FA-76434 / Email MIME structure / Member archive

Classify leaf parts as body, inline or attachment: exact cid reference · case 04

Every part carrying a Content-ID is hidden inline even when the HTML never references it.

Member previewVariant 4 · 3 implementations · 8 checks per implementation

Case contract

parts are the leaves of a multipart/mixed message in order: {type, disp, cid, filename}. Rules in order: an explicit "attachment" disposition (case-insensitive) is an attachment even when referenced; a part whose cid is exactly one of html_cids is inline; the first text/* part without a (non-empty) filename is the body; an explicit inline image/* is inline; everything else is an attachment.

Why this case matters

Disposition decides what the reader sees in the message body and what is offered for download.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
cid substring	`["body", "inline", "inline"]`	`["body", "inline", "attachment"]`	Failed

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