Gate the FX reclaimer on the transport, both directions; move the release's persist off the drain and onto the project save

The drain no longer dirties a project on its own initiative — a spent park record rides the user's next save via OnSaveExtensionConfig.

src/app/main.cpp

@@ -250,18 +250,25 @@ static void OnBeginLoadProjectState(bool isUndo, project_config_extension_t* /*r
         g_session.requestReload();
 }
 
-// Intentional no-ops: ReaSampler stores state via project EXT STATE, not this
-// extension's own project lines. The struct is registered ONLY for the
-// BeginLoadProjectState undo/redo notification.
+// Intentional no-op: ReaSampler stores state via project EXT STATE, not this
+// extension's own project lines.
 static bool OnProcessExtensionLine(const char* /*line*/, ProjectStateContext* /*ctx*/,
                                    bool /*isUndo*/, project_config_extension_t* /*reg*/)
 {
     return false;  // we own no project lines — ext state carries our data
 }
 
-static void OnSaveExtensionConfig(ProjectStateContext* /*ctx*/, bool /*isUndo*/,
+// We write no lines into `ctx` — this is the FX reclaimer's one durability point. Its
+// spent park records ride the user's save rather than dirtying the project on the
+// reclaimer's own initiative (fx_reclaim.h's ReleaseFlush).
+//
+// A save only: an isUndo pass is REAPER capturing an undo point, not writing the file,
+// and clearing the pending flush on one would leave the record unspent on disk for good.
+static void OnSaveExtensionConfig(ProjectStateContext* /*ctx*/, bool isUndo,
                                   project_config_extension_t* /*reg*/)
 {
+    if (!isUndo)
+        reasampler::fxReclaimFlushRelease(g_session);
 }
 
 // Storage must outlive registration — REAPER holds this pointer until we unregister it.