Move FFmpeg runtime to frontend

docs/PROJECT-STRUCTURE.md

@@ -119,7 +119,7 @@ S:\Game Hacking\Eushully\Himegari\           ← workspace root (three siblings)
     │                                       layout-3 numbered state/history/gfx, DAT/STH pair + BMP codec,
     │                                       and profile-owned state
     │   ├── Age.Engine.Frontend/             platform-neutral frontend support: diagnostics/options, page
-    │                                       location, performance logging, movie decoder/runtime contracts,
+    │                                       location, performance logging, movie runtime/FFmpeg decoding,
     │                                       audio alignment, surface registry, and WAV sanitization
     │   └── Age.Engine.Text.Windows/         optional exact Windows GDI gray-4 reference backend; kept
     │                                       outside the platform-neutral VM/runtime core
@@ -156,8 +156,9 @@ through project references rather than compiling duplicate linked sources. The f
 `PageLocatorState`, `GodotTimelineLog`, `GodotTraceSink`, `StepLimitDiagnosticFormatter`, `GodotVmOptions`,
 `PerformanceFrameLog`, and `WindowLaunchOptions`. It also owns the internal movie decoder boundary/runtime,
 audio-timeline alignment, movie-surface registry, and RIFF/WAVE sanitizer; only the `Himegari` and
-`Age.Engine.Tests` assemblies receive explicit friend access to that internal API. FFmpeg interop and decoder
-implementation remain under `godot/` until their separate ownership slice.
+`Age.Engine.Tests` assemblies receive explicit friend access to that internal API. FFmpeg native interop and the
+asynchronous/paced decoder also live here; the `Age.MovieCorpusGate` tool receives friend access to the native
+frame-source seam and references this project rather than compiling an interop source link.
 
 `godot/GodotAdvHost.cs` retains cross-domain host coordination. Its partial-class companion
 `godot/GodotAdvHost.AdvText.cs` owns live/retained ADV text, surface glyph rasterization and caching,

docs/remake-architecture-and-roadmap.md

@@ -841,6 +841,13 @@ do not mix mechanical moves with semantic changes.
    in Godot while implementing the moved boundary through that friend access. Both solution builds and runtime
    validation remain green.
 
+   The third bounded build-graph slice moved the unchanged FFmpeg native interop and asynchronous/paced decoder
+   from `godot/` into `Age.Engine.Frontend`. The two remaining movie test source links and the corpus tool's native
+   source link were replaced by project references. Friend access now also names only the `Age.MovieCorpusGate`
+   assembly required by the native frame-source seam; native ABI resolution, decoder pacing, seek/audio behavior,
+   failure handling, and teardown remain unchanged. Engine, Godot, and corpus-gate builds plus runtime validation
+   remain green.
+
 5. **Close repository-policy and storage gaps.** Add an explicit project license, third-party notices and
    checksums/provenance for committed binaries, consistent editor/build policy, a pinned .NET SDK, and a
    CI entry point built on the same validation driver. Remove the empty workspace-root `.git` directory and
@@ -1195,9 +1202,9 @@ layer's rendering diverges from ADV; save layout.
 
 ## 8. Immediate next step
 Begin step 4 of the **codebase consolidation** maintenance slice: make the build graph express source ownership
-without changing behavior. Move `FfmpegMovieNative.cs` and `FfmpegMovieDecoder.cs` from `godot/` into
-`Age.Engine.Frontend` next. Replace both test source links and the movie corpus gate's native-source link with
-project references, granting narrowly scoped friend access to the corpus-gate assembly while preserving native
-ABI, decoder pacing, failure, and teardown behavior.
+without changing behavior. Move the reusable `MovieCorpusGate.cs` implementation from
+`tools/movie-corpus-gate/` into `Age.Engine.Frontend` next. Leave the tool's `Program.cs` as its command-line entry
+point, remove the final test source link, preserve the internal friend boundary, and verify that no production
+`.cs` files are compiled through cross-project links.
 Concrete playthrough blockers may still preempt this bounded maintenance work; the consolidation effort does
 not replace Phase B gameplay validation or the open cross-platform gates.

engine/Age.Engine.Frontend/Properties/AssemblyInfo.cs

@@ -1,4 +1,5 @@
 using System.Runtime.CompilerServices;
 
 [assembly: InternalsVisibleTo("Age.Engine.Tests")]
+[assembly: InternalsVisibleTo("Age.MovieCorpusGate")]
 [assembly: InternalsVisibleTo("Himegari")]

engine/Age.Engine.Tests/Age.Engine.Tests.csproj

@@ -24,8 +24,6 @@
     <ProjectReference Include="..\Age.Engine\Age.Engine.csproj" />
     <ProjectReference Include="..\Age.Engine.Frontend\Age.Engine.Frontend.csproj" />
     <ProjectReference Include="..\Age.Engine.Text.Windows\Age.Engine.Text.Windows.csproj" />
-    <Compile Include="..\..\godot\FfmpegMovieNative.cs" Link="FfmpegMovieNative.cs" />
-    <Compile Include="..\..\godot\FfmpegMovieDecoder.cs" Link="FfmpegMovieDecoder.cs" />
     <Compile Include="..\..\tools\movie-corpus-gate\MovieCorpusGate.cs" Link="MovieCorpusGate.cs" />
   </ItemGroup>
 

tools/movie-corpus-gate/Age.MovieCorpusGate.csproj

@@ -8,6 +8,6 @@
   </PropertyGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\engine\Age.Engine\Age.Engine.csproj" />
-    <Compile Include="..\..\godot\FfmpegMovieNative.cs" Link="FfmpegMovieNative.cs" />
+    <ProjectReference Include="..\..\engine\Age.Engine.Frontend\Age.Engine.Frontend.csproj" />
   </ItemGroup>
 </Project>