Q-W1 pt2: core/shell/app relocation + sub-namespaces; one concrete ui::Rect (LTRB fork retired); slot_map split from bank_book; BankIndex→BankModel; 59/59 green

src/core/instrument/map/bridge_marshal.h

@@ -0,0 +1,37 @@
+// bridge_marshal.h — PURE marshalling helper for the REAPER VST-host bridge read.
+// NO VST3, NO REAPER types at the boundary.
+//
+// The bridge shell (reaper_bridge.cpp) resolves REAPER API functions by name over the
+// host callback and invokes them; the one fiddly-and-easy-to-get-wrong part around
+// GetProjExtState — interpreting its int return against the buffer it filled — is pure
+// and unit-tested here. Mirror of capture_paths / wav_trim splitting the arithmetic out
+// of a REAPER-facing shell.
+//
+// The S1 spike ALSO carried a string-scan JSON reader (extractJsonStringField) as a
+// stand-in until the instrument could parse the bank properly. S4 retired it: the
+// instrument now parses the "reasampler" bank blob through the SHARED bank_book /
+// bank_model JSON path (sample_map.cpp), so there is no second JSON parser. This module
+// is back to its one honest job — the API-return decode.
+//
+// Verified against vendor/reaper-sdk/sdk/reaper_plugin_functions.h:
+//   int  GetProjExtState (ReaProject*, extname, key, valOutNeedBig, valOutNeedBig_sz);
+//        -- returns the length written (0 when the key is absent).
+
+#pragma once
+
+#include <optional>
+#include <string>
+
+namespace reasampler::instrument::map {
+
+// Interpret a GetProjExtState result: the int return value (bytes the API reports for
+// the key) and the buffer it filled. Returns the value only when the API reported a
+// non-empty result AND the buffer is non-empty — REAPER writes 0 and leaves the buffer
+// untouched for an absent key, and we must not treat stale buffer contents as a hit.
+//
+// `apiReturn` is GetProjExtState's return; `buffer` is the NUL-terminated string it
+// wrote (already truncated to the C string by the caller).
+std::optional<std::string> decodeGetProjExtState(int apiReturn,
+                                                  const std::string& buffer);
+
+}  // namespace reasampler::instrument::map