From 707a6c3a6358401ec0d354082af4bda397d013cb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ng=C3=B4=20Qu=E1=BB=91c=20=C4=90=E1=BA=A1t?=
 <datlechin@gmail.com>
Date: Tue, 24 Mar 2026 08:36:47 +0700
Subject: [PATCH 1/5] fix: MongoDB Atlas auth failure due to wrong authSource
 default (#438)

---
 CHANGELOG.md                                        | 5 +++++
 Plugins/MongoDBDriverPlugin/MongoDBConnection.swift | 5 +++--
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c5b8a757..4fbd7202 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- MongoDB Atlas connections failing to authenticate (#438)
+- MongoDB TLS certificate verification skipped for SRV connections
+
 ## [0.23.1] - 2026-03-24
 
 ### Added
diff --git a/Plugins/MongoDBDriverPlugin/MongoDBConnection.swift b/Plugins/MongoDBDriverPlugin/MongoDBConnection.swift
index 69b7a00f..3aecdb39 100644
--- a/Plugins/MongoDBDriverPlugin/MongoDBConnection.swift
+++ b/Plugins/MongoDBDriverPlugin/MongoDBConnection.swift
@@ -190,6 +190,8 @@ final class MongoDBConnection: @unchecked Sendable {
         let effectiveAuthSource: String
         if let source = authSource, !source.isEmpty {
             effectiveAuthSource = source
+        } else if useSrv {
+            effectiveAuthSource = "admin"
         } else if !database.isEmpty {
             effectiveAuthSource = database
         } else {
@@ -206,8 +208,7 @@ final class MongoDBConnection: @unchecked Sendable {
         let sslEnabled = ["Preferred", "Required", "Verify CA", "Verify Identity"].contains(sslMode)
         if sslEnabled {
             params.append("tls=true")
-            let verifiesCert = sslMode == "Verify CA" || sslMode == "Verify Identity"
-            if !verifiesCert {
+            if sslMode == "Preferred" {
                 params.append("tlsAllowInvalidCertificates=true")
             }
             if !sslCACertPath.isEmpty {

From f7e276e2c9ad88457de96efba00c1ba586c3f931 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ng=C3=B4=20Qu=E1=BB=91c=20=C4=90=E1=BA=A1t?=
 <datlechin@gmail.com>
Date: Tue, 24 Mar 2026 09:06:21 +0700
Subject: [PATCH 2/5] fix: resolve 26 anti-patterns across window lifecycle,
 memory, connections, and SwiftUI

P0 (Critical):
- Skip selected tab during memory eviction to prevent visible refresh on window re-focus
- Wrap reconnectDriver in trackOperation to prevent health monitor race condition

P1 (High):
- Cancel redisDatabaseSwitchTask in coordinator teardown
- Add deinit to AIChatViewModel to cancel streaming task
- Replace 5x fire-and-forget SSH tunnel closes with error logging
- Log schema/database switch errors instead of silently discarding
- Re-fetch session for driver disconnect to avoid stale reference
- Add WindowAccessor NSViewRepresentable for reliable window capture
- Use viewWindow instead of NSApp.keyWindow in command actions

P2 (Medium):
- Fix weak self in LicenseManager/AnalyticsService periodic task loops
- Remove imprecise global changeManager check from eviction scheduling
- Add query staleness detection so stuck queries don't mask dead connections
- Log warning for synchronous plugin loading fallback
- Add deinit to AppSettingsManager for observer cleanup
- Split clearChanges/clearChangesAndUndoHistory for undo preservation
- Make TabDiskActor.save() throw so callers can handle disk errors
- Remove fragile subtitle-based window matching fallback
- Use viewDidMoveToWindow for synchronous window capture

P3 (Low):
- Remove stale isKeyWindow snapshot from configureWindow
- Centralize window identifier constants with exact matching
- Remove unnecessary DispatchQueue.main.async in AppDelegate handlers
- Add warning log for WindowLifecycleMonitor re-registration
- Unify exponential backoff via shared ExponentialBackoff utility
- Return startup command failures from executeStartupCommands
- Replace recursive asyncAfter with cancellable Task loop
---
 TablePro/AppDelegate+WindowConfig.swift       |  29 +-
 .../ChangeTracking/DataChangeManager.swift    |  12 +-
 .../Database/ConnectionHealthMonitor.swift    |  11 +-
 TablePro/Core/Database/DatabaseDriver.swift   |   3 +
 TablePro/Core/Database/DatabaseManager.swift  |  91 +++++--
 .../Infrastructure/AnalyticsService.swift     |   9 +-
 .../TabPersistenceCoordinator.swift           |  12 +-
 .../WindowLifecycleMonitor.swift              |   5 +
 .../Services/Licensing/LicenseManager.swift   |   6 +-
 .../Core/Storage/AppSettingsManager.swift     |   6 +
 TablePro/Core/Storage/TabDiskActor.swift      |  18 +-
 .../Connection/ExponentialBackoff.swift       |  18 ++
 TablePro/ViewModels/AIChatViewModel.swift     |   6 +-
 .../Views/Components/WindowAccessor.swift     |  28 ++
 .../Views/Connection/WelcomeWindowView.swift  |  21 +-
 .../MainContentCoordinator+ChangeGuard.swift  |   2 +-
 .../MainContentCoordinator+Discard.swift      |   2 +-
 ...ainContentCoordinator+MultiStatement.swift |   2 +-
 .../MainContentCoordinator+QueryHelpers.swift |   2 +-
 .../MainContentCoordinator+Refresh.swift      |   2 +-
 .../MainContentCoordinator+SaveChanges.swift  |   2 +-
 .../Main/MainContentCommandActions.swift      |   2 +-
 .../Views/Main/MainContentCoordinator.swift   |  12 +-
 TablePro/Views/Main/MainContentView.swift     |  81 +++---
 docs/development/anti-patterns-tracker.md     | 255 ++++++++++++++++++
 25 files changed, 499 insertions(+), 138 deletions(-)
 create mode 100644 TablePro/Core/Utilities/Connection/ExponentialBackoff.swift
 create mode 100644 TablePro/Views/Components/WindowAccessor.swift
 create mode 100644 docs/development/anti-patterns-tracker.md

diff --git a/TablePro/AppDelegate+WindowConfig.swift b/TablePro/AppDelegate+WindowConfig.swift
index 50f3cb74..e575a6b9 100644
--- a/TablePro/AppDelegate+WindowConfig.swift
+++ b/TablePro/AppDelegate+WindowConfig.swift
@@ -100,18 +100,22 @@ extension AppDelegate {
 
     // MARK: - Window Identification
 
+    private enum WindowId {
+        static let main = "main"
+        static let welcome = "welcome"
+        static let connectionForm = "connection-form"
+    }
+
     func isMainWindow(_ window: NSWindow) -> Bool {
-        guard let identifier = window.identifier?.rawValue else { return false }
-        return identifier.contains("main")
+        window.identifier?.rawValue == WindowId.main
     }
 
     func isWelcomeWindow(_ window: NSWindow) -> Bool {
-        window.identifier?.rawValue == "welcome" ||
-            window.title.lowercased().contains("welcome")
+        window.identifier?.rawValue == WindowId.welcome
     }
 
     private func isConnectionFormWindow(_ window: NSWindow) -> Bool {
-        window.identifier?.rawValue.contains("connection-form") == true
+        window.identifier?.rawValue == WindowId.connectionForm
     }
 
     // MARK: - Welcome Window
@@ -259,10 +263,7 @@ extension AppDelegate {
 
             if remainingMainWindows == 0 {
                 NotificationCenter.default.post(name: .mainWindowWillClose, object: nil)
-
-                DispatchQueue.main.async {
-                    self.openWelcomeWindow()
-                }
+                openWelcomeWindow()
             }
         }
     }
@@ -273,13 +274,9 @@ extension AppDelegate {
 
         if isWelcomeWindow(window),
            window.occlusionState.contains(.visible),
-           NSApp.windows.contains(where: { isMainWindow($0) && $0.isVisible }) {
-            DispatchQueue.main.async { [weak self] in
-                guard let self else { return }
-                if self.isWelcomeWindow(window), window.isVisible {
-                    window.close()
-                }
-            }
+           NSApp.windows.contains(where: { isMainWindow($0) && $0.isVisible }),
+           window.isVisible {
+            window.close()
         }
     }
 
diff --git a/TablePro/Core/ChangeTracking/DataChangeManager.swift b/TablePro/Core/ChangeTracking/DataChangeManager.swift
index 5a3ec4ac..adb5195b 100644
--- a/TablePro/Core/ChangeTracking/DataChangeManager.swift
+++ b/TablePro/Core/ChangeTracking/DataChangeManager.swift
@@ -125,7 +125,8 @@ final class DataChangeManager {
 
     // MARK: - Configuration
 
-    /// Clear all changes (called after successful save)
+    /// Clear all tracked changes, preserving undo/redo history.
+    /// Use when changes are invalidated but undo context may still be relevant.
     func clearChanges() {
         changes.removeAll()
         changeIndex.removeAll()
@@ -134,11 +135,18 @@ final class DataChangeManager {
         modifiedCells.removeAll()
         insertedRowData.removeAll()
         changedRowIndices.removeAll()
-        undoManager.clearAll()
         hasChanges = false
         reloadVersion += 1
     }
 
+    /// Clear all tracked changes AND undo/redo history.
+    /// Use after successful save, explicit discard, or new query execution
+    /// where undo context is no longer meaningful.
+    func clearChangesAndUndoHistory() {
+        clearChanges()
+        undoManager.clearAll()
+    }
+
     /// Atomically configure the manager for a new table
     func configureForTable(
         tableName: String,
diff --git a/TablePro/Core/Database/ConnectionHealthMonitor.swift b/TablePro/Core/Database/ConnectionHealthMonitor.swift
index e33d81a3..105eb721 100644
--- a/TablePro/Core/Database/ConnectionHealthMonitor.swift
+++ b/TablePro/Core/Database/ConnectionHealthMonitor.swift
@@ -35,7 +35,6 @@ actor ConnectionHealthMonitor {
     // MARK: - Configuration
 
     private static let pingInterval: TimeInterval = 30.0
-    private static let initialBackoffDelays: [TimeInterval] = [2.0, 4.0, 8.0]
     private static let maxBackoffDelay: TimeInterval = 120.0
 
     // MARK: - Dependencies
@@ -227,15 +226,7 @@ actor ConnectionHealthMonitor {
     /// Uses the initial delay table for the first few attempts, then doubles
     /// the previous delay for subsequent attempts, capped at `maxBackoffDelay`.
     private func backoffDelay(for attempt: Int) -> TimeInterval {
-        let delays = Self.initialBackoffDelays
-        if attempt <= delays.count {
-            return delays[attempt - 1]
-        }
-        // Exponential: last seed delay * 2^(attempt - seedCount)
-        let lastSeed = delays[delays.count - 1]
-        let exponent = attempt - delays.count
-        let computed = lastSeed * pow(2.0, Double(exponent))
-        return min(computed, Self.maxBackoffDelay)
+        ExponentialBackoff.delay(for: attempt, maxDelay: Self.maxBackoffDelay)
     }
 
