Added the visual briefing assistant (#893)

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

@@ -0,0 +1,51 @@
+namespace AIStudio.Assistants.VisualBriefing;
+
+/// <summary>
+/// Guards parts compiled by AI Studio after the model-controlled contracts have been validated.
+/// </summary>
+internal static class VisualBriefingCompilerInvariant
+{
+    private const string USER_MESSAGE = "AI Studio could not assemble this briefing because its own compiler produced an invalid part. This is a defect in AI Studio, not in the model response.";
+
+    /// <summary>
+    /// Fails the build when compiled parts violate the artifact contract.
+    /// </summary>
+    /// <param name="stage">The stage running the compilation.</param>
+    /// <param name="compilerIssue">The compiler issue, or an empty string when the parts are valid.</param>
+    /// <exception cref="VisualBriefingBuildException">Thrown when the compiled parts are invalid.</exception>
+    internal static void Guard(VisualBriefingBuildStage stage, string compilerIssue)
+    {
+        if (string.IsNullOrEmpty(compilerIssue))
+            return;
+
+        throw new VisualBriefingBuildException(
+            VisualBriefingFailureCode.COMPILER_INVARIANT_VIOLATED,
+            stage,
+            USER_MESSAGE,
+            $"Stage={stage}; CompilerIssue={compilerIssue}");
+    }
+
+    /// <summary>
+    /// Runs a compilation and translates structural failures into a compiler invariant failure.
+    /// </summary>
+    /// <typeparam name="T">The compilation result type.</typeparam>
+    /// <param name="stage">The stage running the compilation.</param>
+    /// <param name="compile">The compilation to run.</param>
+    /// <returns>The compilation result.</returns>
+    /// <exception cref="VisualBriefingBuildException">Thrown when the compilation fails structurally.</exception>
+    internal static T Guard<T>(VisualBriefingBuildStage stage, Func<T> compile)
+    {
+        try
+        {
+            return compile();
+        }
+        catch (InvalidDataException exception)
+        {
+            throw new VisualBriefingBuildException(
+                VisualBriefingFailureCode.COMPILER_INVARIANT_VIOLATED,
+                stage,
+                USER_MESSAGE,
+                $"Stage={stage}; CompilerIssue={exception.Message}");
+        }
+    }
+}