fix: infer connection for macOS native tab bar "+" button (#576)

When the user clicks the macOS native tab bar "+" (not the app toolbar
button), SwiftUI creates a new window with payload=nil. This caused the
new window to have no connection context, triggering tab restoration
from disk which clears session.tables across all windows.

Infer the connectionId from the key window via WindowLifecycleMonitor
and create a proper new-tab payload so the new tab inherits the
correct connection.

Author: datlechin

TablePro/ContentView.swift

@@ -36,11 +36,24 @@ struct ContentView: View {
     private let storage = ConnectionStorage.shared
 
     init(payload: EditorTabPayload?) {
-        self.payload = payload
+        // When payload is nil (macOS native tab bar "+" button), infer
+        // the connectionId from the key window so the new tab inherits
+        // the correct connection instead of showing an empty state.
+        var effectivePayload = payload
+        if effectivePayload == nil, let keyWindow = NSApp.keyWindow,
+           let connectionId = WindowLifecycleMonitor.shared.connectionIdFromWindow(keyWindow) {
+            effectivePayload = EditorTabPayload(
+                connectionId: connectionId,
+                tabType: .query,
+                isNewTab: true
+            )
+        }
+        self.payload = effectivePayload
+
         let defaultTitle: String
-        if let tableName = payload?.tableName {
+        if let tableName = effectivePayload?.tableName {
             defaultTitle = tableName
-        } else if let connectionId = payload?.connectionId,
+        } else if let connectionId = effectivePayload?.connectionId,
                   let connection = DatabaseManager.shared.activeSessions[connectionId]?.connection {
             let langName = PluginManager.shared.queryLanguageName(for: connection.type)
             defaultTitle = "\(langName) Query"
@@ -52,15 +65,15 @@ struct ContentView: View {
         // For Cmd+T (new tab), the session already exists. Resolve synchronously
         // to avoid the "Connecting..." flash while waiting for async onChange.
         var resolvedSession: ConnectionSession?
-        if let connectionId = payload?.connectionId {
+        if let connectionId = effectivePayload?.connectionId {
             resolvedSession = DatabaseManager.shared.activeSessions[connectionId]
         }
         _currentSession = State(initialValue: resolvedSession)
 
         if let session = resolvedSession {
             _rightPanelState = State(initialValue: RightPanelState())
             _sessionState = State(initialValue: SessionStateFactory.create(
-                connection: session.connection, payload: payload
+                connection: session.connection, payload: effectivePayload
             ))
         } else {
             _rightPanelState = State(initialValue: nil)

TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift

@@ -119,6 +119,12 @@ internal final class WindowLifecycleMonitor {
         return entries[windowId]?.connectionId
     }
 
+    /// Look up the connectionId for a given NSWindow by matching its reference.
+    internal func connectionIdFromWindow(_ window: NSWindow) -> UUID? {
+        purgeStaleEntries()
+        return entries.values.first { $0.window === window }?.connectionId
+    }
+
     /// Check if any windows are registered for a connection.
     internal func hasWindows(for connectionId: UUID) -> Bool {
         purgeStaleEntries()