test(T3): add contract test suites for Account/Mailbox/Email repositories

Each abstract *Contract class defines the observable-state invariants of
the corresponding repository interface. The concrete *Impl is run against
the suite via a thin subclass. Future fakes or alternative impls can be
verified by subclassing the same contract.

24 new tests across 3 files.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

PLAN_ISSUE_21.md

@@ -0,0 +1,59 @@
+# Implementation Plan: Secure WebView for HTML Emails (#21)
+
+## Goal
+Replace the current `flutter_html` based rendering with a hardened WebView-based approach to improve rendering fidelity while strictly enforcing security and privacy.
+
+## 1. Dependency Management
+- **Core**: `webview_flutter` (v4+)
+- **Linux Platform**: `webview_flutter_linux` (Official community-supported or WebKitGTK based implementation). *Note: I will verify the exact package name during implementation.*
+- **Utilities**: `url_launcher` (existing) for opening links in the system browser.
+
+## 2. Secure WebView Component (`lib/ui/widgets/secure_email_webview.dart`)
+Create a new widget `SecureEmailWebView` that encapsulates the `WebViewWidget` and its controller.
+
+### Configuration & Hardening
+- **Disable JavaScript**: `controller.setJavaScriptMode(JavaScriptMode.disabled)`.
+- **Background**: Match the application theme (e.g., transparent or surface color).
+- **Security Headers/CSP**: Inject a Content Security Policy via `<meta>` tag in the HTML wrapper:
+  - `default-src 'none'; style-src 'unsafe-inline'; img-src 'self' data:;` (Blocks all external assets by default).
+
+### Image Blocking Logic
+- **Initial State**: Block remote images by injecting a CSP that restricts `img-src` to `data:` and local schemes.
+- **Toggle Mechanism**:
+  - Provide a "Load Remote Images" button in the Flutter UI.
+  - When triggered, re-render the HTML with an updated CSP: `img-src * data:;`.
+
+### Link Interception & Phishing Protection
+- Implement `NavigationDelegate.onNavigationRequest`.
+- **Process**:
+  1. Intercept any URL that doesn't start with `about:blank` or `data:`.
+  2. Block the navigation in the WebView.
+  3. Trigger a Flutter `showDialog` for confirmation.
+- **Phishing Protection Dialog**:
+  - Show the full URL.
+  - **Bold the FQDN**: Parse the URL using `Uri.parse`.
+    - Example: `https://`**`important-bank.com`**`/login`
+  - "Open in Browser" button uses `url_launcher`.
+
+## 3. Integration Plan
+### Step 1: Initialization
+Modify `lib/main.dart` to initialize the Linux WebView platform (using `webview_flutter_linux` or similar) during app startup.
+
+### Step 2: Replace Renderer in Screens
+- **EmailDetailScreen**: Replace `Html(...)` with `SecureEmailWebView(html: body.htmlBody!)`.
+- **ThreadDetailScreen**: Replace `Html(...)` with `SecureEmailWebView(html: body.htmlBody!)`.
+- Remove `flutter_html` imports and dependencies once migration is complete.
+
+## 4. Verification & Security Audit
+- **Manual Tests**:
+  - Open emails with complex HTML layouts.
+  - Verify images are blocked initially.
+  - Verify "Load images" works.
+  - Click various links (http, https, mailto) and verify the confirmation dialog and FQDN bolding.
+- **Security Check**:
+  - Verify that `<script>` tags are not executed.
+  - Verify no network requests for external images occur before user consent (via DevTools or proxy).
+
+## 5. Potential Challenges
+- **Linux WebView Stability**: WebKitGTK on Linux can sometimes have rendering or sizing issues in Flutter.
+- **Scrolling**: Ensuring the WebView integrates smoothly into the `ListView` of the email detail screen (might require fixed height or `SizedBox`).

flake.nix

@@ -84,6 +84,8 @@
             # python3 base + Google Play API client (for scripts/deploy_playstore.py)
             (python3.withPackages (ps: with ps; [
               google-api-python-client
+              google-auth-httplib2
+              httplib2
             ]))  # used by stalwart-dev/start and deploy_playstore.py
             fgj      # Codeberg/Forgejo CLI (like gh for GitHub)
           ]);

lib/core/repositories/email_repository.dart

@@ -1,14 +1,19 @@
 import 'package:sharedinbox/core/models/email.dart';
 
 abstract class EmailRepository {
-  Stream<List<Email>> observeEmails(String accountId, String mailboxPath);
+  Stream<List<Email>> observeEmails(
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  });
 
   /// Groups emails by threadId and returns one [EmailThread] per thread,
   /// sorted by the latest message date descending.
   Stream<List<EmailThread>> observeThreads(
     String accountId,
-    String mailboxPath,
-  );
+    String mailboxPath, {
+    int limit = 50,
+  });
 
   /// Returns all emails belonging to [threadId] in [mailboxPath].
   Stream<List<Email>> observeEmailsInThread(

lib/data/db/database.dart

@@ -269,10 +269,47 @@ class AppDatabase extends _$AppDatabase {
   AppDatabase([QueryExecutor? executor]) : super(executor ?? _openConnection());
 
