Ξ-W2-T1 remediation: print master gain into the bake, derive the window from the dialed sound, reset play mode to Trigger

src/shell/instrument/reasampler_processor.h

@@ -11,6 +11,7 @@
 #include <cstdint>
 #include <memory>
 #include <mutex>
+#include <optional>
 #include <string>
 #include <vector>
 
@@ -130,9 +131,9 @@ public:
 
     // Adopt a landed bake in ONE act: the new capture becomes this instance's ref and
     // selection, the parameter set and master gain go neutral, and a single reload
-    // publishes both together. The ordering is the whole point — a reset published ahead
-    // of the re-point would put neutral parameters under the OLD capture for a block.
-    // UI thread only.
+    // publishes all three together. The ordering is the whole point — anything published
+    // ahead of the re-point would apply neutral settings to the OLD capture, which is the
+    // one thing they are meaningless against. UI thread only.
     void adoptBakedCapture(const SampleRefEntry& entry, const InstrumentParams& reset,
                            double masterGainLinear);
 
@@ -304,6 +305,10 @@ private:
     std::atomic<std::uint64_t> drainIdleGeneration_{0};
     std::vector<std::unique_ptr<LoadedInstrument>> graveyard_;  // drained on reclaim + setActive(false) + terminate
     std::mutex reloadMutex_;  // serializes off-thread reloads + graveyard access
+    // A master gain that must reach the audio thread in the SAME swap as the next publish —
+    // the bake's reset, which the old capture would be the wrong thing to apply it to.
+    // Guarded by reloadMutex_, consumed by publishBuiltLocked.
+    std::optional<double> gainAtNextPublish_;
 
     // The loaded capture's id ("" = no pick -> silence). Off-thread only, not read on the
     // audio thread.