Baseline: WPF/Avalonia/Cli/Core + plans (BROWSER_FEATURES_PLAN v2, MOBILE_PLAN v1)

VideoDownloader.Core/Dash/DashModels.cs

@@ -0,0 +1,20 @@
+namespace VideoDownloader.Core.Dash;
+
+public record DashSegment(Uri Url, int Index);
+
+/// <summary>하나의 AdaptationSet(비디오 또는 오디오) 최고화질 표현의 세그먼트 묶음.</summary>
+public sealed class DashTrack
+{
+    public Uri? InitUrl { get; init; }
+    public IReadOnlyList<DashSegment> Segments { get; init; } = Array.Empty<DashSegment>();
+    public bool IsFmp4 => InitUrl != null;
+}
+
+/// <summary>DASH(MPD) 파싱 결과 — 클리어(비DRM) 비디오(필수) + 오디오(선택) 트랙.</summary>
+public sealed class DashManifest
+{
+    public DashTrack? Video { get; init; }
+    public DashTrack? Audio { get; init; }
+    /// <summary>총 재생시간(초). 진행률 산정용.</summary>
+    public double DurationSec { get; init; }
+}