Fix: File Previews Were Blank and Training Uploads Failed

Details

A file you attached in chat or opened from Drive showed an empty grey box instead of the document, even though your employee could read it perfectly well. That is the worst shape a bug can take: nothing is broken where you are looking, so you assume the file itself did not arrive and upload it again. Separately, uploading a file on the Training page failed outright with an error that explained nothing, which made it impossible to tell a rejected file from a broken page. Both are fixed. Previews render again everywhere a file appears, in chat and in Drive, and training files upload and start learning as they should. When an upload genuinely cannot be accepted, the message now names the reason instead of leaving you guessing at it. One number worth knowing while you are here: a file can be up to 72 MB, and one message can carry 72 MB in total across everything attached to it. That is the size we can actually deliver end to end, so it is stated rather than discovered.

What changed

• See PDFs, documents and spreadsheets preview in chat and Drive again
• Upload files on the Training page and have them go through
• Get a clear reason when an upload cannot be accepted
• Files up to 72 MB each, the size we can actually deliver