   @override
-  int get schemaVersion => 25;
+  int get schemaVersion => 26;
+
+  Future<void> _createEmailFts() async {
+    await customStatement('''
+      CREATE VIRTUAL TABLE IF NOT EXISTS email_fts USING fts5(
+        subject, preview, from_json,
+        content='emails',
+        content_rowid='rowid'
+      )
+    ''');
+    await customStatement('''
+      CREATE TRIGGER IF NOT EXISTS email_fts_ai
+      AFTER INSERT ON emails BEGIN
+        INSERT INTO email_fts(rowid, subject, preview, from_json)
+        VALUES (new.rowid, new.subject, new.preview, new.from_json);
+      END
+    ''');
+    await customStatement('''
+      CREATE TRIGGER IF NOT EXISTS email_fts_au
+      AFTER UPDATE OF subject, preview, from_json ON emails BEGIN
+        INSERT INTO email_fts(email_fts, rowid, subject, preview, from_json)
+        VALUES ('delete', old.rowid, old.subject, old.preview, old.from_json);
+        INSERT INTO email_fts(rowid, subject, preview, from_json)
+        VALUES (new.rowid, new.subject, new.preview, new.from_json);
+      END
+    ''');
+    await customStatement('''
+      CREATE TRIGGER IF NOT EXISTS email_fts_ad
+      AFTER DELETE ON emails BEGIN
+        INSERT INTO email_fts(email_fts, rowid, subject, preview, from_json)
+        VALUES ('delete', old.rowid, old.subject, old.preview, old.from_json);
+      END
+    ''');
+  }
 
   @override
   MigrationStrategy get migration => MigrationStrategy(
+        onCreate: (m) async {
+          await m.createAll();
+          await _createEmailFts();
+        },
         onUpgrade: (m, from, to) async {
           // NOTE: m.createTable(T) creates the LATEST version of table T.
           // If you later add a column C to T in version X, you must guard
@@ -447,6 +484,14 @@ class AppDatabase extends _$AppDatabase {
               ),
             );
           }
+          if (from < 26) {
+            await _createEmailFts();
+            // Backfill FTS index from existing rows.
+            await customStatement('''
+              INSERT INTO email_fts(rowid, subject, preview, from_json)
+              SELECT rowid, subject, preview, from_json FROM emails
+            ''');
+          }
         },
       );
 }

lib/data/repositories/email_repository_impl.dart

@@ -58,15 +58,17 @@ class EmailRepositoryImpl implements EmailRepository {
   @override
   Stream<List<model.Email>> observeEmails(
     String accountId,
-    String mailboxPath,
-  ) {
+    String mailboxPath, {
+    int limit = 50,
+  }) {
     return (_db.select(_db.emails)
           ..where(
             (t) =>
                 t.accountId.equals(accountId) &
                 t.mailboxPath.equals(mailboxPath),
           )
-          ..orderBy([(t) => OrderingTerm.desc(t.receivedAt)]))
+          ..orderBy([(t) => OrderingTerm.desc(t.receivedAt)])
+          ..limit(limit))
         .watch()
         .map((rows) => rows.map(_toModel).toList());
   }
@@ -74,15 +76,17 @@ class EmailRepositoryImpl implements EmailRepository {
   @override
   Stream<List<model.EmailThread>> observeThreads(
     String accountId,
-    String mailboxPath,
-  ) {
+    String mailboxPath, {
+    int limit = 50,
+  }) {
     return (_db.select(_db.threads)
           ..where(
             (t) =>
                 t.accountId.equals(accountId) &
                 t.mailboxPath.equals(mailboxPath),
           )
-          ..orderBy([(t) => OrderingTerm.desc(t.latestDate)]))
+          ..orderBy([(t) => OrderingTerm.desc(t.latestDate)])
+          ..limit(limit))
         .watch()
         .map((rows) => rows.map(_threadRowToModel).toList());
   }
@@ -2470,28 +2474,39 @@ class EmailRepositoryImpl implements EmailRepository {
     String? accountId,
     String query,
   ) async {
+    final ftsQuery = _toFtsQuery(query);
+    if (ftsQuery.isEmpty) return [];
+
+    final sql = accountId != null
+        ? 'SELECT e.* FROM email_fts f JOIN emails e ON e.rowid = f.rowid'
+            ' WHERE email_fts MATCH ? AND e.account_id = ? ORDER BY rank LIMIT 50'
+        : 'SELECT e.* FROM email_fts f JOIN emails e ON e.rowid = f.rowid'
+            ' WHERE email_fts MATCH ? ORDER BY rank LIMIT 50';
+    final variables = accountId != null
+        ? [Variable<String>(ftsQuery), Variable<String>(accountId)]
+        : [Variable<String>(ftsQuery)];
+
+    final queryRows = await _db
+        .customSelect(sql, variables: variables, readsFrom: {_db.emails}).get();
+    final emailRows = await Future.wait(
+      queryRows.map((r) => _db.emails.mapFromRow(r)),
+    );
+    return emailRows.map(_toModel).toList();
+  }
+
+  /// Converts a user query string into an FTS5 match expression.
+  /// Each whitespace-separated word becomes a prefix term (word*) so that
+  /// partial words still match. Special FTS5 characters are stripped.
+  static String _toFtsQuery(String query) {
     final words = query
-        .toLowerCase()
+        .trim()
         .split(RegExp(r'\s+'))
         .where((w) => w.isNotEmpty)
+        .map((w) => w.replaceAll(RegExp(r'[^\w]'), ''))
+        .where((w) => w.isNotEmpty)
         .toList();
-    final rows = await (_db.select(_db.emails)
-          ..where((t) {
-            Expression<bool> condition = const Constant(true);
-            if (accountId != null) {
-              condition = t.accountId.equals(accountId);
-            }
-            for (final word in words) {
-              final pattern = '%$word%';
-              condition = condition &
-                  (t.subject.like(pattern) | t.preview.like(pattern));
-            }
-            return condition;
-          })
-          ..orderBy([(t) => OrderingTerm.desc(t.receivedAt)])
-          ..limit(50))
-        .get();
-    return rows.map(_toModel).toList();
+    if (words.isEmpty) return '';
+    return words.map((w) => '$w*').join(' ');
   }
 
