new Psar();
+        // Close(105) > Open(95) → long mode → SAR = low(90)
+        _ = psar.Update(new TBar(DateTime.UtcNow, 95, 110, 90, 105, 1000));
+
+        Assert.Equal(90.0, psar.Sar);
+        Assert.True(psar.IsLong);
+    }
+
+    [Fact]
+    public void FirstBar_Downtrend_SarEqualsHigh()
+    {
+        var psar = new Psar();
+        // Close(90) < Open(105) → short mode → SAR = high(110)
+        _ = psar.Update(new TBar(DateTime.UtcNow, 105, 110, 85, 90, 1000));
+
+        Assert.Equal(110.0, psar.Sar);
+        Assert.False(psar.IsLong);
+    }
+
+    [Fact]
+    public void Sar_BelowPrice_InUptrend()
+    {
+        var psar = new Psar();
+
+        // Steady uptrend - SAR should trail below
+        for (int i = 0; i < 20; i++)
+        {
+            double price = 100.0 + i * 2;
+            _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(i),
+                price + 1, price - 1, price + 0.5, price, 1000));
+        }
+
+        double lastClose = 100.0 + 19 * 2;
+        Assert.True(psar.Sar < lastClose, "SAR should be below price in uptrend");
+        Assert.True(psar.IsLong, "Should be in long mode during uptrend");
+    }
+
+    [Fact]
+    public void Sar_AbovePrice_InDowntrend()
+    {
+        var psar = new Psar();
+
+        // Steady downtrend - SAR should trail above
+        for (int i = 0; i < 20; i++)
+        {
+            double price = 200.0 - i * 2;
+            _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(i),
+                price + 1, price - 1, price + 0.5, price, 1000));
+        }
+
+        double lastClose = 200.0 - 19 * 2;
+        Assert.True(psar.Sar > lastClose, "SAR should be above price in downtrend");
+        Assert.False(psar.IsLong, "Should be in short mode during downtrend");
+    }
+
+    [Fact]
+    public void IsHot_TrueAfterFirstBar()
+    {
+        var psar = new Psar();
+
+        Assert.False(psar.IsHot);
+
+        _ = psar.Update(new TBar(DateTime.UtcNow, 100, 95, 98, 97, 1000));
+
+        Assert.True(psar.IsHot);
+    }
+}
+
+// ── C) State + Bar Correction ────────────────────────────────────────────
+public sealed class PsarStateCorrectionTests
+{
+    [Fact]
+    public void IsNew_True_AdvancesState()
+    {
+        var psar = new Psar();
+
+        _ = psar.Update(new TBar(DateTime.UtcNow, 105, 95, 100, 100, 1000), isNew: true);
+        var first = psar.Last;
+
+        _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(1), 110, 100, 105, 105, 1000), isNew: true);
+        var second = psar.Last;
+
+        Assert.NotEqual(first.Time, second.Time);
+    }
+
+    [Fact]
+    public void IsNew_False_CorrectionRestoresState()
+    {
+        var psar = new Psar();
+        var dt = DateTime.UtcNow;
+
+        // Feed some bars to warm up
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(dt.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000), isNew: true);
+        }
+
+        // New bar
+        _ = psar.Update(new TBar(dt.AddMinutes(5), 110, 105, 108, 107, 1000), isNew: true);
+
+        // Correct the bar (isNew=false with different values)
+        _ = psar.Update(new TBar(dt.AddMinutes(5), 111, 104, 109, 108, 1000), isNew: false);
+
+        // Another correction should produce same result
+        _ = psar.Update(new TBar(dt.AddMinutes(5), 111, 104, 109, 108, 1000), isNew: false);
+        var corrected1 = psar.Sar;
+
+        _ = psar.Update(new TBar(dt.AddMinutes(5), 111, 104, 109, 108, 1000), isNew: false);
+        var corrected2 = psar.Sar;
+
+        Assert.Equal(corrected1, corrected2);
+    }
+
+    [Fact]
+    public void IterativeCorrections_ProduceSameResult()
+    {
+        var psar = new Psar();
+        var dt = DateTime.UtcNow;
+
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(dt.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000), isNew: true);
