feat(graph): Slide node type — present decks straight from the mesh

src/MeshWeaver.Graph/Configuration/GraphConfigurationExtensions.cs

@@ -32,6 +32,7 @@ public TBuilder AddGraph()
                 .AddReleaseType()
                 .AddMarkdownType()
                 .AddHtmlType()
+                .AddSlideType()
                 .AddCommentType()
                 .AddTrackedChangeType()
                 .AddAccessAssignmentType()

src/MeshWeaver.Graph/Configuration/SlideNodeType.cs

@@ -0,0 +1,80 @@
+using MeshWeaver.Data;
+using MeshWeaver.Mesh;
+
+namespace MeshWeaver.Graph.Configuration;
+
+/// <summary>
+/// Provides configuration for Slide node types in the graph.
+/// A Slide is one page of a presentation deck: its <see cref="SlideContent"/> carries
+/// the slide body (markdown — raw HTML/SVG passes through the markdown pipeline, so
+/// authors have full visual freedom), optional speaker notes, and an optional CSS
+/// background for the stage.
+/// <para>
+/// A <b>deck</b> is not a node type of its own: any parent node whose children are
+/// Slide nodes is a deck, and the slides play in <see cref="MeshNode.Order"/>
+/// (lower first, null last). The Slide views resolve prev/next from the sibling
+/// Slide nodes of the same parent — see <see cref="SlideLayoutAreas"/>.
+/// </para>
+/// </summary>
+public static class SlideNodeType
+{
+    /// <summary>
+    /// The NodeType value used to identify slide nodes.
+    /// </summary>
+    public const string NodeType = "Slide";
+
+    /// <summary>
+    /// Registers the built-in "Slide" MeshNode on the mesh builder.
+    /// </summary>
+    public static TBuilder AddSlideType<TBuilder>(this TBuilder builder) where TBuilder : MeshBuilder
+    {
+        builder.AddMeshNodes(CreateMeshNode());
+        builder.ConfigureNodeTypeAccess(a => a.WithPublicRead(NodeType));
+        return builder;
+    }
+
+    /// <summary>
+    /// Creates a MeshNode definition for the Slide node type.
+    /// This provides HubConfiguration for nodes with nodeType="Slide".
+    /// </summary>
+    public static MeshNode CreateMeshNode() => new(NodeType)
+    {
+        Name = "Slide",
+        Icon = "/static/NodeTypeIcons/presentation.svg",
+        HubConfiguration = config => config
+            .AddSlideViews()
+            .AddMeshDataSource(s => s.WithContentType<SlideContent>())
+    };
+}
+
+/// <summary>
+/// The content of a Slide MeshNode — one page of a presentation deck.
+/// Immutable; every mutation goes through
+/// <c>workspace.GetMeshNodeStream(path).Update(...)</c>.
+/// </summary>
+public record SlideContent
+{
+    /// <summary>
+    /// The slide body as markdown. Raw HTML and SVG pass through the markdown
+    /// pipeline unchanged, so a slide can be anything from a bullet list to a
+    /// full-bleed illustration.
+    /// </summary>
+    public string? Content { get; init; }
+
+    /// <summary>
+    /// Speaker notes (markdown). Shown only in the Notes view, never on the stage.
+    /// </summary>
+    public string? Notes { get; init; }
+
+    /// <summary>
+    /// CSS background for the slide stage (e.g. a gradient like
+    /// <c>linear-gradient(135deg, #667eea 0%, #764ba2 100%)</c>).
+    /// When null, the stage uses the theme-aware default gradient.
+    /// </summary>
+    public string? Background { get; init; }
+
+    /// <summary>
+    /// Reserved for a future slide-transition effect. Default null (no transition).
+    /// </summary>
+    public string? Transition { get; init; }
+}

src/MeshWeaver.Graph/MeshNodeExtensions.cs

@@ -363,6 +363,9 @@ public static ITypeRegistry WithGraphTypes(this ITypeRegistry typeRegistry)
         typeRegistry.WithType(typeof(CodeConfiguration), nameof(CodeConfiguration));
         typeRegistry.WithType(typeof(Comment), nameof(Comment));
         typeRegistry.WithType(typeof(MarkdownContent), nameof(MarkdownContent));
+        // Slide MeshNode Content — presentation pages (see SlideNodeType). Registered
+        // under the short name so slide nodes round-trip typed across hub boundaries.
+        typeRegistry.WithType(typeof(SlideContent), nameof(SlideContent));
         // Backend-computed editable-field metadata sent to the GUI inside the node-content editor control.
         typeRegistry.WithType(typeof(MeshNodeEditorField), nameof(MeshNodeEditorField));
         // Security content types (AccessAssignment / PartitionAccessPolicy / RoleAssignment / Role).