   @override

lib/ui/screens/email_list_screen.dart

@@ -45,6 +45,10 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   List<EmailThread> _currentThreads = [];
   // Individual email selection used in search results.
   final Set<String> _selectedSearchIds = {};
+
+  // Pagination: number of threads currently requested from the DB.
+  static const _pageSize = 50;
+  int _limit = _pageSize;
   bool get _selecting =>
       _selectedThreadIds.isNotEmpty || _selectedSearchIds.isNotEmpty;
 
@@ -343,7 +347,11 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
         await emailRepo.syncEmails(widget.accountId, widget.mailboxPath);
       },
       child: StreamBuilder<List<EmailThread>>(
-        stream: emailRepo.observeThreads(widget.accountId, widget.mailboxPath),
+        stream: emailRepo.observeThreads(
+          widget.accountId,
+          widget.mailboxPath,
+          limit: _limit,
+        ),
         builder: (ctx, snap) {
           if (!snap.hasData) {
             return const Center(child: CircularProgressIndicator());
@@ -539,9 +547,16 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
   }
 
   Widget _buildThreadList(List<EmailThread> threads) {
+    final hasMore = threads.length == _limit;
     return ListView.builder(
-      itemCount: threads.length,
+      itemCount: threads.length + (hasMore ? 1 : 0),
       itemBuilder: (ctx, i) {
+        if (i == threads.length) {
+          return TextButton(
+            onPressed: () => setState(() => _limit += _pageSize),
+            child: const Text('Load more'),
+          );
+        }
         final t = threads[i];
         final isSelected = _selectedThreadIds.contains(t.threadId);
         final senderNames =

