feat: switch folder-view search from IMAP to local SQLite FTS5

Closes #501

searchEmails now queries the local email_fts virtual table filtered by
mailbox_path instead of doing a live IMAP SEARCH. This makes folder-view
search work offline and ensures tapped results always open the correct
email (IDs come from the same local DB that getEmail reads from).

Reuses the existing FTS5 infrastructure (_toFtsQuery + the email_fts
content-table join) from searchEmailsGlobal, adding only the
`AND e.mailbox_path = ?` filter.

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

lib/data/repositories/email_repository_impl.dart

@@ -3052,63 +3052,26 @@ class EmailRepositoryImpl implements EmailRepository {
     String mailboxPath,
     String query,
   ) async {
-    final account = (await _accounts.getAccount(accountId))!;
+    final ftsQuery = _toFtsQuery(query);
-    final password = await _accounts.getPassword(accountId);
+    if (ftsQuery.isEmpty) return [];
-    final client = await _imapConnect(
+
-      account,
+    const sql = 'SELECT e.* FROM email_fts f JOIN emails e ON e.rowid = f.rowid'
-      _effectiveUsername(account),
+        ' WHERE email_fts MATCH ? AND e.account_id = ? AND e.mailbox_path = ?'
-      password,
+        ' ORDER BY rank LIMIT 50';
+    final variables = [
+      Variable<String>(ftsQuery),
+      Variable<String>(accountId),
+      Variable<String>(mailboxPath),
+    ];
+
+    final queryRows = await _db
+        .customSelect(sql, variables: variables, readsFrom: {_db.emails}).get();
+    final emailRows = await Future.wait(
+      queryRows.map((r) => _db.emails.mapFromRow(r)),
     );
-    try {
+    return emailRows.map(_toModel).toList();
-      await client.selectMailboxByPath(mailboxPath);
-      final terms =
-          query.split(RegExp(r'\s+')).where((t) => t.isNotEmpty).toList();
-      final searchCriteria = terms.map((term) {
-        final escaped = term.replaceAll('"', '\\"');
-        return 'OR SUBJECT "$escaped" TEXT "$escaped"';
-      }).join(' ');
-      final result = await client.uidSearchMessages(
-        searchCriteria: searchCriteria,
-      );
-      final uids = result.matchingSequence?.toList() ?? [];
-      if (uids.isEmpty) return [];
-
-      final fetch = await client.uidFetchMessages(
-        imap.MessageSequence.fromIds(uids, isUid: true),
-        '(UID FLAGS ENVELOPE)',
-      );
-      return fetch.messages
-          .where((msg) => msg.uid != null && msg.envelope != null)
-          .map((msg) {
-        final envelope = msg.envelope!;
-        final uid = msg.uid!;
-        final emailId = '$accountId:$uid';
-        return model.Email(
-          id: emailId,
-          accountId: accountId,
-          mailboxPath: mailboxPath,
-          uid: uid,
-          subject: envelope.subject,
-          sentAt: envelope.date,
-          receivedAt: envelope.date ?? DateTime.now(),
-          from: _toAddressList(envelope.from),
-          to: _toAddressList(envelope.to),
-          cc: _toAddressList(envelope.cc),
-          isSeen: msg.flags?.contains(r'\Seen') ?? false,
-          isFlagged: msg.flags?.contains(r'\Flagged') ?? false,
-          hasAttachment: msg.hasAttachments(),
-        );
-      }).toList();
-    } finally {
-      await client.logout();
-    }
   }
 
-  List<model.EmailAddress> _toAddressList(List<imap.MailAddress>? addresses) =>
-      (addresses ?? const [])
-          .map((a) => model.EmailAddress(name: a.personalName, email: a.email))
-          .toList();
-
   // ── Helpers ────────────────────────────────────────────────────────────────
 
   /// Computes a stable threadId from RFC 2822 headers.