+        }
+
+        // Add new bar then correct 3 times
+        _ = psar.Update(new TBar(dt.AddMinutes(5), 110, 100, 108, 105, 1000), isNew: true);
+
+        double[] results = new double[3];
+        for (int i = 0; i < 3; i++)
+        {
+            _ = psar.Update(new TBar(dt.AddMinutes(5), 112, 101, 110, 107, 1000), isNew: false);
+            results[i] = psar.Sar;
+        }
+
+        Assert.Equal(results[0], results[1]);
+        Assert.Equal(results[1], results[2]);
+    }
+
+    [Fact]
+    public void Reset_ClearsAllState()
+    {
+        var psar = new Psar();
+
+        for (int i = 0; i < 10; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000));
+        }
+
+        Assert.True(psar.IsHot);
+
+        psar.Reset();
+
+        Assert.False(psar.IsHot);
+        Assert.True(double.IsNaN(psar.Sar));
+    }
+}
+
+// ── D) Warmup / Convergence ──────────────────────────────────────────────
+public sealed class PsarWarmupTests
+{
+    [Fact]
+    public void IsHot_FlipsAfterFirstBar()
+    {
+        var psar = new Psar();
+
+        Assert.False(psar.IsHot);
+
+        _ = psar.Update(new TBar(DateTime.UtcNow, 100, 95, 98, 97, 1000));
+
+        Assert.True(psar.IsHot);
+    }
+
+    [Fact]
+    public void WarmupPeriod_EqualsOne()
+    {
+        var psar = new Psar();
+
+        Assert.Equal(1, psar.WarmupPeriod);
+    }
+}
+
+// ── E) Robustness ────────────────────────────────────────────────────────
+public sealed class PsarRobustnessTests
+{
+    [Fact]
+    public void NaN_Input_UsesLastValidValue()
+    {
+        var psar = new Psar();
+        var dt = DateTime.UtcNow;
+
+        // Feed valid bars
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(dt.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000));
+        }
+
+        // Feed NaN bar
+        _ = psar.Update(new TBar(dt.AddMinutes(5), double.NaN, double.NaN, double.NaN, double.NaN, 0));
+
+        Assert.True(double.IsFinite(psar.Sar));
+    }
+
+    [Fact]
+    public void Infinity_Input_UsesLastValidValue()
+    {
+        var psar = new Psar();
+        var dt = DateTime.UtcNow;
+
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(dt.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000));
+        }
+
+        _ = psar.Update(new TBar(dt.AddMinutes(5),
+            double.PositiveInfinity, double.NegativeInfinity, double.PositiveInfinity, double.PositiveInfinity, 0));
+
+        Assert.True(double.IsFinite(psar.Sar));
+    }
+
+    [Fact]
+    public void FirstBar_NaN_ReturnsNaN()
+    {
+        var psar = new Psar();
+
+        _ = psar.Update(new TBar(DateTime.UtcNow, double.NaN, double.NaN, double.NaN, double.NaN, 0));
+
+        Assert.True(double.IsNaN(psar.Last.Value));
+    }
+}
+
+// ── F) Consistency ───────────────────────────────────────────────────────
+public sealed class PsarConsistencyTests
+{
+    private static TBarSeries CreateGbmBars(int count = 500)
+    {
+        var gbm = new GBM(startPrice: 100.0, mu: 0.05, sigma: 0.20, seed: 42);
+        return gbm.Fetch(count, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    }
+
+    [Fact]
+    public void Streaming_MatchesBatch()
+    {
+        var bars = CreateGbmBars();
+
+        // Streaming
+        var streaming = new Psar();
+        var streamResults = new double[bars.Count];
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = streaming.Update(bars[i], isNew: true);
+            streamResults[i] = streaming.Sar;
+        }
+
+        // Batch
+        var batchResults = Psar.Batch(bars);
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            Assert.Equal(streamResults[i], batchResults[i].Value, precision: 10);
+        }
+    }
+
+    [Fact]
+    public void TValue_Update_MatchesTBar_Update()
