The bug that lived in Unicode

A file download kept failing on accented filenames. I blamed the API. I blamed the URL encoding. I blamed the server. The actual culprit: two ways to spell the same letter that look identical but aren't. The task was simple. Download file attachments from our code hosting platform. Parse the issue description, find the file references, build the URLs, fetch the files. It worked perfectly. Until someone uploaded a file with an accent in the name. The symptom The download returned 404. Not a server error, not a timeout — a clean "this file does not exist." Except it did exist. I could see it in the web interface. I could download it manually. The URL looked correct. I checked the URL encoding. Correct. I checked the API endpoint format. Correct. I checked authentication. Fine. I rebuilt the URL from scratch, character by character, and it still returned 404. The wrong hypotheses First theory: the API is broken. It's not. Thousands of files download fine. Only the ones with accented chara