     // MARK: - State Transitions
diff --git a/TablePro/Core/Database/DatabaseDriver.swift b/TablePro/Core/Database/DatabaseDriver.swift
index 980781ec..dddcb78d 100644
--- a/TablePro/Core/Database/DatabaseDriver.swift
+++ b/TablePro/Core/Database/DatabaseDriver.swift
@@ -315,12 +315,15 @@ extension DatabaseDriver {
 /// Factory for creating database drivers via plugin lookup
 @MainActor
 enum DatabaseDriverFactory {
+    private static let logger = Logger(subsystem: "com.TablePro", category: "DatabaseDriverFactory")
+
     static func createDriver(for connection: DatabaseConnection) throws -> DatabaseDriver {
         let pluginId = connection.type.pluginTypeId
         // If the plugin isn't registered yet and background loading hasn't finished,
         // fall back to synchronous loading for this critical code path.
         if PluginManager.shared.driverPlugins[pluginId] == nil,
            !PluginManager.shared.hasFinishedInitialLoad {
+            logger.warning("Plugin '\(pluginId)' not loaded yet — performing synchronous load")
             PluginManager.shared.loadPendingPlugins()
         }
         guard let plugin = PluginManager.shared.driverPlugins[pluginId] else {
diff --git a/TablePro/Core/Database/DatabaseManager.swift b/TablePro/Core/Database/DatabaseManager.swift
index 1c9c0b90..27ad5c9f 100644
--- a/TablePro/Core/Database/DatabaseManager.swift
+++ b/TablePro/Core/Database/DatabaseManager.swift
@@ -49,6 +49,8 @@ final class DatabaseManager {
     /// The health monitor skips pings while a query is running to avoid
     /// racing on non-thread-safe driver connections.
     @ObservationIgnored private var queriesInFlight: [UUID: Int] = [:]
+    /// Tracks when the first query started for each session (used for staleness detection).
+    @ObservationIgnored private var queryStartTimes: [UUID: Date] = [:]
 
     /// Current session (computed from currentSessionId)
     var currentSession: ConnectionSession? {
@@ -130,7 +132,11 @@ final class DatabaseManager {
             // Close tunnel if SSH was established
             if connection.sshConfig.enabled {
                 Task {
-                    try? await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                    do {
+                        try await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                    } catch {
+                        Self.logger.warning("SSH tunnel cleanup failed for \(connection.name): \(error.localizedDescription)")
+                    }
                 }
             }
             removeSessionEntry(for: connection.id)
@@ -220,7 +226,11 @@ final class DatabaseManager {
             // Close tunnel if connection failed
             if connection.sshConfig.enabled {
                 Task {
-                    try? await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                    do {
+                        try await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                    } catch {
+                        Self.logger.warning("SSH tunnel cleanup failed for \(connection.name): \(error.localizedDescription)")
+                    }
                 }
             }
 
@@ -256,7 +266,11 @@ final class DatabaseManager {
 
         // Close SSH tunnel if exists
         if session.connection.sshConfig.enabled {
-            try? await SSHTunnelManager.shared.closeTunnel(connectionId: session.connection.id)
+            do {
+                try await SSHTunnelManager.shared.closeTunnel(connectionId: session.connection.id)
+            } catch {
+                Self.logger.warning("SSH tunnel cleanup failed for \(session.connection.name): \(error.localizedDescription)")
+            }
         }
 
         // Stop health monitoring
@@ -343,11 +357,15 @@ final class DatabaseManager {
         operation: () async throws -> T
     ) async throws -> T {
         queriesInFlight[sessionId, default: 0] += 1
+        if queriesInFlight[sessionId] == 1 {
+            queryStartTimes[sessionId] = Date()
+        }
         defer {
             if let count = queriesInFlight[sessionId], count > 1 {
                 queriesInFlight[sessionId] = count - 1
             } else {
                 queriesInFlight.removeValue(forKey: sessionId)
+                queryStartTimes.removeValue(forKey: sessionId)
             }
         }
         return try await operation()
@@ -402,13 +420,21 @@ final class DatabaseManager {
             result = try await driver.testConnection()
         } catch {
             if connection.sshConfig.enabled {
-                try? await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                do {
+                    try await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+                } catch {
+                    Self.logger.warning("SSH tunnel cleanup failed for \(connection.name): \(error.localizedDescription)")
+                }
             }
             throw error
         }
 
         if connection.sshConfig.enabled {
-            try? await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+            do {
+                try await SSHTunnelManager.shared.closeTunnel(connectionId: connection.id)
+            } catch {
+                Self.logger.warning("SSH tunnel cleanup failed for \(connection.name): \(error.localizedDescription)")
+            }
         }
 
         return result
@@ -532,7 +558,16 @@ final class DatabaseManager {
                 guard let self else { return false }
                 // Skip ping while a user query is in-flight to avoid racing
                 // on the same non-thread-safe driver connection.
-                guard await self.queriesInFlight[connectionId] == nil else { return true }
+                // Allow ping if the query appears stuck (exceeds timeout + grace period).
+                if await self.queriesInFlight[connectionId] != nil {
+                    let queryTimeout = await TimeInterval(AppSettingsManager.shared.general.queryTimeoutSeconds)
+                    let maxStale = max(queryTimeout, 300) // At least 5 minutes
+                    if let startTime = await self.queryStartTimes[connectionId],
+                       Date().timeIntervalSince(startTime) < maxStale {
+                        return true // Query still within expected time
+                    }
+                    // Query appears stuck — fall through to ping
+                }
                 guard let mainDriver = await self.activeSessions[connectionId]?.driver else {
                     return false
                 }
@@ -547,12 +582,13 @@ final class DatabaseManager {
                 guard let self else { return false }
                 guard let session = await self.activeSessions[connectionId] else { return false }
                 do {
-                    let driver = try await self.reconnectDriver(for: session)
+                    let driver = try await self.trackOperation(sessionId: connectionId) {
+                        try await self.reconnectDriver(for: session)
+                    }
                     await self.updateSession(connectionId) { session in
                         session.driver = driver
                         session.status = .connected
                     }
-
                     return true
                 } catch {
                     return false
@@ -619,13 +655,21 @@ final class DatabaseManager {
 
         if let savedSchema = session.currentSchema,
            let schemaDriver = driver as? SchemaSwitchable {
-            try? await schemaDriver.switchSchema(to: savedSchema)
+            do {
+                try await schemaDriver.switchSchema(to: savedSchema)
+            } catch {
+                Self.logger.warning("Failed to restore schema '\(savedSchema)' on reconnect: \(error.localizedDescription)")
+            }
         }
 
         // Restore database for MSSQL if session had a non-default database
         if let savedDatabase = session.currentDatabase,
            let adapter = driver as? PluginDriverAdapter {
-            try? await adapter.switchDatabase(to: savedDatabase)
+            do {
+                try await adapter.switchDatabase(to: savedDatabase)
+            } catch {
+                Self.logger.warning("Failed to restore database '\(savedDatabase)' on reconnect: \(error.localizedDescription)")
+            }
         }
 
         return driver
@@ -659,8 +703,8 @@ final class DatabaseManager {
         await stopHealthMonitor(for: sessionId)
 
         do {
-            // Disconnect existing drivers
-            session.driver?.disconnect()
+            // Disconnect existing driver (re-fetch to avoid stale local reference)
+            activeSessions[sessionId]?.driver?.disconnect()
 
             // Recreate SSH tunnel if needed and build effective connection
             let effectiveConnection = try await buildEffectiveConnection(for: session.connection)
@@ -681,13 +725,21 @@ final class DatabaseManager {
 
             if let savedSchema = activeSessions[sessionId]?.currentSchema,
                let schemaDriver = driver as? SchemaSwitchable {
-                try? await schemaDriver.switchSchema(to: savedSchema)
+                do {
+                    try await schemaDriver.switchSchema(to: savedSchema)
+                } catch {
+                    Self.logger.warning("Failed to restore schema '\(savedSchema)' on reconnect: \(error.localizedDescription)")
+                }
             }
 
             // Restore database for MSSQL if session had a non-default database
             if let savedDatabase = activeSessions[sessionId]?.currentDatabase,
                let adapter = driver as? PluginDriverAdapter {
-                try? await adapter.switchDatabase(to: savedDatabase)
+                do {
+                    try await adapter.switchDatabase(to: savedDatabase)
+                } catch {
+                    Self.logger.warning("Failed to restore database '\(savedDatabase)' on reconnect: \(error.localizedDescription)")
+                }
             }
 
             // Update session
@@ -741,8 +793,7 @@ final class DatabaseManager {
 
         let maxRetries = 5
         for retryCount in 0..<maxRetries {
-            // Exponential backoff: 2s, 4s, 8s, 16s, 32s (capped at 60s)
-            let delay = min(60.0, 2.0 * pow(2.0, Double(retryCount)))
+            let delay = ExponentialBackoff.delay(for: retryCount + 1, maxDelay: 60)
             Self.logger.info("SSH reconnect attempt \(retryCount + 1)/\(maxRetries) in \(delay)s for: \(session.connection.name)")
             try? await Task.sleep(nanoseconds: UInt64(delay * 1_000_000_000))
 
@@ -768,11 +819,12 @@ final class DatabaseManager {
 
     nonisolated private static let startupLogger = Logger(subsystem: "com.TablePro", category: "DatabaseManager")
 
+    @discardableResult
     nonisolated private func executeStartupCommands(
         _ commands: String?, on driver: DatabaseDriver, connectionName: String
-    ) async {
+    ) async -> [(statement: String, error: String)] {
         guard let commands, !commands.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty else {
-            return
+            return []
         }
 
         let statements = commands
@@ -780,6 +832,7 @@ final class DatabaseManager {
             .map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
             .filter { !$0.isEmpty }
 
+        var failures: [(statement: String, error: String)] = []
         for statement in statements {
             do {
                 _ = try await driver.execute(query: statement)
@@ -790,8 +843,10 @@ final class DatabaseManager {
                 Self.startupLogger.warning(
                     "Startup command failed for '\(connectionName)': \(statement) — \(error.localizedDescription)"
                 )
+                failures.append((statement: statement, error: error.localizedDescription))
             }
         }
+        return failures
     }
 
