Merge Insert as FX: load ReaSampler 9000 onto the selected track from the panel

# Conflicts:
#	src/shell/actions/CLAUDE.md

src/shell/panel/CLAUDE.md

@@ -10,8 +10,8 @@ VST3 editor (`shell/instrument/`).
 
 Pure layout/hit-test/palette modules the panel draws through (`theme`,
 `component_geometry`, `bank_grid`, `tab_strip`, `mode_switch`, `action_bar`,
-`footer_bar`, `overflow_menu`, `prune_button`, `mode_enable`, `tooltip`, `card_drag`,
-`card_meta`) live in `core/ui` / `core/model` and are documented there — this
+`footer_bar`, `overflow_menu`, `prune_button`, `mode_enable`, `insert_fx_enable`,
+`tooltip`, `card_drag`, `card_meta`) live in `core/ui` / `core/model` and are documented there — this
 directory consumes them but does not own them. The promptless bank-mutation verbs
 (`bankOpCreate`/`Rename`/`Delete`/… + `persistBankOp`) that `panel_bank_ops` skins
 live in `shell/bank_ops`, a sibling directory, not here.

src/shell/panel/panel_layout.cpp

@@ -128,6 +128,17 @@ std::vector<ActionBarRow> topBarRows() {
     rows.push_back({"INSERT_SELECTED_CONFORM", "Insert Conform",
                     "insert selected sample at edit cursor (conform to tempo)",
                     ActionCluster::Placement, true});
+    // The one top-bar row with a live/dead gate: it places the PLAYER, and one instance
+    // holds one capture. Only the payload half of the fold is knowable at draw time —
+    // core/ui/insert_fx_enable.h states why the track half stays a press-time message.
+    // Counts through focusedSelectionIds() (not the raw selection) so the drawn state
+    // can't diverge from doInsertAsFx's own count — the raw selection can go stale
+    // against live membership (e.g. an undo/redo book restore) without being cleared.
+    rows.push_back({"LOAD_INSTRUMENT_ON_TRACK", "Insert as FX",
+                    "insert selected sample as ReaSampler 9000 on the selected track",
+                    ActionCluster::Placement,
+                    insertFxButtonEnabled(
+                        static_cast<int>(focusedSelectionIds().size()))});
     return rows;
 }
 
@@ -268,12 +279,27 @@ bool currentTooltip(int w, int h, std::string& textOut, int& ax, int& ay, int& a
         if (s.index == hv.index) { slot = &s; break; }
     if (!slot) return false;
 
+    const ActionBarRow& row = rows[static_cast<std::size_t>(hv.index)];
+
+    // Insert as FX paints dead only for the payload axis (NoCapture/MultiCapture);
+    // speak that refusal here rather than the generic phrase, so a dead button says
+    // WHY. NoTrack stays a press-time message (insert_fx_enable.h: track selection
+    // has no change callback, so it is only ever knowable at press time).
+    if (row.suffix == "LOAD_INSTRUMENT_ON_TRACK" && !row.enabled) {
+        const InsertFxRefusal refusal =
+            insertFxRefusal(static_cast<int>(focusedSelectionIds().size()), /*trackSelected=*/true);
+        if (refusal != InsertFxRefusal::None) {
+            textOut = insertFxRefusalMessage(refusal);
+            ax = slot->x; ay = slot->y; aw = slot->width; ah = slot->height;
+            return true;
+        }
+    }
+
     // fullName is stored prefix-free; strip defensively in case a source ever
     // carries the display prefix. Tooltip carries name + binding when bound
     // (e.g. "capture selected item — F5"), name only when unbound.
-    const std::string phrase = stripActionPrefix(rows[static_cast<std::size_t>(hv.index)].fullName,
-                                                 actionDisplayPrefix());
-    const int cmd = resolveBarCommandId(rows[static_cast<std::size_t>(hv.index)]);
+    const std::string phrase = stripActionPrefix(row.fullName, actionDisplayPrefix());
+    const int cmd = resolveBarCommandId(row);
     const std::string binding = barBindingText(cmd);
     textOut = binding.empty() ? phrase : phrase + " \xe2\x80\x94 " + binding;  // " — " (em dash, UTF-8)
     ax = slot->x; ay = slot->y; aw = slot->width; ah = slot->height;

src/shell/panel/panel_state.h

@@ -41,6 +41,7 @@
 #include "core/ui/component_geometry.h"
 #include "core/ui/drag_out.h"
 #include "core/ui/footer_bar.h"
+#include "core/ui/insert_fx_enable.h"
 #include "core/ui/mode_enable.h"
 #include "core/ui/overflow_menu.h"
 #include "core/ui/prune_button.h"
@@ -134,6 +135,10 @@ using ui::hitTestMenuButton;
 using ui::hitTestPruneButton;
 using ui::hitTestSlot;
 using ui::hitTestTabStrip;
+using ui::insertFxButtonEnabled;
+using ui::insertFxRefusal;
+using ui::insertFxRefusalMessage;
+using ui::InsertFxRefusal;
 using ui::kCardNameScrimAlpha;
 using ui::kCardStripHeight;
 using ui::kCardStripPad;
@@ -420,8 +425,9 @@ struct ActionBarRow {
     std::string shortLabel;
     std::string fullName;
     ActionCluster cluster = ActionCluster::Capture;
-    bool enabled = true;  // opposite-mode gate for bottom-bar tag buttons; always true
-                          // for the top bar (unconditional triggers)
+    bool enabled = true;  // opposite-mode gate for the bottom-bar tag buttons, and the
+                          // payload gate for the top bar's Insert as FX; every other top-
+                          // bar row is an unconditional trigger and stays true
 };
 
 // Modifier state at event time. Alt = the replace modifier.