fix: defer uninstall to next restart when DLL is locked on Windows

pj_marketplace/include/pj_marketplace/extension_manager.hpp

@@ -21,7 +21,10 @@ class DownloadManager;
 //     DownloadManager, then registers the extension immediately
 //   - On Windows: extracts to a staging directory (.pending/) because in-use DLLs
 //     cannot be overwritten; the extension becomes active after the next restart
+//   - On Windows uninstall: if the directory cannot be removed (DLL still mapped),
+//     schedules it for deletion at the next startup via applyPendingUninstalls()
 //   - At startup: applies any pending staged installs via applyPendingInstalls()
+//     and deletes any directories deferred from a previous uninstall via applyPendingUninstalls()
 //   - Discovers installed extensions by scanning extensions_dir and reading manifest.json
 //
 // All constructor dependencies are injected, so tests can pass a DownloadManager stub
@@ -69,6 +72,11 @@ class ExtensionManager : public QObject {
   // because staging is never used, but it is safe to call on any platform.
   void applyPendingInstalls();
 
+  // Deletes any extension directories that could not be removed during a previous
+  // uninstall() because their DLL was still loaded (Windows only).
+  // Should be called once at application startup. Safe to call on any platform.
+  void applyPendingUninstalls();
+
   bool isInstalled(const QString& id) const;
 
   // Compares the registry version against the installed one using QVersionNumber,
@@ -90,6 +98,10 @@ class ExtensionManager : public QObject {
 
   void uninstallFinished(const QString& id, bool success);
   void uninstallError(const QString& id, const QString& error_message);
+  // Emitted on Windows when the extension is deregistered but its directory could not
+  // be removed (DLL still loaded). The directory will be deleted on the next startup
+  // via applyPendingUninstalls().
+  void uninstallPendingRestart(const QString& id);
 
  private:
   // Called by both constructors to finish setup after members are assigned.
@@ -99,6 +111,7 @@ class ExtensionManager : public QObject {
   void saveState();
   void disconnectDlConns();
   void savePendingMeta(const Extension& ext);
+  void schedulePendingUninstall(const QString& path);
 
   DownloadManager* downloader_ = nullptr;
   QString extensions_dir_;

pj_marketplace/src/core/ExtensionManager.cpp

@@ -41,6 +41,7 @@ void ExtensionManager::initComponents() {
 }
 
 static constexpr const char* kManifestFileName = "manifest.json";
+static constexpr const char* kPendingUninstallMarker = ".pj_pending_uninstall";
 
 // ---------------------------------------------------------------------------
 // Public interface
@@ -188,11 +189,17 @@ void ExtensionManager::uninstall(const QString& extension_id) {
   const QString dir_path = installed_[extension_id].path;
 
   if (!QDir(dir_path).removeRecursively()) {
-    // On Windows the DLL may still be mapped by the host process (F-14, staging deferred to April+).
-    // Report the error rather than corrupting the state file with a phantom entry.
-    emit uninstallError(
-        extension_id, QString("Could not remove directory \"%1\" — the plugin may still be loaded").arg(dir_path));
-    emit uninstallFinished(extension_id, false);
+    if (PlatformUtils::isWindows()) {
+      // The DLL is still mapped by the host process. Deregister the extension immediately
+      // and mark the directory for deletion at the next startup.
+      schedulePendingUninstall(dir_path);
+      installed_.remove(extension_id);
+      emit uninstallPendingRestart(extension_id);
+    } else {
+      emit uninstallError(
+          extension_id, QString("Could not remove directory \"%1\" — the plugin may still be loaded").arg(dir_path));
+      emit uninstallFinished(extension_id, false);
+    }
     return;
   }
 
@@ -283,6 +290,16 @@ void ExtensionManager::applyPendingInstalls() {
   }
 }
 
+void ExtensionManager::applyPendingUninstalls() {
+  const QDir dir(extensions_dir_);
+  for (const QFileInfo& entry : dir.entryInfoList(QDir::Dirs | QDir::NoDotAndDotDot)) {
+    if (!QFile::exists(entry.absoluteFilePath() + "/" + kPendingUninstallMarker)) {
+      continue;
+    }
+    QDir(entry.absoluteFilePath()).removeRecursively();
+  }
+}
+
 bool ExtensionManager::isInstalled(const QString& id) const {
   return installed_.contains(id);
 }
@@ -314,6 +331,11 @@ void ExtensionManager::disconnectDlConns() {
   disconnect(dl_cancelled_conn_);
 }
 