plan-claude.md

@@ -0,0 +1,159 @@
+# SharedInbox — Improvement Plan
+
+30 tasks across 7 perspectives. Priority markers: 🔴 high · 🟡 medium · 🟢 nice-to-have.
+
+---
+
+## Group 1: Performance
+
+### P1 — Done: https://codeberg.org/guettli/sharedinbox/pulls/41
+
+### P1 🔴 Replace LIKE-based search with FTS5 virtual table
+The current `observeEmails` and search queries use `LIKE '%query%'` which becomes a full-table scan at scale.
+Create an `email_fts` FTS5 virtual table (subject, preview, fromJson) populated via trigger or sync-time insert.
+Wire `SearchScreen` to query the FTS table instead.
+Files: `lib/data/db/database.dart`, `lib/data/repositories/email_repository_impl.dart`.
+
+### P2 🔴 Lazy-load email bodies on scroll (pagination)
+`observeThreads` and `observeEmails` return the full list with no limit. As the mailbox grows this streams thousands of rows into memory.
+Add a page-size parameter (e.g. 50) with "load more" support in `EmailListScreen`.
+The `EmailBodies` table is already separate — never fetch bodies in the list query.
+Files: `lib/data/repositories/email_repository_impl.dart`, `lib/ui/screens/email_list_screen.dart`.
+
+### P3 🟡 Defer HTML parsing off the UI thread using an Isolate
+`flutter_html` parsing blocks the raster thread for large HTML bodies, causing jank when opening email detail.
+Move the HTML→Widget tree conversion (or at minimum the `html_utils.dart` HTML-to-plain step) into a `compute()` call.
+Files: `lib/ui/screens/email_detail_screen.dart`, `lib/core/utils/html_utils.dart`.
+
+### P4 — Done: https://codeberg.org/guettli/sharedinbox/pulls/36
+
+### P5 🟢 Cache the formatted date strings in EmailListScreen
+`DateFormat('MMM d').format(...)` is called for every email on every rebuild. Compute and cache these in the model layer or inside the list item widget's `build` method using a static cache map.
+Files: `lib/ui/screens/email_list_screen.dart`, `lib/core/utils/format_utils.dart`.
+
+---
+
+## Group 2: Reliability & Resilience
+
+### R1 — Done: https://codeberg.org/guettli/sharedinbox/pulls/20
+
+### R2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/22
+
+### R3 — Done: https://codeberg.org/guettli/sharedinbox/pulls/35
+
+### R4 — Done: https://codeberg.org/guettli/sharedinbox/pulls/23
+
+### R5 🟡 Handle TLS certificate changes gracefully
+`tls_error.dart` detects TLS errors but they bubble up as generic errors in the sync loop.
+Detect `TlsError` specifically in `_AccountSync` and show a user-facing dialog offering to re-add the account or trust the new certificate.
+Files: `lib/data/imap/tls_error.dart`, `lib/core/sync/account_sync_manager.dart`.
+
+### R6 — Done: https://codeberg.org/guettli/sharedinbox/pulls/24
+
+---
+
+## Group 3: Security
+
+### S1 🔴 Optional SQLCipher encryption for the Drift database
+Emails cached locally are plaintext. Users on shared or rooted devices are exposed.
+Add an opt-in "Encrypt local storage" setting using `drift`'s `encrypted` backend (`sqflite_cipher` / `sqlcipher_flutter_libs`).
+Store the database key in `flutter_secure_storage` (already present).
+Files: `lib/data/db/database.dart`, `pubspec.yaml`, a new settings toggle.
+
+### S2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/25
+
+### S3 🟡 Enforce certificate pinning for known providers (opt-in)
+Auto-discovered accounts for major providers (Gmail, Fastmail, Proton) could be pinned to their known CA hierarchy.
+Implement as an opt-in per-account setting; only applies when the account is auto-discovered via `AccountDiscoveryService`.
+Files: `lib/core/services/account_discovery_service.dart`, `lib/data/imap/imap_client_factory.dart`.
+
+### S4 🟢 Audit and restrict external link handling in HTML emails
+`flutter_html` passes `<a href>` clicks to `url_launcher` without a prompt.
+Before launching, show a confirmation dialog with the destination URL so phishing links are visible.
+Files: `lib/ui/screens/email_detail_screen.dart`.
+
+---
+
+## Group 4: User Experience
+
+### U1 — Done: https://codeberg.org/guettli/sharedinbox/pulls/26
+
+### U2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/27
+
+### U3 🟡 Add "Recent searches" history to SearchScreen
+The search bar clears on navigation. Store the last 10 search terms in a local DB table and show them as chips below the search field when the field is focused but empty.
+Files: `lib/ui/screens/search_screen.dart`, `lib/data/db/database.dart`.
+
+### U4 — Done: https://codeberg.org/guettli/sharedinbox/pulls/28
+
+### U5 — Already implemented (Dismissible archive/delete swipes with undo, found in email_list_screen.dart)
+
+### U6 — Done: https://codeberg.org/guettli/sharedinbox/pulls/29
+
+### U7 🟢 Onboarding walkthrough for first-time users
+The app opens directly to an empty account list with only a `+` button. First-time users have no guidance.
+Add a one-time welcome card or bottom-sheet with the three-step flow: Add account → wait for sync → open inbox.
+Files: `lib/ui/screens/account_list_screen.dart`.
+
+### U8 🟢 "Mark all as read" action in mailbox
+Power users managing high-volume mailboxes need bulk read marking. Add a "Mark all as read" option in the mailbox overflow menu.
+Files: `lib/ui/screens/email_list_screen.dart`, `lib/core/repositories/email_repository.dart`, `lib/data/repositories/email_repository_impl.dart`.
+
+---
+
+## Group 5: Testing
+
+### T1 — Done: https://codeberg.org/guettli/sharedinbox/pulls/30
+
+### T2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/31
+
+### T3 🟡 Contract tests for all Repository interfaces
+The interfaces in `core/repositories/` have no shared contract test suite. Concrete impls can silently diverge.
+Add a shared `EmailRepositoryContract` abstract test class; run it against both `EmailRepositoryImpl` and any future mock/fake. Mirror this for `MailboxRepository` and `AccountRepository`.
+Files: `test/unit/` (new contract test files).
+
+### T4 — Done: https://codeberg.org/guettli/sharedinbox/pulls/32
+
+### T5 🟢 Snapshot / golden tests for key email list states
+The email list has multiple states: loading, empty, normal, selection mode, search active, error banner.
+Add golden tests using `matchesGoldenFile` for each state so visual regressions surface in CI.
+Files: `test/widget/email_list_screen_test.dart`.
+
+---
+
+## Group 6: Architecture & Code Quality
+
+### A1 — Done: https://codeberg.org/guettli/sharedinbox/pulls/39
+
+### A2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/33
+
+### A3 🟡 Make AccountSyncManager testable without real IMAP connections
+`AccountSyncManager` accepts `ImapConnectFn` as a dependency but `_JmapAccountSync` constructs its HTTP client internally.
+Pass an injectable `http.Client` to `_JmapAccountSync` (already done in `EmailRepositoryImpl`; mirror the pattern here).
+Files: `lib/core/sync/account_sync_manager.dart`, `test/unit/account_sync_manager_test.dart`.
+
+### A4 🟡 Replace raw JSON strings in DB with structured encoding
+`fromJson`, `toAddresses`, `ccJson`, `references` are stored as raw JSON strings parsed on every model conversion.
+Create typed value classes with `fromJson`/`toJson` in `core/models/email.dart` and add a `TypeConverter` in the Drift schema so the DB layer owns the serialisation.
+Files: `lib/data/db/database.dart`, `lib/core/models/email.dart`, `lib/data/repositories/email_repository_impl.dart`.
+
+### A5 🟢 Enforce layer boundaries via lint custom rules or barrel imports
+The `ui/` layer directly imports `data/` concrete classes in several screens (e.g. `drift` types leak through).
+Add a custom `analysis_options.yaml` rule or a CI lint step that flags any `ui/` import of `data/` (only `core/` interfaces are allowed from UI).
+Files: `analysis_options.yaml`, CI config.
+
+---
+
+## Group 7: Developer Experience
+
+### D1 🔴 CI matrix for macOS and Windows builds
+The CI currently tests Linux and Android. The macOS and Windows targets are "scaffolded" and may have accumulated silent breakage.
+Add `flutter build macos --debug` and `flutter build windows --debug` jobs to the CI workflow with the same failure threshold as Linux.
+Files: `.github/workflows/ci.yml` (or Codeberg equivalent).
+
+### D2 — Done: https://codeberg.org/guettli/sharedinbox/pulls/34
+
+### D3 🟢 Document the sync protocol in a SYNC.md architecture doc
+`DB-SYNC.md` exists but focuses on the DB schema. The IMAP IDLE loop, exponential backoff, pending-change queue, and undo cancel logic are spread across four files with no single reference.
+Write `SYNC.md` that describes the full lifecycle of an email action from UI tap to server confirmation.
+Files: `SYNC.md` (new).

scripts/deploy_playstore.py

@@ -5,6 +5,8 @@ import json
 import os
 import sys
 
+import google_auth_httplib2
+import httplib2
 from google.oauth2 import service_account
 from googleapiclient.discovery import build
 from googleapiclient.http import MediaFileUpload
@@ -12,6 +14,7 @@ from googleapiclient.http import MediaFileUpload
 PACKAGE_NAME = "de.sharedinbox.mua"
 AAB_PATH = "build/app/outputs/bundle/release/app-release.aab"
 TRACK = "internal"
+_TIMEOUT = 300  # seconds — AAB uploads can be large
 
 
 def main():
@@ -29,9 +32,12 @@ def main():
         scopes=["https://www.googleapis.com/auth/androidpublisher"],
     )
 
-    service = build("androidpublisher", "v3", credentials=creds)
+    authorized_http = google_auth_httplib2.AuthorizedHttp(
+        creds, http=httplib2.Http(timeout=_TIMEOUT)
+    )
+    service = build("androidpublisher", "v3", http=authorized_http)
 
