fix(bank_panel): drive new-content baseline re-arm from persist's load signal

The detector re-armed its GuidBaseline on a pointer compare (proj != lastProject),
a weaker signal than persist's GUID-primary identity. On a load onto a recycled
ReaProject* the baseline never reset, so the just-loaded project's pre-existing
tracks diffed against the previous project and were mass-tagged into the active
mode — opening a Design-saved project mis-tagged its Arrange tracks. Re-arm now
rides persist's authoritative load signal via bankPanelNotifyProjectLoaded().

src/bank_panel.cpp

@@ -227,15 +227,26 @@ struct PanelState {
     //
     // Each timer tick diffs the live track+item GUID set against the previous tick to
     // auto-tag content created SINCE the last tick into the then-active mode. The
-    // baseline carries the first-poll-after-open guard so pre-existing content is never
-    // mass-tagged (it stays Arrange). `lastProject` detects a project switch so the
-    // baseline re-arms per project (a switch never diffs across two projects). Both live
-    // for the extension's lifetime alongside the session, independent of panel open/close
-    // — detection must run whether or not the dock is visible (content is created in the
-    // arrange, not the panel).
+    // baseline carries the first-poll-after-open guard (GuidBaseline self-arms on its
+    // first observe()) so pre-existing content is never mass-tagged (it stays Arrange).
+    //
+    // Project-load re-arm is driven by persist's AUTHORITATIVE load lifecycle, NOT by a
+    // pointer compare here. main.cpp calls bankPanelNotifyProjectLoaded() on the exact
+    // tick persist restores a project's membership + active mode (the same tick it
+    // reapplies the active mode); that sets reloadPending so the NEXT detect tick this
+    // same tick re-baselines against the fully-loaded set and reports nothing new. This
+    // replaces the former `proj != lastProject` re-arm, which used a WEAKER signal than
+    // persist (pointer-only vs persist's GUID-primary identity) and so missed a load onto
+    // a RECYCLED ReaProject* address — the just-loaded project's pre-existing tracks then
+    // diffed against the previous project's stale baseline and were mass-tagged into the
+    // active mode (the reload-mis-tag bug). Coordinating with persist's signal makes the
+    // two identity checks agree by construction.
+    //
+    // Lives for the extension's lifetime alongside the session, independent of panel
+    // open/close — detection must run whether or not the dock is visible (content is
+    // created in the arrange, not the panel).
     GuidBaseline contentBaseline;
-    ReaProject*  lastProject = nullptr;
-    bool         sawProject = false;  // false until the first detect tick sees a project
+    bool         reloadPending = false;  // set by bankPanelNotifyProjectLoaded; drained next detect tick
 };
 
 PanelState g_panel;
@@ -714,14 +725,19 @@ void detectNewContent() {
 
     ReaProject* proj = EnumProjects(-1, nullptr, 0);
 
-    // Project switch (or first ever tick) re-arms the first-poll guard so we never diff
-    // across two projects. GUID-address recycling is bounded here: a missed reset can at
-    // worst re-baseline against the wrong project for one tick; the identity-of-record
-    // (persist's minted project GUID) governs the bank/model reload, not this detector.
-    if (!g_panel.sawProject || proj != g_panel.lastProject) {
+    // A project (re)load re-arms the first-poll guard so we never diff across two
+    // projects. The signal is persist's — main.cpp calls bankPanelNotifyProjectLoaded()
+    // on the tick persist restores the project's membership + active mode, which sets
+    // reloadPending. Draining it here re-baselines against the fully-loaded set (that
+    // same tick's reapply-active-mode enumerated those tracks, so they are present),
+    // and the observe() below returns nothing new — pre-existing untagged tracks stay
+    // Arrange. GuidBaseline self-arms on its first observe() for the very first tick, so
+    // no separate first-tick handling is needed here. Using persist's GUID-primary load
+    // signal (not a local pointer compare) is what fixes the reload-mis-tag: the two
+    // identity checks can no longer diverge on a recycled ReaProject* address.
+    if (g_panel.reloadPending) {
         g_panel.contentBaseline.reset();
-        g_panel.lastProject = proj;
-        g_panel.sawProject = true;
+        g_panel.reloadPending = false;
     }
 
     std::set<std::string> live;
@@ -1141,6 +1157,18 @@ std::vector<std::string> bankPanelSelectedSampleIds() {
     return ids;
 }
 
+void bankPanelNotifyProjectLoaded() {
+    // Persist restored a project's membership + active mode this tick (main.cpp calls
+    // this from the same consumeLoadSignal() branch that reapplies the active mode).
+    // Arm the new-content detector to re-baseline on its next tick so the just-loaded
+    // project's pre-existing content is treated as the baseline (nothing new) rather
+    // than diffed against the previous project and mass-tagged into the active mode.
+    // A flag (not an inline reset) because detectNewContent owns the baseline and runs
+    // later in the SAME OnTimer tick — it drains this and re-baselines against the live
+    // set in one place, keeping the reset and the observe() adjacent and ordered.
+    g_panel.reloadPending = true;
+}
+
 void bankPanelRefresh() {
     // New-content auto-tag detection runs EVERY tick regardless of panel open/close:
     // tracks/items are created in the arrange view, not the panel, so detection must