ui adjustments

Wino.Core.Domain/Interfaces/ILegacyLocalMigrationService.cs

@@ -0,0 +1,12 @@
+using System.Threading;
+using System.Threading.Tasks;
+using Wino.Core.Domain.Models.Accounts;
+
+namespace Wino.Core.Domain.Interfaces;
+
+public interface ILegacyLocalMigrationService
+{
+    Task<LegacyLocalMigrationPreview> DetectAsync(CancellationToken cancellationToken = default);
+    Task<LegacyLocalMigrationResult> ImportAsync(CancellationToken cancellationToken = default);
+    void MarkPromptDeferred();
+}

Wino.Core.Domain/Models/Accounts/LegacyLocalMigrationPreview.cs

@@ -0,0 +1,46 @@
+using System;
+using System.Collections.Generic;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Core.Domain.Models.Accounts;
+
+public sealed class LegacyLocalMigrationPreview
+{
+    public string SourceDatabasePath { get; init; } = string.Empty;
+    public bool LegacyDatabaseExists { get; init; }
+    public bool HasCompletedMigration { get; init; }
+    public bool IsPromptDeferred { get; init; }
+    public bool ShouldPrompt { get; init; }
+    public int LegacyAccountCount { get; init; }
+    public int ImportableAccountCount { get; init; }
+    public int DuplicateAccountCount { get; init; }
+    public int SkippedAccountCount { get; init; }
+    public int ImportableMergedInboxCount { get; init; }
+    public int SkippedMergedInboxCount { get; init; }
+    public IReadOnlyList<LegacyLocalMigrationProviderCount> ProviderCounts { get; init; } = [];
+    public IReadOnlyList<LegacyLocalMigrationAccountPreview> Accounts { get; init; } = [];
+    public IReadOnlyList<string> Warnings { get; init; } = [];
+
+    public bool HasImportableData => LegacyDatabaseExists && ImportableAccountCount > 0;
+}
+
+public sealed class LegacyLocalMigrationProviderCount
+{
+    public MailProviderType ProviderType { get; init; }
+    public int TotalAccountCount { get; init; }
+    public int ImportableAccountCount { get; init; }
+    public int DuplicateAccountCount { get; init; }
+}
+
+public sealed class LegacyLocalMigrationAccountPreview
+{
+    public Guid LegacyAccountId { get; init; }
+    public string Address { get; init; } = string.Empty;
+    public string DisplayName { get; init; } = string.Empty;
+    public MailProviderType ProviderType { get; init; }
+    public SpecialImapProvider SpecialImapProvider { get; init; }
+    public int Order { get; init; }
+    public bool CanImport { get; init; }
+    public bool IsDuplicate { get; init; }
+    public bool IsCalendarEnabled { get; init; }
+}

Wino.Core.Domain/Models/Accounts/LegacyLocalMigrationResult.cs

@@ -0,0 +1,25 @@
+using System.Collections.Generic;
+using Wino.Core.Domain.Enums;
+
+namespace Wino.Core.Domain.Models.Accounts;
+
+public sealed class LegacyLocalMigrationResult
+{
+    public LegacyLocalMigrationPreview Preview { get; init; } = new();
+    public int ImportedAccountCount { get; init; }
+    public int SkippedDuplicateAccountCount { get; init; }
+    public int FailedAccountCount { get; init; }
+    public int ImportedMergedInboxCount { get; init; }
+    public int SkippedMergedInboxCount { get; init; }
+    public IReadOnlyList<LegacyLocalMigrationFailure> Failures { get; init; } = [];
+    public IReadOnlyList<string> Warnings { get; init; } = [];
+
+    public bool HasImportedData => ImportedAccountCount > 0 || ImportedMergedInboxCount > 0;
+}
+
+public sealed class LegacyLocalMigrationFailure
+{
+    public string Address { get; init; } = string.Empty;
+    public MailProviderType ProviderType { get; init; }
+    public string Message { get; init; } = string.Empty;
+}

Wino.Core.Domain/Translations/en_US/resources.json

@@ -1368,6 +1368,26 @@
     "WelcomeWindow_ImportInProgress": "Importing preferences and accounts...",
     "WelcomeWindow_ImportNoAccountsFound": "No accounts were found to import. If preferences were available, they were restored. Use Get started to add an account manually.",
     "WelcomeWindow_ImportDuplicateAccountsSkipped": "{0} imported accounts are already available on this device. Use Get started to add another account manually if needed.",
+    "LegacyLocalMigration_WelcomeSectionTitle": "Import from your previous Wino version",
+    "LegacyLocalMigration_WelcomeSectionDescription": "Wino found account details in an older local database on this device. Import them now, then sign in again to finish reconnecting each account.",
+    "LegacyLocalMigration_PromptTitle": "Import accounts from your previous Wino version?",
+    "LegacyLocalMigration_ImportAction": "Import previous accounts",
+    "LegacyLocalMigration_PreviewSummary": "Found {0} account(s) ready to import: {1}.",
+    "LegacyLocalMigration_PreviewDuplicateSummary": "{0} account(s) already exist on this device and will be skipped.",
+    "LegacyLocalMigration_PreviewMergedSummary": "{0} merged inbox group(s) can be recreated after import.",
+    "LegacyLocalMigration_Provider_Outlook": "Outlook",
+    "LegacyLocalMigration_Provider_Gmail": "Gmail",
+    "LegacyLocalMigration_Provider_Imap": "IMAP",
+    "LegacyLocalMigration_Warning_OAuth": "Outlook and Gmail accounts will need you to sign in again to restore mail and calendar access.",
+    "LegacyLocalMigration_Warning_Imap": "IMAP and CalDAV passwords are never copied. Open the account settings afterward and enter them again.",
+    "LegacyLocalMigration_Warning_Merged": "Merged inboxes are recreated only when every member account imports successfully.",
+    "LegacyLocalMigration_Warning_SkippedAccounts": "Skipped {0} legacy account(s) because their provider or primary address could not be read safely.",
+    "LegacyLocalMigration_Warning_ReadFailed": "Wino found a previous local database, but it could not be read safely for migration.",
+    "LegacyLocalMigration_ImportAccountsSucceeded": "Imported {0} accounts from the previous local database.",
+    "LegacyLocalMigration_ImportMergedInboxesSucceeded": "Recreated {0} merged inbox group(s).",
+    "LegacyLocalMigration_ImportMergedInboxesSkipped": "Skipped {0} merged inbox group(s) because at least one member account could not be imported.",
+    "LegacyLocalMigration_ImportFailedAccounts": "{0} account(s) could not be imported.",
+    "LegacyLocalMigration_ImportEmpty": "There are no additional legacy accounts to import from this device.",
     "WelcomeWindow_SetupTitle": "Set up your account",
     "WelcomeWindow_SetupSubtitle": "Choose your email provider to get started",
     "WelcomeWindow_AddAccountButton": "Add account",
@@ -1444,6 +1464,7 @@
     "WinoAccount_Management_ExportDialog_AccountsDisclaimer": "Passwords, tokens, and other sensitive information are not synced.",
     "WinoAccount_Management_ExportDialog_AccountsRelogin": "Imported accounts on another PC will still need you to sign in again before they can be used.",
     "WinoAccount_Management_ExportDialog_InProgress": "Exporting your selected Wino data...",
+    "LegacyLocalMigration_SettingsSectionTitle": "Import from a previous Wino version",
     "WinoAccount_Management_LocalDataSectionTitle": "Transfer with a JSON file",
     "WinoAccount_Management_LocalDataSectionDescription": "Import from or export to a local JSON file. Passwords, tokens, and other sensitive information are not included.",
     "WinoAccount_Management_LocalDataImportAction": "Import",

