refactor: replace timing hacks with structured signals

CHANGELOG.md

@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Use sheet presentation for all file open/save panels instead of free-floating dialogs
 - Replace event monitor with native SwiftUI .onKeyPress() in connection switcher
 - Extract reusable SearchFieldView component from 4 custom search field implementations
+- Replace timing hacks with structured signals (polling loops, arbitrary delays)
 
 ### Changed
 

TablePro/AppDelegate+ConnectionHandler.swift

@@ -264,10 +264,18 @@ extension AppDelegate {
         Task { @MainActor [weak self] in
             defer { self?.isProcessingQueuedURLs = false }
 
-            var ready = false
-            for _ in 0..<25 {
-                if WindowOpener.shared.openWindow != nil { ready = true; break }
-                try? await Task.sleep(for: .milliseconds(200))
+            let ready = await withTaskGroup(of: Bool.self) { group in
+                group.addTask {
+                    await WindowOpener.shared.waitUntilReady()
+                    return true
+                }
+                group.addTask {
+                    try? await Task.sleep(for: .seconds(5))
+                    return false
+                }
+                let result = await group.next() ?? false
+                group.cancelAll()
+                return result
             }
             guard let self else { return }
             if !ready {

TablePro/AppDelegate+FileOpen.swift

@@ -244,10 +244,8 @@ extension AppDelegate {
 
     private func handleConnectionShareFile(_ url: URL) {
         openWelcomeWindow()
-        // Delay to ensure WelcomeWindowView's .onReceive is registered after window renders
-        DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
-            NotificationCenter.default.post(name: .connectionShareFileOpened, object: url)
-        }
+        pendingConnectionShareURL = url
+        NotificationCenter.default.post(name: .connectionShareFileOpened, object: url)
     }
 
     // MARK: - Plugin Install

TablePro/AppDelegate+WindowConfig.swift

@@ -151,22 +151,6 @@ extension AppDelegate {
         NotificationCenter.default.post(name: .openWelcomeWindow, object: nil)
     }
 
-    func configureWelcomeWindow() {
-        Task { @MainActor [weak self] in
-            for _ in 0 ..< 5 {
-                guard let self else { return }
-                let found = NSApp.windows.contains(where: { self.isWelcomeWindow($0) })
-                if found {
-                    for window in NSApp.windows where self.isWelcomeWindow(window) {
-                        self.configureWelcomeWindowStyle(window)
-                    }
-                    return
-                }
-                try? await Task.sleep(for: .milliseconds(50))
-            }
-        }
-    }
-
     private func configureWelcomeWindowStyle(_ window: NSWindow) {
         window.standardWindowButton(.miniaturizeButton)?.isHidden = true
         window.standardWindowButton(.zoomButton)?.isHidden = true

TablePro/AppDelegate.swift

@@ -59,6 +59,9 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     /// Prevents duplicate connections when the same file is opened twice rapidly.
     var connectingFilePaths = Set<String>()
 
+    /// Connection share file URL pending consumption by WelcomeViewModel.setUp()
+    var pendingConnectionShareURL: URL?
+
     // MARK: - NSApplicationDelegate
 
     func application(_ application: NSApplication, open urls: [URL]) {
@@ -105,8 +108,6 @@ class AppDelegate: NSObject, NSApplicationDelegate {
             _ = QueryHistoryStorage.shared
         }
 
-        configureWelcomeWindow()
-
         let settings = AppSettingsStorage.shared.loadGeneral()
         if settings.startupBehavior == .reopenLast,
            let lastConnectionId = AppSettingsStorage.shared.loadLastConnectionId() {

TablePro/Core/Services/Infrastructure/WindowOpener.swift

@@ -15,9 +15,30 @@ internal final class WindowOpener {
 
     internal static let shared = WindowOpener()
 
+    private var readyContinuation: CheckedContinuation<Void, Never>?
+
     /// Set on appear by ContentView, WelcomeViewModel, or ConnectionFormView.
     /// Safe to store — OpenWindowAction is app-scoped, not view-scoped.
-    internal var openWindow: OpenWindowAction?
+    internal var openWindow: OpenWindowAction? {
+        didSet {
+            if openWindow != nil {
+                readyContinuation?.resume()
+                readyContinuation = nil
+            }
+        }
+    }
+
+    /// Suspends until openWindow is set. Returns immediately if already available.
+    internal func waitUntilReady() async {
+        if openWindow != nil { return }
+        await withCheckedContinuation { continuation in
+            if openWindow != nil {
+                continuation.resume()
+            } else {
+                readyContinuation = continuation
+            }
+        }
+    }
 
     /// Ordered queue of pending payloads — windows requested via openNativeTab
     /// but not yet acknowledged by MainContentView.configureWindow.