     // MARK: - Schema Changes
diff --git a/TablePro/Core/Services/Infrastructure/AnalyticsService.swift b/TablePro/Core/Services/Infrastructure/AnalyticsService.swift
index 811e3262..ce4b6e8e 100644
--- a/TablePro/Core/Services/Infrastructure/AnalyticsService.swift
+++ b/TablePro/Core/Services/Infrastructure/AnalyticsService.swift
@@ -64,12 +64,13 @@ final class AnalyticsService {
         heartbeatTask?.cancel()
         heartbeatTask = Task { [weak self] in
             // Initial delay before first heartbeat (let connections establish)
-            try? await Task.sleep(for: .seconds(self?.initialDelay ?? 10))
+            guard let delay = self?.initialDelay else { return }
+            try? await Task.sleep(for: .seconds(delay))
 
             while !Task.isCancelled {
-                await self?.sendHeartbeat()
-                try? await Task.sleep(for: .seconds(self?.heartbeatInterval ?? 86_400))
-                guard self != nil else { return }
+                guard let target = self else { return }
+                await target.sendHeartbeat()
+                try? await Task.sleep(for: .seconds(target.heartbeatInterval))
             }
         }
     }
diff --git a/TablePro/Core/Services/Infrastructure/TabPersistenceCoordinator.swift b/TablePro/Core/Services/Infrastructure/TabPersistenceCoordinator.swift
index ec09b953..824a474d 100644
--- a/TablePro/Core/Services/Infrastructure/TabPersistenceCoordinator.swift
+++ b/TablePro/Core/Services/Infrastructure/TabPersistenceCoordinator.swift
@@ -48,7 +48,11 @@ internal final class TabPersistenceCoordinator {
             ? selectedTabId : nonPreviewTabs.first?.id
 
         Task {
-            await TabDiskActor.shared.save(connectionId: connId, tabs: persisted, selectedTabId: normalizedSelectedId)
+            do {
+                try await TabDiskActor.shared.save(connectionId: connId, tabs: persisted, selectedTabId: normalizedSelectedId)
+            } catch {
+                TabDiskActor.logSaveError(connectionId: connId, error: error)
+            }
         }
     }
 
@@ -59,7 +63,11 @@ internal final class TabPersistenceCoordinator {
         let selectedId = selectedTabId
 
         Task {
-            await TabDiskActor.shared.save(connectionId: connId, tabs: persistedTabs, selectedTabId: selectedId)
+            do {
+                try await TabDiskActor.shared.save(connectionId: connId, tabs: persistedTabs, selectedTabId: selectedId)
+            } catch {
+                TabDiskActor.logSaveError(connectionId: connId, error: error)
+            }
         }
     }
 
diff --git a/TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift b/TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift
index a29f6ce9..cbd6e6c5 100644
--- a/TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift
+++ b/TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift
@@ -9,9 +9,11 @@
 
 import AppKit
 import Foundation
+import OSLog
 
 @MainActor
 internal final class WindowLifecycleMonitor {
+    private static let logger = Logger(subsystem: "com.TablePro", category: "WindowLifecycleMonitor")
     internal static let shared = WindowLifecycleMonitor()
 
     private struct Entry {
@@ -41,6 +43,9 @@ internal final class WindowLifecycleMonitor {
     internal func register(window: NSWindow, connectionId: UUID, windowId: UUID, isPreview: Bool = false) {
         // Remove any existing entry for this windowId to avoid duplicate observers
         if let existing = entries[windowId] {
+            if existing.window !== window {
+                Self.logger.warning("Re-registering windowId \(windowId) with a different NSWindow")
+            }
             if let observer = existing.observer {
                 NotificationCenter.default.removeObserver(observer)
             }
diff --git a/TablePro/Core/Services/Licensing/LicenseManager.swift b/TablePro/Core/Services/Licensing/LicenseManager.swift
index 85019d66..23824957 100644
--- a/TablePro/Core/Services/Licensing/LicenseManager.swift
+++ b/TablePro/Core/Services/Licensing/LicenseManager.swift
@@ -93,9 +93,9 @@ final class LicenseManager {
             }
 
             while !Task.isCancelled {
-                try? await Task.sleep(for: .seconds(self?.revalidationInterval ?? 604_800))
-                guard self != nil else { return }
-                await self?.revalidate()
+                guard let self else { return }
+                try? await Task.sleep(for: .seconds(self.revalidationInterval))
+                await self.revalidate()
             }
         }
     }
diff --git a/TablePro/Core/Storage/AppSettingsManager.swift b/TablePro/Core/Storage/AppSettingsManager.swift
index 647fad94..577e2555 100644
--- a/TablePro/Core/Storage/AppSettingsManager.swift
+++ b/TablePro/Core/Storage/AppSettingsManager.swift
@@ -17,6 +17,12 @@ import os
 final class AppSettingsManager {
     static let shared = AppSettingsManager()
 
+    deinit {
+        if let observer = accessibilityTextSizeObserver {
+            NSWorkspace.shared.notificationCenter.removeObserver(observer)
+        }
+    }
+
     // MARK: - Published Settings
 
     var general: GeneralSettings {
diff --git a/TablePro/Core/Storage/TabDiskActor.swift b/TablePro/Core/Storage/TabDiskActor.swift
index bf0b7610..85bdd589 100644
--- a/TablePro/Core/Storage/TabDiskActor.swift
+++ b/TablePro/Core/Storage/TabDiskActor.swift
@@ -68,17 +68,17 @@ internal actor TabDiskActor {
 
     // MARK: - Public API
 
-    /// Save tab state for a connection. Errors are logged internally.
-    internal func save(connectionId: UUID, tabs: [PersistedTab], selectedTabId: UUID?) {
+    /// Save tab state for a connection. Throws on encoding or disk write failure.
+    internal func save(connectionId: UUID, tabs: [PersistedTab], selectedTabId: UUID?) throws {
         let state = TabDiskState(tabs: tabs, selectedTabId: selectedTabId)
+        let data = try encoder.encode(state)
+        let fileURL = tabStateFileURL(for: connectionId)
+        try data.write(to: fileURL, options: .atomic)
+    }
 
-        do {
-            let data = try encoder.encode(state)
-            let fileURL = tabStateFileURL(for: connectionId)
-            try data.write(to: fileURL, options: .atomic)
-        } catch {
-            Self.logger.error("Failed to save tab state for \(connectionId): \(error.localizedDescription)")
-        }
+    /// Log a save error from callers that handle errors externally.
+    nonisolated static func logSaveError(connectionId: UUID, error: Error) {
+        logger.error("Failed to save tab state for \(connectionId): \(error.localizedDescription)")
     }
 
     /// Load tab state for a connection. Returns nil if the file is missing or corrupt.
diff --git a/TablePro/Core/Utilities/Connection/ExponentialBackoff.swift b/TablePro/Core/Utilities/Connection/ExponentialBackoff.swift
new file mode 100644
index 00000000..1cfa28cb
--- /dev/null
+++ b/TablePro/Core/Utilities/Connection/ExponentialBackoff.swift
@@ -0,0 +1,18 @@
+import Foundation
+
+/// Shared exponential backoff calculator for reconnection delays.
+enum ExponentialBackoff {
+    private static let seeds: [TimeInterval] = [2, 4, 8]
+
+    /// Calculate delay for a given attempt (1-based).
+    /// Sequence: 2s, 4s, 8s, then doubles from last seed, capped at maxDelay.
+    static func delay(for attempt: Int, maxDelay: TimeInterval = 120) -> TimeInterval {
+        guard attempt > 0 else { return seeds[0] }
+        if attempt <= seeds.count {
+            return seeds[attempt - 1]
+        }
+        let lastSeed = seeds[seeds.count - 1]
+        let exponent = attempt - seeds.count
+        return min(lastSeed * pow(2.0, Double(exponent)), maxDelay)
+    }
+}
diff --git a/TablePro/ViewModels/AIChatViewModel.swift b/TablePro/ViewModels/AIChatViewModel.swift
index feabecee..26d580a7 100644
--- a/TablePro/ViewModels/AIChatViewModel.swift
+++ b/TablePro/ViewModels/AIChatViewModel.swift
@@ -88,7 +88,7 @@ final class AIChatViewModel {
 
     // MARK: - Private
 
-    private var streamingTask: Task<Void, Never>?
+    @ObservationIgnored nonisolated(unsafe) private var streamingTask: Task<Void, Never>?
     private var streamingAssistantID: UUID?
     private var lastUsedFeature: AIFeature = .chat
     private let chatStorage = AIChatStorage.shared
@@ -101,6 +101,10 @@ final class AIChatViewModel {
         loadConversations()
     }
 
+    deinit {
+        streamingTask?.cancel()
+    }
+
     // MARK: - Actions
 
     /// Send the current input text as a user message
diff --git a/TablePro/Views/Components/WindowAccessor.swift b/TablePro/Views/Components/WindowAccessor.swift
new file mode 100644
index 00000000..6cd8c8e8
--- /dev/null
+++ b/TablePro/Views/Components/WindowAccessor.swift
@@ -0,0 +1,28 @@
+import SwiftUI
+
+/// Captures the hosting NSWindow from within a SwiftUI view hierarchy.
+/// Use as a `.background { WindowAccessor { window in ... } }` modifier.
+/// Uses `viewDidMoveToWindow` for synchronous capture — no async deferral,
+/// so the window is available before any notifications fire.
+struct WindowAccessor: NSViewRepresentable {
+    var onWindow: (NSWindow) -> Void
+
+    func makeNSView(context: Context) -> WindowAccessorView {
+        let view = WindowAccessorView()
+        view.onWindow = onWindow
+        return view
+    }
+
+    func updateNSView(_ nsView: WindowAccessorView, context: Context) {}
+}
+
+final class WindowAccessorView: NSView {
+    var onWindow: ((NSWindow) -> Void)?
+
+    override func viewDidMoveToWindow() {
+        super.viewDidMoveToWindow()
+        if let window {
+            onWindow?(window)
+        }
+    }
+}
diff --git a/TablePro/Views/Connection/WelcomeWindowView.swift b/TablePro/Views/Connection/WelcomeWindowView.swift
index 6e14af26..2c58e52d 100644
--- a/TablePro/Views/Connection/WelcomeWindowView.swift
+++ b/TablePro/Views/Connection/WelcomeWindowView.swift
@@ -755,26 +755,15 @@ struct WelcomeWindowView: View {
 
     /// Focus the connection form window as soon as it's available
     private func focusConnectionFormWindow() {
-        // Poll rapidly until window is found (much faster than fixed delay)
-        func attemptFocus(remainingAttempts: Int = 10) {
-            for window in NSApp.windows {
-                if window.identifier?.rawValue.contains("connection-form") == true
-                    || window.title == "Connection"
-                {
+        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))
             }
-            // Window not found yet, try again in 20ms
-            if remainingAttempts > 0 {
-                DispatchQueue.main.asyncAfter(deadline: .now() + 0.02) {
-                    attemptFocus(remainingAttempts: remainingAttempts - 1)
-                }
-            }
-        }
-        // Start immediately on next run loop
-        DispatchQueue.main.async {
-            attemptFocus()
         }
     }
 }
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+ChangeGuard.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+ChangeGuard.swift
index eb3e5025..c1394aa0 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+ChangeGuard.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+ChangeGuard.swift
@@ -30,7 +30,7 @@ extension MainContentCoordinator {
             let window = NSApp.keyWindow
             let confirmed = await confirmDiscardChanges(action: action, window: window)
             if confirmed {
-                changeManager.clearChanges()
+                changeManager.clearChangesAndUndoHistory()
             }
             completion(confirmed)
         }
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+Discard.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+Discard.swift
index b2dc2c64..f0a22778 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+Discard.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+Discard.swift
@@ -74,7 +74,7 @@ extension MainContentCoordinator {
 
         pendingTruncates.removeAll()
         pendingDeletes.removeAll()
-        changeManager.clearChanges()
+        changeManager.clearChangesAndUndoHistory()
 
         if let index = tabManager.selectedTabIndex {
             tabManager.tabs[index].pendingChanges = TabPendingChanges()
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
index 7ea549ef..fc77a090 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
@@ -134,7 +134,7 @@ extension MainContentCoordinator {
                     updatedTab.errorMessage = nil
                     tabManager.tabs[idx] = updatedTab
 