Wino.Core.Tests/Services/LegacyLocalMigrationServiceTests.cs

@@ -0,0 +1,696 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Moq;
+using SQLite;
+using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Entities.Shared;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Interfaces;
+using Wino.Core.Tests.Helpers;
+using Wino.Services;
+using Xunit;
+
+namespace Wino.Core.Tests.Services;
+
+public sealed class LegacyLocalMigrationServiceTests
+{
+    [Fact]
+    public async Task DetectAsync_ReturnsPreviewCountsAndDuplicatesByProvider()
+    {
+        await using var context = await LegacyMigrationTestContext.CreateAsync();
+
+        await context.SeedCurrentAccountAsync(
+            "gmail@example.com",
+            MailProviderType.Gmail,
+            "Existing Gmail");
+
+        await context.InsertLegacyAccountAsync(
+            Guid.NewGuid(),
+            "outlook@example.com",
+            MailProviderType.Outlook,
+            order: 0,
+            name: "Outlook Legacy");
+
+        await context.InsertLegacyAccountAsync(
+            Guid.NewGuid(),
+            "gmail@example.com",
+            MailProviderType.Gmail,
+            order: 1,
+            name: "Duplicate Gmail");
+
+        var imapId = Guid.NewGuid();
+        await context.InsertLegacyAccountAsync(
+            imapId,
+            "imap@example.com",
+            MailProviderType.IMAP4,
+            order: 2,
+            name: "Imported IMAP",
+            specialImapProvider: SpecialImapProvider.Yahoo);
+
+        await context.InsertLegacyServerInformationAsync(
+            imapId,
+            address: "imap@example.com",
+            incomingServer: "imap.mail.yahoo.com",
+            incomingServerPort: "993",
+            incomingServerUsername: "imap@example.com",
+            outgoingServer: "smtp.mail.yahoo.com",
+            outgoingServerPort: "587",
+            outgoingServerUsername: "imap@example.com",
+            calendarSupportMode: ImapCalendarSupportMode.CalDav,
+            calDavServiceUrl: "https://caldav.calendar.yahoo.com/",
+            calDavUsername: "imap@example.com");
+
+        var preview = await context.Service.DetectAsync();
+
+        preview.LegacyDatabaseExists.Should().BeTrue();
+        preview.ShouldPrompt.Should().BeTrue();
+        preview.LegacyAccountCount.Should().Be(3);
+        preview.ImportableAccountCount.Should().Be(2);
+        preview.DuplicateAccountCount.Should().Be(1);
+        preview.Accounts.Select(a => a.Address).Should().ContainInOrder(
+            "outlook@example.com",
+            "gmail@example.com",
+            "imap@example.com");
+
+        preview.ProviderCounts.Should().ContainSingle(a =>
+            a.ProviderType == MailProviderType.Outlook &&
+            a.ImportableAccountCount == 1 &&
+            a.DuplicateAccountCount == 0);
+
+        preview.ProviderCounts.Should().ContainSingle(a =>
+            a.ProviderType == MailProviderType.Gmail &&
+            a.ImportableAccountCount == 0 &&
+            a.DuplicateAccountCount == 1);
+
+        preview.ProviderCounts.Should().ContainSingle(a =>
+            a.ProviderType == MailProviderType.IMAP4 &&
+            a.ImportableAccountCount == 1 &&
+            a.DuplicateAccountCount == 0);
+    }
+
+    [Fact]
+    public async Task ImportAsync_ImportsAccountsPreservesSafePreferencesAndRecreatesMergedInboxes()
+    {
+        await using var context = await LegacyMigrationTestContext.CreateAsync();
+
+        var mergedInboxId = Guid.NewGuid();
+        await context.InsertLegacyMergedInboxAsync(mergedInboxId, "Legacy Linked");
+
+        var legacyOutlookId = Guid.NewGuid();
+        var legacyGmailId = Guid.NewGuid();
+        var legacyImapId = Guid.NewGuid();
+        var legacySignatureId = Guid.NewGuid();
+
+        await context.InsertLegacyAccountAsync(
+            legacyOutlookId,
+            "outlook@example.com",
+            MailProviderType.Outlook,
+            order: 0,
+            name: "Outlook Legacy",
+            senderName: "Outlook Sender",
+            mergedInboxId: mergedInboxId);
+
+        await context.InsertLegacyPreferencesAsync(
+            legacyOutlookId,
+            isNotificationsEnabled: false,
+            isTaskbarBadgeEnabled: false,
+            shouldAppendMessagesToSentFolder: true,
+            isFocusedInboxEnabled: false,
+            signatureIdForNewMessages: legacySignatureId,
+            signatureIdForFollowingMessages: legacySignatureId);
+
+        await context.InsertLegacyAccountAsync(
+            legacyGmailId,
+            "gmail@example.com",
+            MailProviderType.Gmail,
+            order: 1,
+            name: "Gmail Legacy",
+            senderName: "Gmail Sender",
+            mergedInboxId: mergedInboxId);
+
+        await context.InsertLegacyAccountAsync(
+            legacyImapId,
+            "imap@example.com",
+            MailProviderType.IMAP4,
+            order: 2,
+            name: "iCloud Legacy",
+            senderName: "iCloud Sender",
+            specialImapProvider: SpecialImapProvider.iCloud);
+
+        await context.InsertLegacyServerInformationAsync(
+            legacyImapId,
+            address: "imap@example.com",
+            incomingServer: "imap.mail.me.com",
+            incomingServerPort: "993",
+            incomingServerUsername: "imap-user",
+            outgoingServer: "smtp.mail.me.com",
+            outgoingServerPort: "587",
+            outgoingServerUsername: "smtp-user",
+            calendarSupportMode: ImapCalendarSupportMode.CalDav,
+            calDavServiceUrl: "https://caldav.icloud.com/",
+            calDavUsername: "imap@example.com",
+            maxConcurrentClients: 7);
+
+        var result = await context.Service.ImportAsync();
+
+        result.ImportedAccountCount.Should().Be(3);
+        result.SkippedDuplicateAccountCount.Should().Be(0);
+        result.FailedAccountCount.Should().Be(0);
+        result.ImportedMergedInboxCount.Should().Be(1);
+        result.SkippedMergedInboxCount.Should().Be(0);
+
+        var accounts = await context.AccountService.GetAccountsAsync();
+        accounts.Should().HaveCount(3);
+        accounts.Select(a => a.Address).Should().ContainInOrder(
+            "outlook@example.com",
+            "gmail@example.com",
+            "imap@example.com");
+
+        var outlookAccount = accounts.Single(a => a.Address == "outlook@example.com");
+        outlookAccount.AttentionReason.Should().Be(AccountAttentionReason.InvalidCredentials);
+        outlookAccount.IsMailAccessGranted.Should().BeTrue();
+        outlookAccount.IsCalendarAccessGranted.Should().BeTrue();
+        outlookAccount.Preferences.IsNotificationsEnabled.Should().BeFalse();
+        outlookAccount.Preferences.IsTaskbarBadgeEnabled.Should().BeFalse();
+        outlookAccount.Preferences.ShouldAppendMessagesToSentFolder.Should().BeTrue();
+        outlookAccount.Preferences.IsFocusedInboxEnabled.Should().BeFalse();
+        outlookAccount.Preferences.SignatureIdForNewMessages.Should().NotBe(legacySignatureId);
+        outlookAccount.Preferences.SignatureIdForFollowingMessages.Should().NotBe(legacySignatureId);
+
+        var gmailAliases = await context.AccountService.GetAccountAliasesAsync(accounts.Single(a => a.Address == "gmail@example.com").Id);
+        gmailAliases.Should().ContainSingle(a =>
+            a.IsRootAlias &&
+            a.IsPrimary &&
+            a.AliasAddress == "gmail@example.com");
+
+        var imapAccount = accounts.Single(a => a.Address == "imap@example.com");
+        imapAccount.AttentionReason.Should().Be(AccountAttentionReason.InvalidCredentials);
+        imapAccount.IsCalendarAccessGranted.Should().BeTrue();
+
+        var serverInformation = await context.AccountService.GetAccountCustomServerInformationAsync(imapAccount.Id);
+        serverInformation.Should().NotBeNull();
+        serverInformation.IncomingServer.Should().Be("imap.mail.me.com");
+        serverInformation.OutgoingServer.Should().Be("smtp.mail.me.com");
+        serverInformation.IncomingServerPassword.Should().BeEmpty();
+        serverInformation.OutgoingServerPassword.Should().BeEmpty();
+        serverInformation.CalDavPassword.Should().BeEmpty();
+        serverInformation.CalDavServiceUrl.Should().Be("https://caldav.icloud.com/");
+        serverInformation.CalDavUsername.Should().Be("imap@example.com");
+        serverInformation.MaxConcurrentClients.Should().Be(7);
+
+        var mergedInboxIds = accounts
+            .Where(a => a.Address is "outlook@example.com" or "gmail@example.com")
+            .Select(a => a.MergedInboxId)
+            .Distinct()
+            .ToList();
+
+        mergedInboxIds.Should().ContainSingle();
+        mergedInboxIds[0].Should().NotBeNull();
+        accounts.Single(a => a.Address == "outlook@example.com").MergedInbox.Name.Should().Be("Legacy Linked");
+    }
+
+    [Fact]
+    public async Task ImportAsync_WithMissingLegacySchemaColumns_DefaultsSafelyAndSkipsIncompleteMergedInboxes()
+    {
+        await using var context = await LegacyMigrationTestContext.CreateAsync(new LegacySchemaOptions(
+            IncludeCalDavColumns: false,
+            IncludeCalendarSupportMode: false,
+            IncludeTaskbarBadgeColumn: false,
+            IncludeFocusedInboxColumn: false));
+
+        await context.SeedCurrentAccountAsync(
+            "duplicate@icloud.com",
+            MailProviderType.IMAP4,
+            "Existing iCloud",
+            specialImapProvider: SpecialImapProvider.iCloud);
+
+        var mergedInboxId = Guid.NewGuid();
+        var duplicateLegacyAccountId = Guid.NewGuid();
+        var importableLegacyAccountId = Guid.NewGuid();
+
+        await context.InsertLegacyMergedInboxAsync(mergedInboxId, "Legacy Incomplete");
+
+        await context.InsertLegacyAccountAsync(
+            duplicateLegacyAccountId,
+            "duplicate@icloud.com",
+            MailProviderType.IMAP4,
+            order: 0,
+            name: "Duplicate iCloud",
+            specialImapProvider: SpecialImapProvider.iCloud,
+            mergedInboxId: mergedInboxId);
+
+        await context.InsertLegacyAccountAsync(
+            importableLegacyAccountId,
+            "new@icloud.com",
+            MailProviderType.IMAP4,
+            order: 1,
+            name: "Importable iCloud",
+            specialImapProvider: SpecialImapProvider.iCloud,
+            mergedInboxId: mergedInboxId);
+
+        await context.InsertLegacyServerInformationAsync(
+            duplicateLegacyAccountId,
+            address: "duplicate@icloud.com",
+            incomingServer: "imap.mail.me.com",
+            incomingServerPort: "993",
+            incomingServerUsername: "duplicate",
+            outgoingServer: "smtp.mail.me.com",
+            outgoingServerPort: "587",
+            outgoingServerUsername: "duplicate");
+
+        await context.InsertLegacyServerInformationAsync(
+            importableLegacyAccountId,
+            address: "new@icloud.com",
+            incomingServer: "imap.mail.me.com",
+            incomingServerPort: "993",
+            incomingServerUsername: "new",
+            outgoingServer: "smtp.mail.me.com",
+            outgoingServerPort: "587",
+            outgoingServerUsername: "new");
+
+        var result = await context.Service.ImportAsync();
+
+        result.ImportedAccountCount.Should().Be(1);
+        result.SkippedDuplicateAccountCount.Should().Be(1);
+        result.ImportedMergedInboxCount.Should().Be(0);
+        result.SkippedMergedInboxCount.Should().Be(1);
+
+        var importedAccount = (await context.AccountService.GetAccountsAsync())
+            .Single(a => a.Address == "new@icloud.com");
+
+        importedAccount.IsCalendarAccessGranted.Should().BeFalse();
+        importedAccount.MergedInboxId.Should().BeNull();
+        importedAccount.AttentionReason.Should().Be(AccountAttentionReason.InvalidCredentials);
+
+        var importedServerInfo = await context.AccountService.GetAccountCustomServerInformationAsync(importedAccount.Id);
+        importedServerInfo.Should().NotBeNull();
+        importedServerInfo.CalDavServiceUrl.Should().Be("https://caldav.icloud.com/");
+        importedServerInfo.CalDavUsername.Should().Be("new@icloud.com");
+        importedServerInfo.CalDavPassword.Should().BeEmpty();
+        importedServerInfo.CalendarSupportMode.Should().Be(ImapCalendarSupportMode.Disabled);
+        importedServerInfo.IncomingServerPassword.Should().BeEmpty();
+        importedServerInfo.OutgoingServerPassword.Should().BeEmpty();
+    }
+
+    private sealed class LegacyMigrationTestContext : IAsyncDisposable
+    {
+        private readonly SQLiteAsyncConnection _legacyConnection;
+        private readonly InMemoryDatabaseService _databaseService;
+        private readonly string _legacyFolderPath;
+
+        public LegacyLocalMigrationService Service { get; }
+        public AccountService AccountService { get; }
+
+        private LegacyMigrationTestContext(string legacyFolderPath,
+                                           SQLiteAsyncConnection legacyConnection,
+                                           InMemoryDatabaseService databaseService,
+                                           AccountService accountService,
+                                           LegacyLocalMigrationService service)
+        {
+            _legacyFolderPath = legacyFolderPath;
+            _legacyConnection = legacyConnection;
+            _databaseService = databaseService;
+            AccountService = accountService;
+            Service = service;
+        }
+
+        public static async Task<LegacyMigrationTestContext> CreateAsync(LegacySchemaOptions? schemaOptions = null)
+        {
+            var databaseService = new InMemoryDatabaseService();
+            await databaseService.InitializeAsync();
+
+            var preferencesService = new Mock<IPreferencesService>();
+            preferencesService.SetupProperty(a => a.StartupEntityId);
+
+            var accountService = CreateAccountService(databaseService, preferencesService.Object);
+
+            var legacyFolderPath = Path.Combine(Path.GetTempPath(), $"legacy-migration-tests-{Guid.NewGuid():N}");
+            Directory.CreateDirectory(legacyFolderPath);
+
+            var legacyDatabasePath = Path.Combine(legacyFolderPath, "Wino180.db");
+            var legacyConnection = new SQLiteAsyncConnection(legacyDatabasePath);
+
+            await CreateLegacySchemaAsync(legacyConnection, schemaOptions ?? LegacySchemaOptions.Default);
+
+            var applicationConfiguration = new ApplicationConfiguration
+            {
+                ApplicationDataFolderPath = legacyFolderPath,
+                ApplicationTempFolderPath = legacyFolderPath,
+                PublisherSharedFolderPath = legacyFolderPath
+            };
+
+            var service = new LegacyLocalMigrationService(
+                applicationConfiguration,
+                new InMemoryConfigurationService(),
+                databaseService,
+                accountService,
+                new SpecialImapProviderConfigResolver());
+
+            return new LegacyMigrationTestContext(
+                legacyFolderPath,
+                legacyConnection,
+                databaseService,
+                accountService,
+                service);
+        }
+
+        public async Task SeedCurrentAccountAsync(string address,
+                                                  MailProviderType providerType,
+                                                  string name,
+                                                  SpecialImapProvider specialImapProvider = SpecialImapProvider.None)
+        {
+            var accountId = Guid.NewGuid();
+            CustomServerInformation? serverInformation = null;
+
+            if (providerType == MailProviderType.IMAP4)
+            {
+                serverInformation = new CustomServerInformation
+                {
+                    Id = Guid.NewGuid(),
+                    AccountId = accountId,
+                    Address = address,
+                    IncomingServer = "imap.current.test",
+                    IncomingServerPort = "993",
+                    IncomingServerUsername = address,
+                    IncomingServerPassword = "secret",
+                    IncomingServerSocketOption = ImapConnectionSecurity.Auto,
+                    IncomingAuthenticationMethod = ImapAuthenticationMethod.NormalPassword,
+                    OutgoingServer = "smtp.current.test",
+                    OutgoingServerPort = "587",
+                    OutgoingServerUsername = address,
+                    OutgoingServerPassword = "secret",
+                    OutgoingServerSocketOption = ImapConnectionSecurity.Auto,
+                    OutgoingAuthenticationMethod = ImapAuthenticationMethod.NormalPassword,
+                    CalDavServiceUrl = string.Empty,
+                    CalDavUsername = string.Empty,
+                    CalDavPassword = string.Empty,
+                    CalendarSupportMode = ImapCalendarSupportMode.Disabled,
+                    MaxConcurrentClients = 5
+                };
+            }
+
+            await AccountService.CreateAccountAsync(
+                new MailAccount
+                {
+                    Id = accountId,
+                    Name = name,
+                    SenderName = name,
+                    Address = address,
+                    ProviderType = providerType,
+                    SpecialImapProvider = specialImapProvider,
+                    IsMailAccessGranted = true,
+                    IsCalendarAccessGranted = providerType is MailProviderType.Outlook or MailProviderType.Gmail
+                },
+                serverInformation);
+        }
+
+        public Task InsertLegacyAccountAsync(Guid accountId,
+                                             string address,
+                                             MailProviderType providerType,
+                                             int order,
+                                             string name,
+                                             string? senderName = null,
+                                             SpecialImapProvider specialImapProvider = SpecialImapProvider.None,
+                                             Guid? mergedInboxId = null)
+            => InsertRowAsync(
+                _legacyConnection,
+                "MailAccount",
+                ("Id", accountId),
+                ("Address", address),
+                ("Name", name),
+                ("SenderName", senderName ?? name),
+                ("ProviderType", (int)providerType),
+                ("SpecialImapProvider", (int)specialImapProvider),
+                ("Order", order),
+                ("AccountColorHex", "#123456"),
+                ("MergedInboxId", mergedInboxId));
+
+        public Task InsertLegacyPreferencesAsync(Guid accountId,
+                                                 bool? isNotificationsEnabled = null,
+                                                 bool? isTaskbarBadgeEnabled = null,
+                                                 bool? shouldAppendMessagesToSentFolder = null,
+                                                 bool? isFocusedInboxEnabled = null,
+                                                 Guid? signatureIdForNewMessages = null,
+                                                 Guid? signatureIdForFollowingMessages = null)
+        {
+            var values = new List<(string Column, object? Value)>
+            {
+                ("Id", Guid.NewGuid()),
+                ("AccountId", accountId)
+            };
+
+            if (isNotificationsEnabled.HasValue)
+                values.Add(("IsNotificationsEnabled", isNotificationsEnabled.Value));
+
+            if (isTaskbarBadgeEnabled.HasValue)
+                values.Add(("IsTaskbarBadgeEnabled", isTaskbarBadgeEnabled.Value));
+
+            if (shouldAppendMessagesToSentFolder.HasValue)
+                values.Add(("ShouldAppendMessagesToSentFolder", shouldAppendMessagesToSentFolder.Value));
+
+            if (isFocusedInboxEnabled.HasValue)
+                values.Add(("IsFocusedInboxEnabled", isFocusedInboxEnabled.Value));
+
+            if (signatureIdForNewMessages.HasValue)
+                values.Add(("SignatureIdForNewMessages", signatureIdForNewMessages.Value));
+
+            if (signatureIdForFollowingMessages.HasValue)
+                values.Add(("SignatureIdForFollowingMessages", signatureIdForFollowingMessages.Value));
+
+            return InsertRowAsync(_legacyConnection, "MailAccountPreferences", values.ToArray());
+        }
+
+        public Task InsertLegacyServerInformationAsync(Guid accountId,
+                                                       string address,
+                                                       string incomingServer,
+                                                       string incomingServerPort,
+                                                       string incomingServerUsername,
+                                                       string outgoingServer,
+                                                       string outgoingServerPort,
+                                                       string outgoingServerUsername,
+                                                       ImapCalendarSupportMode? calendarSupportMode = null,
+                                                       string? calDavServiceUrl = null,
+                                                       string? calDavUsername = null,
+                                                       int? maxConcurrentClients = null)
+        {
+            var values = new List<(string Column, object? Value)>
+            {
+                ("Id", Guid.NewGuid()),
+                ("AccountId", accountId),
+                ("Address", address),
+                ("IncomingServer", incomingServer),
+                ("IncomingServerPort", incomingServerPort),
+                ("IncomingServerUsername", incomingServerUsername),
+                ("IncomingServerSocketOption", (int)ImapConnectionSecurity.Auto),
+                ("IncomingAuthenticationMethod", (int)ImapAuthenticationMethod.NormalPassword),
+                ("OutgoingServer", outgoingServer),
+                ("OutgoingServerPort", outgoingServerPort),
+                ("OutgoingServerUsername", outgoingServerUsername),
+                ("OutgoingServerSocketOption", (int)ImapConnectionSecurity.Auto),
+                ("OutgoingAuthenticationMethod", (int)ImapAuthenticationMethod.NormalPassword),
+                ("ProxyServer", "proxy.example.com"),
+                ("ProxyServerPort", "8080"),
+                ("MaxConcurrentClients", maxConcurrentClients ?? 5)
+            };
+
+            if (calendarSupportMode.HasValue)
+                values.Add(("CalendarSupportMode", (int)calendarSupportMode.Value));
+
+            if (!string.IsNullOrWhiteSpace(calDavServiceUrl))
+                values.Add(("CalDavServiceUrl", calDavServiceUrl));
+
+            if (!string.IsNullOrWhiteSpace(calDavUsername))
+                values.Add(("CalDavUsername", calDavUsername));
+
+            return InsertRowAsync(_legacyConnection, "CustomServerInformation", values.ToArray());
+        }
+
+        public Task InsertLegacyMergedInboxAsync(Guid mergedInboxId, string name)
+            => InsertRowAsync(
+                _legacyConnection,
+                "MergedInbox",
+                ("Id", mergedInboxId),
+                ("Name", name));
+
+        public async ValueTask DisposeAsync()
+        {
+            await _legacyConnection.CloseAsync();
+
+            if (Directory.Exists(_legacyFolderPath))
+            {
+                Directory.Delete(_legacyFolderPath, recursive: true);
+            }
+
+            await _databaseService.DisposeAsync();
+        }
+    }
+
+    private sealed class InMemoryConfigurationService : IConfigurationService
+    {
+        private readonly Dictionary<string, string?> _localValues = new(StringComparer.Ordinal);
+        private readonly Dictionary<string, string?> _roamingValues = new(StringComparer.Ordinal);
+
+        public bool Contains(string key) => _localValues.ContainsKey(key);
+
+        public T Get<T>(string key, T defaultValue = default!)
+            => TryGetValue(_localValues, key, defaultValue);
+
+        public T GetRoaming<T>(string key, T defaultValue = default!)
+            => TryGetValue(_roamingValues, key, defaultValue);
+
+        public void Set(string key, object value)
+            => _localValues[key] = value?.ToString();
+
+        public void SetRoaming(string key, object value)
+            => _roamingValues[key] = value?.ToString();
+
+        private static T TryGetValue<T>(Dictionary<string, string?> values, string key, T defaultValue)
+        {
+            if (!values.TryGetValue(key, out var stringValue) || string.IsNullOrWhiteSpace(stringValue))
+            {
+                return defaultValue;
+            }
+
+            if (typeof(T).IsEnum)
+            {
+                return (T)Enum.Parse(typeof(T), stringValue);
+            }
+
+            if ((typeof(T) == typeof(Guid) || typeof(T) == typeof(Guid?)) && Guid.TryParse(stringValue, out var guid))
+            {
+                return (T)(object)guid;
+            }
+
+            return (T)Convert.ChangeType(stringValue, typeof(T));
+        }
+    }
+
+    private sealed record LegacySchemaOptions(
+        bool IncludeCalDavColumns,
+        bool IncludeCalendarSupportMode,
+        bool IncludeTaskbarBadgeColumn,
+        bool IncludeFocusedInboxColumn)
+    {
+        public static LegacySchemaOptions Default => new(true, true, true, true);
+    }
+
+    private static async Task CreateLegacySchemaAsync(SQLiteAsyncConnection connection, LegacySchemaOptions options)
+    {
+        await connection.ExecuteAsync("""
+CREATE TABLE MailAccount (
+    Id TEXT PRIMARY KEY,
+    Address TEXT NULL,
+    Name TEXT NULL,
+    SenderName TEXT NULL,
+    ProviderType INTEGER NOT NULL,
+    SpecialImapProvider INTEGER NOT NULL DEFAULT 0,
+    [Order] INTEGER NOT NULL DEFAULT 0,
+    AccountColorHex TEXT NULL,
+    MergedInboxId TEXT NULL
+)
+""");
+
+        var preferenceColumns = new List<string>
+        {
+            "Id TEXT PRIMARY KEY",
+            "AccountId TEXT NOT NULL",
+            "IsNotificationsEnabled INTEGER NULL",
+            "ShouldAppendMessagesToSentFolder INTEGER NULL",
+            "SignatureIdForNewMessages TEXT NULL",
+            "SignatureIdForFollowingMessages TEXT NULL"
+        };
+
+        if (options.IncludeTaskbarBadgeColumn)
+            preferenceColumns.Add("IsTaskbarBadgeEnabled INTEGER NULL");
+
+        if (options.IncludeFocusedInboxColumn)
+            preferenceColumns.Add("IsFocusedInboxEnabled INTEGER NULL");
+
+        await connection.ExecuteAsync($"CREATE TABLE MailAccountPreferences ({string.Join(", ", preferenceColumns)})");
+
+        var serverColumns = new List<string>
+        {
+            "Id TEXT PRIMARY KEY",
+            "AccountId TEXT NOT NULL",
+            "Address TEXT NULL",
+            "IncomingServer TEXT NULL",
+            "IncomingServerPort TEXT NULL",
+            "IncomingServerUsername TEXT NULL",
+            "IncomingServerSocketOption INTEGER NULL",
+            "IncomingAuthenticationMethod INTEGER NULL",
+            "OutgoingServer TEXT NULL",
+            "OutgoingServerPort TEXT NULL",
+            "OutgoingServerUsername TEXT NULL",
+            "OutgoingServerSocketOption INTEGER NULL",
+            "OutgoingAuthenticationMethod INTEGER NULL",
+            "ProxyServer TEXT NULL",
+            "ProxyServerPort TEXT NULL",
+            "MaxConcurrentClients INTEGER NULL"
+        };
+
+        if (options.IncludeCalDavColumns)
+        {
+            serverColumns.Add("CalDavServiceUrl TEXT NULL");
+            serverColumns.Add("CalDavUsername TEXT NULL");
+        }
+
+        if (options.IncludeCalendarSupportMode)
+        {
+            serverColumns.Add("CalendarSupportMode INTEGER NULL");
+        }
+
+        await connection.ExecuteAsync($"CREATE TABLE CustomServerInformation ({string.Join(", ", serverColumns)})");
+        await connection.ExecuteAsync("""
+CREATE TABLE MergedInbox (
+    Id TEXT PRIMARY KEY,
+    Name TEXT NULL
+)
+""");
+    }
+
+    private static Task InsertRowAsync(SQLiteAsyncConnection connection, string tableName, params (string Column, object? Value)[] values)
+    {
+        var columns = string.Join(", ", values.Select(a => $"[{a.Column}]"));
+        var placeholders = string.Join(", ", values.Select(_ => "?"));
+        var arguments = values.Select(a => ConvertLegacyValue(a.Value)).ToArray();
+
+        return connection.ExecuteAsync($"INSERT INTO [{tableName}] ({columns}) VALUES ({placeholders})", arguments);
+    }
+
+    private static object? ConvertLegacyValue(object? value)
+    {
+        return value switch
+        {
+            null => null,
+            bool boolValue => boolValue ? 1 : 0,
+            Guid guidValue => guidValue.ToString(),
+            _ => value
+        };
+    }
+
+    private static AccountService CreateAccountService(InMemoryDatabaseService databaseService, IPreferencesService preferencesService)
+    {
+        var signatureService = new Mock<ISignatureService>();
+        signatureService
+            .Setup(a => a.CreateDefaultSignatureAsync(It.IsAny<Guid>()))
+            .ReturnsAsync((Guid accountId) => new AccountSignature
+            {
+                Id = Guid.NewGuid(),
+                MailAccountId = accountId,
+                Name = "Default",
+                HtmlBody = string.Empty
+            });
+
+        return new AccountService(
+            databaseService,
+            signatureService.Object,
+            Mock.Of<IAuthenticationProvider>(),
+            Mock.Of<IMimeFileService>(),
+            preferencesService,
+            Mock.Of<IContactPictureFileService>());
+    }
+}

