Fix webcache download loop and reject malformed paths

- Track failed downloads to avoid retrying them infinitely within a session
- Reject paths containing absolute paths (starting with /, containing //, or :/)
  to prevent malformed URLs like "evidence//Users/..."

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: OmniTroid

src/webcache.cpp

@@ -70,6 +70,13 @@ void WebCache::resolveOrDownload(const QString &relativePath, const QStringList
     return;
   }
 
+  // Reject paths containing absolute paths (they shouldn't be passed to webcache)
+  // Check for Unix absolute paths embedded anywhere, or Windows drive letters
+  if (relativePath.startsWith('/') || relativePath.contains("//") || relativePath.contains(":/"))
+  {
+    return;
+  }
+
   // Check if webcache is enabled
   if (!Options::getInstance().webcacheEnabled())
   {
@@ -95,6 +102,12 @@ void WebCache::resolveOrDownload(const QString &relativePath, const QStringList
     return;
   }
 
+  // Check if this path previously failed (don't retry within this session)
+  if (m_failed_downloads.contains(relativePath))
+  {
+    return;
+  }
+
   // Try each suffix
   for (const QString &suffix : suffixes)
   {
@@ -140,6 +153,7 @@ void WebCache::onDownloadFinished(QNetworkReply *reply)
   if (reply->error() != QNetworkReply::NoError)
   {
     qDebug() << "WebCache: Download failed for" << reply->url().toString() << "-" << reply->errorString();
+    m_failed_downloads.insert(relativePath);
     reply->deleteLater();
     return;
   }
@@ -149,6 +163,7 @@ void WebCache::onDownloadFinished(QNetworkReply *reply)
   if (statusCode != 200)
   {
     qDebug() << "WebCache: Download returned status" << statusCode << "for" << reply->url().toString();
+    m_failed_downloads.insert(relativePath);
     reply->deleteLater();
     return;
   }

src/webcache.h

@@ -6,6 +6,7 @@
 #include <QNetworkAccessManager>
 #include <QNetworkReply>
 #include <QObject>
+#include <QSet>
 #include <QString>
 #include <QVector>
 
@@ -66,6 +67,9 @@ private Q_SLOTS:
   // Key: relative path, Value: list of suffixes being tried
   QHash<QString, bool> m_pending_downloads;
 
+  // Track failed downloads to avoid retrying them repeatedly
+  QSet<QString> m_failed_downloads;
+
   /**
    * @brief Initiates an async download for the given remote URL.
    * @param remoteUrl The full URL to download from.