Bug: windows mcp tool server error

[970263611]

[alderg]

Thanks for the report — the screenshot made this easy to pin down, and it's now fixed on main (41ae42f).

What happened: On Windows the server opens the generated diagram by writing a
temporary .url (InternetShortcut) file and launching it — that's needed because
cmd's start drops the #create= fragment that carries the diagram. But the
Windows shell refuses .url files whose URL exceeds INTERNET_MAX_URL_LENGTH
(2083 characters) and shows exactly the dialog you hit — Win32 error 122, "The
data area passed to a system call is too small." Since the whole compressed
diagram rides in the URL, anything beyond a small diagram blew past the limit.

The fix: URLs over ~2000 characters are now opened through a temporary HTML
page that forwards the browser to the full URL from JavaScript, where no shell
length limit applies (verified with a 300-node diagram, a ~7.8 KB URL). Short
URLs keep the existing .url path.

The fix will ship in the next @drawio/mcp release on npm.