Ψ-W1-T3 review remediation: soften the double-fire claim to unspecified-by-SDK, mark the unload mirror [verify — DAW], fix stale comment, drop redundant assertions, dedupe hook-partitioning comments, drop what-comment; file the action_registry test-seam deferral.

src/shell/actions/ingest.cpp

@@ -479,7 +479,7 @@ void ingestRegisterActions(reaper_plugin_info_t* rec, ReaSamplerSession* session
     g_customImportMediaExplorer.uniqueSectionId = kSectionMediaExplorer;
     g_customImportMediaExplorer.idStr           = g_idImportMxStr.c_str();
     g_customImportMediaExplorer.name            = g_labelImportStr.c_str();
-    g_customImportMediaExplorer.extra           = nullptr;  // reserved
+    g_customImportMediaExplorer.extra           = nullptr;
     g_cmdImportMediaExplorerMx =
         rec->Register("custom_action", (void*)&g_customImportMediaExplorer);
     if (!g_cmdImportMediaExplorerMx)
@@ -496,8 +496,8 @@ bool ingestHandleCommand(int command) {
 
 bool ingestHandleSectionCommand(int command) {
     if (command == 0 || !g_session) return false;
-    // ONLY the Media Explorer id. The Main entry has its own distinct id and is claimed by
-    // ingestHandleCommand off "hookcommand"; claiming it here too would double-fire it.
+    // ONLY the Media Explorer id — partitioning contract: root `CLAUDE.md`
+    // §"REAPER extension contract".
     if (command == g_cmdImportMediaExplorerMx) { doImportFromMediaExplorer(); return true; }
     return false;
 }