MIME type

How it works

HTTP Content-Type and mail MIME types carry it. A wrong label makes a browser download a PDF as text or block a file. The label is not the format. Sniffing can disagree. Set it from the real container.

A .mov is served as application/octet-stream and downloads. Served as text/plain, the browser shows garbage. They set video/quicktime. The bytes did not change.

How it differs

MIME type is not a checksum. It does not prove integrity.

Double extensions and a generic type hide a mismatch.

Set the type you tested.

On the ticket

• The practical close is a log line: time, actor, byte count, result.
• Without that line the transfer is a story.
• With it, the next person can see whether this door did what the ticket claimed.
• If the path is shared, say so in the partner profile so a later change does not silently pick a different limit, key, or region.
• On a real ticket, write down the door, the byte count, and the clock.
• For mime type, that means naming the host or bucket, the expected size, and the time the other side must have a complete file.
• A progress bar is not that record.
• A 200 response that arrives before the complete call is not that record.
• If a retry is allowed, say how many and whether it resumes.
• If a person must approve the send, name the person.
• Partners who receive mime type files should match on hash or size before they import.
• A same-length corrupt file passes a size check and fails a hash.
• Keep the published hash off the only channel an attacker can edit, or treat it as a corruption check rather than a substitution check.
• When the path changes, new key, new region, new cap, update the profile the same day so the next run does not use a stale limit.