최종 감사: 계획↔구현 매핑 문서(IMPLEMENTATION_AUDIT.md), slnx에 Mobile 추가, HlsDownloader._muxer ctor 누락 회귀 RED→GREEN 수정(103 tests), 빌드머신 아티팩트 갱신(linux-x64/osx-arm64)

VideoDownloader.Tests/Platform/HlsMuxerWiringTests.cs

@@ -0,0 +1,72 @@
+using System.Net;
+using System.Net.Http;
+using VideoDownloader.Core.Config;
+using VideoDownloader.Core.Hls;
+using VideoDownloader.Core.Models;
+using VideoDownloader.Core.Platform;
+
+namespace VideoDownloader.Tests.Platform;
+
+/// <summary>HlsDownloader 가 주입된 IMediaMuxer 를 실제 리먹스 경로에서 사용하는지 검증(RED: ctor 미할당 회귀 방지).</summary>
+public class HlsMuxerWiringTests
+{
+    private sealed class RecordingMuxer : IMediaMuxer
+    {
+        public int RemuxCalls;
+        public Task RemuxAsync(string ffmpeg, string input, string output, CancellationToken ct)
+        {
+            RemuxCalls++;
+            File.WriteAllText(output, "remuxed"); // 성공 시뮬레이션
+            return Task.CompletedTask;
+        }
+        public Task DownloadDashAsync(string ffmpeg, Uri mpdUrl, string output, double durationSec,
+            HttpClient http, IProgress<DownloadProgress>? progress, CancellationToken ct) => Task.CompletedTask;
+        public string? ResolveFfmpeg(AppConfig config) => "ffmpeg";
+    }
+
+    [Fact]
+    public async Task HlsDownloader_주입된_뮥서로_리먹스한다()
+    {
+        if (!OperatingSystem.IsWindows()) return;
+        using var server = new HttpListener();
+        var port = Random.Shared.Next(20000, 60000);
+        server.Prefixes.Add($"http://127.0.0.1:{port}/");
+        server.Start();
+
+        var seg = new byte[16];
+        using var listenerTask = Task.Run(async () =>
+        {
+            for (var i = 0; i < 3; i++)
+            {
+                var ctx = await server.GetContextAsync();
+                var path = ctx.Request.Url!.AbsolutePath;
+                var body = path.EndsWith(".m3u8")
+                    ? "#EXTM3U\n#EXT-X-TARGETDURATION:2\n#EXTINF:2.0,\nseg0.ts\n#EXTINF:2.0,\nseg1.ts\n#EXT-X-ENDLIST\n"
+                    : null;
+                var buf = body != null ? System.Text.Encoding.UTF8.GetBytes(body) : seg;
+                ctx.Response.ContentType = body != null ? "application/vnd.apple.mpegurl" : "video/mp2t";
+                await ctx.Response.OutputStream.WriteAsync(buf);
+                ctx.Response.Close();
+            }
+        });
+
+        var muxer = new RecordingMuxer();
+        var config = new AppConfig();
+        var dl = new HlsDownloader(new HttpClient(), config, muxer);
+        var outBase = Path.Combine(Path.GetTempPath(), $"hls-{Guid.NewGuid():N}");
+        try
+        {
+            var result = await dl.DownloadAsync(new Uri($"http://127.0.0.1:{port}/index.m3u8"), outBase);
+            Assert.True(muxer.RemuxCalls > 0, "주입한 IMediaMuxer.RemuxAsync 가 호출되어야 한다");
+            Assert.EndsWith(".mp4", result);
+        }
+        finally
+        {
+            server.Stop();
+            try { await listenerTask; } catch { }
+            foreach (var f in Directory.GetFiles(Path.GetTempPath(), Path.GetFileName(outBase) + "*"))
+                File.Delete(f);
+            if (Directory.Exists(outBase + ".parts")) Directory.Delete(outBase + ".parts", true);
+        }
+    }
+}