TablePro/ViewModels/WelcomeViewModel.swift

@@ -181,6 +181,12 @@ final class WelcomeViewModel {
 
         loadConnections()
         linkedConnections = LinkedFolderWatcher.shared.linkedConnections
+
+        if let appDelegate = NSApp.delegate as? AppDelegate,
+           let pendingURL = appDelegate.pendingConnectionShareURL {
+            appDelegate.pendingConnectionShareURL = nil
+            activeSheet = .importFile(pendingURL)
+        }
     }
 
     deinit {
@@ -504,15 +510,25 @@ final class WelcomeViewModel {
     }
 
     func focusConnectionFormWindow() {
+        if let window = NSApp.windows.first(where: { $0.identifier?.rawValue == "connection-form" }) {
+            window.makeKeyAndOrderFront(nil)
+            return
+        }
+
+        var observer: NSObjectProtocol?
+        observer = NotificationCenter.default.addObserver(
+            forName: NSWindow.didBecomeKeyNotification,
+            object: nil,
+            queue: .main
+        ) { notification in
+            guard let window = notification.object as? NSWindow,
+                  window.identifier?.rawValue == "connection-form" else { return }
+            if let observer { NotificationCenter.default.removeObserver(observer) }
+        }
+
         Task { @MainActor in
-            for _ in 0..<10 {
-                for window in NSApp.windows where
-                    window.identifier?.rawValue == "connection-form" {
-                    window.makeKeyAndOrderFront(nil)
-                    return
-                }
-                try? await Task.sleep(for: .milliseconds(20))
-            }
+            try? await Task.sleep(for: .milliseconds(500))
+            if let observer { NotificationCenter.default.removeObserver(observer) }
         }
     }
 

TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift

@@ -250,11 +250,10 @@ extension MainContentCoordinator {
     ) {
         let isNonSQL = PluginManager.shared.editorLanguage(for: connectionType) != .sql
 
-        // Phase 2a: Exact row count
+        // Phase 2a: Exact row count (background priority to let Phase 1 render first)
         // Redis/non-SQL drivers don't support SELECT COUNT(*); use approximate count instead.
-        Task { [weak self] in
+        Task(priority: .background) { [weak self] in
             guard let self else { return }
-            try? await Task.sleep(nanoseconds: 200_000_000)
             guard !self.isTearingDown else { return }
             guard let mainDriver = DatabaseManager.shared.driver(for: connectionId) else { return }
 
@@ -289,9 +288,8 @@ extension MainContentCoordinator {
         // Phase 2b: Fetch enum/set values (not applicable for non-SQL databases)
         guard !isNonSQL else { return }
         guard let enumDriver = DatabaseManager.shared.driver(for: connectionId) else { return }
-        Task { [weak self] in
+        Task(priority: .background) { [weak self] in
             guard let self else { return }
-            try? await Task.sleep(nanoseconds: 200_000_000)
             guard !self.isTearingDown else { return }
 
             // Use schema if available, otherwise fetch column info for enum parsing

TablePro/Views/Main/MainContentView.swift

@@ -277,8 +277,7 @@ struct MainContentView: View {
             .onChange(of: tabManager.selectedTabId) { _, newTabId in
                 pendingTabSwitch?.cancel()
                 pendingTabSwitch = Task { @MainActor in
-                    // Let other onChange handlers (tabs, resultColumns) settle first
-                    try? await Task.sleep(for: .milliseconds(16))
+                    await Task.yield()
                     guard !Task.isCancelled else { return }
                     handleTabSelectionChange(from: previousSelectedTabId, to: newTabId)
                     previousSelectedTabId = newTabId