Fix OOP pcap capture race with archive packaging

src/Fluxzy.Core.Pcap/OutOfProcessCaptureContext.cs

@@ -124,6 +124,7 @@ public void Flush()
 
             lock (this) {
                 _writer.Write((byte) MessageType.Flush);
+                _writer.Flush();
             }
         }
 

src/Fluxzy/Commands/StartCommandBuilder.cs

@@ -308,7 +308,11 @@ public async Task Run(InvocationContext invocationContext, CancellationToken pro
             var uaParserProvider = parseUserAgent ? new UaParserUserAgentInfoProvider() : null;
             var systemProxyManager = new SystemProxyRegistrationManager(new NativeProxySetterManager().Get());
 
-            await using var scope = new ProxyScope(() => new FluxzyNetOutOfProcessHost(), a => new OutOfProcessCaptureContext(a));
+            // Scope owns the out-of-proc capture subprocess lifetime. It must be disposed
+            // BEFORE PackDirectoryToFile runs so the subprocess closes its pcapng FileStreams
+            // and flushes all buffered packet data to disk; otherwise small captures can sit
+            // in the 4 KB FileStream buffer and the packager's Length==0 skip drops them.
+            await using (var scope = new ProxyScope(() => new FluxzyNetOutOfProcessHost(), a => new OutOfProcessCaptureContext(a))) {
 
             if (!ValidateSetting(invocationContext, proxyStartUpSetting)) {
                 invocationContext.ExitCode = 1;
@@ -390,6 +394,8 @@ public async Task Run(InvocationContext invocationContext, CancellationToken pro
                 }
             }
 
+            } // scope dispose: subprocess exits, pcapng FileStreams closed + flushed
+
             invocationContext.Console.Out.WriteLine("Proxy ended, gracefully");
 
             if (outFileInfo != null) {

test/Fluxzy.Tests/Cli/CliTestBase.cs

@@ -132,7 +132,8 @@ protected async Task Run_Cli_Output(string proto, CaptureType rawCap,
                 if (rawCap != CaptureType.None)
                 {
                     var rawCapStream = archiveReader.GetRawCaptureStream(connection.Id);
-                    Assert.True(await rawCapStream!.DrainAsync(disposeStream: true) > 0);
+                    Assert.NotNull(rawCapStream);
+                    Assert.True(await rawCapStream.DrainAsync(disposeStream: true) > 0);
                 }
 
                 if (rule)