Added tests which guard the prompts and the protected data of visual briefings

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingArtifactService.Assembly.cs

@@ -370,7 +370,10 @@ public sealed partial class VisualBriefingArtifactService
     /// <summary>
     /// Defines <c>AddProtectedArtifactData</c> for the visual briefing feature.
     /// </summary>
-    private static JsonElement AddProtectedArtifactData(VisualBriefingManifest manifest, VisualBriefingRevisionRequest request)
+    /// <remarks>
+    /// Internal, so that a test can check the JSON it writes.
+    /// </remarks>
+    internal static JsonElement AddProtectedArtifactData(VisualBriefingManifest manifest, VisualBriefingRevisionRequest request)
     {
         var source = request.Data;
         var dictionary = JsonSerializer.Deserialize<Dictionary<string, JsonElement>>(source.GetRawText(), JSON_OPTIONS) ?? [];

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

@@ -107,7 +107,8 @@ internal sealed class VisualBriefingContentStage(StructuredLlmStageRunner stageR
           Do not return source references, reset controls, filter controls, or entries for ASSET components; AI Studio creates all of them deterministically.
           """;
 
-    private static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingEvidenceArtifact evidence, VisualBriefingPlanArtifact plan)
+    // Internal, so that a test can check the JSON this prompt carries:
+    internal static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingEvidenceArtifact evidence, VisualBriefingPlanArtifact plan)
     {
         var components = plan.Sections.SelectMany(section => section.Components).ToArray();
         var componentIds = components.Select(component => component.ComponentId).ToArray();

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

@@ -96,7 +96,8 @@ internal sealed class VisualBriefingEvidenceStage(StructuredLlmStageRunner stage
           Include only facts supported by the supplied material.
           """;
 
-    private static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingPreparedSources preparedSources)
+    // Internal, so that a test can check the JSON this prompt carries:
+    internal static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingPreparedSources preparedSources)
     {
         // The model never sees internal source GUIDs, only short handles. The file name is what lets
         // it tell the attached documents apart, which are supplied in the same canonical order:

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

@@ -107,7 +107,8 @@ internal sealed class VisualBriefingPlanStage(StructuredLlmStageRunner stageRunn
           Choose HORIZONTAL for a concise overview with few milestones and VERTICAL for longer or explanation-rich chronological narratives.
           """;
 
-    private static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingEvidenceArtifact evidence) =>
+    // Internal, so that a test can check the JSON this prompt carries:
+    internal static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingEvidenceArtifact evidence) =>
         $"""
          Audience: {manifest.Settings.AudienceProfile}; {manifest.Settings.AudienceAgeGroup}; {manifest.Settings.AudienceOrganizationalLevel}; {manifest.Settings.AudienceExpertise}
          Scope instruction: {manifest.Settings.Instruction}

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

@@ -181,7 +181,8 @@ internal sealed class VisualBriefingPresentationStage(StructuredLlmStageRunner s
           MindWork AI Studio owns all colors, typography, surfaces, and chart styling.
           """;
 
-    private static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingPlanArtifact plan, VisualBriefingPresentationArtifact? parent)
+    // Internal, so that a test can check the JSON this prompt carries:
+    internal static string BuildPrompt(VisualBriefingManifest manifest, VisualBriefingPlanArtifact plan, VisualBriefingPresentationArtifact? parent)
     {
         var parentJson = parent is null ? "none" : JsonSerializer.Serialize(new { parent.Layout, parent.Profile }, VisualBriefingJson.Canonical);
         return $"""