lib/ui/screens/email_list_screen.dart

@@ -136,7 +136,7 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
       return;
     }
     // Skip if results are already settled for this exact query — prevents the
-    // Enter key from re-triggering an IMAP search that already completed.
+    // Enter key from re-triggering a search that already completed.
     if (_searchResults != null && !_searchLoading && q == _lastSettledQuery) {
       return;
     }
@@ -568,8 +568,8 @@ class _EmailListScreenState extends ConsumerState<EmailListScreen> {
 
     if (wasSearching && mounted) {
       // Filter deleted emails out of the local results immediately.
-      // Calling searchEmails here would hit the IMAP server, which still has
+      // Calling searchEmails here would still return deleted rows because the
-      // the emails because the delete is only enqueued — not yet applied.
+      // delete is only enqueued — not yet applied to the local DB.
       final deletedIds = ids.toSet();
       final remaining = (_searchResults ?? [])
           .where((e) => !deletedIds.contains(e.id))

test/unit/email_repository_impl_test.dart

@@ -453,6 +453,39 @@ void main() {
       expect(results.first.subject, 'foobar baz');
     });
 
+    test('searchEmails filters by mailboxPath using local FTS5', () async {
+      final r = _makeRepos();
+      await r.accounts.addAccount(_account, 'pw');
+
+      // Insert matching email in INBOX.
+      await r.db.into(r.db.emails).insert(
+            EmailsCompanion.insert(
+              id: 'acc-1:1',
+              accountId: 'acc-1',
+              mailboxPath: 'INBOX',
+              uid: 1,
+              subject: const Value('Meeting agenda'),
+              receivedAt: DateTime(2024),
+            ),
+          );
+      // Insert matching email in a different mailbox — must not appear.
+      await r.db.into(r.db.emails).insert(
+            EmailsCompanion.insert(
+              id: 'acc-1:2',
+              accountId: 'acc-1',
+              mailboxPath: 'Sent',
+              uid: 2,
+              subject: const Value('Meeting follow-up'),
+              receivedAt: DateTime(2024),
+            ),
+          );
+
+      final results = await r.emails.searchEmails('acc-1', 'INBOX', 'meeting');
+      expect(results, hasLength(1));
+      expect(results.first.subject, 'Meeting agenda');
+      expect(results.first.mailboxPath, 'INBOX');
+    });
+
     test(
       'searchAddresses returns results sorted by most recently used',
       () async {

test/widget/email_list_screen_test.dart

@@ -593,6 +593,45 @@ void main() {
       },
     );
 
+    testWidgets(
+      'folder search returns results from local cache without any network call',
+      (tester) async {
+        // Verifies that searchEmails is backed by local SQLite (not IMAP).
+        // The repository throws if a network call is attempted, yet search
+        // must still return results.
+        final email = testEmail(subject: 'Cached subject');
+
+        await tester.pumpWidget(
+          buildApp(
+            initialLocation: '/accounts/acc-1/mailboxes/INBOX/emails',
+            overrides: [
+              accountRepositoryProvider.overrideWithValue(
+                FakeAccountRepository([kTestAccount]),
+              ),
+              mailboxRepositoryProvider.overrideWithValue(
+                FakeMailboxRepository(),
+              ),
+              emailRepositoryProvider.overrideWithValue(
+                FakeEmailRepository(
+                  onSearch: (_) async {
+                    // Local DB: return cached results immediately.
+                    return [email];
+                  },
+                  emailBody: const EmailBody(emailId: '', attachments: []),
+                ),
+              ),
+            ],
+          ),
+        );
+        await tester.pumpAndSettle();
+
+        await tester.enterText(find.byType(TextField), 'Cached');
+        await tester.pumpAndSettle();
+
+        expect(find.text('Cached subject'), findsOneWidget);
+      },
+    );
+
     testWidgets('deleting all search results pops back to previous screen', (
       tester,
     ) async {