fix(extractor): PipeReader/PipeWriter are not IDisposable — stop flagging them as leaks (mined FP)

.github/workflows/ci.yml

@@ -135,6 +135,7 @@ jobs:
             frontend/roslyn/samples/WhenAnyValueViewModel.cs \
             frontend/roslyn/samples/DiCaptiveSample.cs \
             frontend/roslyn/samples/SampleTypes.cs \
+            frontend/roslyn/samples/PipeFieldsSample.cs \
             -o "$RUNNER_TEMP/facts.json"
           cat "$RUNNER_TEMP/facts.json"
       - name: Check facts through the core
@@ -154,6 +155,13 @@ jobs:
           if echo "$out" | grep -q "OrdersViewModel.cs"; then
             echo "FAIL: disposed subscription wrongly reported"; exit 1
           fi
+          # Mined FP regression (Pipelines.Sockets.Unofficial): System.IO.Pipelines PipeReader/PipeWriter
+          # END WITH Reader/Writer but are NOT IDisposable (they finish via Complete(), not Dispose()), so
+          # an undisposed PipeReader/PipeWriter FIELD must NOT be flagged as a leak —
+          # IsNonDisposableReaderWriter excludes them from the field-disposable name heuristic.
+          if echo "$out" | grep -q "PipeFieldsSample.cs"; then
+            echo "FAIL: PipeReader/PipeWriter field wrongly reported as an undisposed-disposable leak"; exit 1
+          fi
           # a lambda handler has no stored delegate, so it can NEVER be `-=`'d — the
           # finding says so. (Same injected source as Customer -> also a warning.)
           echo "$out" | grep -qE "LambdaHandlerViewModel\.cs:[0-9]+: warning: \[OWN001\]" \

frontend/roslyn/OwnSharp.Extractor/Program.cs

@@ -1412,8 +1412,19 @@
 static bool IsDisposableType(string t) =>
     t is "IDisposable" or "IAsyncDisposable" or "CancellationTokenSource"
        or "HttpClient" or "SerialPort" or "SqlConnection"
-    || t.EndsWith("Stream") || t.EndsWith("Reader") || t.EndsWith("Writer")
-    || t.EndsWith("Subscription");
+    || ((t.EndsWith("Stream") || t.EndsWith("Reader") || t.EndsWith("Writer")
+            || t.EndsWith("Subscription"))
+        && !IsNonDisposableReaderWriter(t));
+
+// BCL `…Reader`/`…Writer` types that the EndsWith name heuristic above matches but that are NOT
+// IDisposable: System.IO.Pipelines `PipeReader`/`PipeWriter` finish via `Complete()`, not `Dispose()`.
+// Excluding them stops the field-disposable detector flagging an undisposed PipeReader/PipeWriter
+// field as a leak — a FALSE POSITIVE mined on Pipelines.Sockets.Unofficial (SocketConnection's
+// `_input`/`_output`). Matched on the exact bare or `System.IO.Pipelines`-qualified spelling — NOT
+// any simple-name match, so a project's own disposable `MyLib.PipeReader` is still flagged (Codex).
+static bool IsNonDisposableReaderWriter(string t) =>
+    t is "PipeReader" or "PipeWriter"
+      or "System.IO.Pipelines.PipeReader" or "System.IO.Pipelines.PipeWriter";
 
 // --- P-006: DI registration + constructor graph (DI001 captive dependency) ---
 // A syntactic pass over the same trees, independent of the event/disposable
@@ -1782,7 +1793,7 @@
     .Split(Path.PathSeparator, StringSplitOptions.RemoveEmptyEntries)
     .Where(p => p.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
     .ToList();
 var refNames = new HashSet<string>(tpa.Select(Path.GetFileName), StringComparer.OrdinalIgnoreCase);
 var references = tpa.Select(p => (MetadataReference)MetadataReference.CreateFromFile(p)).ToList();
 // P-004 WPF profile: widen the reference set with assemblies named by the
 // OWN_EXTRA_REF_DIRS env var (colon-separated dirs) — e.g. the WindowsDesktop ref

frontend/roslyn/samples/PipeFieldsSample.cs

@@ -0,0 +1,47 @@
+using System;
+using System.IO.Pipelines;
+using System.Threading;
+using System.Threading.Tasks;
+
+// Mined false-positive regression guard (Pipelines.Sockets.Unofficial). `System.IO.Pipelines`
+// PipeReader/PipeWriter END WITH "Reader"/"Writer", so the field-disposable NAME heuristic used to
+// classify them as IDisposable and flag an undisposed PipeReader/PipeWriter FIELD as a leak. But they
+// are NOT IDisposable — they finish via Complete(), not Dispose(). A class that constructs such fields
+// and never disposes them must produce NO finding (mirrors SocketConnection._input/_output, which the
+// checker wrongly reported before IsNonDisposableReaderWriter excluded these types).
+public sealed class PipeHolder
+{
+    private readonly PipeReader _input;
+    private readonly PipeWriter _output;
+
+    public PipeHolder()
+    {
+        _input = new NullReader();    // constructed (a `new`) -> a disposable-field candidate before the fix
+        _output = new NullWriter();
+    }
+
+    // No Dispose: PipeReader/PipeWriter are completed by the consumer, not disposed -> not a leak.
+}
+
+// Minimal PipeReader/PipeWriter implementations so the sample is self-contained (the abstract BCL
+// types resolve from the framework reference set). PipeReader/PipeWriter expose Complete(), not
+// Dispose() — they are not IDisposable.
+internal sealed class NullReader : PipeReader
+{
+    public override void AdvanceTo(SequencePosition consumed) => throw new NotImplementedException();
+    public override void AdvanceTo(SequencePosition consumed, SequencePosition examined) => throw new NotImplementedException();
+    public override void CancelPendingRead() => throw new NotImplementedException();
+    public override void Complete(Exception exception = null) => throw new NotImplementedException();
+    public override ValueTask<ReadResult> ReadAsync(CancellationToken cancellationToken = default) => throw new NotImplementedException();
+    public override bool TryRead(out ReadResult result) => throw new NotImplementedException();
+}
+
+internal sealed class NullWriter : PipeWriter
+{
+    public override void Advance(int bytes) => throw new NotImplementedException();
+    public override void CancelPendingFlush() => throw new NotImplementedException();
+    public override void Complete(Exception exception = null) => throw new NotImplementedException();
+    public override ValueTask<FlushResult> FlushAsync(CancellationToken cancellationToken = default) => throw new NotImplementedException();
+    public override Memory<byte> GetMemory(int sizeHint = 0) => throw new NotImplementedException();
+    public override Span<byte> GetSpan(int sizeHint = 0) => throw new NotImplementedException();
+}