FA-76749 / Email MIME structure / Member archive

Detect a calendar invitation inside a message: attached calendar · case 04

An attached calendar file is treated as a live invitation.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

Walk multiparts but never descend into message/rfc822 parts. A text/calendar part, or any part whose filename ends in ".ics" (case-insensitive), with an attachment disposition only counts as an attached .ics file. Other text/calendar parts with a method parameter contribute their method (trimmed, upper-cased; parameter names case-insensitive). Result {method: the single distinct method, "AMBIGUOUS" for several, None for none; count: contributing parts; attachments_ics}.

Why this case matters

Clients show accept/decline controls only for real invitations addressed to the reader.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
attached calendar with method	`{"attachments_ics": 0, "count": 1, "method": "PUBLISH"}`	`{"attachments_ics": 1, "count": 0, "method": null}`	Failed

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