fx_reclaim: use GetCurrentProjectInLoadSave for the save hook, stop disarming ReleaseFlush on one write, validate project before cached-track lookup

src/shell/persist/session.h

@@ -31,6 +31,9 @@
 #include "core/version/app_version.h"
 #include "core/view/view_mode_model.h"
 
+// Forward-declared to keep this header SDK-free; the .cpp includes the real SDK header.
+class ReaProject;
+
 namespace reasampler {
 
 // Owns the session's BankBook (pool + named banks) and drives persistence
@@ -147,9 +150,12 @@ public:
     // The same write with the dirty mark OMITTED, for a caller already inside REAPER's
     // own project save: marking dirty there would leave the project modified the instant
     // it was saved, which is the whole reason that caller exists (fx_reclaim's
-    // ReleaseFlush). Not a general-purpose sibling — a mutation site that skips the dirty
-    // mark silently loses its write when the user closes without saving.
-    bool flushViewState();
+    // ReleaseFlush). `project` is the SAVING project the caller resolved (e.g. via
+    // GetCurrentProjectInLoadSave()) — this call trusts it rather than re-deriving the
+    // active tab, which is exactly the mismatch fx_reclaim's caller exists to avoid. Not
+    // a general-purpose sibling — a mutation site that skips the dirty mark silently
+    // loses its write when the user closes without saving.
+    bool flushViewState(ReaProject* project);
 
     // Report-only prune dry-run: feeds the pure core with (present, referenced,
     // owned) — `present` from the folder enumeration, the other two from the