test: verify sync errors always appear in the sync log

Add _CapturingSyncLogRepository and two tests (IMAP + JMAP) that assert
a failed sync cycle produces an error entry in the sync log. Also
replace .ignore() in the catch blocks with a proper try-catch so the
sync log write is genuinely attempted and any secondary failure is
logged to stdout rather than silently dropped.

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

lib/core/sync/account_sync_manager.dart

@@ -140,21 +140,23 @@ class _AccountSync implements _SyncLoop {
         await _idle();
         _backoffSeconds = 5;
       } catch (e, st) {
-        _syncLog
-            .log(
-              accountId: account.id,
-              success: false,
-              errorMessage: e.toString(),
-              protocol: 'imap',
-              emailsFetched: 0,
-              emailsSkipped: 0,
-              mailboxesSynced: 0,
-              pendingFlushed: 0,
-              bytesTransferred: 0,
-              startedAt: startedAt,
-              finishedAt: DateTime.now(),
-            )
-            .ignore();
+        try {
+          await _syncLog.log(
+            accountId: account.id,
+            success: false,
+            errorMessage: e.toString(),
+            protocol: 'imap',
+            emailsFetched: 0,
+            emailsSkipped: 0,
+            mailboxesSynced: 0,
+            pendingFlushed: 0,
+            bytesTransferred: 0,
+            startedAt: startedAt,
+            finishedAt: DateTime.now(),
+          );
+        } catch (logErr) {
+          log('Failed to write IMAP sync log entry: $logErr');
+        }
         log(
           'Sync failed for ${account.email}, retrying in ${_backoffSeconds}s',
           error: e,
@@ -286,21 +288,23 @@ class _JmapAccountSync implements _SyncLoop {
         _backoffSeconds = 5;
         await _wait();
       } catch (e, st) {
-        _syncLog
-            .log(
-              accountId: account.id,
-              success: false,
-              errorMessage: e.toString(),
-              protocol: 'jmap',
-              emailsFetched: 0,
-              emailsSkipped: 0,
-              mailboxesSynced: 0,
-              pendingFlushed: 0,
-              bytesTransferred: 0,
-              startedAt: startedAt,
-              finishedAt: DateTime.now(),
-            )
-            .ignore();
+        try {
+          await _syncLog.log(
+            accountId: account.id,
+            success: false,
+            errorMessage: e.toString(),
+            protocol: 'jmap',
+            emailsFetched: 0,
+            emailsSkipped: 0,
+            mailboxesSynced: 0,
+            pendingFlushed: 0,
+            bytesTransferred: 0,
+            startedAt: startedAt,
+            finishedAt: DateTime.now(),
+          );
+        } catch (logErr) {
+          log('Failed to write JMAP sync log entry: $logErr');
+        }
         log(
           'JMAP sync failed for ${account.email}, retrying in ${_backoffSeconds}s',
           error: e,

test/unit/account_sync_manager_test.dart

@@ -9,6 +9,7 @@ import 'package:sharedinbox/core/models/mailbox.dart';
 import 'package:sharedinbox/core/repositories/account_repository.dart';
 import 'package:sharedinbox/core/repositories/email_repository.dart';
 import 'package:sharedinbox/core/repositories/mailbox_repository.dart';
+import 'package:sharedinbox/core/repositories/sync_log_repository.dart';
 import 'package:sharedinbox/core/sync/account_sync_manager.dart';
 
 // ── Fakes ─────────────────────────────────────────────────────────────────────
@@ -184,6 +185,45 @@ class FailingJmapEmailRepository extends FakeEmailRepository {
   }
 }
 
+class _CapturingSyncLogRepository implements SyncLogRepository {
+  final List<SyncLogEntry> entries = [];
+
+  @override
+  Future<void> log({
+    required String accountId,
+    required bool success,
+    String? errorMessage,
+    required String protocol,
+    required int emailsFetched,
+    required int emailsSkipped,
+    required int mailboxesSynced,
+    required int pendingFlushed,
+    required int bytesTransferred,
+    required DateTime startedAt,
+    required DateTime finishedAt,
+  }) async {
+    entries.add(
+      SyncLogEntry(
+        id: entries.length,
+        result: success ? 'ok' : 'error',
+        errorMessage: errorMessage,
+        protocol: protocol,
+        emailsFetched: emailsFetched,
+        emailsSkipped: emailsSkipped,
+        mailboxesSynced: mailboxesSynced,
+        pendingFlushed: pendingFlushed,
+        bytesTransferred: bytesTransferred,
+        startedAt: startedAt,
+        finishedAt: finishedAt,
+      ),
+    );
+  }
+
+  @override
+  Stream<List<SyncLogEntry>> observeSyncLogs(String accountId) =>
+      Stream.value(List.of(entries));
+}
+
 // ── Tests ─────────────────────────────────────────────────────────────────────
 
 void main() {
@@ -349,5 +389,57 @@ void main() {
         async.flushMicrotasks();
       });
     });
+
+    group('sync errors are visible in the sync log', () {
+      test('IMAP sync failure writes an error entry to the sync log', () {
+        fakeAsync((async) {
+          final accounts = FakeAccountRepository();
+          final syncLog = _CapturingSyncLogRepository();
+          final mgr = AccountSyncManager(
+            accounts,
+            FailingMailboxRepository(),
+            FakeEmailRepository(),
+            syncLog: syncLog,
+          );
+          mgr.start();
+          accounts.push([_account]);
+          async.flushMicrotasks();
+
+          expect(syncLog.entries, hasLength(1));
+          expect(syncLog.entries.first.isOk, isFalse);
+          expect(syncLog.entries.first.errorMessage, isNotEmpty);
+          expect(syncLog.entries.first.protocol, 'imap');
+
+          mgr.dispose();
+          async.elapse(const Duration(seconds: 10));
+          async.flushMicrotasks();
+        });
+      });
+
+      test('JMAP sync failure writes an error entry to the sync log', () {
+        fakeAsync((async) {
+          final accounts = FakeAccountRepository();
+          final syncLog = _CapturingSyncLogRepository();
+          final mgr = AccountSyncManager(
+            accounts,
+            FakeMailboxRepositoryWithInbox(),
+            FailingJmapEmailRepository(),
+            syncLog: syncLog,
+          );
+          mgr.start();
+          accounts.push([_jmapAccount]);
+          async.flushMicrotasks();
+
+          expect(syncLog.entries, hasLength(1));
+          expect(syncLog.entries.first.isOk, isFalse);
+          expect(syncLog.entries.first.errorMessage, isNotEmpty);
+          expect(syncLog.entries.first.protocol, 'jmap');
+
+          mgr.dispose();
+          async.elapse(const Duration(seconds: 10));
+          async.flushMicrotasks();
+        });
+      });
+    });
   });
 }