+    {
+        var ch1 = new Psar();
+        var ch2 = new Psar();
+
+        double[] prices = [100, 102, 98, 105, 99, 103, 107, 95, 110, 108];
+
+        for (int i = 0; i < prices.Length; i++)
+        {
+            double p = prices[i];
+            // TBar with equal OHLC
+            _ = ch1.Update(new TBar(DateTime.UtcNow.AddMinutes(i), p, p, p, p, 0), isNew: true);
+            // TValue
+            _ = ch2.Update(new TValue(DateTime.UtcNow.AddMinutes(i), p), isNew: true);
+        }
+
+        Assert.Equal(ch1.Sar, ch2.Sar);
+    }
+
+    [Fact]
+    public void Reversal_DetectedOnPriceCrossover()
+    {
+        var psar = new Psar();
+        var dt = DateTime.UtcNow;
+
+        // Start in uptrend
+        _ = psar.Update(new TBar(dt, 100, 90, 95, 105, 1000), isNew: true);
+        Assert.True(psar.IsLong);
+
+        // Continue uptrend
+        for (int i = 1; i <= 5; i++)
+        {
+            double price = 105 + i * 2;
+            _ = psar.Update(new TBar(dt.AddMinutes(i),
+                price + 1, price - 1, price + 0.5, price, 1000), isNew: true);
+        }
+        Assert.True(psar.IsLong);
+
+        // Sharp reversal — price drops below SAR
+        double sarBeforeReversal = psar.Sar;
+        _ = psar.Update(new TBar(dt.AddMinutes(10),
+            sarBeforeReversal - 5, sarBeforeReversal - 20,
+            sarBeforeReversal - 18, sarBeforeReversal - 15, 1000), isNew: true);
+
+        Assert.False(psar.IsLong, "Should reverse to short after price crosses below SAR");
+    }
+
+    [Fact]
+    public void Update_TSeries_MatchesStreaming()
+    {
+        var bars = CreateGbmBars(100);
+
+        // Streaming
+        var streaming = new Psar();
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = streaming.Update(bars[i], isNew: true);
+        }
+        double streamLast = streaming.Sar;
+
+        // TSeries batch
+        var batch = new Psar();
+        _ = batch.Update(bars);
+
+        Assert.Equal(streamLast, batch.Sar, precision: 10);
+    }
+}
+
+// ── G) Span API Tests ────────────────────────────────────────────────────
+public sealed class PsarSpanTests
+{
+    [Fact]
+    public void Batch_Span_InvalidAfStart_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() =>
+            Psar.Batch(new double[10], new double[10], new double[10], new double[10], new double[10], afStart: 0));
+        Assert.Equal("afStart", ex.ParamName);
+    }
+
+    [Fact]
+    public void Batch_Span_MismatchedLengths_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() =>
+            Psar.Batch(new double[10], new double[10], new double[5], new double[10], new double[10]));
+        Assert.Equal("high", ex.ParamName);
+    }
+
+    [Fact]
+    public void Batch_Span_OutputTooShort_Throws()
+    {
+        var ex = Assert.Throws<ArgumentException>(() =>
+            Psar.Batch(new double[10], new double[10], new double[10], new double[10], new double[5]));
+        Assert.Equal("output", ex.ParamName);
+    }
+
+    [Fact]
+    public void Batch_Span_Empty_NoException()
+    {
+        var output = Array.Empty<double>();
+        var ex = Record.Exception(() =>
+            Psar.Batch(ReadOnlySpan<double>.Empty, ReadOnlySpan<double>.Empty,
+                ReadOnlySpan<double>.Empty, ReadOnlySpan<double>.Empty, output.AsSpan()));
+        Assert.Null(ex);
+    }
+}
+
+// ── H) Event / Chainability ──────────────────────────────────────────────
+public sealed class PsarEventTests
+{
+    [Fact]
+    public void Pub_FiresOnUpdate()
+    {
+        var psar = new Psar();
+        int fireCount = 0;
+
+        psar.Pub += (object? _, in TValueEventArgs _e) => { fireCount++; };
+
+        _ = psar.Update(new TBar(DateTime.UtcNow, 100, 95, 98, 97, 1000));
+
+        Assert.Equal(1, fireCount);
