Add the FX reclaimer: a debounced, time-boxed convergence loop that offlines parked chains and restores returning ones off the switch path

src/app/CMakeLists.txt

@@ -39,6 +39,7 @@ add_library(reaper_reasampler MODULE
     ${LICE_SRC}
     ${REASAMPLER_SRC_DIR}/shell/capture/insert.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/view.cpp
+    ${REASAMPLER_SRC_DIR}/shell/view/fx_reclaim.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/view_lanes.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/view_park.cpp
     ${REASAMPLER_SRC_DIR}/shell/view/view_reconcile.cpp
@@ -72,6 +73,9 @@ target_include_directories(reaper_reasampler PRIVATE ${SDK_INC} ${WDL_INC})
 # has none — its TUs are compiled into this target directly.
 reasampler_test(view_park LINK view_mode_model)
 reasampler_test(view_reconcile LINK applied_state view_mode_model)
+# The reclaimer's drain loop is templated on its host for exactly this reason: the
+# ordering, budget, debounce and resume bookkeeping run against a fake chain.
+reasampler_test(fx_reclaim LINK fx_state)
 
 # Bank-package import: the promptless verb plus its action skin. Kept as its own
 # appended block rather than merged into the lists above, so the two package

src/app/main.cpp

@@ -38,6 +38,7 @@
 #include "shell/panel/panel_input.h"             // bankPanelRefresh / bankPanelNotifyProjectLoaded
 #include "shell/panel/panel_window.h"            // panel lifecycle (init/toggle/open-query/shutdown)
 #include "shell/persist/session.h"               // ReaSamplerSession
+#include "shell/view/fx_reclaim.h"               // the FX reclaimer's tick
 #include "shell/view/view.h"                     // applyMode
 #include "shell/view/view_lanes.h"               // reconcileManagedLanes
 #include "shell/view/view_reconcile.h"           // reconcileAppliedFlags
@@ -215,6 +216,15 @@ static void OnTimer()
         reasampler::applyMode(g_session.view(), g_session.view().activeModeId(), nullptr);
     }
 
+    // Converge the FX chains toward what the view state says they should be — the
+    // 1897ms of TrackFX_SetOffline a mode switch no longer pays synchronously. Same
+    // idle discipline as the realtime fast path above: a SINGLE BOOL TEST when there is
+    // nothing to converge. Ordered AFTER the load block deliberately — a reload replaces
+    // the view model wholesale, and the applyMode above is what re-derives the queue
+    // from it, so draining first would spend a tick against the outgoing model.
+    if (reasampler::g_fxReclaimPending)
+        reasampler::fxReclaimTick(g_session.view(), nullptr);
+
     reasampler::bankPanelRefresh();  // cheap fingerprint compare; no-op when unchanged/closed
 }