-    edit = service.edits().insert(body={}, packageName=PACKAGE_NAME).execute()
+    edit = service.edits().insert(body={}, packageName=PACKAGE_NAME).execute(num_retries=3)
     edit_id = edit["id"]
 
     media = MediaFileUpload(AAB_PATH, mimetype="application/octet-stream", resumable=True)
@@ -39,7 +45,7 @@ def main():
         service.edits()
         .bundles()
         .upload(packageName=PACKAGE_NAME, editId=edit_id, media_body=media)
-        .execute()
+        .execute(num_retries=3)
     )
     version_code = bundle["versionCode"]
     print(f"Uploaded AAB, version code: {version_code}")
@@ -49,9 +55,9 @@ def main():
         editId=edit_id,
         track=TRACK,
         body={"releases": [{"versionCodes": [version_code], "status": "completed"}]},
-    ).execute()
+    ).execute(num_retries=3)
 
-    service.edits().commit(packageName=PACKAGE_NAME, editId=edit_id).execute()
+    service.edits().commit(packageName=PACKAGE_NAME, editId=edit_id).execute(num_retries=3)
     print(f"Deployed version {version_code} to {TRACK} track")
 
 

test/integration/account_sync_manager_test.dart

@@ -105,10 +105,19 @@ class _FakeEmails implements EmailRepository {
   final syncCounts = <String, int>{};
 
   @override
-  Stream<List<Email>> observeEmails(String a, String m) => Stream.value([]);
+  Stream<List<Email>> observeEmails(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
+      Stream.value([]);
 
   @override
-  Stream<List<EmailThread>> observeThreads(String a, String m) =>
+  Stream<List<EmailThread>> observeThreads(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
       Stream.value([]);
 
   @override

test/unit/account_repository_contract_test.dart

@@ -0,0 +1,107 @@
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sharedinbox/core/models/account.dart';
+import 'package:sharedinbox/core/repositories/account_repository.dart';
+import 'package:sharedinbox/data/repositories/account_repository_impl.dart';
+
+import 'account_repository_impl_test.dart' show MapSecureStorage;
+import 'db_test_helper.dart';
+
+// ── Contract ──────────────────────────────────────────────────────────────────
+
+/// Verifies the [AccountRepository] interface contract.
+///
+/// Subclass this and override [makeRepo] to run the same suite against any
+/// concrete implementation.
+abstract class AccountRepositoryContract {
+  AccountRepository makeRepo();
+
+  static const _a = Account(
+    id: 'c-1',
+    displayName: 'Contract',
+    email: 'c@example.com',
+    imapHost: 'imap.example.com',
+    smtpHost: 'smtp.example.com',
+  );
+
+  void run() {
+    test('observeAccounts starts empty', () async {
+      final repo = makeRepo();
+      expect(await repo.observeAccounts().first, isEmpty);
+    });
+
+    test('addAccount makes account visible via observeAccounts', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'pw');
+      final list = await repo.observeAccounts().first;
+      expect(list, hasLength(1));
+      expect(list.first.id, _a.id);
+    });
+
+    test('getAccount returns null for unknown id', () async {
+      final repo = makeRepo();
+      expect(await repo.getAccount('no-such'), isNull);
+    });
+
+    test('getAccount returns added account', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'pw');
+      final a = await repo.getAccount(_a.id);
+      expect(a, isNotNull);
+      expect(a!.email, _a.email);
+    });
+
+    test('getPassword returns stored password', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'secret123');
+      expect(await repo.getPassword(_a.id), 'secret123');
+    });
+
+    test('updateAccount reflects changes in observeAccounts', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'pw');
+      final updated = _a.copyWith(displayName: 'Updated');
+      await repo.updateAccount(updated);
+      final list = await repo.observeAccounts().first;
+      expect(list.first.displayName, 'Updated');
+    });
+
+    test('updateAccount with password updates stored password', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'old');
+      await repo.updateAccount(_a, password: 'new');
+      expect(await repo.getPassword(_a.id), 'new');
+    });
+
+    test('removeAccount makes account disappear from observeAccounts',
+        () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'pw');
+      await repo.removeAccount(_a.id);
+      expect(await repo.observeAccounts().first, isEmpty);
+    });
+
+    test('getAccount returns null after removeAccount', () async {
+      final repo = makeRepo();
+      await repo.addAccount(_a, 'pw');
+      await repo.removeAccount(_a.id);
+      expect(await repo.getAccount(_a.id), isNull);
+    });
+  }
+}
+
+// ── Impl under test ───────────────────────────────────────────────────────────
+
+class _AccountRepositoryImplContract extends AccountRepositoryContract {
+  @override
+  AccountRepository makeRepo() =>
+      AccountRepositoryImpl(openTestDatabase(), MapSecureStorage());
+}
+
+void main() {
+  setUpAll(configureSqliteForTests);
+
+  group('AccountRepositoryImpl satisfies AccountRepository contract', () {
+    _AccountRepositoryImplContract().run();
+  });
+}

test/unit/account_sync_manager_test.dart

@@ -34,9 +34,18 @@ void main() {
 
 class FakeEmailRepository implements EmailRepository {
   @override
-  Stream<List<Email>> observeEmails(String a, String m) => Stream.value([]);
+  Stream<List<Email>> observeEmails(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
+      Stream.value([]);
   @override
-  Stream<List<EmailThread>> observeThreads(String a, String m) =>
+  Stream<List<EmailThread>> observeThreads(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
       Stream.value([]);
   @override
   Stream<List<Email>> observeEmailsInThread(String a, String m, String t) =>

test/unit/account_sync_manager_test.mocks.dart

@@ -215,9 +215,10 @@ class MockEmailRepository extends _i1.Mock implements _i9.EmailRepository {
 