-                    changeManager.clearChanges()
+                    changeManager.clearChangesAndUndoHistory()
                     changeManager.reloadVersion += 1
                 }
             } catch {
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
index b2d4962b..b31c7787 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
@@ -193,7 +193,7 @@ extension MainContentCoordinator {
         // doesn't linger while Phase 2 metadata loads in background.
         // Only clear if there are no pending edits from the user.
         if isEditable && !changeManager.hasChanges {
-            changeManager.clearChanges()
+            changeManager.clearChangesAndUndoHistory()
         }
     }
 
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+Refresh.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+Refresh.swift
index 461208a1..7f4ba906 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+Refresh.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+Refresh.swift
@@ -29,7 +29,7 @@ extension MainContentCoordinator {
                 let confirmed = await confirmDiscardChanges(action: .refresh, window: window)
                 if confirmed {
                     onDiscard()
-                    changeManager.clearChanges()
+                    changeManager.clearChangesAndUndoHistory()
                     // Only execute query if we're in a table tab
                     // Query tabs should not auto-execute on refresh (use Cmd+Enter to execute)
                     if let tabIndex = tabManager.selectedTabIndex,
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+SaveChanges.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+SaveChanges.swift
index d194aa90..a610badb 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+SaveChanges.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+SaveChanges.swift
@@ -228,7 +228,7 @@ extension MainContentCoordinator {
                     throw error
                 }
 
-                changeManager.clearChanges()
+                changeManager.clearChangesAndUndoHistory()
                 if let index = tabManager.selectedTabIndex {
                     tabManager.tabs[index].pendingChanges = TabPendingChanges()
                     tabManager.tabs[index].errorMessage = nil
diff --git a/TablePro/Views/Main/MainContentCommandActions.swift b/TablePro/Views/Main/MainContentCommandActions.swift
index 9c2c269b..5a1533e0 100644
--- a/TablePro/Views/Main/MainContentCommandActions.swift
+++ b/TablePro/Views/Main/MainContentCommandActions.swift
@@ -375,7 +375,7 @@ final class MainContentCommandActions {
     }
 
     private func discardAndClose() {
-        coordinator?.changeManager.clearChanges()
+        coordinator?.changeManager.clearChangesAndUndoHistory()
         pendingTruncates.wrappedValue.removeAll()
         pendingDeletes.wrappedValue.removeAll()
         rightPanelState.editState.clearEdits()
diff --git a/TablePro/Views/Main/MainContentCoordinator.swift b/TablePro/Views/Main/MainContentCoordinator.swift
index bb42b5b4..3698cd4d 100644
--- a/TablePro/Views/Main/MainContentCoordinator.swift
+++ b/TablePro/Views/Main/MainContentCoordinator.swift
@@ -204,13 +204,17 @@ final class MainContentCoordinator {
         }
     }()
 
-    /// Evict row data for all tabs in this coordinator to free memory.
+    /// Evict row data for background tabs in this coordinator to free memory.
     /// Called when the coordinator's native window-tab becomes inactive.
-    /// Data is re-fetched automatically when the tab becomes active again.
+    /// The currently selected tab is kept in memory so the user sees no
+    /// refresh flicker when switching back — matching native macOS behavior.
+    /// Background tabs are re-fetched automatically when selected.
     func evictInactiveRowData() {
+        let selectedId = tabManager.selectedTabId
         for tab in tabManager.tabs where !tab.rowBuffer.isEvicted
             && !tab.resultRows.isEmpty
             && !tab.pendingChanges.hasChanges
+            && tab.id != selectedId
         {
             tab.rowBuffer.evict()
         }
@@ -351,6 +355,8 @@ final class MainContentCoordinator {
         currentQueryTask = nil
         changeManagerUpdateTask?.cancel()
         changeManagerUpdateTask = nil
+        redisDatabaseSwitchTask?.cancel()
+        redisDatabaseSwitchTask = nil
         for task in activeSortTasks.values { task.cancel() }
         activeSortTasks.removeAll()
 
@@ -933,7 +939,7 @@ final class MainContentCoordinator {
                         guard let self else { return }
                         guard capturedGeneration == queryGeneration else { return }
                         guard !Task.isCancelled else { return }
-                        changeManager.clearChanges()
+                        changeManager.clearChangesAndUndoHistory()
                     }
                 }
             } catch {
diff --git a/TablePro/Views/Main/MainContentView.swift b/TablePro/Views/Main/MainContentView.swift
index 730a18b0..b9742f11 100644
--- a/TablePro/Views/Main/MainContentView.swift
+++ b/TablePro/Views/Main/MainContentView.swift
@@ -192,6 +192,11 @@ struct MainContentView: View {
     /// Split into two halves to help the Swift type checker with the long modifier chain.
     private var bodyContent: some View {
         bodyContentCore
+            .background {
+                WindowAccessor { window in
+                    configureWindow(window)
+                }
+            }
             .task(id: currentTab?.tableName) {
                 // Only load metadata after the tab has executed at least once —
                 // avoids a redundant DB query racing with the initial data query
@@ -215,33 +220,7 @@ struct MainContentView: View {
                 coordinator.aiViewModel = rightPanelState.aiViewModel
                 coordinator.rightPanelState = rightPanelState
 
-                // Register NSWindow reference and set per-connection tab grouping
-                DispatchQueue.main.async {
-                    // Find our window by title rather than keyWindow to avoid races
-                    // when multiple windows open simultaneously
-                    let targetTitle = windowTitle
-                    let window = NSApp.keyWindow
-                        ?? NSApp.windows.first { $0.isVisible && $0.title == targetTitle }
-                    guard let window else { return }
-                    let isPreview = tabManager.selectedTab?.isPreview ?? payload?.isPreview ?? false
-                    if isPreview {
-                        window.subtitle = "\(connection.name) — Preview"
-                    } else {
-                        window.subtitle = connection.name
-                    }
-                    window.tabbingIdentifier = "com.TablePro.main.\(connection.id.uuidString)"
-                    window.tabbingMode = .preferred
-                    coordinator.windowId = windowId
-
-                    WindowLifecycleMonitor.shared.register(
-                        window: window,
-                        connectionId: connection.id,
-                        windowId: windowId,
-                        isPreview: isPreview
-                    )
-                    viewWindow = window
-                    isKeyWindow = window.isKeyWindow
-                }
+                // Window registration is handled by WindowAccessor in .background
             }
             .onDisappear {
                 // Mark teardown intent synchronously so deinit doesn't warn
@@ -273,14 +252,7 @@ struct MainContentView: View {
                     // Tab state is NOT cleared here — it's preserved for next reconnect.
                     // Only handleTabsChange(count=0) clears state (user explicitly closed all tabs).
                     guard !WindowLifecycleMonitor.shared.hasWindows(for: connectionId) else { return }
-
-                    let hasVisibleWindow = NSApp.windows.contains { window in
-                        window.isVisible && (window.subtitle == connectionName
-                            || window.subtitle == "\(connectionName) — Preview")
-                    }
-                    if !hasVisibleWindow {
-                        await DatabaseManager.shared.disconnectSession(connectionId)
-                    }
+                    await DatabaseManager.shared.disconnectSession(connectionId)
                 }
             }
             .onChange(of: pendingChangeTrigger) {
@@ -353,13 +325,12 @@ struct MainContentView: View {
 
                 // Schedule row data eviction for inactive native window-tabs.
                 // 5s delay avoids thrashing when quickly switching between tabs.
-                // Skip eviction entirely if the active tab has unsaved in-memory changes,
-                // since evictInactiveRowData only checks tab-level pendingChanges.
+                // Per-tab pendingChanges checks inside evictInactiveRowData() protect
+                // tabs with unsaved changes from eviction.
                 evictionTask?.cancel()
                 evictionTask = Task { @MainActor in
                     try? await Task.sleep(for: .seconds(5))
                     guard !Task.isCancelled else { return }
-                    guard !changeManager.hasChanges else { return }
                     coordinator.evictInactiveRowData()
                 }
             }
@@ -605,6 +576,30 @@ struct MainContentView: View {
             || AppState.shared.hasStructureChanges
     }
 
+    /// Configure the hosting NSWindow — called by WindowAccessor when the window is available.
+    private func configureWindow(_ window: NSWindow) {
+        let isPreview = tabManager.selectedTab?.isPreview ?? payload?.isPreview ?? false
+        if isPreview {
+            window.subtitle = "\(connection.name) — Preview"
+        } else {
+            window.subtitle = connection.name
+        }
+        window.tabbingIdentifier = "com.TablePro.main.\(connection.id.uuidString)"
+        window.tabbingMode = .preferred
+        coordinator.windowId = windowId
+
+        WindowLifecycleMonitor.shared.register(
+            window: window,
+            connectionId: connection.id,
+            windowId: windowId,
+            isPreview: isPreview
+        )
+        viewWindow = window
+
+        // Update command actions window reference now that it's available
+        commandActions?.window = window
+    }
+
     private func setupCommandActions() {
         let actions = MainContentCommandActions(
             coordinator: coordinator,
@@ -621,16 +616,8 @@ struct MainContentView: View {
             rightPanelState: rightPanelState,
             editingCell: $editingCell
         )
-        actions.window = NSApp.keyWindow
+        actions.window = viewWindow
         commandActions = actions
-
-        // Safety fallback: if window wasn't key yet at onAppear time,
-        // retry on next run loop when the window is guaranteed to be visible
-        if actions.window == nil {
-            DispatchQueue.main.async { [weak actions] in
-                actions?.window = NSApp.keyWindow
-            }
-        }
     }
 
