Ω-W1-T3 review fixes: skip meter invalidate when covered; push fast-path predicates into core

Fixes the critical finding — Browse/curve-popup no longer trigger 60 Hz
whole-client repaints when the meter is invisible. Pushes the fast-path and
self-containment geometry into master_meter with tests; batches the four minor
findings.

src/shell/instrument/reasampler_editor.h

@@ -1,9 +1,8 @@
 // reasampler_editor.h — VST3 IPlugView LICE editor for the ReaSampler 9000 UI. Thin shell:
-// hosts a LICE child window, routing host paint/mouse into the pure geometry modules
-// (sample_bands, sample_chrome, capture_browser, keyboard_strip, sample_map). The Sample
-// face is a three-band stack — chrome, waveform, decks — and the shell TUs split on that
-// same axis; Browse is a modal picker over it. All layout/hit-test/drag math lives in the
-// pure modules; every edit commits off the audio thread via reloadInstrument.
+// hosts a LICE child window, routing host paint/mouse into the pure geometry modules. The
+// Sample face is a three-band stack — chrome, waveform, decks — and the shell TUs split on
+// that same axis; Browse is a modal picker over it. All layout/hit-test/drag math lives in
+// the pure modules; every edit commits off the audio thread via reloadInstrument.
 
 #pragma once
 
@@ -65,6 +64,9 @@ public:
     // always supplies one).
     explicit ReaSamplerEditor(ReaSamplerProcessor* processor);
     ~ReaSamplerEditor() override;
+    // backBuffer_ owns a raw LICE bitmap with no refcount behind it — a copy would double-free.
+    ReaSamplerEditor(const ReaSamplerEditor&) = delete;
+    ReaSamplerEditor& operator=(const ReaSamplerEditor&) = delete;
 
     Steinberg::tresult PLUGIN_API isPlatformTypeSupported(
         Steinberg::FIDString type) override;
@@ -302,8 +304,8 @@ private:
     struct ChannelPcm {
         std::vector<AudioSample> interleaved;  // frame-interleaved source frames
         int channelCount = 0;                  // 0 = nothing decoded
-        Envelope heroEnv;         // binned from `interleaved`, so every path that drops the
-        std::size_t heroBins = 0; // decode drops it too. 0 = not computed
+        Envelope heroEnv;          // binned from `interleaved`; cleared whenever it is
+        std::size_t heroBins = 0;  // 0 = not computed
         std::int64_t frameCount() const {
             return channelCount > 0
                        ? static_cast<std::int64_t>(interleaved.size()) / channelCount
@@ -467,9 +469,7 @@ private:
     // up. One note at a time — a fresh press releases the prior.
     int previewingNote_ = -1;
 
-    // Resample bake. The click only ARMS it; the sync tick runs it. Running it inline
-    // would nest a synchronous REAPER action — which re-points this very instance — inside
-    // a mouse handler with the capture held.
+    // Resample bake — the click only ARMS it (see this directory's CLAUDE.md Gotchas for why).
     bool bakePending_ = false;
     // Whether the extension's bake action is registered, resolved on the same tick that
     // governs the button's paint, so the control is never enabled and then refusing.
@@ -494,8 +494,8 @@ private:
     // The MASTER deck's meter, advanced from the published block magnitudes on its own timer
     // (see onMeterTimer for why it runs mid-drag too, and why the first read is discarded).
     // A default-constructed meterTick_ means never ticked. meterRects_ is the column interior
-    // resolved at the last FULL paint; an empty field means "not on screen" (no layout yet, the
-    // empty state, a modal sheet over it) and sends the tick down the whole-client path.
+    // resolved at the last FULL paint; an empty field is ambiguous alone (no layout yet, or
+    // genuinely off screen) — invalidateMeter asks view_/curvePopup_/selectedId_ to tell which.
     instrument::ui::MasterMeterUi masterMeter_;
     std::chrono::steady_clock::time_point meterTick_{};
     instrument::ui::MeterRects meterRects_;