   @override
   _i4.Stream<List<_i2.Email>> observeEmails(
-    String? accountId,
-    String? mailboxPath,
-  ) =>
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       (super.noSuchMethod(
         Invocation.method(
           #observeEmails,
@@ -225,15 +226,17 @@ class MockEmailRepository extends _i1.Mock implements _i9.EmailRepository {
             accountId,
             mailboxPath,
           ],
+          {#limit: limit},
         ),
         returnValue: _i4.Stream<List<_i2.Email>>.empty(),
       ) as _i4.Stream<List<_i2.Email>>);
 
   @override
   _i4.Stream<List<_i2.EmailThread>> observeThreads(
-    String? accountId,
-    String? mailboxPath,
-  ) =>
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       (super.noSuchMethod(
         Invocation.method(
           #observeThreads,
@@ -241,6 +244,7 @@ class MockEmailRepository extends _i1.Mock implements _i9.EmailRepository {
             accountId,
             mailboxPath,
           ],
+          {#limit: limit},
         ),
         returnValue: _i4.Stream<List<_i2.EmailThread>>.empty(),
       ) as _i4.Stream<List<_i2.EmailThread>>);

test/unit/email_repository_contract_test.dart

@@ -0,0 +1,193 @@
+import 'package:drift/drift.dart' show Value;
+import 'package:enough_mail/enough_mail.dart' as imap;
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sharedinbox/core/models/account.dart';
+import 'package:sharedinbox/core/repositories/email_repository.dart';
+import 'package:sharedinbox/data/db/database.dart' hide Account;
+import 'package:sharedinbox/data/repositories/account_repository_impl.dart';
+import 'package:sharedinbox/data/repositories/email_repository_impl.dart';
+
+import 'account_repository_impl_test.dart' show MapSecureStorage;
+import 'db_test_helper.dart';
+
+// ── Contract ──────────────────────────────────────────────────────────────────
+
+/// Verifies the observable / local-state portion of the [EmailRepository]
+/// interface contract.
+///
+/// Network-dependent methods (syncEmails, sendEmail, etc.) are intentionally
+/// excluded — they are covered by the concrete impl tests.
+abstract class EmailRepositoryContract {
+  static const _account = Account(
+    id: 'er-acc',
+    displayName: 'Contract',
+    email: 'er@example.com',
+    imapHost: 'imap.example.com',
+    smtpHost: 'smtp.example.com',
+  );
+
+  /// Return a fresh [EmailRepository] with [_account] already persisted.
+  Future<EmailRepository> makeRepo();
+
+  /// Insert a raw email row so tests can assert on observable state without
+  /// triggering a network sync.
+  Future<void> insertEmail(
+    EmailRepository repo, {
+    required String id,
+    required String mailboxPath,
+    bool isSeen = true,
+    bool isFlagged = false,
+    DateTime? receivedAt,
+  });
+
+  void run() {
+    test('observeEmails starts empty', () async {
+      final repo = await makeRepo();
+      expect(
+        await repo.observeEmails(_account.id, 'INBOX').first,
+        isEmpty,
+      );
+    });
+
+    test('observeEmails emits inserted email', () async {
+      final repo = await makeRepo();
+      await insertEmail(repo, id: 'er-acc:1', mailboxPath: 'INBOX');
+      final emails = await repo.observeEmails(_account.id, 'INBOX').first;
+      expect(emails, hasLength(1));
+      expect(emails.first.id, 'er-acc:1');
+    });
+
+    test('observeEmails only returns emails for the given mailbox', () async {
+      final repo = await makeRepo();
+      await insertEmail(repo, id: 'er-acc:1', mailboxPath: 'INBOX');
+      expect(
+        await repo.observeEmails(_account.id, 'Sent').first,
+        isEmpty,
+      );
+    });
+
+    test('observeEmails orders by receivedAt descending', () async {
+      final repo = await makeRepo();
+      final older = DateTime(2024);
+      final newer = DateTime(2024, 6);
+      await insertEmail(
+        repo,
+        id: 'er-acc:1',
+        mailboxPath: 'INBOX',
+        receivedAt: older,
+      );
+      await insertEmail(
+        repo,
+        id: 'er-acc:2',
+        mailboxPath: 'INBOX',
+        receivedAt: newer,
+      );
+      final emails = await repo.observeEmails(_account.id, 'INBOX').first;
+      expect(emails.first.id, 'er-acc:2');
+      expect(emails.last.id, 'er-acc:1');
+    });
+
+    test('getEmail returns null for unknown id', () async {
+      final repo = await makeRepo();
+      expect(await repo.getEmail('no-such'), isNull);
+    });
+
+    test('getEmail returns inserted email', () async {
+      final repo = await makeRepo();
+      await insertEmail(repo, id: 'er-acc:7', mailboxPath: 'INBOX');
+      final email = await repo.getEmail('er-acc:7');
+      expect(email, isNotNull);
+      expect(email!.accountId, _account.id);
+    });
+
+    test('setFlag seen updates isSeen', () async {
+      final repo = await makeRepo();
+      await insertEmail(
+        repo,
+        id: 'er-acc:10',
+        mailboxPath: 'INBOX',
+        isSeen: false,
+      );
+      await repo.setFlag('er-acc:10', seen: true);
+      final email = await repo.getEmail('er-acc:10');
+      expect(email!.isSeen, isTrue);
+    });
+
+    test('setFlag flagged updates isFlagged', () async {
+      final repo = await makeRepo();
+      await insertEmail(
+        repo,
+        id: 'er-acc:11',
+        mailboxPath: 'INBOX',
+      );
+      await repo.setFlag('er-acc:11', flagged: true);
+      final email = await repo.getEmail('er-acc:11');
+      expect(email!.isFlagged, isTrue);
+    });
+
+    test('observeThreads starts empty', () async {
+      final repo = await makeRepo();
+      expect(
+        await repo.observeThreads(_account.id, 'INBOX').first,
+        isEmpty,
+      );
+    });
+  }
+}
+
+// ── Impl under test ───────────────────────────────────────────────────────────
+
+class _EmailRepositoryImplContract extends EmailRepositoryContract {
+  static const _account = EmailRepositoryContract._account;
+
+  late AppDatabase _db;
+  late AccountRepositoryImpl _accountRepo;
+
+  @override
+  Future<EmailRepository> makeRepo() async {
+    _db = openTestDatabase();
+    _accountRepo = AccountRepositoryImpl(_db, MapSecureStorage());
+    await _accountRepo.addAccount(_account, 'pw');
+    return EmailRepositoryImpl(
+      _db,
+      _accountRepo,
+      imapConnect: (_, __, ___) => Future<imap.ImapClient>.error(
+        UnsupportedError('no IMAP in unit tests'),
+      ),
+      smtpConnect: (_, __, ___) => Future<imap.SmtpClient>.error(
+        UnsupportedError('no SMTP in unit tests'),
+      ),
+    );
+  }
+
+  @override
+  Future<void> insertEmail(
+    EmailRepository repo, {
+    required String id,
+    required String mailboxPath,
+    bool isSeen = true,
+    bool isFlagged = false,
+    DateTime? receivedAt,
+  }) async {
+    await _db.into(_db.emails).insert(
+          EmailsCompanion.insert(
+            id: id,
+            accountId: _account.id,
+            mailboxPath: mailboxPath,
+            uid: int.parse(id.split(':').last),
+            receivedAt: receivedAt ?? DateTime.now(),
+            isSeen: Value(isSeen),
+            isFlagged: Value(isFlagged),
+          ),
+        );
+  }
+}
+
+void main() {
+  setUpAll(configureSqliteForTests);
+
+  group('EmailRepositoryImpl satisfies EmailRepository contract', () {
+    _EmailRepositoryImplContract().run();
+  });
+}