+    }
+
+    [Fact]
+    public void Pub_FiresOnEachUpdate()
+    {
+        var psar = new Psar();
+        int fireCount = 0;
+
+        psar.Pub += (object? _, in TValueEventArgs _e) => { fireCount++; };
+
+        for (int i = 0; i < 5; i++)
+        {
+            double price = 100.0 + i;
+            _ = psar.Update(new TBar(DateTime.UtcNow.AddMinutes(i), price + 2, price - 2, price + 1, price, 1000));
+        }
+
+        Assert.Equal(5, fireCount);
+    }
+}
+
+// ── I) Prime Tests ───────────────────────────────────────────────────────
+public sealed class PsarPrimeTests
+{
+    [Fact]
+    public void Prime_TBarSeries_SetsState()
+    {
+        var gbm = new GBM(startPrice: 100.0, mu: 0.05, sigma: 0.20, seed: 42);
+        var bars = gbm.Fetch(50, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+
+        var psar = new Psar();
+        psar.Prime(bars);
+
+        Assert.True(psar.IsHot);
+        Assert.True(double.IsFinite(psar.Sar));
+    }
+
+    [Fact]
+    public void Prime_EmptySource_NoException()
+    {
+        var psar = new Psar();
+        var bars = new TBarSeries();
+
+        var ex = Record.Exception(() => psar.Prime(bars));
+        Assert.Null(ex);
+        Assert.False(psar.IsHot);
+    }
+}

lib/reversals/psar/tests/Psar.Validation.Tests.cs

@@ -0,0 +1,300 @@
+// PSAR Validation Tests - Parabolic Stop And Reverse
+// Cross-validated against Skender.Stock.Indicators GetParabolicSar(), TALib SAR, and OoplesFinance CalculateParabolicSAR.
+
+using OoplesFinance.StockIndicators;
+using OoplesFinance.StockIndicators.Models;
+using Skender.Stock.Indicators;
+using TALib;
+
+namespace QuanTAlib.Tests;
+
+public sealed class PsarValidationTests
+{
+    private static TBarSeries CreateGbmBars(int count = 500, int seed = 42)
+    {
+        var gbm = new GBM(startPrice: 100.0, mu: 0.05, sigma: 0.20, seed: seed);
+        return gbm.Fetch(count, DateTime.UtcNow.Ticks, TimeSpan.FromMinutes(1));
+    }
+
+    // ── Cross-library: Skender ───────────────────────────────────────────
+
+    [Fact]
+    public void StreamingMatchesSkender()
+    {
+        var _data = new ValidationTestData();
+
+        // Skender: GetParabolicSar(accelerationStep, maxAccelerationFactor, initialFactor)
+        var skenderResults = _data.SkenderQuotes
+            .GetParabolicSar(0.02, 0.2, 0.02)
+            .ToList();
+
+        // QuanTAlib streaming
+        var psar = new Psar(afStart: 0.02, afIncrement: 0.02, afMax: 0.20);
+        var ourValues = new double[_data.Bars.Count];
+        for (int i = 0; i < _data.Bars.Count; i++)
+        {
+            _ = psar.Update(_data.Bars[i], isNew: true);
+            ourValues[i] = psar.Sar;
+        }
+
+        // Compare warm values (skip first bar where SAR is initialization)
+        int matched = 0;
+        for (int i = 2; i < skenderResults.Count && i < _data.Bars.Count; i++)
+        {
+            if (skenderResults[i].Sar.HasValue && double.IsFinite(ourValues[i]))
+            {
+                Assert.Equal(
+                    skenderResults[i].Sar!.Value,
+                    ourValues[i],
+                    precision: 6);
+                matched++;
+            }
+        }
+
+        Assert.True(matched > 0, "Should have matched at least one warm value");
+        _data.Dispose();
+    }
+
+    // ── Self-Consistency: Streaming == Batch ──────────────────────────────
+
+    [Fact]
+    public void StreamingMatchesBatch()
+    {
+        var bars = CreateGbmBars();
+
+        // Streaming
+        var streaming = new Psar();
+        var streamValues = new double[bars.Count];
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = streaming.Update(bars[i], isNew: true);
+            streamValues[i] = streaming.Sar;
+        }
+
+        // Batch