     // MARK: - Database Switcher
diff --git a/docs/development/anti-patterns-tracker.md b/docs/development/anti-patterns-tracker.md
new file mode 100644
index 00000000..f635f189
--- /dev/null
+++ b/docs/development/anti-patterns-tracker.md
@@ -0,0 +1,255 @@
+# Anti-Patterns & Incorrect Behavior Tracker
+
+Status legend: `[ ]` = TODO, `[x]` = Fixed, `[-]` = Won't fix
+
+---
+
+## 1. Window Lifecycle & Focus Management
+
+### 1.1 [x] Active tab evicted on window focus loss (CRITICAL)
+- **File**: `TablePro/Views/Main/MainContentView.swift:349-365`
+- **Problem**: When the window loses focus, `evictInactiveRowData()` evicts ALL tabs including the currently visible one. When the user switches back, the visible grid re-fetches data, causing a visible refresh flicker.
+- **Correct behavior**: Native macOS apps (Xcode, Safari, TablePlus) keep the active tab's content in memory. Only background/non-visible tabs should be eviction candidates.
+- **Fix**: `evictInactiveRowData()` must skip the currently selected tab.
+
+### 1.2 [x] Unreliable window discovery via NSApp.keyWindow (HIGH)
+- **File**: `TablePro/Views/Main/MainContentView.swift:219-244`
+- **Problem**: Window registration uses `DispatchQueue.main.async` then queries `NSApp.keyWindow`, which can return the wrong window in multi-window scenarios. Fallback uses fragile title-based matching.
+- **Fix**: Capture the window through SwiftUI's view hierarchy (NSViewRepresentable) instead of querying global state.
+
+### 1.3 [x] Duplicate window discovery pattern in command actions (HIGH)
+- **File**: `TablePro/Views/Main/MainContentView.swift:624-633`
+- **Problem**: `actions.window = NSApp.keyWindow` with async retry if nil. Same unreliable pattern as 1.2.
+- **Fix**: Share the window reference captured in 1.2's fix.
+
+### 1.4 [x] Fragile subtitle-based window matching (MEDIUM)
+- **File**: `TablePro/Views/Main/MainContentView.swift:276-283`
+- **Problem**: `window.subtitle == connectionName` is fragile -- subtitles can be empty, duplicated, or changed. Inconsistent with `WindowLifecycleMonitor.hasWindows()` used elsewhere.
+- **Fix**: Always use `WindowLifecycleMonitor.hasWindows(for: connectionId)` as single source of truth.
+
+### 1.5 [x] Notification observer fires before window registration (MEDIUM)
+- **File**: `TablePro/Views/Main/MainContentView.swift:324-348`
+- **Problem**: `viewWindow` is set asynchronously in `onAppear`, so `didBecomeKeyNotification` observers that compare `notificationWindow === viewWindow` silently miss early notifications when `viewWindow` is still nil.
+- **Fix**: Ensure window registration completes before subscribing to notifications, or queue missed notifications.
+
+### 1.6 [x] Stale isKeyWindow initialization (MEDIUM)
+- **File**: `TablePro/Views/Main/MainContentView.swift:243`
+- **Problem**: `isKeyWindow = window.isKeyWindow` is a single-point-in-time snapshot that's immediately stale. The notification handlers already track this separately, creating dual sources of truth.
+- **Fix**: Remove the synchronous initialization; let `didBecomeKeyNotification`/`didResignKeyNotification` be the sole source.
+
+### 1.7 [x] Inconsistent window identifier matching (LOW)
+- **File**: `TablePro/AppDelegate+WindowConfig.swift:103-115`
+- **Problem**: `isMainWindow` uses `.contains("main")`, `isWelcomeWindow` uses `== "welcome"` OR title fallback, `isConnectionFormWindow` uses `.contains("connection-form")`. Substring matching can match unintended windows.
+- **Fix**: Use exact matching with a centralized `WindowIdentifier` enum/constants.
+
+### 1.8 [-] ObjectIdentifier-based window tracking (LOW)
+- **File**: `TablePro/AppDelegate+WindowConfig.swift:210-248`
+- **Problem**: `configuredWindows` uses `ObjectIdentifier(window)` which is memory-address-based. If an NSWindow is deallocated and a new one allocated at the same address, they get the same identifier.
+- **Fix**: Use UUID-based window identifiers.
+
+### 1.9 [x] Unnecessary DispatchQueue.main.async in notification handlers (LOW)
+- **File**: `TablePro/AppDelegate+WindowConfig.swift:263-282`
+- **Problem**: Window operations dispatched async from notification handlers that already run on main thread. Introduces race windows where window state changes between check and action.
+- **Fix**: Keep critical window operations synchronous when already on main thread.
+
+### 1.10 [-] Duplicate observers for didBecomeKeyNotification (LOW)
+- **Files**: `TablePro/AppDelegate+WindowConfig.swift:210+`, `TablePro/Views/Main/MainContentView.swift:324+`
+- **Problem**: Both AppDelegate and MainContentView observe `NSWindow.didBecomeKeyNotification` independently. Both fire for every window focus change.
+- **Fix**: Centralize in `WindowLifecycleMonitor` and have views subscribe to a custom signal.
+
+---
+
+## 2. Memory Management & Task Lifecycle
+
+### 2.1 [x] Missing redisDatabaseSwitchTask cancellation in teardown (HIGH)
+- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:106-108, 350-355`
+- **Problem**: `currentQueryTask` and `changeManagerUpdateTask` are cancelled in `teardown()`, but `redisDatabaseSwitchTask` is not. This leaves a dangling Task if coordinator is deallocated during a Redis database switch.
+- **Fix**: Add `redisDatabaseSwitchTask?.cancel(); redisDatabaseSwitchTask = nil` to `teardown()`.
+
+### 2.2 [x] Missing deinit in AIChatViewModel (HIGH)
+- **File**: `TablePro/ViewModels/AIChatViewModel.swift:91-92`
+- **Problem**: `streamingTask` is never cancelled if the view model is deallocated while streaming. The Task continues executing in the background.
+- **Fix**: Add `deinit { streamingTask?.cancel() }`.
+
+### 2.3 [x] Weak self with optional chaining in periodic Task loops (MEDIUM)
+- **Files**:
+  - `TablePro/Core/Services/Licensing/LicenseManager.swift:86-100`
+  - `TablePro/Core/Services/Infrastructure/AnalyticsService.swift:63-75`
+- **Problem**: Inside `while !Task.isCancelled` loops, `self?.revalidationInterval ?? 604_800` silently uses the fallback value if self is deallocated, then continues the loop with a default interval forever.
+- **Fix**: Use `guard let self else { return }` at the top of the task, or re-check inside the loop with early exit.
+
+### 2.4 [x] Eviction pending-changes check is incomplete (MEDIUM)
+- **File**: `TablePro/Views/Main/MainContentView.swift:349-365`
+- **Problem**: The pre-eviction check uses `changeManager.hasChanges` (in-memory changes), but `evictInactiveRowData()` checks `tab.pendingChanges.hasChanges` (tab-level). These are different — a tab may have tab-level changes even if `changeManager` is empty.
+- **Fix**: Check both `changeManager.hasChanges` and `tab.pendingChanges.hasChanges` consistently, or defer the check to just before eviction runs.
+
+### 2.5 [x] WindowLifecycleMonitor observer re-registration without full cleanup (LOW)
+- **File**: `TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift:41-66`
+- **Problem**: If `register()` is called twice with the same `windowId` but a different `NSWindow`, the old observer is removed but the old NSWindow is now orphaned without observation.
+- **Fix**: Guard against re-registration with a different window or explicitly unregister the old window.
+
+### 2.6 [-] Fire-and-forget disconnect Task in WindowLifecycleMonitor (LOW)
+- **File**: `TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift:190-211`
+- **Problem**: `Task { await DatabaseManager.shared.disconnectSession(...) }` has no error handling. If disconnect fails, the connection persists as a zombie.
+- **Fix**: Log errors from the disconnect call.
+
+---
+
+## 3. Connection & Query Execution
+
+### 3.1 [x] Missing trackOperation in reconnectDriver (CRITICAL)
+- **File**: `TablePro/Core/Database/DatabaseManager.swift:599-632`
+- **Problem**: `reconnectDriver()` does NOT call `trackOperation()`, so `queriesInFlight` is never incremented. The health monitor's ping (`SELECT 1`) can race with the reconnect on the same driver, causing concurrent driver access.
+- **Fix**: Wrap reconnection in `trackOperation()` or stop the health monitor before reconnecting.
+
+### 3.2 [x] Stale session reference in reconnectSession (HIGH)
+- **File**: `TablePro/Core/Database/DatabaseManager.swift:601-632`
+- **Problem**: Line 649 captures `session` into a local variable. Lines 682-690 re-fetch from `activeSessions[sessionId]`, creating inconsistency. The local `session` could have stale schema/database values.
+- **Fix**: Always re-fetch from `activeSessions[sessionId]` before accessing mutable state, or pass all needed state as parameters.
+
+### 3.3 [x] Fire-and-forget SSH tunnel close (HIGH)
+- **Files**: `TablePro/Core/Database/DatabaseManager.swift:131-135, 220-224, 258-260`
+- **Problem**: SSH tunnels are closed in `Task { try? await ... }` blocks. If the task is cancelled or fails, the tunnel remains open. No error logging. Appears in 3+ locations.
+- **Fix**: `await` the tunnel close synchronously or at minimum log errors.
+
+### 3.4 [x] Discarded schema/database switch errors during reconnect (HIGH)
+- **File**: `TablePro/Core/Database/DatabaseManager.swift:620-629, 682-691`
+- **Problem**: `try? await schemaDriver.switchSchema(to: savedSchema)` silently discards errors. If schema switch fails, the connection operates in the wrong schema without any warning.
+- **Fix**: Log the error and optionally update session status to reflect the failure.
+
+### 3.5 [-] No cancel-await-run synchronization for queries (MEDIUM → demoted to P3)
+- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:37-39`
+- **Problem**: `currentQueryTask?.cancel()` followed immediately by `runQuery()`. Cancel doesn't wait for the running task to finish, so two queries can be in-flight simultaneously writing to the same `QueryTab`.
+- **Fix**: `await` the cancelled task's completion before starting the new query, or use a serial queue.
+
+### 3.6 [x] Health monitor ping skips when queriesInFlight exists (MEDIUM)
+- **File**: `TablePro/Core/Database/DatabaseManager.swift:535`
+- **Problem**: `guard await self.queriesInFlight[connectionId] == nil else { return true }` returns "healthy" if any query is in-flight. But a stuck query would keep the monitor returning true forever, masking a dead connection.
+- **Fix**: Track query start time and consider connections unhealthy if a query has been in-flight beyond a threshold.
+
+### 3.7 [x] Inconsistent exponential backoff between DatabaseManager and HealthMonitor (LOW)
+- **Files**: `DatabaseManager.swift:745`, `ConnectionHealthMonitor.swift:38, 230-238`
+- **Problem**: DatabaseManager uses `2.0 * pow(2.0, retryCount)` formula. HealthMonitor uses a predefined `[2.0, 4.0, 8.0]` array with different progression. Same app, different reconnect timing.
+- **Fix**: Unify backoff strategy into a shared utility.
+
+### 3.8 [x] Synchronous plugin loading fallback on main thread (MEDIUM)
+- **File**: `TablePro/Core/Database/DatabaseDriver.swift:318-333`
+- **Problem**: `PluginManager.shared.loadPendingPlugins()` is called synchronously on main thread when a plugin isn't loaded yet. Can freeze the UI if loading takes >100ms.
+- **Fix**: Pre-load all plugins at app startup, or make this async with a loading indicator.
+
+---
+
+## 4. Architecture & State Management
+
+### 4.1 [-] AppSettingsManager dual notification channels (HIGH → demoted to P3)
+- **File**: `TablePro/Core/Storage/AppSettingsManager.swift:18-193`
+- **Problem**: Settings changes fire BOTH `@Observable` property updates AND `NotificationCenter.post()`. Views that observe both channels get redundant updates. Unclear which to use.
+- **Fix**: Use `@Observable` for local subscriptions, remove `NotificationCenter` posts for setting changes. Keep NotificationCenter only for system-wide events (accessibility).
+
+### 4.2 [x] AppSettingsManager missing observer cleanup (MEDIUM)
+- **File**: `TablePro/Core/Storage/AppSettingsManager.swift:179`
+- **Problem**: `observeAccessibilityTextSizeChanges()` registers a NotificationCenter observer stored in `@ObservationIgnored`. No `deinit` removes it.
+- **Fix**: Add `deinit { if let observer = accessibilityTextSizeObserver { NotificationCenter.default.removeObserver(observer) } }`.
+
+### 4.3 [-] SharedSidebarState registry race condition (MEDIUM → demoted to P3)
+- **File**: `TablePro/Models/UI/SharedSidebarState.swift:51-62`
+- **Problem**: `static var registry: [UUID: SharedSidebarState]` with no synchronization. Concurrent calls from different threads can create duplicate instances for the same connection.
+- **Fix**: Mark SharedSidebarState and registry as `@MainActor`, or use `OSAllocatedUnfairLock`.
+
+### 4.4 [-] Static termination observer never removed (MEDIUM → demoted to P3)
+- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:197-203`
+- **Problem**: `registerTerminationObserver` is static and called once. The observer is never removed and fires for every coordinator instance at app termination.
+- **Fix**: Make instance-level, remove in teardown. Or use a dedicated `AppTerminationManager`.
+
+### 4.5 [x] Undo stack destroyed on tab switch (MEDIUM)
+- **File**: `TablePro/Core/ChangeTracking/DataChangeManager.swift:129-137`
+- **Problem**: `clearChanges()` calls `undoManager.clearAll()`. When switching tabs, if `clearChanges()` is called, the undo history is permanently lost even though changes are persisted via `saveState()`/`restoreState()`.
+- **Fix**: Separate `clearChanges()` (preserves undo) from `clearChangesAndUndoHistory()` (full reset on commit).
+
+### 4.6 [x] Tab state save silently fails on disk errors (MEDIUM)
+- **File**: `TablePro/Core/Storage/TabDiskActor.swift:79-81`
+- **Problem**: File I/O errors during tab state save are logged but never returned. If write fails (disk full), tabs are lost silently.
+- **Fix**: Return `Result<Void, Error>` so callers can retry or alert the user.
+
+### 4.7 [x] Silent startup command failures (LOW)
+- **File**: `TablePro/Core/Database/DatabaseManager.swift:783-793`
+- **Problem**: User-defined startup SQL commands that fail are logged but the connection continues. User expects commands like `SET ROLE` to succeed but has no indication of failure.
+- **Fix**: Collect errors and show a warning: "Startup commands failed. Continue anyway?"
+
+---
+
+## 5. SwiftUI Patterns
+
+### 5.1 [-] Unnecessary DispatchQueue.main.async in SwiftUI callbacks (MEDIUM → demoted to P3)
+- **Files** (8+ locations):
+  - `TablePro/Views/Results/DataGridView.swift:400-403, 433-441, 537-545`
+  - `TablePro/Views/AIChat/AIChatPanelView.swift:205-207, 225-227`
+  - `TablePro/Views/Main/Child/MainEditorContentView.swift:348, 358-365`
+  - `TablePro/Views/Toolbar/ConnectionSwitcherPopover.swift:351-352`
+  - `TablePro/Views/Components/SQLReviewPopover.swift:90-91`
+  - `TablePro/Views/Connection/WelcomeWindowView.swift:770-778`
+  - `TablePro/Views/Results/Extensions/DataGridView+Editing.swift:164-166, 196-199, 218-221`
+- **Problem**: `onAppear`, `onChange`, and body callbacks already execute on main thread. Wrapping in `DispatchQueue.main.async` adds latency and can cause visual glitches or double-renders.
+- **Fix**: Remove unnecessary `DispatchQueue.main.async` wrappers. Use `Task { @MainActor in }` only when deferral is genuinely needed.
+
+### 5.2 [-] Multiple onChange handlers on related state (LOW)
+- **File**: `TablePro/Views/AIChat/AIChatPanelView.swift:210-228`
+- **Problem**: Three separate `onChange` handlers for `messages.last?.content`, `messages.count`, and `activeConversationID` all trigger scrolling. If a new message arrives on a conversation switch, scrolling happens multiple times.
+- **Fix**: Consolidate into a single scroll trigger.
+
+### 5.3 [x] Recursive asyncAfter retry for window focus (LOW)
+- **File**: `TablePro/Views/Connection/WelcomeWindowView.swift:770-778`
+- **Problem**: Recursive `DispatchQueue.main.asyncAfter(deadline: .now() + 0.02)` with retry count. No cancellation if view disappears. Hardcoded timing.
+- **Fix**: Use a cancellable `Task` with `Task.sleep`.
+
+### 5.4 [-] DispatchQueue.main.async in updateNSView path (LOW)
+- **File**: `TablePro/Views/Results/DataGridView.swift:400-403, 433-441`
+- **Problem**: Inside `updateNSView` -> `updateColumns`, a binding update is dispatched to the next cycle. This causes the view to re-evaluate before the flag is cleared, potentially causing flicker.
+- **Fix**: Use `Task.yield()` or accept the binding update synchronously.
+
+---
+
+## Priority Order for Fixes
+
+### P0 - Critical (fix immediately)
+1. **1.1** Active tab evicted on window focus loss
+2. **3.1** Missing trackOperation in reconnectDriver
+
+### P1 - High (fix soon)
+3. **2.1** Missing redisDatabaseSwitchTask cancellation
+4. **2.2** Missing deinit in AIChatViewModel
+5. **3.3** Fire-and-forget SSH tunnel close
+6. **3.4** Discarded schema/database switch errors
+7. **3.2** Stale session reference in reconnectSession
+8. **1.2** Unreliable window discovery via NSApp.keyWindow
+9. **1.3** Duplicate window discovery pattern
+10. **4.1** AppSettingsManager dual notification channels
+
+### P2 - Medium (fix in next cycle)
+11. **2.3** Weak self in periodic Task loops
+12. **2.4** Eviction pending-changes check incomplete
+13. **3.5** No cancel-await-run synchronization
+14. **3.6** Health monitor ping masking stuck queries
+15. **3.8** Synchronous plugin loading on main thread
+16. **4.2** AppSettingsManager missing observer cleanup
+17. **4.3** SharedSidebarState registry race condition
+18. **4.4** Static termination observer never removed
+19. **4.5** Undo stack destroyed on tab switch
+20. **4.6** Tab state save silently fails
+21. **1.4** Fragile subtitle-based window matching
+22. **1.5** Notification observer fires before window registration
+23. **5.1** Unnecessary DispatchQueue.main.async in SwiftUI
+
+### P3 - Low (backlog)
+24. **1.6** Stale isKeyWindow initialization
+25. **1.7** Inconsistent window identifier matching
+26. **1.8** ObjectIdentifier-based window tracking
+27. **1.9** Unnecessary async in notification handlers
+28. **1.10** Duplicate observers for didBecomeKeyNotification
+29. **2.5** WindowLifecycleMonitor observer re-registration
+30. **2.6** Fire-and-forget disconnect Task
+31. **3.7** Inconsistent exponential backoff
+32. **4.7** Silent startup command failures
+33. **5.2** Multiple onChange handlers on related state
+34. **5.3** Recursive asyncAfter retry
+35. **5.4** DispatchQueue.main.async in updateNSView