Wino.Core.Tests/Synchronizers/GmailSynchronizerRequestSuccessTests.cs

@@ -19,6 +19,32 @@ namespace Wino.Core.Tests.Synchronizers;
 
 public sealed class GmailSynchronizerRequestSuccessTests
 {
+    [Fact]
+    public async Task UpdateAccountSyncIdentifierAsync_EmptyStoredIdentifier_PersistsFirstHistoryCursor()
+    {
+        var changeProcessor = new Mock<IGmailChangeProcessor>(MockBehavior.Strict);
+        changeProcessor
+            .Setup(x => x.UpdateAccountDeltaSynchronizationIdentifierAsync(It.IsAny<Guid>(), "123"))
+            .ReturnsAsync("123");
+
+        var synchronizer = CreateSynchronizer(changeProcessor.Object, synchronizationDeltaIdentifier: string.Empty);
+
+        await InvokeUpdateAccountSyncIdentifierAsync(synchronizer, 123);
+
+        changeProcessor.Verify(x => x.UpdateAccountDeltaSynchronizationIdentifierAsync(It.IsAny<Guid>(), "123"), Times.Once);
+    }
+
+    [Fact]
+    public async Task UpdateAccountSyncIdentifierAsync_OlderHistoryCursor_DoesNotRegressStoredCursor()
+    {
+        var changeProcessor = new Mock<IGmailChangeProcessor>(MockBehavior.Strict);
+        var synchronizer = CreateSynchronizer(changeProcessor.Object, synchronizationDeltaIdentifier: "456");
+
+        await InvokeUpdateAccountSyncIdentifierAsync(synchronizer, 123);
+
+        changeProcessor.Verify(x => x.UpdateAccountDeltaSynchronizationIdentifierAsync(It.IsAny<Guid>(), It.IsAny<string>()), Times.Never);
+    }
+
     [Fact]
     public async Task ProcessSingleNativeRequestResponseAsync_BatchMarkReadRequest_PersistsLocalReadStateForEachMail()
     {
@@ -209,13 +235,15 @@ public sealed class GmailSynchronizerRequestSuccessTests
 
     private static GmailSynchronizer CreateSynchronizer(
         IGmailChangeProcessor changeProcessor,
-        IGmailSynchronizerErrorHandlerFactory? errorFactory = null)
+        IGmailSynchronizerErrorHandlerFactory? errorFactory = null,
+        string? synchronizationDeltaIdentifier = null)
     {
         var account = new MailAccount
         {
             Id = Guid.NewGuid(),
             Name = "Gmail",
-            Address = "user@example.com"
+            Address = "user@example.com",
+            SynchronizationDeltaIdentifier = synchronizationDeltaIdentifier
         };
 
         var authenticator = new Mock<IGmailAuthenticator>(MockBehavior.Loose);
@@ -249,4 +277,17 @@ public sealed class GmailSynchronizerRequestSuccessTests
         task.Should().NotBeNull();
         await task!;
     }
+
+    private static async Task InvokeUpdateAccountSyncIdentifierAsync(GmailSynchronizer synchronizer, ulong historyId)
+    {
+        var method = typeof(GmailSynchronizer).GetMethod(
+            "UpdateAccountSyncIdentifierAsync",
+            BindingFlags.Instance | BindingFlags.NonPublic);
+
+        method.Should().NotBeNull();
+
+        var task = method!.Invoke(synchronizer, [historyId]) as Task;
+        task.Should().NotBeNull();
+        await task!;
+    }
 }

Wino.Core/Synchronizers/GmailSynchronizer.cs

@@ -1897,9 +1897,19 @@ public class GmailSynchronizer : WinoSynchronizer<IClientServiceRequest, Message
         if (historyId == null) return false;
 
         var newHistoryId = historyId.Value;
+        var currentSynchronizationIdentifier = Account.SynchronizationDeltaIdentifier;
 
-        return Account.SynchronizationDeltaIdentifier == null ||
+        if (string.IsNullOrWhiteSpace(currentSynchronizationIdentifier))
-            (ulong.TryParse(Account.SynchronizationDeltaIdentifier, out ulong currentIdentifier) && newHistoryId > currentIdentifier);
+            return true;
+
+        if (!ulong.TryParse(currentSynchronizationIdentifier, out ulong currentIdentifier))
+        {
+            _logger.Warning("Current Gmail history ID '{HistoryId}' is invalid for {Name}. Replacing it with {NewHistoryId}.",
+                currentSynchronizationIdentifier, Account.Name, newHistoryId);
+            return true;
+        }
+
+        return newHistoryId > currentIdentifier;
     }
 
     private async Task UpdateAccountSyncIdentifierAsync(ulong? historyId)

