Fix `.tasproj` autoload loading mismatched savestates

src/BizHawk.Client.Common/movie/MovieSession.cs

@@ -2,6 +2,8 @@
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
+
+using BizHawk.Common.PathExtensions;
 using BizHawk.Common.StringExtensions;
 using BizHawk.Emulation.Common;
 
@@ -192,6 +194,8 @@ namespace BizHawk.Client.Common
 			IMovie movie,
 			bool record,
 			string systemId,
+			string loadedRomHash,
+			PathEntryCollection pathEntries,
 			IDictionary<string, string> preferredCores)
 		{
 			if (movie.IsActive() && movie.Changes)
@@ -208,6 +212,22 @@ namespace BizHawk.Client.Common
 					throw new MoviePlatformMismatchException(
 						$"Movie system Id ({movie.SystemID}) does not match the currently loaded platform ({systemId}), unable to load");
 				}
+
+				if (!(string.IsNullOrEmpty(movie.Hash) || loadedRomHash.Equals(movie.Hash, StringComparison.Ordinal))
+					&& movie is TasMovie tasproj)
+				{
+					var result = _dialogParent.ModalMessageBox2(
+						caption: "Discard GreenZone?",
+						text: $"The TAStudio project {movie.Filename.MakeRelativeTo(pathEntries.MovieAbsolutePath())} appears to be for a different game than the one that's loaded.\n"
+							+ "Choose \"No\" to continue anyway, which may lead to an invalid savestate being loaded.\n"
+							+ "Choose \"Yes\" to discard the GreenZone (savestate history). This is safer, and at worst you'll only need to watch through the whole movie.");
+					//TODO add abort option
+					if (result)
+					{
+						tasproj.TasSession.UpdateValues(frame: 0, currentBranch: tasproj.TasSession.CurrentBranch); // wtf is this API --yoshi
+						tasproj.InvalidateEntireGreenzone();
+					}
+				}
 			}
 
 			if (!record)

src/BizHawk.Client.Common/movie/interfaces/IMovieSession.cs

@@ -81,6 +81,8 @@ namespace BizHawk.Client.Common
 			IMovie movie,
 			bool record,
 			string systemId,
+			string loadedRomHash,
+			PathEntryCollection pathEntries,
 			IDictionary<string, string> preferredCores);
 
 		/// <summary>

src/BizHawk.Client.Common/movie/tasproj/TasMovie.cs

@@ -149,6 +149,8 @@ namespace BizHawk.Client.Common
 			}
 		}
 
+		public void InvalidateEntireGreenzone()
+			=> InvalidateAfter(0);
 
 		private (int Frame, IMovieController Controller) _displayCache = (-1, new Bk2Controller("", NullController.Instance.Definition));
 

src/BizHawk.Client.EmuHawk/MainForm.Movie.cs

@@ -27,7 +27,13 @@ namespace BizHawk.Client.EmuHawk
 			{
 				try
 				{
-					MovieSession.QueueNewMovie(movie, record, Emulator.SystemId, Config.PreferredCores);
+					MovieSession.QueueNewMovie(
+						movie,
+						record: record,
+						systemId: Emulator.SystemId,
+						loadedRomHash: Game.Hash,
+						Config.PathEntries,
+						Config.PreferredCores);
 				}
 				catch (MoviePlatformMismatchException ex)
 				{
@@ -54,6 +60,7 @@ namespace BizHawk.Client.EmuHawk
 
 			SetMainformMovieInfo();
 
+			// turns out this was too late for .tasproj autoloading and restoring playback position (loads savestate but wasn't checking game match)
 			if (string.IsNullOrEmpty(MovieSession.Movie.Hash))
 			{
 				AddOnScreenMessage("Movie is missing hash, skipping hash check");