fix: IMAP FETCH timeout and tagged response detection

- sendCommandWaitBytes(): check for tagged response (OK/NO/BAD) BEFORE parsing literals
- Fixed detection of 'A0001 OK ...' responses that were being missed
- Added debug logging on failure for easier troubleshooting
- Increased FETCH timeout from 30s to 120s for large emails with attachments
- Applied same 120s timeout to single UID fallback fetches

src/services/imap/imapconnection.cpp

@@ -168,6 +168,18 @@ bool ImapConnection::sendCommandWaitBytes(const QString &command, QByteArray &re
             const int lineEnd = buffer.indexOf("\r\n", pos);
             if (lineEnd < 0) break;
             const QByteArray line = buffer.mid(pos, lineEnd - pos);
+            
+            // Check for tagged response FIRST (before literal parsing)
+            // Tagged responses: "A0001 OK ...", "A0001 NO ...", "A0001 BAD ..."
+            if (line.startsWith(tagBytes + QByteArrayLiteral(" OK ")) ||
+                line.startsWith(tagBytes + QByteArrayLiteral(" NO ")) ||
+                line.startsWith(tagBytes + QByteArrayLiteral(" BAD ")) ||
+                line.startsWith(tagBytes + QByteArrayLiteral(" "))) {
+                complete = true;
+                loop.quit();
+                break;
+            }
+
             const int open = line.lastIndexOf('{');
             QByteArray literalSize = open >= 0 && line.endsWith('}')
                 ? line.mid(open + 1, line.size() - open - 2) : QByteArray();
@@ -183,11 +195,6 @@ bool ImapConnection::sendCommandWaitBytes(const QString &command, QByteArray &re
                 if (buffer.mid(pos, 2) == QByteArrayLiteral("\r\n")) pos += 2;
                 continue;
             }
-            if (line.startsWith(tagBytes + QByteArrayLiteral(" "))) {
-                complete = true;
-                loop.quit();
-                break;
-            }
             pos = lineEnd + 2;
         }
     };
@@ -212,6 +219,15 @@ bool ImapConnection::sendCommandWaitBytes(const QString &command, QByteArray &re
     m_readyReadConnection = connect(m_socket, &QSslSocket::readyRead, this, &ImapConnection::onReadyRead);
 
     response = buffer;
+    
+    // Debug: log if failed
+    if (timedOut || !complete) {
+        qWarning() << "IMAP command failed:" << command.left(100)
+                   << "- timedOut:" << timedOut
+                   << "- complete:" << complete
+                   << "- response size:" << buffer.size()
+                   << "- last 200 chars:" << QString::fromUtf8(buffer.right(200));
+    }
     if (timedOut || !complete) return false;
     return true;
 }

src/services/imap/imapsynchronizer.cpp

@@ -369,7 +369,8 @@ QVector<MailItem> ImapSynchronizer::fetchMailItems(const QString& folderId, qint
         QString fetchCommand = QString("UID FETCH %1 (BODY.PEEK[] FLAGS INTERNALDATE)")
                                    .arg(batchList);
         QByteArray fetchResponse;
-        if (!conn.sendCommandWaitBytes(fetchCommand, fetchResponse, 30000)) {
+        // Increase timeout to 120s for large emails with attachments
+        if (!conn.sendCommandWaitBytes(fetchCommand, fetchResponse, 120000)) {
             qWarning() << "FETCH failed for batch" << i << "(" << batch.size() << "UIDs)"
                        << "- first UID:" << batch.first() << "last UID:" << batch.last()
                        << "- response:" << QString::fromUtf8(fetchResponse).left(200);
@@ -377,7 +378,7 @@ QVector<MailItem> ImapSynchronizer::fetchMailItems(const QString& folderId, qint
             for (qint64 uid : batch) {
                 QString singleFetchCmd = QString("UID FETCH %1 (BODY.PEEK[] FLAGS INTERNALDATE)").arg(uid);
                 QByteArray singleResponse;
-                if (conn.sendCommandWaitBytes(singleFetchCmd, singleResponse, 30000)) {
+                if (conn.sendCommandWaitBytes(singleFetchCmd, singleResponse, 120000)) {
                     QVector<MailItem> singleItems = parseFetchResponseBytes(singleResponse);
                     for (MailItem& item : singleItems) {
                         item.setFolderId(fid);