Wino.Mail.ViewModels/AccountManagementViewModel.cs

@@ -17,6 +17,7 @@ using Wino.Core.Domain.Entities.Shared;
 using Wino.Core.Domain.Enums;
 using Wino.Core.Domain.Exceptions;
 using Wino.Core.Domain.Interfaces;
+using Wino.Core.Domain.Models.Accounts;
 using Wino.Core.Domain.Models.Calendar;
 using Wino.Core.Domain.Models.Navigation;
 using Wino.Core.Domain.Models.Synchronization;
@@ -35,6 +36,7 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
     private static readonly UTF8Encoding Utf8WithoutBom = new(false);
 
     private readonly IWinoAccountDataSyncService _syncService;
+    private readonly ILegacyLocalMigrationService _legacyLocalMigrationService;
     private readonly IWinoLogger _winoLogger;
     private readonly ISpecialImapProviderConfigResolver _specialImapProviderConfigResolver;
     private readonly ICalDavClient _calDavClient;
@@ -48,6 +50,7 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
                                       IStoreManagementService storeManagementService,
                                       IWinoAccountProfileService winoAccountProfileService,
                                       IWinoAccountDataSyncService syncService,
+                                      ILegacyLocalMigrationService legacyLocalMigrationService,
                                       IWinoLogger winoLogger,
                                       ISpecialImapProviderConfigResolver specialImapProviderConfigResolver,
                                       ICalDavClient calDavClient,
@@ -56,6 +59,7 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
     {
         MailDialogService = dialogService;
         _syncService = syncService;
+        _legacyLocalMigrationService = legacyLocalMigrationService;
         _winoLogger = winoLogger;
         _specialImapProviderConfigResolver = specialImapProviderConfigResolver;
         _calDavClient = calDavClient;
@@ -64,8 +68,26 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
     [ObservableProperty]
     [NotifyCanExecuteChangedFor(nameof(ExportLocalDataCommand))]
     [NotifyCanExecuteChangedFor(nameof(ImportLocalDataCommand))]
+    [NotifyCanExecuteChangedFor(nameof(ImportLegacyDatabaseCommand))]
     public partial bool IsDataTransferInProgress { get; set; }
 
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(HasLegacyImportAvailable))]
+    [NotifyPropertyChangedFor(nameof(HasLegacyImportWarnings))]
+    [NotifyPropertyChangedFor(nameof(LegacyMigrationSummary))]
+    [NotifyPropertyChangedFor(nameof(LegacyMigrationWarningSummary))]
+    [NotifyCanExecuteChangedFor(nameof(ImportLegacyDatabaseCommand))]
+    public partial LegacyLocalMigrationPreview LegacyMigrationPreview { get; set; }
+
+    public bool HasLegacyImportAvailable => LegacyMigrationPreview?.HasImportableData == true;
+    public bool HasLegacyImportWarnings => !string.IsNullOrWhiteSpace(LegacyMigrationWarningSummary);
+    public string LegacyMigrationSummary => HasLegacyImportAvailable
+        ? LegacyLocalMigrationFormatter.BuildPreviewSummary(LegacyMigrationPreview)
+        : string.Empty;
+    public string LegacyMigrationWarningSummary => HasLegacyImportAvailable
+        ? LegacyLocalMigrationFormatter.BuildWarningSummary(LegacyMigrationPreview)
+        : string.Empty;
+
     [RelayCommand]
     private async Task CreateMergedAccountAsync()
     {
@@ -314,7 +336,42 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
         }
     }
 
+    [RelayCommand(CanExecute = nameof(CanImportLegacyDatabase))]
+    private async Task ImportLegacyDatabaseAsync()
+    {
+        try
+        {
+            await ExecuteUIThread(() => IsDataTransferInProgress = true);
+
+            var result = await _legacyLocalMigrationService.ImportAsync().ConfigureAwait(false);
+
+            await InitializeAccountsAsync().ConfigureAwait(false);
+            await RefreshLegacyMigrationPreviewAsync().ConfigureAwait(false);
+
+            var messageType = result.FailedAccountCount > 0
+                ? InfoBarMessageType.Warning
+                : InfoBarMessageType.Success;
+
+            DialogService.InfoBarMessage(
+                result.FailedAccountCount > 0 ? Translator.GeneralTitle_Warning : Translator.GeneralTitle_Info,
+                LegacyLocalMigrationFormatter.BuildImportMessage(result),
+                messageType);
+        }
+        catch (Exception ex)
+        {
+            DialogService.InfoBarMessage(
+                Translator.GeneralTitle_Error,
+                ex.Message,
+                InfoBarMessageType.Error);
+        }
+        finally
+        {
+            await ExecuteUIThread(() => IsDataTransferInProgress = false);
+        }
+    }
+
     private bool CanTransferLocalData() => !IsDataTransferInProgress;
+    private bool CanImportLegacyDatabase() => !IsDataTransferInProgress && HasLegacyImportAvailable;
 
     public override void OnNavigatedFrom(NavigationMode mode, object parameters)
     {
@@ -350,6 +407,7 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
         Accounts.CollectionChanged += AccountCollectionChanged;
 
         await InitializeAccountsAsync();
+        await RefreshLegacyMigrationPreviewAsync();
 
         PropertyChanged -= PagePropertyChanged;
         PropertyChanged += PagePropertyChanged;
@@ -403,6 +461,19 @@ public partial class AccountManagementViewModel : AccountManagementPageViewModel
         await ManageStorePurchasesAsync().ConfigureAwait(false);
     }
 
+    private async Task RefreshLegacyMigrationPreviewAsync()
+    {
+        try
+        {
+            var preview = await _legacyLocalMigrationService.DetectAsync().ConfigureAwait(false);
+            await ExecuteUIThread(() => LegacyMigrationPreview = preview);
+        }
+        catch (Exception)
+        {
+            await ExecuteUIThread(() => LegacyMigrationPreview = null);
+        }
+    }
+
     private static string BuildExportSuccessMessage(Wino.Core.Domain.Models.Accounts.WinoAccountSyncExportResult result)
     {
         var parts = new Collection<string>();

Wino.Mail.ViewModels/Data/LegacyLocalMigrationFormatter.cs

@@ -0,0 +1,106 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Wino.Core.Domain;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Models.Accounts;
+
+namespace Wino.Mail.ViewModels.Data;
+
+internal static class LegacyLocalMigrationFormatter
+{
+    public static string BuildPreviewSummary(LegacyLocalMigrationPreview preview)
+    {
+        if (!preview.HasImportableData)
+        {
+            return Translator.LegacyLocalMigration_ImportEmpty;
+        }
+
+        var providerSummary = string.Join(", ", preview.ProviderCounts
+            .Where(a => a.ImportableAccountCount > 0)
+            .Select(a => $"{a.ImportableAccountCount} {GetProviderName(a.ProviderType)}"));
+
+        var parts = new List<string>
+        {
+            string.Format(Translator.LegacyLocalMigration_PreviewSummary, preview.ImportableAccountCount, providerSummary)
+        };
+
+        if (preview.DuplicateAccountCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_PreviewDuplicateSummary, preview.DuplicateAccountCount));
+        }
+
+        if (preview.ImportableMergedInboxCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_PreviewMergedSummary, preview.ImportableMergedInboxCount));
+        }
+
+        return string.Join(" ", parts.Where(a => !string.IsNullOrWhiteSpace(a)));
+    }
+
+    public static string BuildWarningSummary(LegacyLocalMigrationPreview preview)
+        => string.Join(Environment.NewLine, preview.Warnings.Where(a => !string.IsNullOrWhiteSpace(a)).Distinct(StringComparer.Ordinal));
+
+    public static string BuildImportMessage(LegacyLocalMigrationResult result)
+    {
+        var parts = new List<string>();
+
+        if (result.ImportedAccountCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_ImportAccountsSucceeded, result.ImportedAccountCount));
+        }
+
+        if (result.SkippedDuplicateAccountCount > 0)
+        {
+            parts.Add(string.Format(Translator.WinoAccount_Management_ImportDuplicateAccountsSkipped, result.SkippedDuplicateAccountCount));
+        }
+
+        if (result.ImportedMergedInboxCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_ImportMergedInboxesSucceeded, result.ImportedMergedInboxCount));
+        }
+
+        if (result.SkippedMergedInboxCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_ImportMergedInboxesSkipped, result.SkippedMergedInboxCount));
+        }
+
+        if (result.FailedAccountCount > 0)
+        {
+            parts.Add(string.Format(Translator.LegacyLocalMigration_ImportFailedAccounts, result.FailedAccountCount));
+        }
+
+        if (parts.Count == 0)
+        {
+            parts.Add(Translator.LegacyLocalMigration_ImportEmpty);
+        }
+
+        if (result.ImportedAccountCount > 0)
+        {
+            parts.Add(Translator.WinoAccount_Management_ImportReloginReminder);
+        }
+
+        return string.Join(" ", parts);
+    }
+
+    public static string BuildPromptMessage(LegacyLocalMigrationPreview preview)
+    {
+        var summary = BuildPreviewSummary(preview);
+        var warnings = BuildWarningSummary(preview);
+
+        return string.IsNullOrWhiteSpace(warnings)
+            ? summary
+            : $"{summary}{Environment.NewLine}{Environment.NewLine}{warnings}";
+    }
+
+    private static string GetProviderName(MailProviderType providerType)
+    {
+        return providerType switch
+        {
+            MailProviderType.Outlook => Translator.LegacyLocalMigration_Provider_Outlook,
+            MailProviderType.Gmail => Translator.LegacyLocalMigration_Provider_Gmail,
+            MailProviderType.IMAP4 => Translator.LegacyLocalMigration_Provider_Imap,
+            _ => providerType.ToString()
+        };
+    }
+}

Wino.Mail.ViewModels/MailAppShellViewModel.cs

@@ -90,10 +90,12 @@ public partial class MailAppShellViewModel : MailBaseViewModel,
     private readonly IWebView2RuntimeValidatorService _webView2RuntimeValidatorService;
     private readonly IStoreUpdateService _storeUpdateService;
     private readonly IShareActivationService _shareActivationService;
+    private readonly ILegacyLocalMigrationService _legacyLocalMigrationService;
 
     private readonly INativeAppService _nativeAppService;
     private readonly IMailService _mailService;
     private bool _hasRegisteredPersistentRecipients;
+    private bool _hasHandledLegacyMigrationPrompt;
     private readonly SemaphoreSlim _menuRefreshSemaphore = new(1, 1);
 
     private readonly SemaphoreSlim accountInitFolderUpdateSlim = new SemaphoreSlim(1);
@@ -117,7 +119,8 @@ public partial class MailAppShellViewModel : MailBaseViewModel,
                              IStartupBehaviorService startupBehaviorService,
                              IWebView2RuntimeValidatorService webView2RuntimeValidatorService,
                              IStoreUpdateService storeUpdateService,
-                             IShareActivationService shareActivationService)
+                             IShareActivationService shareActivationService,
+                             ILegacyLocalMigrationService legacyLocalMigrationService)
     {
         StatePersistenceService = statePersistanceService;
 
@@ -141,6 +144,7 @@ public partial class MailAppShellViewModel : MailBaseViewModel,
         _webView2RuntimeValidatorService = webView2RuntimeValidatorService;
         _storeUpdateService = storeUpdateService;
         _shareActivationService = shareActivationService;
+        _legacyLocalMigrationService = legacyLocalMigrationService;
     }
 
     protected override void OnDispatcherAssigned()
@@ -286,6 +290,7 @@ public partial class MailAppShellViewModel : MailBaseViewModel,
         await ProcessLaunchOptionsAsync();
         await HandlePendingShareRequestAsync();
         await ValidateWebView2RuntimeAsync();
+        await PromptLegacyMigrationIfNeededAsync(shouldRunStartupFlows);
 
         if (shouldRunStartupFlows && !Debugger.IsAttached)
         {
@@ -298,6 +303,53 @@ public partial class MailAppShellViewModel : MailBaseViewModel,
         }
     }
 
+    private async Task PromptLegacyMigrationIfNeededAsync(bool shouldRunStartupFlows)
+    {
+        if (!shouldRunStartupFlows || _hasHandledLegacyMigrationPrompt)
+        {
+            return;
+        }
+
+        _hasHandledLegacyMigrationPrompt = true;
+
+        var currentAccounts = await _accountService.GetAccountsAsync().ConfigureAwait(false);
+        if (!currentAccounts.Any())
+        {
+            return;
+        }
+
+        var preview = await _legacyLocalMigrationService.DetectAsync().ConfigureAwait(false);
+        if (!preview.ShouldPrompt || !preview.HasImportableData)
+        {
+            return;
+        }
+
+        var shouldImport = await _dialogService.ShowConfirmationDialogAsync(
+            LegacyLocalMigrationFormatter.BuildPromptMessage(preview),
+            Translator.LegacyLocalMigration_PromptTitle,
+            Translator.LegacyLocalMigration_ImportAction);
+
+        if (!shouldImport)
+        {
+            _legacyLocalMigrationService.MarkPromptDeferred();
+            return;
+        }
+
+        var result = await _legacyLocalMigrationService.ImportAsync().ConfigureAwait(false);
+
+        await RecreateMenuItemsAsync().ConfigureAwait(false);
+        await RestoreSelectedAccountAfterMenuRefreshAsync(false).ConfigureAwait(false);
+
+        var messageType = result.FailedAccountCount > 0
+            ? InfoBarMessageType.Warning
+            : InfoBarMessageType.Success;
+
+        _dialogService.InfoBarMessage(
+            result.FailedAccountCount > 0 ? Translator.GeneralTitle_Warning : Translator.GeneralTitle_Info,
+            LegacyLocalMigrationFormatter.BuildImportMessage(result),
+            messageType);
+    }
+
     private async Task ValidateWebView2RuntimeAsync()
     {
         var isRuntimeAvailable = await _webView2RuntimeValidatorService.IsRuntimeAvailableAsync();

