One window per PGN file, tabbed: the database store stops being a singleton

README.md

@@ -8,7 +8,7 @@ coaches on macOS. Part of the DanceChess family.
 
 ## Features
 
-- **Single-window workflow** — board + notation on top, your game list below.
+- **One window per PGN, as tabs** — board + notation on top, that file's game list below; open files come back on launch.
   Arrow keys browse games and step through moves without ever touching the
   mouse; `Enter` dives into a game, `Esc` comes back.
 - **PGN is the source of truth** — open any .pgn and its games *are* the

app/Studio/Database/GameListView.swift

@@ -45,6 +45,9 @@ struct GameListView: NSViewRepresentable {
     let onDeleteRequest: ((Int64) -> Void)?
     /// Right-click with several rows selected → Merge Selected Games.
     var onMergeRequest: (([Int64]) -> Void)? = nil
+    /// The game to land on when the list first fills (the one last viewed
+    /// in this file); nil = row 0.
+    var initialSelection: Int64? = nil
 
     func makeCoordinator() -> Coordinator { Coordinator(view: self) }
 
@@ -157,23 +160,22 @@ struct GameListView: NSViewRepresentable {
         /// Quiets delegate callbacks during programmatic re-selection.
         private var reselecting = false
         private var didInitialSelect = false
-        /// Startup-only: restore the last-viewed game once, then never again
-        /// (a replaced list must not inherit it).
-        private var pendingInitialId: Int64? = UserDefaults.standard
-            .object(forKey: DatabaseStore.lastSelectedGameKey) as? Int64
+        /// Consumed once, when the list first fills.
+        private var pendingInitialId: Int64?
 
         init(view: GameListView) {
             self.view = view
             self.count = view.count
             self.revision = view.revision
             self.generation = view.generation
+            self.pendingInitialId = view.initialSelection
         }
 
         func resetForNewList() {
             selectedId = nil
             selectedRow = -1
             didInitialSelect = false
-            pendingInitialId = nil // only the startup list restores it
+            pendingInitialId = view.initialSelection
         }
 
         func deselectQuietly() {

app/Studio/Engine/OpeningTreePanel.swift

@@ -9,6 +9,12 @@ import DanceChessCore
 @Observable
 @MainActor
 final class OpeningTreeModel {
+    /// The window's list: the local statistics and the games-reaching-
+    /// this-position filter are about this file.
+    let store: DatabaseStore
+
+    init(store: DatabaseStore) { self.store = store }
+
     private(set) var visible = false
     private(set) var rows: [TreeMove] = []
     private(set) var source: ReferenceSource = AppSettings.shared.referenceSource
@@ -49,7 +55,7 @@ final class OpeningTreeModel {
         errorText = nil
         openingName = nil
         noveltyText = nil
-        DatabaseStore.shared.setPositionFilter(nil)
+        store.setPositionFilter(nil)
     }
 
     func setSource(_ source: ReferenceSource) {
@@ -72,7 +78,7 @@ final class OpeningTreeModel {
         self.fen = fen
         self.parentFen = parentFen
         self.san = san
-        DatabaseStore.shared.setPositionFilter(fen)
+        store.setPositionFilter(fen)
         generation += 1
         let gen = generation
         pending?.cancel()
@@ -82,9 +88,9 @@ final class OpeningTreeModel {
             loading = false
             errorText = nil
             openingName = nil
-            rows = (try? DatabaseStore.shared.db?.openingTree(fen: fen)) ?? []
+            rows = (try? store.db?.openingTree(fen: fen)) ?? []
             if let parentFen, let san,
-               let parentRows = try? DatabaseStore.shared.db?.openingTree(fen: parentFen) {
+               let parentRows = try? store.db?.openingTree(fen: parentFen) {
                 noveltyText = Self.novelty(san: san, in: parentRows,
                                            total: parentRows.reduce(0) { $0 + $1.games },
                                            source: source)
@@ -174,10 +180,10 @@ struct OpeningTreePanel: View {
     @State private var showSettings = false
 
     private var statusText: String {
-        let local = "\(DatabaseStore.shared.matchedCount) in list"
+        let local = "\(tree.store.matchedCount) in list"
         switch tree.source {
         case .database:
-            return "\(DatabaseStore.shared.matchedCount) games reach this position"
+            return "\(tree.store.matchedCount) games reach this position"
         default:
             var parts = ["\(tree.onlineTotal) games"]
             if let name = tree.openingName { parts.append(name) }