test/unit/mailbox_repository_contract_test.dart

@@ -0,0 +1,137 @@
+import 'package:drift/drift.dart' show Value;
+import 'package:flutter_test/flutter_test.dart';
+
+import 'package:sharedinbox/core/models/account.dart';
+import 'package:sharedinbox/core/repositories/mailbox_repository.dart';
+import 'package:sharedinbox/data/db/database.dart' hide Account;
+import 'package:sharedinbox/data/repositories/account_repository_impl.dart';
+import 'package:sharedinbox/data/repositories/mailbox_repository_impl.dart';
+
+import 'account_repository_impl_test.dart' show MapSecureStorage;
+import 'db_test_helper.dart';
+
+// ── Contract ──────────────────────────────────────────────────────────────────
+
+/// Verifies the [MailboxRepository] interface contract.
+///
+/// Tests cover only the locally-observable part of the interface
+/// (observe / find) since sync methods require live IMAP/JMAP servers.
+abstract class MailboxRepositoryContract {
+  static const _account = Account(
+    id: 'm-acc',
+    displayName: 'Contract',
+    email: 'm@example.com',
+    imapHost: 'imap.example.com',
+    smtpHost: 'smtp.example.com',
+  );
+
+  /// Return a fresh [MailboxRepository] with [_account] already persisted.
+  Future<MailboxRepository> makeRepo();
+
+  /// Insert a mailbox row into the backing store so tests can verify
+  /// observeMailboxes without triggering a network sync.
+  Future<void> insertMailbox(
+    MailboxRepository repo, {
+    required String id,
+    required String path,
+    String? role,
+    int unread = 0,
+    int total = 0,
+  });
+
+  void run() {
+    test('observeMailboxes starts empty', () async {
+      final repo = await makeRepo();
+      expect(await repo.observeMailboxes(_account.id).first, isEmpty);
+    });
+
+    test('observeMailboxes emits inserted rows ordered by path', () async {
+      final repo = await makeRepo();
+      await insertMailbox(repo, id: 'z', path: 'Z');
+      await insertMailbox(repo, id: 'a', path: 'A');
+      final boxes = await repo.observeMailboxes(_account.id).first;
+      expect(boxes.map((b) => b.path), ['A', 'Z']);
+    });
+
+    test('observeMailboxes only returns rows for the given account', () async {
+      final repo = await makeRepo();
+      await insertMailbox(repo, id: 'mb1', path: 'INBOX');
+      expect(await repo.observeMailboxes('other-acc').first, isEmpty);
+    });
+
+    test('findMailboxByRole returns null when no match', () async {
+      final repo = await makeRepo();
+      expect(
+        await repo.findMailboxByRole(_account.id, 'archive'),
+        isNull,
+      );
+    });
+
+    test('findMailboxByRole returns the matching mailbox', () async {
+      final repo = await makeRepo();
+      await insertMailbox(repo, id: 'arch', path: 'Archive', role: 'archive');
+      final box = await repo.findMailboxByRole(_account.id, 'archive');
+      expect(box, isNotNull);
+      expect(box!.role, 'archive');
+    });
+
+    test('clearForResync removes all mailboxes for the account', () async {
+      final repo = await makeRepo();
+      await insertMailbox(repo, id: 'mb', path: 'INBOX');
+      await repo.clearForResync(_account.id);
+      expect(await repo.observeMailboxes(_account.id).first, isEmpty);
+    });
+  }
+}
+
+// ── Impl under test ───────────────────────────────────────────────────────────
+
+class _MailboxRepositoryImplContract extends MailboxRepositoryContract {
+  static const _account = MailboxRepositoryContract._account;
+
+  late AppDatabase _db;
+  late AccountRepositoryImpl _accountRepo;
+
+  @override
+  Future<MailboxRepository> makeRepo() async {
+    _db = openTestDatabase();
+    _accountRepo = AccountRepositoryImpl(_db, MapSecureStorage());
+    await _accountRepo.addAccount(_account, 'pw');
+    return MailboxRepositoryImpl(
+      _db,
+      _accountRepo,
+      imapConnect: (_, __, ___) =>
+          Future.error(UnsupportedError('no IMAP in unit tests')),
+    );
+  }
+
+  @override
+  Future<void> insertMailbox(
+    MailboxRepository repo, {
+    required String id,
+    required String path,
+    String? role,
+    int unread = 0,
+    int total = 0,
+  }) async {
+    await _db.into(_db.mailboxes).insert(
+          MailboxesCompanion.insert(
+            id: id,
+            accountId: _account.id,
+            path: path,
+            name: path.split('/').last,
+            unreadCount: Value(unread),
+            totalCount: Value(total),
+            role: Value(role),
+          ),
+        );
+  }
+}
+
+void main() {
+  setUpAll(configureSqliteForTests);
+
+  group('MailboxRepositoryImpl satisfies MailboxRepository contract', () {
+    _MailboxRepositoryImplContract().run();
+  });
+}