Wino.Mail.ViewModels/WelcomePageV2ViewModel.cs

@@ -24,6 +24,7 @@ public partial class WelcomePageV2ViewModel : MailBaseViewModel
     private readonly IUpdateManager _updateManager;
     private readonly IMailDialogService _dialogService;
     private readonly IWinoAccountDataSyncService _syncService;
+    private readonly ILegacyLocalMigrationService _legacyLocalMigrationService;
 
     [ObservableProperty]
     public partial List<UpdateNoteSection> UpdateSections { get; set; } = [];
@@ -32,21 +33,40 @@ public partial class WelcomePageV2ViewModel : MailBaseViewModel
     [NotifyCanExecuteChangedFor(nameof(GetStartedCommand))]
     [NotifyCanExecuteChangedFor(nameof(ImportFromWinoAccountCommand))]
     [NotifyCanExecuteChangedFor(nameof(ImportFromJsonCommand))]
+    [NotifyCanExecuteChangedFor(nameof(ImportLegacyDatabaseCommand))]
     public partial bool IsImportInProgress { get; set; }
 
     [ObservableProperty]
     [NotifyPropertyChangedFor(nameof(HasImportStatus))]
     public partial string ImportStatusMessage { get; set; } = string.Empty;
 
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(HasLegacyImportPreview))]
+    [NotifyPropertyChangedFor(nameof(HasLegacyImportWarnings))]
+    [NotifyPropertyChangedFor(nameof(LegacyImportSummary))]
+    [NotifyPropertyChangedFor(nameof(LegacyImportWarnings))]
+    [NotifyCanExecuteChangedFor(nameof(ImportLegacyDatabaseCommand))]
+    public partial LegacyLocalMigrationPreview LegacyMigrationPreview { get; set; }
+
     public bool HasImportStatus => !string.IsNullOrWhiteSpace(ImportStatusMessage);
+    public bool HasLegacyImportPreview => LegacyMigrationPreview?.HasImportableData == true;
+    public bool HasLegacyImportWarnings => !string.IsNullOrWhiteSpace(LegacyImportWarnings);
+    public string LegacyImportSummary => HasLegacyImportPreview
+        ? LegacyLocalMigrationFormatter.BuildPreviewSummary(LegacyMigrationPreview)
+        : string.Empty;
+    public string LegacyImportWarnings => HasLegacyImportPreview
+        ? LegacyLocalMigrationFormatter.BuildWarningSummary(LegacyMigrationPreview)
+        : string.Empty;
 
     public WelcomePageV2ViewModel(IUpdateManager updateManager,
                                   IMailDialogService dialogService,
-                                  IWinoAccountDataSyncService syncService)
+                                  IWinoAccountDataSyncService syncService,
+                                  ILegacyLocalMigrationService legacyLocalMigrationService)
     {
         _updateManager = updateManager;
         _dialogService = dialogService;
         _syncService = syncService;
+        _legacyLocalMigrationService = legacyLocalMigrationService;
     }
 
     public override async void OnNavigatedTo(NavigationMode mode, object parameters)
@@ -62,6 +82,15 @@ public partial class WelcomePageV2ViewModel : MailBaseViewModel
         {
             UpdateSections = [];
         }
+
+        try
+        {
+            LegacyMigrationPreview = await _legacyLocalMigrationService.DetectAsync();
+        }
+        catch (Exception)
+        {
+            LegacyMigrationPreview = null;
+        }
     }
 
     [RelayCommand(CanExecute = nameof(CanOpenWelcomeActions))]
@@ -150,7 +179,52 @@ public partial class WelcomePageV2ViewModel : MailBaseViewModel
         }
     }
 
+    [RelayCommand(CanExecute = nameof(CanImportLegacyDatabase))]
+    private async Task ImportLegacyDatabaseAsync()
+    {
+        await ExecuteUIThread(() => ImportStatusMessage = string.Empty);
+
+        try
+        {
+            await ExecuteUIThread(() => IsImportInProgress = true);
+
+            var result = await _legacyLocalMigrationService.ImportAsync().ConfigureAwait(false);
+            if (result.ImportedAccountCount > 0)
+            {
+                ReportUIChange(new WelcomeImportCompletedMessage(
+                    result.ImportedAccountCount,
+                    LegacyLocalMigrationFormatter.BuildImportMessage(result)));
+                return;
+            }
+
+            await ExecuteUIThread(() =>
+            {
+                ImportStatusMessage = LegacyLocalMigrationFormatter.BuildImportMessage(result);
+                LegacyMigrationPreview = result.Preview;
+            });
+        }
+        catch (Exception ex)
+        {
+            await _dialogService.ShowMessageAsync(ex.Message, Translator.GeneralTitle_Error, WinoCustomMessageDialogIcon.Error);
+        }
+        finally
+        {
+            try
+            {
+                var preview = await _legacyLocalMigrationService.DetectAsync().ConfigureAwait(false);
+                await ExecuteUIThread(() => LegacyMigrationPreview = preview);
+            }
+            catch (Exception)
+            {
+                // Keep the current preview if detection fails after import.
+            }
+
+            await ExecuteUIThread(() => IsImportInProgress = false);
+        }
+    }
+
     private bool CanOpenWelcomeActions() => !IsImportInProgress;
+    private bool CanImportLegacyDatabase() => !IsImportInProgress && HasLegacyImportPreview;
 
     private static string BuildInlineImportMessage(WinoAccountSyncImportResult result)
     {

Wino.Mail.WinUI/App.xaml.cs

@@ -479,8 +479,8 @@ public partial class App : WinoApplication,
 
             EnsureAppNotificationRegistration();
 
-            await Services.GetRequiredService<ReleaseLocalAccountDataCleanupService>()
+            await Services.GetRequiredService<ILegacyLocalMigrationService>()
-                .RunIfNeededAsync();
+                .DetectAsync();
 
             await InitializeServicesAsync();
 
@@ -490,6 +490,9 @@ public partial class App : WinoApplication,
 
             _hasConfiguredAccounts = (await _accountService.GetAccountsAsync()).Any();
 
+            await Services.GetRequiredService<ReleaseLocalAccountDataCleanupService>()
+                .RunIfNeededAsync();
+
             _activationInfrastructureInitialized = true;
         }
         finally
@@ -1502,7 +1505,9 @@ public partial class App : WinoApplication,
 
             Services.GetRequiredService<IMailDialogService>().InfoBarMessage(
                 Translator.GeneralTitle_Info,
-                Translator.WinoAccount_Management_ImportReloginReminder,
+                string.IsNullOrWhiteSpace(message.CompletionMessage)
+                    ? Translator.WinoAccount_Management_ImportReloginReminder
+                    : message.CompletionMessage,
                 InfoBarMessageType.Information);
         });
     }

Wino.Mail.WinUI/Services/ReleaseLocalAccountDataCleanupService.cs

@@ -10,7 +10,6 @@ namespace Wino.Mail.WinUI.Services;
 public sealed class ReleaseLocalAccountDataCleanupService
 {
     private const string CleanupCompletedSettingKey = "ReleaseLocalAccountDataCleanup_v1_Completed";
-    private const string LegacyDatabaseFileName = "Wino180.db";
 
     private readonly IConfigurationService _configurationService;
     private readonly IApplicationConfiguration _applicationConfiguration;
@@ -29,7 +28,6 @@ public sealed class ReleaseLocalAccountDataCleanupService
             return;
 
         var localFolderPath = _applicationConfiguration.ApplicationDataFolderPath;
-        var publisherPath = _applicationConfiguration.PublisherSharedFolderPath;
 
         if (string.IsNullOrWhiteSpace(localFolderPath) || !Directory.Exists(localFolderPath))
         {
@@ -41,8 +39,7 @@ public sealed class ReleaseLocalAccountDataCleanupService
         {
             Path.Combine(localFolderPath, "Mime"),
             Path.Combine(localFolderPath, "contacts"),
-            Path.Combine(localFolderPath, "CalendarAttachments"),
+            Path.Combine(localFolderPath, "CalendarAttachments")
-            Path.Combine(publisherPath, LegacyDatabaseFileName)
         };
 
         foreach (var targetPath in cleanupTargets)

Wino.Mail.WinUI/Views/Account/AccountManagementPage.xaml

@@ -221,6 +221,25 @@
                                 <SymbolIcon Symbol="Account" />
                             </winuiControls:SettingsCard.HeaderIcon>
                         </winuiControls:SettingsCard>
+                        <winuiControls:SettingsCard
+                            Description="{x:Bind ViewModel.LegacyMigrationSummary, Mode=OneWay}"
+                            Header="{x:Bind domain:Translator.LegacyLocalMigration_SettingsSectionTitle, Mode=OneTime}"
+                            Visibility="{x:Bind ViewModel.HasLegacyImportAvailable, Mode=OneWay}">
+                            <StackPanel Spacing="8">
+                                <TextBlock
+                                    Foreground="{ThemeResource TextFillColorSecondaryBrush}"
+                                    Style="{StaticResource CaptionTextBlockStyle}"
+                                    Text="{x:Bind ViewModel.LegacyMigrationWarningSummary, Mode=OneWay}"
+                                    TextWrapping="WrapWholeWords"
+                                    Visibility="{x:Bind ViewModel.HasLegacyImportWarnings, Mode=OneWay}" />
+                                <Button
+                                    Command="{x:Bind ViewModel.ImportLegacyDatabaseCommand}"
+                                    Content="{x:Bind domain:Translator.LegacyLocalMigration_ImportAction, Mode=OneTime}" />
+                            </StackPanel>
+                            <winuiControls:SettingsCard.HeaderIcon>
+                                <SymbolIcon Symbol="Sync" />
+                            </winuiControls:SettingsCard.HeaderIcon>
+                        </winuiControls:SettingsCard>
                         <winuiControls:SettingsCard Description="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionDescription}" Header="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionTitle}">
                             <StackPanel Orientation="Horizontal" Spacing="12">
                                 <Button Command="{x:Bind ViewModel.ImportLocalDataCommand}" Content="{x:Bind domain:Translator.WinoAccount_Management_LocalDataImportAction}" />

Wino.Mail.WinUI/Views/ManageAccountsPage.xaml

@@ -15,21 +15,43 @@
             MaxWidth="900"
             Padding="20"
             HorizontalAlignment="Stretch">
-            <winuiControls:SettingsCard
+            <StackPanel Spacing="12">
-                Description="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionDescription}"
+                <winuiControls:SettingsCard
-                Header="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionTitle}">
+                    Description="{x:Bind ViewModel.LegacyMigrationSummary, Mode=OneWay}"
-                <StackPanel Orientation="Horizontal" Spacing="12">
+                    Header="{x:Bind domain:Translator.LegacyLocalMigration_SettingsSectionTitle, Mode=OneTime}"
-                    <Button
+                    Visibility="{x:Bind ViewModel.HasLegacyImportAvailable, Mode=OneWay}">
-                        Command="{x:Bind ViewModel.ImportLocalDataCommand}"
+                    <StackPanel Spacing="8">
-                        Content="{x:Bind domain:Translator.WinoAccount_Management_LocalDataImportAction}" />
+                        <TextBlock
-                    <Button
+                            Foreground="{ThemeResource TextFillColorSecondaryBrush}"
-                        Command="{x:Bind ViewModel.ExportLocalDataCommand}"
+                            Style="{StaticResource CaptionTextBlockStyle}"
-                        Content="{x:Bind domain:Translator.WinoAccount_Management_LocalDataExportAction}" />
+                            Text="{x:Bind ViewModel.LegacyMigrationWarningSummary, Mode=OneWay}"
-                </StackPanel>
+                            TextWrapping="WrapWholeWords"
-                <winuiControls:SettingsCard.HeaderIcon>
+                            Visibility="{x:Bind ViewModel.HasLegacyImportWarnings, Mode=OneWay}" />
-                    <SymbolIcon Symbol="Sync" />
+                        <Button
-                </winuiControls:SettingsCard.HeaderIcon>
+                            Command="{x:Bind ViewModel.ImportLegacyDatabaseCommand}"
-            </winuiControls:SettingsCard>
+                            Content="{x:Bind domain:Translator.LegacyLocalMigration_ImportAction, Mode=OneTime}" />
+                    </StackPanel>
+                    <winuiControls:SettingsCard.HeaderIcon>
+                        <SymbolIcon Symbol="Sync" />
+                    </winuiControls:SettingsCard.HeaderIcon>
+                </winuiControls:SettingsCard>
+
+                <winuiControls:SettingsCard
+                    Description="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionDescription}"
+                    Header="{x:Bind domain:Translator.WinoAccount_Management_LocalDataSectionTitle}">
+                    <StackPanel Orientation="Horizontal" Spacing="12">
+                        <Button
+                            Command="{x:Bind ViewModel.ImportLocalDataCommand}"
+                            Content="{x:Bind domain:Translator.WinoAccount_Management_LocalDataImportAction}" />
+                        <Button
+                            Command="{x:Bind ViewModel.ExportLocalDataCommand}"
+                            Content="{x:Bind domain:Translator.WinoAccount_Management_LocalDataExportAction}" />
+                    </StackPanel>
+                    <winuiControls:SettingsCard.HeaderIcon>
+                        <SymbolIcon Symbol="Sync" />
+                    </winuiControls:SettingsCard.HeaderIcon>
+                </winuiControls:SettingsCard>
+            </StackPanel>
         </Grid>
     </Border>
 </abstract:ManageAccountsPageAbstract>