app/Studio/GameArea.swift

@@ -209,18 +209,18 @@ enum SavePrompt {
     static func run(for session: GameSession, canCancel: Bool) -> Bool {
         guard !suppressPrompts else { return true }
         let isNewGame = session.sourceGameId < 0
+        guard let store = session.store, store.canWriteBack else { return true }
         if isNewGame {
-            // scratch entry: worth rescuing only if it has moves and a
-            // single-file list to land in
-            guard session.hasMoves, DatabaseStore.shared.canWriteBack else { return true }
+            // scratch entry: worth rescuing only if it has moves
+            guard session.hasMoves else { return true }
         } else {
             guard session.isModified else { return true }
         }
         let alert = NSAlert()
         alert.messageText = "Unsaved Changes"
         alert.informativeText = isNewGame
-            ? "Save this new game into “\(DatabaseStore.shared.sourceName ?? "the list")”?"
-            : "Save the changes to “\(session.gameTitle)” to the database?"
+            ? "Save this new game into “\(store.sourceName ?? "the list")”?"
+            : "Save the changes to “\(session.gameTitle)” to “\(store.sourceName ?? "the list")”?"
         alert.addButton(withTitle: "Save")
         alert.addButton(withTitle: "Don't Save")
         if canCancel { alert.addButton(withTitle: "Cancel") }
@@ -236,9 +236,12 @@ enum SavePrompt {
 
     @discardableResult
     static func save(_ session: GameSession) -> Bool {
+        guard let store = session.store else {
+            session.errorText = "This game's file is no longer open"
+            return false
+        }
         do {
-            try DatabaseStore.shared.updateGame(id: session.sourceGameId,
-                                                pgn: session.game.toPgn())
+            try store.updateGame(id: session.sourceGameId, pgn: session.game.toPgn())
             session.markSaved()
             return true
         } catch {
@@ -250,8 +253,12 @@ enum SavePrompt {
     /// Appends a newly entered (scratch) game to the open list + PGN file.
     @discardableResult
     static func appendNewGame(_ session: GameSession) -> Bool {
+        guard let store = session.store else {
+            session.errorText = "No open file to save into"
+            return false
+        }
         do {
-            let id = try DatabaseStore.shared.addGame(pgn: session.game.toPgn())
+            let id = try store.addGame(pgn: session.game.toPgn())
             session.attachToDatabase(id: id)
             return true
         } catch {

app/Studio/GameWindow.swift

@@ -8,8 +8,10 @@ import DanceChessCore
 /// The single-window flow lives in MainWindow; this one keeps its own
 /// Open/Paste PGN toolbar for scratch use.
 struct GameWindow: View {
-    /// A `games.id` from the default database, or -1 for a blank board.
-    var gameId: Int64 = -1
+    /// Which file's game, or a blank board (`path` nil / `id` -1). Saving
+    /// needs that file's window to still be open; otherwise the board is
+    /// scratch.
+    var ref: GameRef
 
     @State private var session = GameSession()
     @State private var engine = EngineSession()
@@ -33,8 +35,12 @@ struct GameWindow: View {
             })
             .onAppear {
                 keyMonitor.install { handleKey($0) }
-                if gameId >= 0, let pgn = DatabaseStore.shared.pgn(for: gameId) {
-                    session.loadPgn(pgn, sourceId: gameId)
+                if let path = ref.path,
+                   let store = OpenStores.shared.store(for: URL(fileURLWithPath: path)) {
+                    session.store = store
+                    if ref.id >= 0, let pgn = store.pgn(for: ref.id) {
+                        session.loadPgn(pgn, sourceId: ref.id)
+                    }
                 }
             }
             .onDisappear {
@@ -53,12 +59,12 @@ struct GameWindow: View {
             .toolbar {
                 ToolbarItemGroup {
                     Button("Save", systemImage: "square.and.arrow.down") { saveGame() }
-                        .disabled(!DatabaseStore.shared.canWriteBack)
+                        .disabled(!(session.store?.canWriteBack ?? false))
                         .help("Save this game into the open list and its PGN file (⌘S)")
                     Button("Game Info", systemImage: "square.and.pencil") {
                         showSaveSheet = true
                     }
-                    .disabled(!DatabaseStore.shared.canWriteBack)
+                    .disabled(!(session.store?.canWriteBack ?? false))
                     .help("Edit the game's players, result, event… (⌘I)")
                     Button("Open PGN", systemImage: "folder") { showImporter = true }
                         .help("Load a PGN into this board (scratch, not the list)")
@@ -92,7 +98,7 @@ struct GameWindow: View {
             }
             .sheet(isPresented: $showSaveSheet) {
                 GameInfoSheet(session: session,
-                              listName: DatabaseStore.shared.sourceName ?? "list") {
+                              listName: session.store?.sourceName ?? "list") {
                     if session.sourceGameId >= 0 {
                         SavePrompt.save(session)
                     } else {