An attachment whose bytes were already stored keeps the extension they were stored under

Shipped

October 14, 2026 at 5:19 AM UTC

Author

Kamo

Commit

299a911

The content-addressed key is <imgDatId>.<ext>, and every reader builds it from the attaching Img's own fileExt. Dedup matches on the bytes, so the same screenshot re-sent as .jpg after a .png matched the existing dat, stored nothing, and recorded "jpg" — a key naming an object that was never written, so the attachment answered 410 to everyone (BUG-1200096283021632186). The first Img on a dat is the one whose upload wrote the object; a new attachment of stored content now takes its ext. The file name the member sees is unchanged.