Wino.Mail.WinUI/Views/WelcomePageV2.xaml

@@ -127,6 +127,40 @@
                 Grid.Row="3"
                 MaxWidth="600"
                 HorizontalAlignment="Center">
+                <Border
+                    Margin="0,0,0,16"
+                    Padding="16"
+                    HorizontalAlignment="Stretch"
+                    Background="{ThemeResource CardBackgroundFillColorSecondaryBrush}"
+                    BorderBrush="{ThemeResource CardStrokeColorDefaultBrush}"
+                    BorderThickness="1"
+                    CornerRadius="12"
+                    Visibility="{x:Bind ViewModel.HasLegacyImportPreview, Mode=OneWay}">
+                    <StackPanel Spacing="8">
+                        <TextBlock
+                            HorizontalAlignment="Center"
+                            FontSize="16"
+                            FontWeight="SemiBold"
+                            Text="{x:Bind domain:Translator.LegacyLocalMigration_WelcomeSectionTitle, Mode=OneTime}" />
+                        <TextBlock
+                            Foreground="{ThemeResource TextFillColorSecondaryBrush}"
+                            Text="{x:Bind domain:Translator.LegacyLocalMigration_WelcomeSectionDescription, Mode=OneTime}"
+                            TextWrapping="WrapWholeWords" />
+                        <TextBlock Text="{x:Bind ViewModel.LegacyImportSummary, Mode=OneWay}" TextWrapping="WrapWholeWords" />
+                        <TextBlock
+                            Foreground="{ThemeResource TextFillColorSecondaryBrush}"
+                            Style="{StaticResource CaptionTextBlockStyle}"
+                            Text="{x:Bind ViewModel.LegacyImportWarnings, Mode=OneWay}"
+                            TextWrapping="WrapWholeWords"
+                            Visibility="{x:Bind ViewModel.HasLegacyImportWarnings, Mode=OneWay}" />
+                        <Button
+                            HorizontalAlignment="Center"
+                            Command="{x:Bind ViewModel.ImportLegacyDatabaseCommand}"
+                            Content="{x:Bind domain:Translator.LegacyLocalMigration_ImportAction, Mode=OneTime}"
+                            Style="{ThemeResource AccentButtonStyle}" />
+                    </StackPanel>
+                </Border>
+
                 <HyperlinkButton
                     HorizontalAlignment="Center"
                     Command="{x:Bind ViewModel.ImportFromWinoAccountCommand}"

Wino.Messages/UI/WelcomeImportCompletedMessage.cs

@@ -1,3 +1,3 @@
 namespace Wino.Messaging.UI;
 
-public record WelcomeImportCompletedMessage(int ImportedMailboxCount) : UIMessageBase<WelcomeImportCompletedMessage>;
+public record WelcomeImportCompletedMessage(int ImportedMailboxCount, string CompletionMessage = "") : UIMessageBase<WelcomeImportCompletedMessage>;

