feat: add models and workspace repository layer

YKanBan/Storage/Workspace/WorkspaceSession.cs

@@ -0,0 +1,67 @@
+namespace YKanBan.Storage.Workspace;
+
+/// <summary>
+/// One open workspace for the process lifetime: the exclusive lock plus the
+/// single repository connection. Opening acquires the lock first, so a folder
+/// without .ykanban, or one already locked by another instance, fails before
+/// any database work happens. Disposing releases the repository and then the
+/// lock.
+/// </summary>
+public sealed class WorkspaceSession : IDisposable
+{
+    private readonly WorkspaceLock _workspaceLock;
+
+    /// <summary>
+    /// Initializes the session around an acquired lock and an open repository.
+    /// </summary>
+    /// <param name="folderPath">The canonical workspace folder path.</param>
+    /// <param name="workspaceLock">The exclusive lock held while this session is open.</param>
+    /// <param name="repository">The data access object for this workspace.</param>
+    private WorkspaceSession(string folderPath, WorkspaceLock workspaceLock, WorkspaceRepository repository)
+    {
+        FolderPath = folderPath;
+        _workspaceLock = workspaceLock;
+        Repository = repository;
+    }
+
+    /// <summary>
+    /// Gets the canonical workspace folder path.
+    /// </summary>
+    public string FolderPath { get; }
+
+    /// <summary>
+    /// Gets the data access object for this workspace.
+    /// </summary>
+    public WorkspaceRepository Repository { get; }
+
+    /// <summary>
+    /// Opens a workspace: acquires its exclusive lock and opens its repository.
+    /// </summary>
+    /// <param name="folderPath">The workspace folder to open.</param>
+    /// <returns>The opened session; dispose it to release the lock and connection.</returns>
+    /// <exception cref="WorkspaceNotInitializedException">The folder has no .ykanban structure.</exception>
+    /// <exception cref="WorkspaceLockException">Another instance already holds the lock.</exception>
+    public static WorkspaceSession Open(string folderPath)
+    {
+        WorkspaceLock workspaceLock = WorkspaceLock.Acquire(folderPath);
+        try
+        {
+            var repository = new WorkspaceRepository(folderPath);
+            return new WorkspaceSession(folderPath, workspaceLock, repository);
+        }
+        catch
+        {
+            workspaceLock.Dispose();
+            throw;
+        }
+    }
+
+    /// <summary>
+    /// Releases the repository connection, then the exclusive lock.
+    /// </summary>
+    public void Dispose()
+    {
+        Repository.Dispose();
+        _workspaceLock.Dispose();
+    }
+}