Added the visual briefing assistant (#893)

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

@@ -0,0 +1,64 @@
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace AIStudio.Assistants.VisualBriefing;
+
+/// <summary>
+/// Provides the two JSON configurations used by visual briefing hashing and persistence.
+/// </summary>
+/// <remarks>
+/// The split is deliberate and the two halves must not be merged back together. Hashing needs bytes
+/// that never change, persistence wants output that stays readable as the app evolves. One shared
+/// configuration cannot serve both: improving the readability of stored files would rewrite the very
+/// bytes that older briefings were hashed with, and every one of them would fail its integrity check.
+/// For the same reason both configurations are written out in full instead of sharing a factory, which
+/// is what <see cref="CanonicalJsonConfigurationAttribute"/> and the rule MWAIS0010 enforce: a shared
+/// factory lets a change intended for the persistence side reach the hashed side unnoticed.
+/// </remarks>
+internal static class VisualBriefingJson
+{
+    /// <summary>
+    /// Gets the frozen options whose byte output is hashed into stored briefings.
+    /// </summary>
+    /// <remarks>
+    /// Treat these options as frozen. Their exact bytes are hashed into stored briefings: the artifact
+    /// header is serialized into the briefing document, and reading that document back re-serializes the
+    /// header to recompute the document hash. Every build stage likewise hashes its serialized output,
+    /// and a mismatch makes the store discard the stored artifact. Any change here — a converter, a
+    /// naming policy, an encoder — therefore invalidates every briefing that was ever written, which
+    /// surfaces as a failed integrity check rather than as a build error. This is why enums stay numeric
+    /// here even though the persisted manifest writes their member names.
+    /// </remarks>
+    [CanonicalJsonConfiguration]
+    internal static JsonSerializerOptions Canonical { get; } = new()
+    {
+        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+        PropertyNameCaseInsensitive = false,
+        WriteIndented = false,
+        Encoder = JavaScriptEncoder.Default,
+        UnmappedMemberHandling = JsonUnmappedMemberHandling.Disallow,
+    };
+
+    /// <summary>
+    /// Gets the options for files that are read back by name rather than by hash.
+    /// </summary>
+    /// <remarks>
+    /// These options are free to evolve, because nothing hashes their output. They write the briefing
+    /// manifest and the diagnostics clipboard text, where readable enum names are worth having: stored
+    /// briefings outlive many releases, so a numeric value would silently change meaning as soon as
+    /// somebody inserts or reorders an enum member. Most visual briefing enums carry the converter as an
+    /// attribute already, which applies to both configurations; the converter below only covers the ones
+    /// defined outside the feature, such as the target language and the audience enums. Reading accepts
+    /// numbers as well, so manifests written before this distinction existed keep loading.
+    /// </remarks>
+    internal static JsonSerializerOptions Persistence { get; } = new()
+    {
+        PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+        PropertyNameCaseInsensitive = false,
+        WriteIndented = true,
+        Encoder = JavaScriptEncoder.Default,
+        UnmappedMemberHandling = JsonUnmappedMemberHandling.Disallow,
+        Converters = { new JsonStringEnumConverter() },
+    };
+}