What: Orion's experimental PDF.js viewer feature seems to change PDF file names to "document.pdf" upon clicking the download button, but only for some users.
On this page, I have constructed a test case for demonstrating this issue.Why: I suspected it's only for files which are not accessible to the public, i.e. require some form of logging in (making them hard to reproduce until now).
How: PHP backend that checks for any username entered below, and locks access to the PDF if it hasn't been set & sent yet.
This means authentication is simulated here by requiring to send a passwordless "login."
Previous discussion on OrionFeedback.org: Link
Test files:
Sample PDF file modified from the PDFObject JS library's example file.