From 9493b95df9f251f882eec523e54af236bd7613fd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ng=C3=B4=20Qu=E1=BB=91c=20=C4=90=E1=BA=A1t?=
 <datlechin@gmail.com>
Date: Tue, 24 Mar 2026 09:23:28 +0700
Subject: [PATCH 3/5] fix: address review feedback on anti-patterns PR

- WindowAccessor: deduplicate viewDidMoveToWindow calls, update closure in updateNSView
- AIChatViewModel: add comment explaining nonisolated(unsafe) requirement
- CHANGELOG: add user-visible behavioral changes under [Unreleased]
---
 CHANGELOG.md                                   |  5 +++++
 TablePro/ViewModels/AIChatViewModel.swift      |  2 ++
 TablePro/Views/Components/WindowAccessor.swift | 11 +++++++----
 3 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4fbd7202..6e6a0a34 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - MongoDB Atlas connections failing to authenticate (#438)
 - MongoDB TLS certificate verification skipped for SRV connections
+- Active tab data no longer refreshes when switching back to the app window
+- Undo history preserved when switching between database tables
+- Health monitor now detects stuck queries beyond the configured timeout
+- SSH tunnel closure errors now logged instead of silently discarded
+- Schema/database restore errors during reconnect now logged
 
 ## [0.23.1] - 2026-03-24
 
diff --git a/TablePro/ViewModels/AIChatViewModel.swift b/TablePro/ViewModels/AIChatViewModel.swift
index 26d580a7..b975de1c 100644
--- a/TablePro/ViewModels/AIChatViewModel.swift
+++ b/TablePro/ViewModels/AIChatViewModel.swift
@@ -88,6 +88,8 @@ final class AIChatViewModel {
 
     // MARK: - Private
 
+    /// nonisolated(unsafe) is required because deinit is not @MainActor-isolated,
+    /// so accessing a @MainActor property from deinit requires opting out of isolation.
     @ObservationIgnored nonisolated(unsafe) private var streamingTask: Task<Void, Never>?
     private var streamingAssistantID: UUID?
     private var lastUsedFeature: AIFeature = .chat
diff --git a/TablePro/Views/Components/WindowAccessor.swift b/TablePro/Views/Components/WindowAccessor.swift
index 6cd8c8e8..6f45c8d4 100644
--- a/TablePro/Views/Components/WindowAccessor.swift
+++ b/TablePro/Views/Components/WindowAccessor.swift
@@ -13,16 +13,19 @@ struct WindowAccessor: NSViewRepresentable {
         return view
     }
 
-    func updateNSView(_ nsView: WindowAccessorView, context: Context) {}
+    func updateNSView(_ nsView: WindowAccessorView, context: Context) {
+        nsView.onWindow = onWindow
+    }
 }
 
 final class WindowAccessorView: NSView {
     var onWindow: ((NSWindow) -> Void)?
+    private weak var capturedWindow: NSWindow?
 
     override func viewDidMoveToWindow() {
         super.viewDidMoveToWindow()
-        if let window {
-            onWindow?(window)
-        }
+        guard let window, window !== capturedWindow else { return }
+        capturedWindow = window
+        onWindow?(window)
     }
 }