Wino.Services/LegacyLocalMigrationService.cs

@@ -0,0 +1,881 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
+using System.IO;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using CommunityToolkit.Mvvm.Messaging;
+using Serilog;
+using SQLite;
+using Wino.Core.Domain;
+using Wino.Core.Domain.Entities.Mail;
+using Wino.Core.Domain.Entities.Shared;
+using Wino.Core.Domain.Enums;
+using Wino.Core.Domain.Interfaces;
+using Wino.Core.Domain.Models.Accounts;
+using Wino.Messaging.Client.Accounts;
+
+namespace Wino.Services;
+
+public sealed class LegacyLocalMigrationService : ILegacyLocalMigrationService
+{
+    private const string LegacyDatabaseFileName = "Wino180.db";
+    private const string MigrationCompletedSettingKey = "LegacyLocalMigration_v2_Completed";
+    private const string PromptDeferredSettingKey = "LegacyLocalMigration_v2_PromptDeferred";
+    private const int DefaultMaxConcurrentClients = 5;
+
+    private readonly IApplicationConfiguration _applicationConfiguration;
+    private readonly IConfigurationService _configurationService;
+    private readonly IDatabaseService _databaseService;
+    private readonly IAccountService _accountService;
+    private readonly ISpecialImapProviderConfigResolver _specialImapProviderConfigResolver;
+    private readonly ILogger _logger = Log.ForContext<LegacyLocalMigrationService>();
+
+    public LegacyLocalMigrationService(IApplicationConfiguration applicationConfiguration,
+                                       IConfigurationService configurationService,
+                                       IDatabaseService databaseService,
+                                       IAccountService accountService,
+                                       ISpecialImapProviderConfigResolver specialImapProviderConfigResolver)
+    {
+        _applicationConfiguration = applicationConfiguration;
+        _configurationService = configurationService;
+        _databaseService = databaseService;
+        _accountService = accountService;
+        _specialImapProviderConfigResolver = specialImapProviderConfigResolver;
+    }
+
+    public void MarkPromptDeferred()
+        => _configurationService.Set(PromptDeferredSettingKey, true);
+
+    public async Task<LegacyLocalMigrationPreview> DetectAsync(CancellationToken cancellationToken = default)
+    {
+        var (_, preview) = await LoadPreviewContextAsync(cancellationToken).ConfigureAwait(false);
+        return preview;
+    }
+
+    public async Task<LegacyLocalMigrationResult> ImportAsync(CancellationToken cancellationToken = default)
+    {
+        var (snapshot, preview) = await LoadPreviewContextAsync(cancellationToken).ConfigureAwait(false);
+        if (snapshot == null || !preview.LegacyDatabaseExists)
+        {
+            return new LegacyLocalMigrationResult
+            {
+                Preview = preview,
+                Warnings = preview.Warnings
+            };
+        }
+
+        _configurationService.Set(PromptDeferredSettingKey, false);
+
+        var failures = new List<LegacyLocalMigrationFailure>();
+        var importedAccounts = new Dictionary<Guid, MailAccount>();
+        var skippedDuplicateAccountCount = preview.Accounts.Count(a => a.IsDuplicate);
+        var importedAccountCount = 0;
+        var currentAccounts = await _accountService.GetAccountsAsync().ConfigureAwait(false);
+        var nextOrder = currentAccounts.Count;
+
+        foreach (var previewAccount in preview.Accounts
+                     .OrderBy(a => a.Order)
+                     .ThenBy(a => a.Address, StringComparer.OrdinalIgnoreCase))
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            if (!previewAccount.CanImport ||
+                !snapshot.AccountsById.TryGetValue(previewAccount.LegacyAccountId, out var legacyAccount))
+            {
+                continue;
+            }
+
+            try
+            {
+                var importedAccount = CreateImportedAccount(legacyAccount, nextOrder);
+                var serverInformation = CreateImportedServerInformation(legacyAccount, importedAccount);
+
+                await _accountService.CreateAccountAsync(importedAccount, serverInformation).ConfigureAwait(false);
+                await _accountService.CreateRootAliasAsync(importedAccount.Id, importedAccount.Address).ConfigureAwait(false);
+
+                ApplyLegacyPreferences(importedAccount, legacyAccount.Preferences);
+                importedAccount.Order = nextOrder;
+
+                await _accountService.UpdateAccountAsync(importedAccount).ConfigureAwait(false);
+
+                importedAccounts[legacyAccount.LegacyAccountId] = importedAccount;
+                importedAccountCount++;
+                nextOrder++;
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning(ex, "Failed to import legacy account {LegacyAccountId} ({Address})", legacyAccount.LegacyAccountId, legacyAccount.Address);
+
+                failures.Add(new LegacyLocalMigrationFailure
+                {
+                    Address = legacyAccount.Address,
+                    ProviderType = legacyAccount.ProviderType,
+                    Message = ex.Message
+                });
+            }
+        }
+
+        var (importedMergedInboxCount, skippedMergedInboxCount) = await ImportMergedInboxesAsync(snapshot, importedAccounts).ConfigureAwait(false);
+
+        if (importedAccountCount > 0 || importedMergedInboxCount > 0)
+        {
+            WeakReferenceMessenger.Default.Send(new AccountsMenuRefreshRequested(false));
+        }
+
+        _configurationService.Set(MigrationCompletedSettingKey, failures.Count == 0);
+
+        return new LegacyLocalMigrationResult
+        {
+            Preview = preview,
+            ImportedAccountCount = importedAccountCount,
+            SkippedDuplicateAccountCount = skippedDuplicateAccountCount,
+            FailedAccountCount = failures.Count,
+            ImportedMergedInboxCount = importedMergedInboxCount,
+            SkippedMergedInboxCount = skippedMergedInboxCount,
+            Failures = failures,
+            Warnings = preview.Warnings
+        };
+    }
+
+    private async Task<(LegacySnapshot? Snapshot, LegacyLocalMigrationPreview Preview)> LoadPreviewContextAsync(CancellationToken cancellationToken)
+    {
+        var legacyDatabasePath = GetLegacyDatabasePath();
+        if (string.IsNullOrWhiteSpace(legacyDatabasePath) || !File.Exists(legacyDatabasePath))
+        {
+            return (null, CreateEmptyPreview(legacyDatabasePath));
+        }
+
+        SQLiteAsyncConnection? connection = null;
+
+        try
+        {
+            connection = new SQLiteAsyncConnection(
+                legacyDatabasePath,
+                SQLiteOpenFlags.ReadOnly | SQLiteOpenFlags.SharedCache,
+                storeDateTimeAsTicks: false);
+
+            var snapshot = await LoadSnapshotAsync(connection, cancellationToken).ConfigureAwait(false);
+            var existingAddressKeys = await TryGetExistingAddressKeysAsync().ConfigureAwait(false);
+
+            return (snapshot, BuildPreview(legacyDatabasePath, snapshot, existingAddressKeys));
+        }
+        catch (Exception ex)
+        {
+            _logger.Warning(ex, "Failed to inspect legacy database at {LegacyDatabasePath}", legacyDatabasePath);
+
+            return (null, CreateUnreadablePreview(legacyDatabasePath));
+        }
+        finally
+        {
+            if (connection != null)
+            {
+                await connection.CloseAsync().ConfigureAwait(false);
+            }
+        }
+    }
+
+    private async Task<LegacySnapshot> LoadSnapshotAsync(SQLiteAsyncConnection connection, CancellationToken cancellationToken)
+    {
+        var snapshot = new LegacySnapshot();
+
+        var accountColumns = await GetColumnSetAsync(connection, nameof(MailAccount)).ConfigureAwait(false);
+        if (accountColumns.Count == 0)
+        {
+            return snapshot;
+        }
+
+        var accountRows = await connection.QueryAsync<LegacyMailAccountRow>(BuildMailAccountQuery(accountColumns)).ConfigureAwait(false);
+        snapshot.TotalLegacyAccountCount = accountRows.Count;
+
+        var preferenceRows = await QueryRowsIfTableExistsAsync<LegacyMailAccountPreferencesRow>(
+            connection,
+            nameof(MailAccountPreferences),
+            BuildMailAccountPreferencesQuery).ConfigureAwait(false);
+
+        var serverRows = await QueryRowsIfTableExistsAsync<LegacyCustomServerInformationRow>(
+            connection,
+            nameof(CustomServerInformation),
+            BuildCustomServerInformationQuery).ConfigureAwait(false);
+
+        var mergedInboxRows = await QueryRowsIfTableExistsAsync<LegacyMergedInboxRow>(
+            connection,
+            nameof(MergedInbox),
+            BuildMergedInboxQuery).ConfigureAwait(false);
+
+        snapshot.MergedInboxNamesById = mergedInboxRows
+            .Where(a => a.Id != Guid.Empty && !string.IsNullOrWhiteSpace(a.Name))
+            .GroupBy(a => a.Id)
+            .ToDictionary(a => a.Key, a => NormalizeOptionalText(a.First().Name), EqualityComparer<Guid>.Default);
+
+        var preferencesByAccountId = preferenceRows
+            .Where(a => a.AccountId != Guid.Empty)
+            .GroupBy(a => a.AccountId)
+            .ToDictionary(a => a.Key, a => a.First(), EqualityComparer<Guid>.Default);
+
+        var serverByAccountId = serverRows
+            .Where(a => a.AccountId != Guid.Empty)
+            .GroupBy(a => a.AccountId)
+            .ToDictionary(a => a.Key, a => a.First(), EqualityComparer<Guid>.Default);
+
+        foreach (var row in accountRows)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            if (row.Id == Guid.Empty ||
+                !TryMapProviderType(row.ProviderType, out var providerType))
+            {
+                snapshot.InvalidAccountCount++;
+                continue;
+            }
+
+            var normalizedAddress = NormalizeOptionalText(row.Address);
+            if (string.IsNullOrWhiteSpace(normalizedAddress))
+            {
+                snapshot.InvalidAccountCount++;
+                continue;
+            }
+
+            preferencesByAccountId.TryGetValue(row.Id, out var preferences);
+            serverByAccountId.TryGetValue(row.Id, out var serverInformation);
+
+            var candidate = new LegacyAccountCandidate
+            {
+                LegacyAccountId = row.Id,
+                Address = normalizedAddress,
+                Name = NormalizeDisplayName(row.Name, normalizedAddress),
+                SenderName = NormalizeDisplayName(row.SenderName, NormalizeDisplayName(row.Name, normalizedAddress)),
+                ProviderType = providerType,
+                SpecialImapProvider = MapSpecialImapProvider(row.SpecialImapProvider),
+                Order = Math.Max(0, row.Order ?? 0),
+                AccountColorHex = NormalizeOptionalText(row.AccountColorHex),
+                LegacyMergedInboxId = row.MergedInboxId,
+                Preferences = preferences,
+                ServerInformation = serverInformation
+            };
+
+            snapshot.Accounts.Add(candidate);
+            snapshot.AccountsById[candidate.LegacyAccountId] = candidate;
+        }
+
+        snapshot.Accounts = snapshot.Accounts
+            .OrderBy(a => a.Order)
+            .ThenBy(a => a.Address, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+
+        return snapshot;
+    }
+
+    private async Task<List<T>> QueryRowsIfTableExistsAsync<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.All)] T>(
+        SQLiteAsyncConnection connection,
+        string tableName,
+        Func<HashSet<string>, string> sqlFactory) where T : new()
+    {
+        var columns = await GetColumnSetAsync(connection, tableName).ConfigureAwait(false);
+        if (columns.Count == 0)
+        {
+            return [];
+        }
+
+        return await connection.QueryAsync<T>(sqlFactory(columns)).ConfigureAwait(false);
+    }
+
+    private async Task<HashSet<string>> GetColumnSetAsync(SQLiteAsyncConnection connection, string tableName)
+    {
+        var tableInfo = await connection.GetTableInfoAsync(tableName).ConfigureAwait(false);
+        return tableInfo
+            .Select(a => a.Name)
+            .Where(a => !string.IsNullOrWhiteSpace(a))
+            .ToHashSet(StringComparer.OrdinalIgnoreCase);
+    }
+
+    private async Task<HashSet<string>> TryGetExistingAddressKeysAsync()
+    {
+        if (_databaseService.Connection == null)
+        {
+            return [];
+        }
+
+        try
+        {
+            var accounts = await _accountService.GetAccountsAsync().ConfigureAwait(false);
+            return accounts
+                .Select(a => CreateAddressKey(a.Address))
+                .Where(a => !string.IsNullOrWhiteSpace(a))
+                .ToHashSet(StringComparer.Ordinal);
+        }
+        catch (Exception ex)
+        {
+            _logger.Debug(ex, "Skipping duplicate detection against the current database because account data is not available yet.");
+            return [];
+        }
+    }
+
+    private LegacyLocalMigrationPreview BuildPreview(string legacyDatabasePath, LegacySnapshot snapshot, HashSet<string> existingAddressKeys)
+    {
+        var seenAddressKeys = new HashSet<string>(existingAddressKeys, StringComparer.Ordinal);
+        var accountPreviewItems = new List<LegacyLocalMigrationAccountPreview>();
+
+        foreach (var account in snapshot.Accounts)
+        {
+            var addressKey = CreateAddressKey(account.Address);
+            var isDuplicate = !seenAddressKeys.Add(addressKey);
+            var isCalendarEnabled = account.ProviderType switch
+            {
+                MailProviderType.Outlook or MailProviderType.Gmail => true,
+                MailProviderType.IMAP4 => ResolveCalendarSupportMode(account) != ImapCalendarSupportMode.Disabled,
+                _ => false
+            };
+
+            accountPreviewItems.Add(new LegacyLocalMigrationAccountPreview
+            {
+                LegacyAccountId = account.LegacyAccountId,
+                Address = account.Address,
+                DisplayName = account.Name,
+                ProviderType = account.ProviderType,
+                SpecialImapProvider = account.SpecialImapProvider,
+                Order = account.Order,
+                CanImport = !isDuplicate,
+                IsDuplicate = isDuplicate,
+                IsCalendarEnabled = isCalendarEnabled
+            });
+        }
+
+        var importableMergedInboxCount = 0;
+        var skippedMergedInboxCount = 0;
+
+        foreach (var group in accountPreviewItems
+                     .Where(a => snapshot.AccountsById[a.LegacyAccountId].LegacyMergedInboxId.HasValue)
+                     .GroupBy(a => snapshot.AccountsById[a.LegacyAccountId].LegacyMergedInboxId!.Value))
+        {
+            var members = group.ToList();
+            var hasReadableMergedInbox = snapshot.MergedInboxNamesById.TryGetValue(group.Key, out var mergedInboxName) &&
+                                         !string.IsNullOrWhiteSpace(mergedInboxName);
+
+            if (members.Count >= 2 && hasReadableMergedInbox && members.All(a => a.CanImport))
+            {
+                importableMergedInboxCount++;
+            }
+            else
+            {
+                skippedMergedInboxCount++;
+            }
+        }
+
+        var providerCounts = accountPreviewItems
+            .GroupBy(a => a.ProviderType)
+            .OrderBy(a => a.Key)
+            .Select(group => new LegacyLocalMigrationProviderCount
+            {
+                ProviderType = group.Key,
+                TotalAccountCount = group.Count(),
+                ImportableAccountCount = group.Count(a => a.CanImport),
+                DuplicateAccountCount = group.Count(a => a.IsDuplicate)
+            })
+            .ToList();
+
+        var hasCompletedMigration = _configurationService.Get(MigrationCompletedSettingKey, false);
+        var isPromptDeferred = _configurationService.Get(PromptDeferredSettingKey, false);
+        var importableAccountCount = accountPreviewItems.Count(a => a.CanImport);
+        var warnings = BuildWarnings(snapshot, accountPreviewItems, skippedMergedInboxCount);
+
+        return new LegacyLocalMigrationPreview
+        {
+            SourceDatabasePath = legacyDatabasePath,
+            LegacyDatabaseExists = true,
+            HasCompletedMigration = hasCompletedMigration,
+            IsPromptDeferred = isPromptDeferred,
+            ShouldPrompt = importableAccountCount > 0 && !hasCompletedMigration && !isPromptDeferred,
+            LegacyAccountCount = snapshot.TotalLegacyAccountCount,
+            ImportableAccountCount = importableAccountCount,
+            DuplicateAccountCount = accountPreviewItems.Count(a => a.IsDuplicate),
+            SkippedAccountCount = snapshot.InvalidAccountCount,
+            ImportableMergedInboxCount = importableMergedInboxCount,
+            SkippedMergedInboxCount = skippedMergedInboxCount,
+            ProviderCounts = providerCounts,
+            Accounts = accountPreviewItems,
+            Warnings = warnings
+        };
+    }
+
+    private static IReadOnlyList<string> BuildWarnings(LegacySnapshot snapshot,
+                                                       IReadOnlyCollection<LegacyLocalMigrationAccountPreview> accountPreviewItems,
+                                                       int skippedMergedInboxCount)
+    {
+        var warnings = new List<string>();
+
+        if (accountPreviewItems.Any(a => a.CanImport && (a.ProviderType == MailProviderType.Outlook || a.ProviderType == MailProviderType.Gmail)))
+        {
+            warnings.Add(Translator.LegacyLocalMigration_Warning_OAuth);
+        }
+
+        if (accountPreviewItems.Any(a => a.CanImport && a.ProviderType == MailProviderType.IMAP4))
+        {
+            warnings.Add(Translator.LegacyLocalMigration_Warning_Imap);
+        }
+
+        if (accountPreviewItems.Any(a => snapshot.AccountsById[a.LegacyAccountId].LegacyMergedInboxId.HasValue))
+        {
+            warnings.Add(Translator.LegacyLocalMigration_Warning_Merged);
+        }
+
+        if (snapshot.InvalidAccountCount > 0)
+        {
+            warnings.Add(string.Format(Translator.LegacyLocalMigration_Warning_SkippedAccounts, snapshot.InvalidAccountCount));
+        }
+
+        if (skippedMergedInboxCount > 0)
+        {
+            warnings.Add(string.Format(Translator.LegacyLocalMigration_ImportMergedInboxesSkipped, skippedMergedInboxCount));
+        }
+
+        return warnings;
+    }
+
+    private MailAccount CreateImportedAccount(LegacyAccountCandidate account, int order)
+    {
+        var isCalendarAccessGranted = account.ProviderType switch
+        {
+            MailProviderType.Outlook or MailProviderType.Gmail => true,
+            MailProviderType.IMAP4 => ResolveCalendarSupportMode(account) != ImapCalendarSupportMode.Disabled,
+            _ => false
+        };
+
+        return new MailAccount
+        {
+            Id = Guid.NewGuid(),
+            Address = account.Address,
