fix(windows): accept ordinary drive path separators (#791)

native/windows/README.md

@@ -66,6 +66,11 @@ Windows failures retain their constraint, requested coordinate, Win32 code,
 and system message. Unsupported filesystems and reparse paths are distinct
 from OS access denial and missing packaged controls.
 
+Ordinary drive-absolute paths accept backslashes, forward slashes, or mixed
+separators. File identity retains the original requested spelling. Separator
+translation does not resolve dot components, repeated separators, or extend
+the supported device/UNC namespaces; existing admission checks still apply.
+
 The bearer-token descriptor remains under its immutable private lease until
 `runtime_close` on Windows; POSIX removes the descriptor after the bridge reads
 it. Job ownership guarantees process termination on owner death, not deletion

native/windows/src/authority.hpp

@@ -19,6 +19,16 @@
 
 namespace rea {
 
+// Translate ordinary DOS drive separators without resolving components or
+// changing extended, device, UNC, relative, or drive-relative namespaces.
+inline std::wstring ordinaryDriveSeparators(std::wstring path) {
+  if (path.size() >= 3 && path[1] == L':' &&
+      ((path[0] >= L'A' && path[0] <= L'Z') || (path[0] >= L'a' && path[0] <= L'z')) &&
+      (path[2] == L'\\' || path[2] == L'/'))
+    std::replace(path.begin(), path.end(), L'/', L'\\');
+  return path;
+}
+
 struct Failure : std::runtime_error {
   DWORD win32;
   std::wstring path;

native/windows/src/filesystem.cc

@@ -14,6 +14,7 @@ static std::wstring hex(const unsigned char* bytes, size_t count) {
 }
 
 static std::wstring localPath(std::wstring path) {
+  path = ordinaryDriveSeparators(std::move(path));
   if (path.rfind(L"\\\\?\\", 0) == 0) path.erase(0, 4);
   require(path.size() >= 3 && path[1] == L':' && path[2] == L'\\' &&
           ((path[0] >= L'A' && path[0] <= L'Z') || (path[0] >= L'a' && path[0] <= L'z')),

native/windows/src/process.cc

@@ -44,7 +44,8 @@ static void pipe(Handle& read, Handle& write) {
 
 std::unique_ptr<Process> spawnProcess(const std::wstring& command, const std::wstring& commandLine,
                                     const std::wstring& cwd, const std::vector<std::wstring>& environment) {
-  require(command.size() >= 3 && command[1] == L':' && command[2] == L'\\',
+  const auto executable = ordinaryDriveSeparators(command);
+  require(executable.size() >= 3 && executable[1] == L':' && executable[2] == L'\\',
           "Owned Windows process requires an absolute executable path", command, ERROR_INVALID_PARAMETER);
   auto result = std::make_unique<Process>();
   result->job = createJob();
@@ -102,7 +103,7 @@ std::unique_ptr<Process> spawnProcess(const std::wstring& command, const std::ws
   if (uniqueEnvironment.empty()) variables.push_back(L'\0');
   std::vector<wchar_t> line(commandLine.begin(), commandLine.end()); line.push_back(L'\0');
   PROCESS_INFORMATION process{};
-  require(CreateProcessW(command.c_str(), line.data(), nullptr, nullptr, TRUE,
+  require(CreateProcessW(executable.c_str(), line.data(), nullptr, nullptr, TRUE,
                          CREATE_UNICODE_ENVIRONMENT | EXTENDED_STARTUPINFO_PRESENT | CREATE_SUSPENDED | CREATE_NO_WINDOW,
                          variables.data(), cwd.empty() ? nullptr : cwd.c_str(), &startup.StartupInfo, &process),
           "Create process atomically inside owned Job Object failed", command);