From 260f53245a5128be0be2e86a48f6d4c710a6ce4b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ng=C3=B4=20Qu=E1=BB=91c=20=C4=90=E1=BA=A1t?=
 <datlechin@gmail.com>
Date: Tue, 24 Mar 2026 09:24:57 +0700
Subject: [PATCH 4/5] chore: remove anti-patterns tracker doc

---
 docs/development/anti-patterns-tracker.md | 255 ----------------------
 1 file changed, 255 deletions(-)
 delete mode 100644 docs/development/anti-patterns-tracker.md

diff --git a/docs/development/anti-patterns-tracker.md b/docs/development/anti-patterns-tracker.md
deleted file mode 100644
index f635f189..00000000
--- a/docs/development/anti-patterns-tracker.md
+++ /dev/null
@@ -1,255 +0,0 @@
-# Anti-Patterns & Incorrect Behavior Tracker
-
-Status legend: `[ ]` = TODO, `[x]` = Fixed, `[-]` = Won't fix
-
----
-
-## 1. Window Lifecycle & Focus Management
-
-### 1.1 [x] Active tab evicted on window focus loss (CRITICAL)
-- **File**: `TablePro/Views/Main/MainContentView.swift:349-365`
-- **Problem**: When the window loses focus, `evictInactiveRowData()` evicts ALL tabs including the currently visible one. When the user switches back, the visible grid re-fetches data, causing a visible refresh flicker.
-- **Correct behavior**: Native macOS apps (Xcode, Safari, TablePlus) keep the active tab's content in memory. Only background/non-visible tabs should be eviction candidates.
-- **Fix**: `evictInactiveRowData()` must skip the currently selected tab.
-
-### 1.2 [x] Unreliable window discovery via NSApp.keyWindow (HIGH)
-- **File**: `TablePro/Views/Main/MainContentView.swift:219-244`
-- **Problem**: Window registration uses `DispatchQueue.main.async` then queries `NSApp.keyWindow`, which can return the wrong window in multi-window scenarios. Fallback uses fragile title-based matching.
-- **Fix**: Capture the window through SwiftUI's view hierarchy (NSViewRepresentable) instead of querying global state.
-
-### 1.3 [x] Duplicate window discovery pattern in command actions (HIGH)
-- **File**: `TablePro/Views/Main/MainContentView.swift:624-633`
-- **Problem**: `actions.window = NSApp.keyWindow` with async retry if nil. Same unreliable pattern as 1.2.
-- **Fix**: Share the window reference captured in 1.2's fix.
-
-### 1.4 [x] Fragile subtitle-based window matching (MEDIUM)
-- **File**: `TablePro/Views/Main/MainContentView.swift:276-283`
-- **Problem**: `window.subtitle == connectionName` is fragile -- subtitles can be empty, duplicated, or changed. Inconsistent with `WindowLifecycleMonitor.hasWindows()` used elsewhere.
-- **Fix**: Always use `WindowLifecycleMonitor.hasWindows(for: connectionId)` as single source of truth.
-
-### 1.5 [x] Notification observer fires before window registration (MEDIUM)
-- **File**: `TablePro/Views/Main/MainContentView.swift:324-348`
-- **Problem**: `viewWindow` is set asynchronously in `onAppear`, so `didBecomeKeyNotification` observers that compare `notificationWindow === viewWindow` silently miss early notifications when `viewWindow` is still nil.
-- **Fix**: Ensure window registration completes before subscribing to notifications, or queue missed notifications.
-
-### 1.6 [x] Stale isKeyWindow initialization (MEDIUM)
-- **File**: `TablePro/Views/Main/MainContentView.swift:243`
-- **Problem**: `isKeyWindow = window.isKeyWindow` is a single-point-in-time snapshot that's immediately stale. The notification handlers already track this separately, creating dual sources of truth.
-- **Fix**: Remove the synchronous initialization; let `didBecomeKeyNotification`/`didResignKeyNotification` be the sole source.
-
-### 1.7 [x] Inconsistent window identifier matching (LOW)
-- **File**: `TablePro/AppDelegate+WindowConfig.swift:103-115`
-- **Problem**: `isMainWindow` uses `.contains("main")`, `isWelcomeWindow` uses `== "welcome"` OR title fallback, `isConnectionFormWindow` uses `.contains("connection-form")`. Substring matching can match unintended windows.
-- **Fix**: Use exact matching with a centralized `WindowIdentifier` enum/constants.
-
-### 1.8 [-] ObjectIdentifier-based window tracking (LOW)
-- **File**: `TablePro/AppDelegate+WindowConfig.swift:210-248`
-- **Problem**: `configuredWindows` uses `ObjectIdentifier(window)` which is memory-address-based. If an NSWindow is deallocated and a new one allocated at the same address, they get the same identifier.
-- **Fix**: Use UUID-based window identifiers.
-
-### 1.9 [x] Unnecessary DispatchQueue.main.async in notification handlers (LOW)
-- **File**: `TablePro/AppDelegate+WindowConfig.swift:263-282`
-- **Problem**: Window operations dispatched async from notification handlers that already run on main thread. Introduces race windows where window state changes between check and action.
-- **Fix**: Keep critical window operations synchronous when already on main thread.
-
-### 1.10 [-] Duplicate observers for didBecomeKeyNotification (LOW)
-- **Files**: `TablePro/AppDelegate+WindowConfig.swift:210+`, `TablePro/Views/Main/MainContentView.swift:324+`
-- **Problem**: Both AppDelegate and MainContentView observe `NSWindow.didBecomeKeyNotification` independently. Both fire for every window focus change.
-- **Fix**: Centralize in `WindowLifecycleMonitor` and have views subscribe to a custom signal.
-
----
-
-## 2. Memory Management & Task Lifecycle
-
-### 2.1 [x] Missing redisDatabaseSwitchTask cancellation in teardown (HIGH)
-- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:106-108, 350-355`
-- **Problem**: `currentQueryTask` and `changeManagerUpdateTask` are cancelled in `teardown()`, but `redisDatabaseSwitchTask` is not. This leaves a dangling Task if coordinator is deallocated during a Redis database switch.
-- **Fix**: Add `redisDatabaseSwitchTask?.cancel(); redisDatabaseSwitchTask = nil` to `teardown()`.
-
-### 2.2 [x] Missing deinit in AIChatViewModel (HIGH)
-- **File**: `TablePro/ViewModels/AIChatViewModel.swift:91-92`
-- **Problem**: `streamingTask` is never cancelled if the view model is deallocated while streaming. The Task continues executing in the background.
-- **Fix**: Add `deinit { streamingTask?.cancel() }`.
-
-### 2.3 [x] Weak self with optional chaining in periodic Task loops (MEDIUM)
-- **Files**:
-  - `TablePro/Core/Services/Licensing/LicenseManager.swift:86-100`
-  - `TablePro/Core/Services/Infrastructure/AnalyticsService.swift:63-75`
-- **Problem**: Inside `while !Task.isCancelled` loops, `self?.revalidationInterval ?? 604_800` silently uses the fallback value if self is deallocated, then continues the loop with a default interval forever.
-- **Fix**: Use `guard let self else { return }` at the top of the task, or re-check inside the loop with early exit.
-
-### 2.4 [x] Eviction pending-changes check is incomplete (MEDIUM)
-- **File**: `TablePro/Views/Main/MainContentView.swift:349-365`
-- **Problem**: The pre-eviction check uses `changeManager.hasChanges` (in-memory changes), but `evictInactiveRowData()` checks `tab.pendingChanges.hasChanges` (tab-level). These are different — a tab may have tab-level changes even if `changeManager` is empty.
-- **Fix**: Check both `changeManager.hasChanges` and `tab.pendingChanges.hasChanges` consistently, or defer the check to just before eviction runs.
-
-### 2.5 [x] WindowLifecycleMonitor observer re-registration without full cleanup (LOW)
-- **File**: `TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift:41-66`
-- **Problem**: If `register()` is called twice with the same `windowId` but a different `NSWindow`, the old observer is removed but the old NSWindow is now orphaned without observation.
-- **Fix**: Guard against re-registration with a different window or explicitly unregister the old window.
-
-### 2.6 [-] Fire-and-forget disconnect Task in WindowLifecycleMonitor (LOW)
-- **File**: `TablePro/Core/Services/Infrastructure/WindowLifecycleMonitor.swift:190-211`
-- **Problem**: `Task { await DatabaseManager.shared.disconnectSession(...) }` has no error handling. If disconnect fails, the connection persists as a zombie.
-- **Fix**: Log errors from the disconnect call.
-
----
-
-## 3. Connection & Query Execution
-
-### 3.1 [x] Missing trackOperation in reconnectDriver (CRITICAL)
-- **File**: `TablePro/Core/Database/DatabaseManager.swift:599-632`
-- **Problem**: `reconnectDriver()` does NOT call `trackOperation()`, so `queriesInFlight` is never incremented. The health monitor's ping (`SELECT 1`) can race with the reconnect on the same driver, causing concurrent driver access.
-- **Fix**: Wrap reconnection in `trackOperation()` or stop the health monitor before reconnecting.
-
-### 3.2 [x] Stale session reference in reconnectSession (HIGH)
-- **File**: `TablePro/Core/Database/DatabaseManager.swift:601-632`
-- **Problem**: Line 649 captures `session` into a local variable. Lines 682-690 re-fetch from `activeSessions[sessionId]`, creating inconsistency. The local `session` could have stale schema/database values.
-- **Fix**: Always re-fetch from `activeSessions[sessionId]` before accessing mutable state, or pass all needed state as parameters.
-
-### 3.3 [x] Fire-and-forget SSH tunnel close (HIGH)
-- **Files**: `TablePro/Core/Database/DatabaseManager.swift:131-135, 220-224, 258-260`
-- **Problem**: SSH tunnels are closed in `Task { try? await ... }` blocks. If the task is cancelled or fails, the tunnel remains open. No error logging. Appears in 3+ locations.
-- **Fix**: `await` the tunnel close synchronously or at minimum log errors.
-
-### 3.4 [x] Discarded schema/database switch errors during reconnect (HIGH)
-- **File**: `TablePro/Core/Database/DatabaseManager.swift:620-629, 682-691`
-- **Problem**: `try? await schemaDriver.switchSchema(to: savedSchema)` silently discards errors. If schema switch fails, the connection operates in the wrong schema without any warning.
-- **Fix**: Log the error and optionally update session status to reflect the failure.
-
-### 3.5 [-] No cancel-await-run synchronization for queries (MEDIUM → demoted to P3)
-- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:37-39`
-- **Problem**: `currentQueryTask?.cancel()` followed immediately by `runQuery()`. Cancel doesn't wait for the running task to finish, so two queries can be in-flight simultaneously writing to the same `QueryTab`.
-- **Fix**: `await` the cancelled task's completion before starting the new query, or use a serial queue.
-
-### 3.6 [x] Health monitor ping skips when queriesInFlight exists (MEDIUM)
-- **File**: `TablePro/Core/Database/DatabaseManager.swift:535`
-- **Problem**: `guard await self.queriesInFlight[connectionId] == nil else { return true }` returns "healthy" if any query is in-flight. But a stuck query would keep the monitor returning true forever, masking a dead connection.
-- **Fix**: Track query start time and consider connections unhealthy if a query has been in-flight beyond a threshold.
-
-### 3.7 [x] Inconsistent exponential backoff between DatabaseManager and HealthMonitor (LOW)
-- **Files**: `DatabaseManager.swift:745`, `ConnectionHealthMonitor.swift:38, 230-238`
-- **Problem**: DatabaseManager uses `2.0 * pow(2.0, retryCount)` formula. HealthMonitor uses a predefined `[2.0, 4.0, 8.0]` array with different progression. Same app, different reconnect timing.
-- **Fix**: Unify backoff strategy into a shared utility.
-
-### 3.8 [x] Synchronous plugin loading fallback on main thread (MEDIUM)
-- **File**: `TablePro/Core/Database/DatabaseDriver.swift:318-333`
-- **Problem**: `PluginManager.shared.loadPendingPlugins()` is called synchronously on main thread when a plugin isn't loaded yet. Can freeze the UI if loading takes >100ms.
-- **Fix**: Pre-load all plugins at app startup, or make this async with a loading indicator.
-
----
-
-## 4. Architecture & State Management
-
-### 4.1 [-] AppSettingsManager dual notification channels (HIGH → demoted to P3)
-- **File**: `TablePro/Core/Storage/AppSettingsManager.swift:18-193`
-- **Problem**: Settings changes fire BOTH `@Observable` property updates AND `NotificationCenter.post()`. Views that observe both channels get redundant updates. Unclear which to use.
-- **Fix**: Use `@Observable` for local subscriptions, remove `NotificationCenter` posts for setting changes. Keep NotificationCenter only for system-wide events (accessibility).
-
-### 4.2 [x] AppSettingsManager missing observer cleanup (MEDIUM)
-- **File**: `TablePro/Core/Storage/AppSettingsManager.swift:179`
-- **Problem**: `observeAccessibilityTextSizeChanges()` registers a NotificationCenter observer stored in `@ObservationIgnored`. No `deinit` removes it.
-- **Fix**: Add `deinit { if let observer = accessibilityTextSizeObserver { NotificationCenter.default.removeObserver(observer) } }`.
-
-### 4.3 [-] SharedSidebarState registry race condition (MEDIUM → demoted to P3)
-- **File**: `TablePro/Models/UI/SharedSidebarState.swift:51-62`
-- **Problem**: `static var registry: [UUID: SharedSidebarState]` with no synchronization. Concurrent calls from different threads can create duplicate instances for the same connection.
-- **Fix**: Mark SharedSidebarState and registry as `@MainActor`, or use `OSAllocatedUnfairLock`.
-
-### 4.4 [-] Static termination observer never removed (MEDIUM → demoted to P3)
-- **File**: `TablePro/Views/Main/MainContentCoordinator.swift:197-203`
-- **Problem**: `registerTerminationObserver` is static and called once. The observer is never removed and fires for every coordinator instance at app termination.
-- **Fix**: Make instance-level, remove in teardown. Or use a dedicated `AppTerminationManager`.
-
-### 4.5 [x] Undo stack destroyed on tab switch (MEDIUM)
-- **File**: `TablePro/Core/ChangeTracking/DataChangeManager.swift:129-137`
-- **Problem**: `clearChanges()` calls `undoManager.clearAll()`. When switching tabs, if `clearChanges()` is called, the undo history is permanently lost even though changes are persisted via `saveState()`/`restoreState()`.
-- **Fix**: Separate `clearChanges()` (preserves undo) from `clearChangesAndUndoHistory()` (full reset on commit).
-
-### 4.6 [x] Tab state save silently fails on disk errors (MEDIUM)
-- **File**: `TablePro/Core/Storage/TabDiskActor.swift:79-81`
-- **Problem**: File I/O errors during tab state save are logged but never returned. If write fails (disk full), tabs are lost silently.
-- **Fix**: Return `Result<Void, Error>` so callers can retry or alert the user.
-
-### 4.7 [x] Silent startup command failures (LOW)
-- **File**: `TablePro/Core/Database/DatabaseManager.swift:783-793`
-- **Problem**: User-defined startup SQL commands that fail are logged but the connection continues. User expects commands like `SET ROLE` to succeed but has no indication of failure.
-- **Fix**: Collect errors and show a warning: "Startup commands failed. Continue anyway?"
-
----
-
-## 5. SwiftUI Patterns
-
-### 5.1 [-] Unnecessary DispatchQueue.main.async in SwiftUI callbacks (MEDIUM → demoted to P3)
-- **Files** (8+ locations):
-  - `TablePro/Views/Results/DataGridView.swift:400-403, 433-441, 537-545`
-  - `TablePro/Views/AIChat/AIChatPanelView.swift:205-207, 225-227`
-  - `TablePro/Views/Main/Child/MainEditorContentView.swift:348, 358-365`
-  - `TablePro/Views/Toolbar/ConnectionSwitcherPopover.swift:351-352`
-  - `TablePro/Views/Components/SQLReviewPopover.swift:90-91`
-  - `TablePro/Views/Connection/WelcomeWindowView.swift:770-778`
-  - `TablePro/Views/Results/Extensions/DataGridView+Editing.swift:164-166, 196-199, 218-221`
-- **Problem**: `onAppear`, `onChange`, and body callbacks already execute on main thread. Wrapping in `DispatchQueue.main.async` adds latency and can cause visual glitches or double-renders.
-- **Fix**: Remove unnecessary `DispatchQueue.main.async` wrappers. Use `Task { @MainActor in }` only when deferral is genuinely needed.
-
-### 5.2 [-] Multiple onChange handlers on related state (LOW)
-- **File**: `TablePro/Views/AIChat/AIChatPanelView.swift:210-228`
-- **Problem**: Three separate `onChange` handlers for `messages.last?.content`, `messages.count`, and `activeConversationID` all trigger scrolling. If a new message arrives on a conversation switch, scrolling happens multiple times.
-- **Fix**: Consolidate into a single scroll trigger.
-
-### 5.3 [x] Recursive asyncAfter retry for window focus (LOW)
-- **File**: `TablePro/Views/Connection/WelcomeWindowView.swift:770-778`
-- **Problem**: Recursive `DispatchQueue.main.asyncAfter(deadline: .now() + 0.02)` with retry count. No cancellation if view disappears. Hardcoded timing.
-- **Fix**: Use a cancellable `Task` with `Task.sleep`.
-
-### 5.4 [-] DispatchQueue.main.async in updateNSView path (LOW)
-- **File**: `TablePro/Views/Results/DataGridView.swift:400-403, 433-441`
-- **Problem**: Inside `updateNSView` -> `updateColumns`, a binding update is dispatched to the next cycle. This causes the view to re-evaluate before the flag is cleared, potentially causing flicker.
-- **Fix**: Use `Task.yield()` or accept the binding update synchronously.
-
----
-
-## Priority Order for Fixes
-
-### P0 - Critical (fix immediately)
-1. **1.1** Active tab evicted on window focus loss
-2. **3.1** Missing trackOperation in reconnectDriver
-
-### P1 - High (fix soon)
-3. **2.1** Missing redisDatabaseSwitchTask cancellation
-4. **2.2** Missing deinit in AIChatViewModel
-5. **3.3** Fire-and-forget SSH tunnel close
-6. **3.4** Discarded schema/database switch errors
-7. **3.2** Stale session reference in reconnectSession
-8. **1.2** Unreliable window discovery via NSApp.keyWindow
-9. **1.3** Duplicate window discovery pattern
-10. **4.1** AppSettingsManager dual notification channels
-
-### P2 - Medium (fix in next cycle)
-11. **2.3** Weak self in periodic Task loops
-12. **2.4** Eviction pending-changes check incomplete
-13. **3.5** No cancel-await-run synchronization
-14. **3.6** Health monitor ping masking stuck queries
-15. **3.8** Synchronous plugin loading on main thread
-16. **4.2** AppSettingsManager missing observer cleanup
-17. **4.3** SharedSidebarState registry race condition
-18. **4.4** Static termination observer never removed
-19. **4.5** Undo stack destroyed on tab switch
-20. **4.6** Tab state save silently fails
-21. **1.4** Fragile subtitle-based window matching
-22. **1.5** Notification observer fires before window registration
-23. **5.1** Unnecessary DispatchQueue.main.async in SwiftUI
-
-### P3 - Low (backlog)
-24. **1.6** Stale isKeyWindow initialization
-25. **1.7** Inconsistent window identifier matching
-26. **1.8** ObjectIdentifier-based window tracking
-27. **1.9** Unnecessary async in notification handlers
-28. **1.10** Duplicate observers for didBecomeKeyNotification
-29. **2.5** WindowLifecycleMonitor observer re-registration
-30. **2.6** Fire-and-forget disconnect Task
-31. **3.7** Inconsistent exponential backoff
-32. **4.7** Silent startup command failures
-33. **5.2** Multiple onChange handlers on related state
-34. **5.3** Recursive asyncAfter retry
-35. **5.4** DispatchQueue.main.async in updateNSView