+        var batchResults = Psar.Batch(bars);
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            Assert.Equal(streamValues[i], batchResults[i].Value, precision: 10);
+        }
+    }
+
+    // ── Self-Consistency: Streaming == Span ───────────────────────────────
+
+    [Fact]
+    public void StreamingMatchesSpan()
+    {
+        var bars = CreateGbmBars();
+
+        // Streaming
+        var streaming = new Psar();
+        var streamValues = new double[bars.Count];
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = streaming.Update(bars[i], isNew: true);
+            streamValues[i] = streaming.Sar;
+        }
+
+        // Span
+        var spanOutput = new double[bars.Count];
+        Psar.Batch(bars.OpenValues, bars.HighValues, bars.LowValues, bars.CloseValues, spanOutput);
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            Assert.Equal(streamValues[i], spanOutput[i], precision: 10);
+        }
+    }
+
+    // ── AF Sensitivity ───────────────────────────────────────────────────
+
+    [Fact]
+    public void HigherAfStart_TighterTrailingStop()
+    {
+        var bars = CreateGbmBars(count: 100);
+
+        var slow = new Psar(afStart: 0.01, afIncrement: 0.01, afMax: 0.20);
+        var fast = new Psar(afStart: 0.10, afIncrement: 0.05, afMax: 0.50);
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = slow.Update(bars[i], isNew: true);
+            _ = fast.Update(bars[i], isNew: true);
+        }
+
+        // Higher AF = more responsive = SAR closer to price
+        // Just verify both produce finite output (direction depends on data)
+        Assert.True(double.IsFinite(slow.Sar));
+        Assert.True(double.IsFinite(fast.Sar));
+    }
+
+    // ── Determinism ──────────────────────────────────────────────────────
+
+    [Fact]
+    public void SameInput_ProducesSameOutput()
+    {
+        var bars = CreateGbmBars(count: 200, seed: 123);
+
+        var psar1 = new Psar();
+        var psar2 = new Psar();
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = psar1.Update(bars[i], isNew: true);
+            _ = psar2.Update(bars[i], isNew: true);
+        }
+
+        Assert.Equal(psar1.Sar, psar2.Sar);
+    }
+
+    // ── Calculate Returns Valid Indicator ─────────────────────────────────
+
+    [Fact]
+    public void Calculate_ReturnsValidIndicatorAndResults()
+    {
+        var bars = CreateGbmBars(count: 100);
+
+        var (results, indicator) = Psar.Calculate(bars);
+
+        Assert.NotNull(results);
+        Assert.Equal(bars.Count, results.Count);
+        Assert.True(indicator.IsHot);
+        Assert.True(double.IsFinite(indicator.Sar));
+    }
+
+    // ── Reversal Count Is Reasonable ─────────────────────────────────────
+
+    [Fact]
+    public void ReversalCount_IsReasonable()
+    {
+        var bars = CreateGbmBars(count: 500);
+        var psar = new Psar();
+
+        int reversals = 0;
+        bool prevIsLong = true;
+
+        for (int i = 0; i < bars.Count; i++)
+        {
+            _ = psar.Update(bars[i], isNew: true);
+
+            if (i > 0 && psar.IsLong != prevIsLong)
+            {
+                reversals++;
+            }
+            prevIsLong = psar.IsLong;
+        }
+
+        // In 500 bars of GBM data, expect several reversals but not every bar
+        Assert.True(reversals > 5, $"Expected > 5 reversals, got {reversals}");
+        Assert.True(reversals < 250, $"Expected < 250 reversals, got {reversals}");
+    }
+
+    [Fact]
+    public void StreamingMatchesTalib()
+    {
+        /* TALib SAR uses the same Wilder parabolic SAR formula as QuanTAlib.
+           Parameters: accelerationFactor=0.02 (step), maximum=0.20 (cap).
+           Initialization differences produce a short divergence; values converge after first reversal.
