feat: add FeatureClassifier — heuristic-based feature classification

reports/current.md

@@ -1,6 +1,6 @@
 # NATS .NET Porting Status Report
 
-Generated: 2026-02-27 10:16:59 UTC
+Generated: 2026-02-27 10:17:36 UTC
 
 ## Modules (12 total)
 

reports/report_2dd2321.md

@@ -0,0 +1,35 @@
+# NATS .NET Porting Status Report
+
+Generated: 2026-02-27 10:17:36 UTC
+
+## Modules (12 total)
+
+| Status | Count |
+|--------|-------|
+| verified | 12 |
+
+## Features (3673 total)
+
+| Status | Count |
+|--------|-------|
+| unknown | 3394 |
+| verified | 279 |
+
+## Unit Tests (3257 total)
+
+| Status | Count |
+|--------|-------|
+| deferred | 2680 |
+| n_a | 187 |
+| verified | 390 |
+
+## Library Mappings (36 total)
+
+| Status | Count |
+|--------|-------|
+| mapped | 36 |
+
+
+## Overall Progress
+
+**868/6942 items complete (12.5%)**

tools/NatsNet.PortTracker/Audit/FeatureClassifier.cs

@@ -0,0 +1,91 @@
+namespace NatsNet.PortTracker.Audit;
+
+/// <summary>
+/// Classifies features by inspecting the SourceIndexer for their .NET implementation status.
+/// Priority: n_a lookup -> method-not-found -> stub detection -> verified.
+/// </summary>
+public sealed class FeatureClassifier
+{
+    public record ClassificationResult(string Status, string Reason);
+
+    public record FeatureRecord(
+        long Id,
+        string DotnetClass,
+        string DotnetMethod,
+        string GoFile,
+        string GoMethod);
+
+    private readonly SourceIndexer _indexer;
+
+    // N/A lookup: (goMethod pattern) -> reason
+    // Checked case-insensitively against go_method
+    private static readonly Dictionary<string, string> NaByGoMethod = new(StringComparer.OrdinalIgnoreCase)
+    {
+        ["Noticef"] = ".NET uses Microsoft.Extensions.Logging",
+        ["Debugf"] = ".NET uses Microsoft.Extensions.Logging",
+        ["Tracef"] = ".NET uses Microsoft.Extensions.Logging",
+        ["Warnf"] = ".NET uses Microsoft.Extensions.Logging",
+        ["Errorf"] = ".NET uses Microsoft.Extensions.Logging",
+        ["Fatalf"] = ".NET uses Microsoft.Extensions.Logging",
+    };
+
+    // N/A lookup: go_file + go_method patterns
+    private static readonly List<(Func<FeatureRecord, bool> Match, string Reason)> NaPatterns =
+    [
+        // Signal handling — .NET uses IHostApplicationLifetime
+        (f => f.GoMethod.Equals("handleSignals", StringComparison.OrdinalIgnoreCase), ".NET uses IHostApplicationLifetime"),
+        (f => f.GoMethod.Equals("processSignal", StringComparison.OrdinalIgnoreCase), ".NET uses IHostApplicationLifetime"),
+    ];
+
+    public FeatureClassifier(SourceIndexer indexer)
+    {
+        _indexer = indexer;
+    }
+
+    /// <summary>
+    /// Classify a single feature. Returns status and reason.
+    /// </summary>
+    public ClassificationResult Classify(FeatureRecord feature)
+    {
+        // 1. N/A lookup — check go_method against known patterns
+        if (NaByGoMethod.TryGetValue(feature.GoMethod, out var naReason))
+            return new ClassificationResult("n_a", naReason);
+
+        foreach (var (match, reason) in NaPatterns)
+        {
+            if (match(feature))
+                return new ClassificationResult("n_a", reason);
+        }
+
+        // 2. Handle comma-separated dotnet_class (e.g. "ClosedRingBuffer,ClosedClient")
+        var classNames = feature.DotnetClass.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
+        var methodName = feature.DotnetMethod;
+
+        // Try each class name
+        foreach (var className in classNames)
+        {
+            var methods = _indexer.Lookup(className, methodName);
+            if (methods.Count > 0)
+            {
+                // Found the method — classify based on body analysis
+                // Use the "best" match: prefer non-stub over stub
+                var best = methods.OrderByDescending(m => m.StatementCount).First();
+
+                if (best.IsStub)
+                    return new ClassificationResult("stub", $"Body is throw NotImplementedException at {Path.GetFileName(best.FilePath)}:{best.LineNumber}");
+
+                if (best.IsPartial)
+                    return new ClassificationResult("stub", $"Partial implementation with NotImplementedException at {Path.GetFileName(best.FilePath)}:{best.LineNumber}");
+
+                return new ClassificationResult("verified", $"Method found with {best.StatementCount} statement(s) at {Path.GetFileName(best.FilePath)}:{best.LineNumber}");
+            }
+        }
+
+        // 3. Method not found — check if any class exists
+        var anyClassFound = classNames.Any(c => _indexer.HasClass(c));
+        if (anyClassFound)
+            return new ClassificationResult("deferred", "Class exists but method not found");
+
+        return new ClassificationResult("deferred", "Class not found in .NET source");
+    }
+}