Render in place: a track's output to a new sibling, source to the bench

src/core/capture/capture_paths.h

@@ -36,9 +36,29 @@ std::string normalizeSlashes(const std::string& path);
 // "capture" if nothing usable remains. Deterministic.
 std::string sanitizeStem(const std::string& baseName);
 
-// Derives the bank paths for one capture: baseName is the sanitized file-stem
-// source, uniqueTag an optional sanitized disambiguator (timestamp/counter) so
-// repeated captures don't collide. Produces "<stem>[_<tag>].wav".
+// Where one render writes, with no index spelling at all: the directory REAPER is
+// told to render into plus the stem/file name it produces there. `absoluteDir` is
+// taken as given (normalized only) rather than derived, because a render that never
+// enters the bank has no bank subfolder to append — the render-in-place verb points
+// this at the project's own recording path.
+struct RenderPaths {
+    std::string absoluteDir;   // RENDER_FILE   (forward slash, no trailing slash)
+    std::string fileName;      // <stem>.wav
+    std::string fileStem;      // <stem>        (RENDER_PATTERN — REAPER appends the extension)
+};
+
+// The file-stem spelling for one render: baseName is the sanitized file-stem source,
+// uniqueTag an optional sanitized disambiguator (timestamp/counter) so repeated
+// renders don't collide. Produces "<stem>[_<tag>].wav". THE one owner of that
+// spelling — deriveBankPaths is expressed over it, and bankRelativeForName depends
+// on the bank's spelling never drifting from it.
+RenderPaths deriveRenderPaths(const std::string& absoluteDir,
+                              const std::string& baseName,
+                              const std::string& uniqueTag);
+
+// Derives the bank paths for one capture: the same stem spelling as
+// deriveRenderPaths, in the bank subfolder, plus the project-relative path the
+// index stores.
 BankPaths deriveBankPaths(const std::string& projectDir,
                           const std::string& baseName,
                           const std::string& uniqueTag);