+           We accept up to 2% mismatch for edge-of-reversal rounding at period boundaries. */
+
+        var _data = new ValidationTestData();
+
+        double[] highData = _data.Bars.High.Values.ToArray();
+        double[] lowData = _data.Bars.Low.Values.ToArray();
+        double[] taOut = new double[_data.Bars.Count];
+
+        const double afStep = 0.02;
+        const double afMax = 0.20;
+
+        var retCode = Functions.Sar<double>(
+            highData, lowData,
+            0..^0, taOut, out var outRange,
+            afStep, afMax);
+        Assert.Equal(TALib.Core.RetCode.Success, retCode);
+
+        (int offset, int length) = outRange.GetOffsetAndLength(taOut.Length);
+        Assert.True(length > 100, $"TALib SAR produced only {length} values");
+
+        // QuanTAlib streaming
+        var psar = new Psar(afStart: afStep, afIncrement: afStep, afMax: afMax);
+        var qlSar = new double[_data.Bars.Count];
+        for (int i = 0; i < _data.Bars.Count; i++)
+        {
+            _ = psar.Update(_data.Bars[i], isNew: true);
+            qlSar[i] = psar.Sar;
+        }
+
+        // Skip the first ~5 bars (initialization divergence), then require exact match.
+        int skipBars = 5;
+        int compared = 0;
+        int matched = 0;
+        for (int j = skipBars; j < length; j++)
+        {
+            int qi = j + offset;
+            if (!double.IsFinite(qlSar[qi]) || !double.IsFinite(taOut[j])) { continue; }
+            compared++;
+            double diff = Math.Abs(qlSar[qi] - taOut[j]);
+            if (diff <= 1e-9) { matched++; }
+        }
+
+        // After initialization, QuanTAlib and TALib SAR should converge fully.
+        // Accept up to 2% mismatch for edge-of-reversal rounding at period boundaries.
+        double matchRate = compared > 0 ? (double)matched / compared : 0;
+        Assert.True(matchRate >= 0.98,
+            $"TALib SAR match rate {matchRate:P1} ({matched}/{compared}) < 98% — unexpected divergence");
+
+        _data.Dispose();
+    }
+
+    // ── Cross-library: OoplesFinance ────────────────────────────────────
+
+    /// <summary>
+    /// Structural validation against Ooples <c>CalculateParabolicSAR</c>.
+    /// Ooples PSAR uses the same Wilder acceleration factor algorithm (start=0.02, increment=0.02, max=0.2).
+    /// Cross-library numeric equality is not asserted because reversal-point initialization
+    /// diverges across implementations when the very first bar direction is ambiguous.
+    /// Both must produce finite, positive output on the same OHLCV data.
+    /// </summary>
+    [Fact]
+    public void Psar_MatchesOoples_Structural()
+    {
+        var _data = new ValidationTestData();
+
+        var ooplesData = _data.SkenderQuotes.Select(q => new TickerData
+        {
+            Date = q.Date,
+            Open = (double)q.Open,
+            High = (double)q.High,
+            Low = (double)q.Low,
+            Close = (double)q.Close,
+            Volume = (double)q.Volume
+        }).ToList();
+
+        var stockData = new StockData(ooplesData);
+        var oResult = stockData.CalculateParabolicSAR(start: 0.02, increment: 0.02, maximum: 0.2);
+        var oValues = oResult.OutputValues.Values.First();
+
+        var psar = new Psar(afStart: 0.02, afIncrement: 0.02, afMax: 0.20);
+        var qValues = new System.Collections.Generic.List<double>();
+        foreach (var bar in _data.Data)
+        {
+            qValues.Add(psar.Update(bar).Value);
+        }
+
+        Assert.True(oValues.Count > 0, "Ooples PSAR must produce output");
+
+        int finiteCount = 0;
+        int warmup = 5;
+        for (int i = warmup; i < Math.Min(oValues.Count, qValues.Count); i++)
+        {
+            if (double.IsFinite(oValues[i]) && double.IsFinite(qValues[i]) && qValues[i] > 0)
+            {
+                finiteCount++;
+            }
+        }
+
+        Assert.True(finiteCount > 100, $"Expected >100 finite positive PSAR pairs, got {finiteCount}");
+
+        _data.Dispose();
+    }
+}