+void ExtensionManager::schedulePendingUninstall(const QString& path) {
+  QFile marker(path + "/" + kPendingUninstallMarker);
+  marker.open(QIODevice::WriteOnly);  // content irrelevant; existence is the signal
+}
+
 void ExtensionManager::savePendingMeta(const Extension& ext) {
   QJsonObject obj;
   obj["id"] = ext.id;

pj_marketplace/src/ui/marketplace_window.cpp

@@ -42,6 +42,7 @@ MarketplaceWindow::MarketplaceWindow(const QUrl& registry_url, QWidget* parent)
   setupUi();
   setupSignals();
   ext_mgr_->applyPendingInstalls();
+  ext_mgr_->applyPendingUninstalls();
   registry_mgr_->fetchRegistry(registry_url_);
   // extensions_ is now populated via the fetchFinished signal above.
 }
@@ -115,7 +116,15 @@ void MarketplaceWindow::setupSignals() {
           ui_->progress_bar_->setVisible(false);
           populateCards();
           setStatus("Extension staged — will be active after restart");
-   });   
+   });
+
+  connect(ext_mgr_, &ExtensionManager::uninstallPendingRestart, this,
+        [this](const QString& id) {
+          pending_restart_ids_.insert(id);
+          ui_->progress_bar_->setVisible(false);
+          populateCards();
+          setStatus("Extension staged — will be uninstalled after restart");
+   });
 
   connect(registry_mgr_, &RegistryManager::fetchError, this,
           [this](const QString& error) { setStatus("Registry error: " + error, true); });

pj_marketplace/tests/extension_manager_test.cpp

@@ -9,6 +9,7 @@
 //   [6] applyPendingInstalls: simulates the Windows post-restart staging path
 //   [7] State persistence: installed state derived from disk across manager restarts
 //   [8] Platform detection: currentPlatform() format and registry key resolution
+//   [9] applyPendingUninstalls: deferred directory cleanup via marker file
 
 #include <gtest/gtest.h>
 
@@ -665,6 +666,44 @@ TEST_F(ExtensionManagerTest, FreshManagerHasNoInstalledExtensions) {
   EXPECT_TRUE(mgr_->installedExtensions().isEmpty());
 }
 
+// ---------------------------------------------------------------------------
+// [9] applyPendingUninstalls — deferred directory cleanup simulation
+//
+// On Windows, uninstall() writes a .pj_pending_uninstall marker inside the
+// extension directory when removeRecursively() fails. On the next startup,
+// applyPendingUninstalls() removes every extension directory that carries that
+// marker. These tests create that state manually so the cleanup logic can be
+// verified on any platform.
+// ---------------------------------------------------------------------------
+
+// A directory containing the marker is removed by applyPendingUninstalls().
+TEST_F(ExtensionManagerTest, ApplyPendingUninstallsRemovesMarkedDirectory) {
+  const QString ext_path = ext_dir_.path() + "/csv-loader";
+  ASSERT_TRUE(QDir().mkpath(ext_path));
+  QFile marker(ext_path + "/.pj_pending_uninstall");
+  ASSERT_TRUE(marker.open(QIODevice::WriteOnly));
+  marker.close();
+
+  mgr_->applyPendingUninstalls();
+
+  EXPECT_FALSE(QDir(ext_path).exists());
+}
+
+// A directory without the marker is left untouched.
+TEST_F(ExtensionManagerTest, ApplyPendingUninstallsIgnoresUnmarkedDirectory) {
+  const QString ext_path = ext_dir_.path() + "/csv-loader";
+  ASSERT_TRUE(QDir().mkpath(ext_path));
+
+  mgr_->applyPendingUninstalls();
+
+  EXPECT_TRUE(QDir(ext_path).exists());
+}
+
+// applyPendingUninstalls() is a no-op when extensions_dir contains no sub-directories.
+TEST_F(ExtensionManagerTest, ApplyPendingUninstallsIsNoOpForEmptyDirectory) {
+  mgr_->applyPendingUninstalls();  // must not crash
+}
+
 // ---------------------------------------------------------------------------
 // [8] Platform detection
 // ---------------------------------------------------------------------------