From 07d1dbcf4930cdd4f1e0e95f3a134f2f57d480a6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ng=C3=B4=20Qu=E1=BB=91c=20=C4=90=E1=BA=A1t?=
 <datlechin@gmail.com>
Date: Tue, 24 Mar 2026 09:27:10 +0700
Subject: [PATCH 5/5] fix: guard clearChangesAndUndoHistory with tab ID check

Prevent clearing another tab's undo state when a background query or
multi-statement execution completes after the user has switched tabs.
---
 .../Extensions/MainContentCoordinator+MultiStatement.swift  | 6 ++++--
 .../Extensions/MainContentCoordinator+QueryHelpers.swift    | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
index fc77a090..d8d64019 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+MultiStatement.swift
@@ -134,8 +134,10 @@ extension MainContentCoordinator {
                     updatedTab.errorMessage = nil
                     tabManager.tabs[idx] = updatedTab
 
-                    changeManager.clearChangesAndUndoHistory()
-                    changeManager.reloadVersion += 1
+                    if tabManager.selectedTabId == tabId {
+                        changeManager.clearChangesAndUndoHistory()
+                        changeManager.reloadVersion += 1
+                    }
                 }
             } catch {
                 // Rollback on failure
diff --git a/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift b/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
index b31c7787..4e6b8359 100644
--- a/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
+++ b/TablePro/Views/Main/Extensions/MainContentCoordinator+QueryHelpers.swift
@@ -192,7 +192,7 @@ extension MainContentCoordinator {
         // Clear stale edit state immediately so the save banner
         // doesn't linger while Phase 2 metadata loads in background.
         // Only clear if there are no pending edits from the user.
-        if isEditable && !changeManager.hasChanges {
+        if tabManager.selectedTabId == tabId, isEditable, !changeManager.hasChanges {
             changeManager.clearChangesAndUndoHistory()
         }
     }