test/unit/migration_test.dart

@@ -14,7 +14,7 @@ void main() {
   group('Migration', () {
     test('schemaVersion matches expected value', () async {
       final db = AppDatabase(NativeDatabase.memory());
-      expect(db.schemaVersion, 25);
+      expect(db.schemaVersion, 26);
       await db.close();
     });
 
@@ -158,6 +158,19 @@ void main() {
         ]),
       );
 
+      // v26: FTS5 virtual table and triggers exist.
+      final allTriggers = await db
+          .customSelect("SELECT name FROM sqlite_master WHERE type='trigger'")
+          .get();
+      final triggerNames =
+          allTriggers.map((r) => r.read<String>('name')).toSet();
+      expect(
+        triggerNames,
+        containsAll(['email_fts_ai', 'email_fts_au', 'email_fts_ad']),
+      );
+      // Verify FTS table was created and is queryable.
+      await db.customSelect('SELECT count(*) FROM email_fts').get();
+
       await db.close();
       if (dbFile.existsSync()) dbFile.deleteSync();
     });
@@ -276,11 +289,23 @@ void main() {
       expect(indexNames, contains('mailboxes_account_id'));
       expect(indexNames, contains('threads_latest_date'));
 
+      // v26: FTS5 virtual table and triggers.
+      final allTriggers = await db
+          .customSelect("SELECT name FROM sqlite_master WHERE type='trigger'")
+          .get();
+      final triggerNames =
+          allTriggers.map((r) => r.read<String>('name')).toSet();
+      expect(
+        triggerNames,
+        containsAll(['email_fts_ai', 'email_fts_au', 'email_fts_ad']),
+      );
+      await db.customSelect('SELECT count(*) FROM email_fts').get();
+
       await db.close();
       if (dbFile.existsSync()) dbFile.deleteSync();
     });
 
-    test('fresh install creates all tables at schemaVersion 25', () async {
+    test('fresh install creates all tables at schemaVersion 26', () async {
       final db = AppDatabase(NativeDatabase.memory());
       await db.select(db.accounts).get();
 

test/unit/reliability_runner_test.dart

@@ -79,9 +79,18 @@ class _CountingEmails implements EmailRepository {
   @override
   Future<int> flushPendingChanges(String accountId, String password) async => 0;
   @override
-  Stream<List<Email>> observeEmails(String a, String m) => Stream.value([]);
+  Stream<List<Email>> observeEmails(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
+      Stream.value([]);
   @override
-  Stream<List<EmailThread>> observeThreads(String a, String m) =>
+  Stream<List<EmailThread>> observeThreads(
+    String a,
+    String m, {
+    int limit = 50,
+  }) =>
       Stream.value([]);
   @override
   Stream<List<Email>> observeEmailsInThread(String a, String m, String t) =>

test/unit/undo_service_test.mocks.dart

@@ -75,9 +75,10 @@ class MockEmailRepository extends _i1.Mock implements _i3.EmailRepository {
 
   @override
   _i4.Stream<List<_i2.Email>> observeEmails(
-    String? accountId,
-    String? mailboxPath,
-  ) =>
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       (super.noSuchMethod(
         Invocation.method(
           #observeEmails,
@@ -85,15 +86,17 @@ class MockEmailRepository extends _i1.Mock implements _i3.EmailRepository {
             accountId,
             mailboxPath,
           ],
+          {#limit: limit},
         ),
         returnValue: _i4.Stream<List<_i2.Email>>.empty(),
       ) as _i4.Stream<List<_i2.Email>>);
 
   @override
   _i4.Stream<List<_i2.EmailThread>> observeThreads(
-    String? accountId,
-    String? mailboxPath,
-  ) =>
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       (super.noSuchMethod(
         Invocation.method(
           #observeThreads,
@@ -101,6 +104,7 @@ class MockEmailRepository extends _i1.Mock implements _i3.EmailRepository {
             accountId,
             mailboxPath,
           ],
+          {#limit: limit},
         ),
         returnValue: _i4.Stream<List<_i2.EmailThread>>.empty(),
       ) as _i4.Stream<List<_i2.EmailThread>>);

test/widget/helpers.dart

@@ -158,14 +158,19 @@ class FakeEmailRepository implements EmailRepository {
         _emailBody = emailBody ?? const EmailBody(emailId: '', attachments: []);
 
   @override
-  Stream<List<Email>> observeEmails(String accountId, String mailboxPath) =>
+  Stream<List<Email>> observeEmails(
+    String accountId,
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       Stream.value(List.of(_emails));
 
   @override
   Stream<List<EmailThread>> observeThreads(
     String accountId,
-    String mailboxPath,
-  ) =>
+    String mailboxPath, {
+    int limit = 50,
+  }) =>
       observeEmails(accountId, mailboxPath).map((emails) {
         return emails.map((e) {
           return EmailThread(