refactor: use structured rich text for Notes editing

Sources/ConjureKit/NotesStore.swift

@@ -24,6 +24,7 @@ public struct Note: Identifiable {
 public final class NotesStore {
     public private(set) var notes: [Note] = []
     private let directory: URL
+    private var legacyIDs: Set<UUID> = []
 
     public init(directory: URL = FileManager.default.urls(
         for: .applicationSupportDirectory, in: .userDomainMask
@@ -34,16 +35,26 @@ public final class NotesStore {
             at: directory, includingPropertiesForKeys: nil
         ).filter { $0.pathExtension.lowercased() == "rtfd" }
             .sorted { $0.lastPathComponent < $1.lastPathComponent }
-        notes = try files.map { url in
+        var loaded: [Note] = []
+        for url in files {
             guard let id = UUID(uuidString: url.deletingPathExtension().lastPathComponent) else {
                 throw CocoaError(.fileReadCorruptFile)
             }
-            let contents = try NSAttributedString(
-                url: url, options: [.documentType: NSAttributedString.DocumentType.rtfd],
-                documentAttributes: nil
-            )
-            return Note(id: id, contents: contents)
+            let wrapper = try FileWrapper(url: url, options: .immediate)
+            guard wrapper.isDirectory else { throw CocoaError(.fileReadCorruptFile) }
+            let contents: NSAttributedString
+            if wrapper.fileWrappers?[NoteDocument.metadataFilename] != nil {
+                contents = try NoteDocument.contents(from: wrapper)
+            } else {
+                guard let legacy = NSAttributedString(rtfdFileWrapper: wrapper, documentAttributes: nil) else {
+                    throw CocoaError(.fileReadCorruptFile)
+                }
+                contents = NoteDocument.importMarkdown(legacy)
+                legacyIDs.insert(id)
+            }
+            loaded.append(Note(id: id, contents: contents))
         }
+        notes = loaded
     }
 
     public func create() throws -> UUID {
@@ -69,14 +80,29 @@ public final class NotesStore {
         }
         try FileManager.default.removeItem(at: directory.appendingPathComponent(id.uuidString + ".rtfd"))
         notes.remove(at: index)
+        legacyIDs.remove(id)
     }
 
     private func save(_ note: Note) throws {
-        let wrapper = try note.contents.fileWrapper(
-            from: NSRange(location: 0, length: note.contents.length),
-            documentAttributes: [.documentType: NSAttributedString.DocumentType.rtfd]
-        )
+        let wrapper = try NoteDocument.fileWrapper(note.contents)
         let url = directory.appendingPathComponent(note.id.uuidString + ".rtfd", isDirectory: true)
+        if legacyIDs.contains(note.id) {
+            let backups = directory.appendingPathComponent("LegacyBackups", isDirectory: true)
+            try FileManager.default.createDirectory(at: backups, withIntermediateDirectories: true)
+            let backup = backups.appendingPathComponent(note.id.uuidString + ".rtfd", isDirectory: true)
+            if !FileManager.default.fileExists(atPath: backup.path) {
+                // copyItem leaves the live legacy package untouched if backup creation fails.
+                try FileManager.default.copyItem(at: url, to: backup)
+            } else {
+                // A previous failed save may already have preserved the original package.
+                let original = try FileWrapper(url: backup, options: .immediate)
+                guard original.isDirectory,
+                      NSAttributedString(rtfdFileWrapper: original, documentAttributes: nil) != nil else {
+                    throw CocoaError(.fileWriteFileExists)
+                }
+            }
+        }
         try wrapper.write(to: url, options: .atomic, originalContentsURL: url)
+        legacyIDs.remove(note.id)
     }
 }