Reduced memory usage and fixed several memory leaks (#933)

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingAssistant.razor.Projects.cs

@@ -138,6 +138,11 @@ public partial class VisualBriefingAssistant
         this.MediaTranscriptionService.ClearOwnerState(MediaImportOwner.ForVisualBriefing(id));
         await this.Store.DeleteAsync(id);
         await this.Store.ForgetSelectionAsync(id);
+
+        // The briefing is gone, so neither its build state nor its progress snapshot is of use:
+        this.BuildOrchestrator.ForgetBriefing(id);
+        this.BuildProgressService.Forget(id);
+
         this.ClearSelectedProject();
 
         await this.ReloadListAsync();

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingAssistant.razor.cs

@@ -158,7 +158,7 @@ public partial class VisualBriefingAssistant : MSGComponentBase
         await this.ReloadListAsync();
         await this.ConsumePendingMediaOutcomesAsync();
         _ = this.MonitorSourceStatusAsync(this.sourceMonitorCancellation.Token);
-        var deferredInstruction = this.MessageBus.CheckDeferredMessages<string>(Event.SEND_TO_VISUAL_BRIEFING_ASSISTANT).FirstOrDefault();
+        var deferredInstruction = this.MessageBus.TakeDeferredMessages<string>(Event.SEND_TO_VISUAL_BRIEFING_ASSISTANT).LastOrDefault();
 
         if (!string.IsNullOrWhiteSpace(deferredInstruction))
         {

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingBuildOrchestrator.cs

@@ -63,6 +63,21 @@ internal sealed partial class VisualBriefingBuildOrchestrator
     public VisualBriefingOperationDiagnostics? GetDiagnostics(Guid briefingId) =>
         this.liveDiagnostics.GetValueOrDefault(briefingId);
 
+    /// <summary>
+    /// Drops what we kept for a briefing which does not exist anymore.
+    /// </summary>
+    /// <remarks>
+    /// Both dictionaries only ever grew: every briefing which was built once stayed in them for as
+    /// long as the app was running. The build lock is not disposed, because another build might
+    /// still wait on it.
+    /// </remarks>
+    /// <param name="briefingId">The identifier of the deleted briefing.</param>
+    public void ForgetBriefing(Guid briefingId)
+    {
+        this.buildLocks.TryRemove(briefingId, out _);
+        this.liveDiagnostics.TryRemove(briefingId, out _);
+    }
+
     /// <summary>
     /// Builds or resumes a visual briefing operation.
     /// </summary>

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingBuildProgressService.cs

@@ -33,4 +33,14 @@ public sealed class VisualBriefingBuildProgressService
     /// </summary>
     public VisualBriefingBuildRecord? GetLatest(Guid briefingId) =>
         this.latest.GetValueOrDefault(briefingId);
+
+    /// <summary>
+    /// Drops the snapshot of a briefing which does not exist anymore.
+    /// </summary>
+    /// <remarks>
+    /// A snapshot is a complete build record. Without this, every briefing which was ever built
+    /// kept one for as long as the app was running.
+    /// </remarks>
+    /// <param name="briefingId">The identifier of the deleted briefing.</param>
+    public void Forget(Guid briefingId) => this.latest.TryRemove(briefingId, out _);
 }

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingStore.Projects.cs

@@ -398,6 +398,7 @@ public sealed partial class VisualBriefingStore
         finally
         {
             gate.Release();
+            this.ForgetLock(briefingId);
         }
     }
 

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingStore.cs

@@ -167,6 +167,16 @@ public sealed partial class VisualBriefingStore(
     /// </summary>
     private SemaphoreSlim GetLock(Guid briefingId) => this.briefingLocks.GetOrAdd(briefingId, _ => new(1, 1));
 
+    /// <summary>
+    /// Drops the lock of a briefing which does not exist anymore.
+    /// </summary>
+    /// <remarks>
+    /// Otherwise, this dictionary keeps one entry per briefing the app ever touched. We do not
+    /// dispose the semaphore: another operation might still wait on it, and disposing it under
+    /// their feet would turn a deleted briefing into an exception somewhere else.
+    /// </remarks>
+    private void ForgetLock(Guid briefingId) => this.briefingLocks.TryRemove(briefingId, out _);
+
     /// <summary>
     /// Defines <c>BriefingDirectory</c> for the visual briefing feature.
     /// </summary>