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src/Models/SessionData.cs

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+using System.Collections.Generic;
+
+namespace MarkdownEditor.Models;
+
+/// <summary>
+/// Represents a complete application session state.
+/// </summary>
+public class SessionData
+{
+    /// <summary>
+    /// Gets or sets the list of tabs that were open in the session.
+    /// </summary>
+    public List<SessionTabInfo> Tabs { get; set; } = new();
+
+    /// <summary>
+    /// Gets or sets the index of the tab that was selected when the session was saved.
+    /// </summary>
+    public int SelectedTabIndex { get; set; }
+}