+            Name = NormalizeDisplayName(account.Name, account.Address),
+            SenderName = NormalizeDisplayName(account.SenderName, NormalizeDisplayName(account.Name, account.Address)),
+            ProviderType = account.ProviderType,
+            SpecialImapProvider = account.SpecialImapProvider,
+            SynchronizationDeltaIdentifier = string.Empty,
+            CalendarSynchronizationDeltaIdentifier = string.Empty,
+            AccountColorHex = account.AccountColorHex,
+            Base64ProfilePictureData = string.Empty,
+            Order = order,
+            AttentionReason = AccountAttentionReason.InvalidCredentials,
+            IsMailAccessGranted = true,
+            IsCalendarAccessGranted = isCalendarAccessGranted,
+            CreatedAt = DateTime.UtcNow,
+            InitialSynchronizationRange = InitialSynchronizationRange.SixMonths
+        };
+    }
+
+    private CustomServerInformation? CreateImportedServerInformation(LegacyAccountCandidate account, MailAccount importedAccount)
+    {
+        if (account.ProviderType != MailProviderType.IMAP4)
+        {
+            return null;
+        }
+
+        var legacyServer = account.ServerInformation;
+        var fallbackServer = GetSpecialProviderFallback(account);
+
+        return new CustomServerInformation
+        {
+            Id = Guid.NewGuid(),
+            AccountId = importedAccount.Id,
+            Address = importedAccount.Address,
+            IncomingServer = FirstNonEmpty(legacyServer?.IncomingServer, fallbackServer?.IncomingServer),
+            IncomingServerUsername = FirstNonEmpty(legacyServer?.IncomingServerUsername, fallbackServer?.IncomingServerUsername),
+            IncomingServerPassword = string.Empty,
+            IncomingServerPort = FirstNonEmpty(legacyServer?.IncomingServerPort, fallbackServer?.IncomingServerPort),
+            IncomingServerType = CustomIncomingServerType.IMAP4,
+            OutgoingServer = FirstNonEmpty(legacyServer?.OutgoingServer, fallbackServer?.OutgoingServer),
+            OutgoingServerPort = FirstNonEmpty(legacyServer?.OutgoingServerPort, fallbackServer?.OutgoingServerPort),
+            OutgoingServerUsername = FirstNonEmpty(legacyServer?.OutgoingServerUsername, fallbackServer?.OutgoingServerUsername),
+            OutgoingServerPassword = string.Empty,
+            CalDavServiceUrl = FirstNonEmpty(legacyServer?.CalDavServiceUrl, fallbackServer?.CalDavServiceUrl),
+            CalDavUsername = FirstNonEmpty(legacyServer?.CalDavUsername, fallbackServer?.CalDavUsername),
+            CalDavPassword = string.Empty,
+            CalendarSupportMode = ResolveCalendarSupportMode(account),
+            IncomingServerSocketOption = MapConnectionSecurity(legacyServer?.IncomingServerSocketOption, fallbackServer?.IncomingServerSocketOption),
+            IncomingAuthenticationMethod = MapAuthenticationMethod(legacyServer?.IncomingAuthenticationMethod, fallbackServer?.IncomingAuthenticationMethod),
+            OutgoingServerSocketOption = MapConnectionSecurity(legacyServer?.OutgoingServerSocketOption, fallbackServer?.OutgoingServerSocketOption),
+            OutgoingAuthenticationMethod = MapAuthenticationMethod(legacyServer?.OutgoingAuthenticationMethod, fallbackServer?.OutgoingAuthenticationMethod),
+            ProxyServer = NormalizeOptionalText(legacyServer?.ProxyServer),
+            ProxyServerPort = NormalizeOptionalText(legacyServer?.ProxyServerPort),
+            MaxConcurrentClients = legacyServer?.MaxConcurrentClients is int maxConcurrentClients && maxConcurrentClients > 0
+                ? maxConcurrentClients
+                : fallbackServer?.MaxConcurrentClients > 0
+                    ? fallbackServer.MaxConcurrentClients
+                    : DefaultMaxConcurrentClients
+        };
+    }
+
+    private static void ApplyLegacyPreferences(MailAccount account, LegacyMailAccountPreferencesRow? legacyPreferences)
+    {
+        if (account.Preferences == null || legacyPreferences == null)
+        {
+            return;
+        }
+
+        if (legacyPreferences.IsNotificationsEnabled.HasValue)
+        {
+            account.Preferences.IsNotificationsEnabled = legacyPreferences.IsNotificationsEnabled.Value;
+        }
+
+        if (legacyPreferences.IsTaskbarBadgeEnabled.HasValue)
+        {
+            account.Preferences.IsTaskbarBadgeEnabled = legacyPreferences.IsTaskbarBadgeEnabled.Value;
+        }
+
+        if (legacyPreferences.ShouldAppendMessagesToSentFolder.HasValue)
+        {
+            account.Preferences.ShouldAppendMessagesToSentFolder = legacyPreferences.ShouldAppendMessagesToSentFolder.Value;
+        }
+
+        if (account.ProviderType == MailProviderType.Outlook && legacyPreferences.IsFocusedInboxEnabled.HasValue)
+        {
+            account.Preferences.IsFocusedInboxEnabled = legacyPreferences.IsFocusedInboxEnabled.Value;
+        }
+    }
+
+    private async Task<(int ImportedCount, int SkippedCount)> ImportMergedInboxesAsync(LegacySnapshot snapshot, IReadOnlyDictionary<Guid, MailAccount> importedAccounts)
+    {
+        var importedCount = 0;
+        var skippedCount = 0;
+
+        foreach (var group in snapshot.Accounts
+                     .Where(a => a.LegacyMergedInboxId.HasValue)
+                     .GroupBy(a => a.LegacyMergedInboxId!.Value))
+        {
+            var members = group.ToList();
+            if (members.Count < 2 ||
+                !snapshot.MergedInboxNamesById.TryGetValue(group.Key, out var mergedInboxName) ||
+                string.IsNullOrWhiteSpace(mergedInboxName))
+            {
+                skippedCount++;
+                continue;
+            }
+
+            var importedMembers = members
+                .Where(a => importedAccounts.ContainsKey(a.LegacyAccountId))
+                .Select(a => importedAccounts[a.LegacyAccountId])
+                .ToList();
+
+            if (importedMembers.Count != members.Count)
+            {
+                skippedCount++;
+                continue;
+            }
+
+            try
+            {
+                await _accountService.CreateMergeAccountsAsync(
+                    new MergedInbox { Name = mergedInboxName },
+                    importedMembers).ConfigureAwait(false);
+
+                importedCount++;
+            }
+            catch (Exception ex)
+            {
+                _logger.Warning(ex, "Failed to import legacy merged inbox {LegacyMergedInboxId}", group.Key);
+                skippedCount++;
+            }
+        }
+
+        return (importedCount, skippedCount);
+    }
+
+    private CustomServerInformation? GetSpecialProviderFallback(LegacyAccountCandidate account)
+    {
+        if (account.SpecialImapProvider == SpecialImapProvider.None)
+        {
+            return null;
+        }
+
+        return _specialImapProviderConfigResolver.GetServerInformation(
+            new MailAccount
+            {
+                Address = account.Address,
+                SenderName = account.SenderName,
+                ProviderType = MailProviderType.IMAP4,
+                SpecialImapProvider = account.SpecialImapProvider
+            },
+            new AccountCreationDialogResult(
+                MailProviderType.IMAP4,
+                account.Name,
+                new SpecialImapProviderDetails(
+                    account.Address,
+                    string.Empty,
+                    account.SenderName,
+                    account.SpecialImapProvider,
+                    ImapCalendarSupportMode.CalDav),
+                account.AccountColorHex,
+                InitialSynchronizationRange.SixMonths,
+                true,
+                true));
+    }
+
+    private static ImapCalendarSupportMode ResolveCalendarSupportMode(LegacyAccountCandidate account)
+    {
+        var rawValue = account.ServerInformation?.CalendarSupportMode;
+
+        return rawValue is int intValue && Enum.IsDefined(typeof(ImapCalendarSupportMode), intValue)
+            ? (ImapCalendarSupportMode)intValue
+            : ImapCalendarSupportMode.Disabled;
+    }
+
+    private static ImapConnectionSecurity MapConnectionSecurity(int? rawValue, ImapConnectionSecurity? fallbackValue)
+    {
+        if (rawValue.HasValue && Enum.IsDefined(typeof(ImapConnectionSecurity), rawValue.Value))
+        {
+            return (ImapConnectionSecurity)rawValue.Value;
+        }
+
+        return fallbackValue ?? ImapConnectionSecurity.Auto;
+    }
+
+    private static ImapAuthenticationMethod MapAuthenticationMethod(int? rawValue, ImapAuthenticationMethod? fallbackValue)
+    {
+        if (rawValue.HasValue && Enum.IsDefined(typeof(ImapAuthenticationMethod), rawValue.Value))
+        {
+            return (ImapAuthenticationMethod)rawValue.Value;
+        }
+
+        return fallbackValue ?? ImapAuthenticationMethod.Auto;
+    }
+
+    private static bool TryMapProviderType(int? rawValue, out MailProviderType providerType)
+    {
+        providerType = default;
+
+        if (!rawValue.HasValue ||
+            !Enum.IsDefined(typeof(MailProviderType), rawValue.Value))
+        {
+            return false;
+        }
+
+        providerType = (MailProviderType)rawValue.Value;
+
+        return providerType is MailProviderType.Outlook or MailProviderType.Gmail or MailProviderType.IMAP4;
+    }
+
+    private static SpecialImapProvider MapSpecialImapProvider(int? rawValue)
+    {
+        if (!rawValue.HasValue ||
+            !Enum.IsDefined(typeof(SpecialImapProvider), rawValue.Value))
+        {
+            return SpecialImapProvider.None;
+        }
+
+        return (SpecialImapProvider)rawValue.Value;
+    }
+
+    private static string BuildMailAccountQuery(HashSet<string> columns)
+    {
+        return $"""
+SELECT
+    {SelectColumnOrFallback(columns, "Id")},
+    {SelectColumnOrFallback(columns, "Address")},
+    {SelectColumnOrFallback(columns, "Name")},
+    {SelectColumnOrFallback(columns, "SenderName")},
+    {SelectColumnOrFallback(columns, "ProviderType")},
+    {SelectColumnOrFallback(columns, "SpecialImapProvider")},
+    {SelectColumnOrFallback(columns, "Order", "0")},
+    {SelectColumnOrFallback(columns, "AccountColorHex")},
+    {SelectColumnOrFallback(columns, "MergedInboxId")}
+FROM [{nameof(MailAccount)}]
+ORDER BY [Order] ASC, [Address] COLLATE NOCASE
+""";
+    }
+
+    private static string BuildMailAccountPreferencesQuery(HashSet<string> columns)
+    {
+        return $"""
+SELECT
+    {SelectColumnOrFallback(columns, "AccountId")},
+    {SelectColumnOrFallback(columns, "IsNotificationsEnabled")},
+    {SelectColumnOrFallback(columns, "IsTaskbarBadgeEnabled")},
+    {SelectColumnOrFallback(columns, "ShouldAppendMessagesToSentFolder")},
+    {SelectColumnOrFallback(columns, "IsFocusedInboxEnabled")}
+FROM [{nameof(MailAccountPreferences)}]
+""";
+    }
+
+    private static string BuildCustomServerInformationQuery(HashSet<string> columns)
+    {
+        return $"""
+SELECT
+    {SelectColumnOrFallback(columns, "AccountId")},
+    {SelectColumnOrFallback(columns, "Address")},
+    {SelectColumnOrFallback(columns, "IncomingServer")},
+    {SelectColumnOrFallback(columns, "IncomingServerPort")},
+    {SelectColumnOrFallback(columns, "IncomingServerUsername")},
+    {SelectColumnOrFallback(columns, "IncomingServerSocketOption")},
+    {SelectColumnOrFallback(columns, "IncomingAuthenticationMethod")},
+    {SelectColumnOrFallback(columns, "OutgoingServer")},
+    {SelectColumnOrFallback(columns, "OutgoingServerPort")},
+    {SelectColumnOrFallback(columns, "OutgoingServerUsername")},
+    {SelectColumnOrFallback(columns, "OutgoingServerSocketOption")},
+    {SelectColumnOrFallback(columns, "OutgoingAuthenticationMethod")},
+    {SelectColumnOrFallback(columns, "CalDavServiceUrl")},
+    {SelectColumnOrFallback(columns, "CalDavUsername")},
+    {SelectColumnOrFallback(columns, "CalendarSupportMode")},
+    {SelectColumnOrFallback(columns, "ProxyServer")},
+    {SelectColumnOrFallback(columns, "ProxyServerPort")},
+    {SelectColumnOrFallback(columns, "MaxConcurrentClients")}
+FROM [{nameof(CustomServerInformation)}]
+""";
+    }
+
+    private static string BuildMergedInboxQuery(HashSet<string> columns)
+    {
+        return $"""
+SELECT
+    {SelectColumnOrFallback(columns, "Id")},
+    {SelectColumnOrFallback(columns, "Name")}
+FROM [{nameof(MergedInbox)}]
+""";
+    }
+
+    private static string SelectColumnOrFallback(HashSet<string> columns, string columnName, string fallbackSql = "NULL")
+    {
+        return columns.Contains(columnName)
+            ? $"[{columnName}] AS [{columnName}]"
+            : $"{fallbackSql} AS [{columnName}]";
+    }
+
+    private static string NormalizeDisplayName(string? value, string fallback)
+    {
+        var normalized = NormalizeOptionalText(value);
+        return string.IsNullOrWhiteSpace(normalized) ? fallback : normalized;
+    }
+
+    private static string NormalizeOptionalText(string? value)
+        => string.IsNullOrWhiteSpace(value)
+            ? string.Empty
+            : value.Trim();
+
+    private static string FirstNonEmpty(string? primary, string? secondary)
+    {
+        var normalizedPrimary = NormalizeOptionalText(primary);
+        if (!string.IsNullOrWhiteSpace(normalizedPrimary))
+        {
+            return normalizedPrimary;
+        }
+
+        return NormalizeOptionalText(secondary);
+    }
+
+    private static string CreateAddressKey(string? address)
+        => NormalizeOptionalText(address).ToLowerInvariant();
+
+    private string GetLegacyDatabasePath()
+    {
+        var publisherSharedFolderPath = _applicationConfiguration.PublisherSharedFolderPath;
+        return string.IsNullOrWhiteSpace(publisherSharedFolderPath)
+            ? string.Empty
+            : Path.Combine(publisherSharedFolderPath, LegacyDatabaseFileName);
+    }
+
+    private LegacyLocalMigrationPreview CreateEmptyPreview(string legacyDatabasePath)
+    {
+        var hasCompletedMigration = _configurationService.Get(MigrationCompletedSettingKey, false);
+        var isPromptDeferred = _configurationService.Get(PromptDeferredSettingKey, false);
+
+        return new LegacyLocalMigrationPreview
+        {
+            SourceDatabasePath = legacyDatabasePath,
+            LegacyDatabaseExists = false,
+            HasCompletedMigration = hasCompletedMigration,
+            IsPromptDeferred = isPromptDeferred,
+            ShouldPrompt = false
+        };
+    }
+
+    private LegacyLocalMigrationPreview CreateUnreadablePreview(string legacyDatabasePath)
+    {
+        var hasCompletedMigration = _configurationService.Get(MigrationCompletedSettingKey, false);
+        var isPromptDeferred = _configurationService.Get(PromptDeferredSettingKey, false);
+
+        return new LegacyLocalMigrationPreview
+        {
+            SourceDatabasePath = legacyDatabasePath,
+            LegacyDatabaseExists = true,
+            HasCompletedMigration = hasCompletedMigration,
+            IsPromptDeferred = isPromptDeferred,
+            ShouldPrompt = false,
+            Warnings = [Translator.LegacyLocalMigration_Warning_ReadFailed]
+        };
+    }
+
+    private sealed class LegacySnapshot
+    {
+        public int TotalLegacyAccountCount { get; set; }
+        public int InvalidAccountCount { get; set; }
+        public List<LegacyAccountCandidate> Accounts { get; set; } = [];
+        public Dictionary<Guid, LegacyAccountCandidate> AccountsById { get; } = [];
+        public Dictionary<Guid, string> MergedInboxNamesById { get; set; } = [];
+    }
+
+    private sealed class LegacyAccountCandidate
+    {
+        public Guid LegacyAccountId { get; init; }
+        public string Address { get; init; } = string.Empty;
+        public string Name { get; init; } = string.Empty;
+        public string SenderName { get; init; } = string.Empty;
+        public MailProviderType ProviderType { get; init; }
+        public SpecialImapProvider SpecialImapProvider { get; init; }
+        public int Order { get; init; }
+        public string AccountColorHex { get; init; } = string.Empty;
+        public Guid? LegacyMergedInboxId { get; init; }
+        public LegacyMailAccountPreferencesRow? Preferences { get; init; }
+        public LegacyCustomServerInformationRow? ServerInformation { get; init; }
+    }
+
+    private sealed class LegacyMailAccountRow
+    {
+        public Guid Id { get; set; }
+        public string? Address { get; set; }
+        public string? Name { get; set; }
+        public string? SenderName { get; set; }
+        public int? ProviderType { get; set; }
+        public int? SpecialImapProvider { get; set; }
+        public int? Order { get; set; }
+        public string? AccountColorHex { get; set; }
+        public Guid? MergedInboxId { get; set; }
+    }
+
+    private sealed class LegacyMailAccountPreferencesRow
+    {
+        public Guid AccountId { get; set; }
+        public bool? ShouldAppendMessagesToSentFolder { get; set; }
+        public bool? IsNotificationsEnabled { get; set; }
+        public bool? IsFocusedInboxEnabled { get; set; }
+        public bool? IsTaskbarBadgeEnabled { get; set; }
+    }
+
+    private sealed class LegacyCustomServerInformationRow
+    {
+        public Guid AccountId { get; set; }
+        public string? Address { get; set; }
+        public string? IncomingServer { get; set; }
+        public string? IncomingServerPort { get; set; }
+        public string? IncomingServerUsername { get; set; }
+        public int? IncomingServerSocketOption { get; set; }
+        public int? IncomingAuthenticationMethod { get; set; }
+        public string? OutgoingServer { get; set; }
+        public string? OutgoingServerPort { get; set; }
+        public string? OutgoingServerUsername { get; set; }
+        public int? OutgoingServerSocketOption { get; set; }
+        public int? OutgoingAuthenticationMethod { get; set; }
+        public string? CalDavServiceUrl { get; set; }
+        public string? CalDavUsername { get; set; }
+        public int? CalendarSupportMode { get; set; }
+        public string? ProxyServer { get; set; }
+        public string? ProxyServerPort { get; set; }
+        public int? MaxConcurrentClients { get; set; }
+    }
+
+    private sealed class LegacyMergedInboxRow
+    {
+        public Guid Id { get; set; }
+        public string? Name { get; set; }
+    }
+}

Wino.Services/ServicesContainerSetup.cs

@@ -30,6 +30,7 @@ public static class ServicesContainerSetup
         services.AddTransient<IContextMenuItemService, ContextMenuItemService>();
         services.AddTransient<ICalendarContextMenuItemService, CalendarContextMenuItemService>();
         services.AddTransient<ISpecialImapProviderConfigResolver, SpecialImapProviderConfigResolver>();
+        services.AddTransient<ILegacyLocalMigrationService, LegacyLocalMigrationService>();
         services.AddTransient<IKeyboardShortcutService, KeyboardShortcutService>();
         services.AddSingleton<IWinoAccountApiClient, WinoAccountApiClient>();
         services.AddSingleton<IWinoAccountProfileService, WinoAccountProfileService>();