Ξ-W2-T1: the resample bake chain — instrument renders, extension banks, one click re-points and resets

src/core/instrument/bake/bake_plan.h

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+// bake_plan — the programmed note resolved against a concrete sample rate: the frame
+// window the offline pass renders, and the two event frames inside it.
+//
+// Separate from bake_render because the plan is what a preview and a bake must agree on;
+// the render is only one consumer of it.
+
+#pragma once
+
+#include <cstdint>
+#include <optional>
+
+#include "core/instrument/note/note_program.h"
+
+namespace reasampler::instrument::bake {
+
+// Until the capture-signal popup ships, the bake needs a program to render. A zero end
+// offset ends the capture exactly at note-off, which truncates every release — so the
+// default opens the window past the gate by this much.
+inline constexpr double kDefaultReleaseTailMs = 500.0;
+
+// The program a bake uses when nothing has been entered: one quarter note at the default
+// velocity, opening at note-on and closing kDefaultReleaseTailMs after the release starts.
+note::NoteProgram defaultBakeProgram();
+
+// The render window in frames. Frame 0 is the start of the captured file, NOT note-on:
+// a negative start offset opens the capture before the note, and noteOnFrame is where the
+// note actually lands inside it.
+struct BakePlan {
+    std::int64_t totalFrames = 0;
+    std::int64_t noteOnFrame = 0;   // in [0, totalFrames]
+    std::int64_t noteOffFrame = 0;  // in [noteOnFrame, totalFrames]
+    // The capture's root: rendering AT root is what makes the root survivable, which is
+    // why the root parameter is the one processing control a bake does not reset.
+    int note = 60;
+    int velocity = 100;
+    int sampleRate = 0;
+};
+
+// nullopt for a collapsed window, a non-positive rate, or a window that rounds to no
+// frames — a degenerate buffer is refused rather than rendered. `rootNote` and the
+// resolved velocity are clamped into MIDI range.
+std::optional<BakePlan> planBake(const note::ResolvedNote& resolved, int sampleRate,
+                                 int rootNote);
+
+}  // namespace reasampler::instrument::bake