- Replace fetch(redirect:manual) with XMLHttpRequest in file-upload-queue.js.
The previous fetch-based redirect detection was broken because opaque
redirects hide the Location header. XHR's responseURL reliably exposes
the final URL after server-side redirects.
- Add console.log tracing at every decision point in submit interception:
entry, hasFiles check, enctype check, double-submit guard, XHR status,
redirect detection, error fallback.
- Add error_log entry-point logging to all 16 admin action files plus
the partage/index.php submission handler and password gate. Each logs:
request method, content type/length, POST keys, file counts, and
queue-specific file counts where applicable.
- Add double-submit guard (_xamxamActiveSubmit) to prevent duplicate
XHR sends when the native submit handler fires after interception.
