Bake window: derived note lengths carry exact durations, not ladder rungs — a long take is no longer cut at 384 beats

Hold keeps its picker. Also: one home for the %-fold, duration-ordered Hold travel, and a corrupt tail degrades to absent rather than fabricating one.

src/shell/instrument/reasampler_editor.h

@@ -342,9 +342,22 @@ private:
 
     // Whether the loaded sound's bake window needs the user's Hold — the pure predicate
     // (bake_plan.h) answered against the markers this face is showing. Decodes and reads the
-    // bank, so it is called on the sync tick, not per paint.
+    // bank, so it is called on the sync tick, not per paint, and memoized against the inputs
+    // below on top of that.
     bool resolveBakeHoldNeeded();
 
+    // What that answer was last computed against. Invalidated wholesale by refreshFromBank,
+    // which is where the bank half of the input changes.
+    struct HoldNeedKey {
+        std::string sampleId;
+        std::optional<SampleLoop> loopOverride;
+        std::int64_t crossfade = 0;
+        bool operator==(const HoldNeedKey& other) const;
+    };
+    HoldNeedKey holdNeedKey_;
+    bool holdNeedValid_ = false;
+    bool holdNeedAnswer_ = false;
+
     // Writes `m` into params_ as the loop/start override. Does NOT call commitAndReload —
     // callers decide live-drag vs final commit.
     void applyMarkers(const SetupMarkers& m);