Checkpoint 4: harden native paths, authoring workflows and Player lifecycle

include/faset/core/io.hpp

@@ -5,6 +5,19 @@
 #include <string_view>
 
 namespace faset {
+// Text/JSON/process arguments use UTF-8. Keep filesystem paths in native form
+// internally; narrow path constructors/string() depend on the Windows code page.
+std::filesystem::path path_from_utf8(std::string_view text);
+std::string path_to_utf8(const std::filesystem::path& path);
+std::string generic_path_to_utf8(const std::filesystem::path& path);
+// Use only at file-I/O boundaries, never for serialized paths or identity comparisons.
+// Windows: absolute, normalized extended-length path; other systems: unchanged.
+std::filesystem::path native_io_path(const std::filesystem::path& path);
+#ifdef _WIN32
+// Thin wmain adapter: preserve the CRT's Unicode argument parsing and pass UTF-8
+// to the shared application entry. No process/global code-page change is needed.
+int run_utf8_main(int argc, wchar_t** argv, int (*entry)(int, char**)) noexcept;
+#endif
 std::string new_id();
 std::string read_text(const std::filesystem::path& path);
 Json read_json(const std::filesystem::path& path);