Context

In our private allure2 fork, we use the source field of attachments not only for file paths but also to support data:, http:, https:, and file: protocols. Basically, remote-hosted attachment files (or JSON-only allure-results with no binary ballast).

While this works quite well, an optional size property would be extremely helpful for remote attachments — it would eliminate the need for HTTP roundtrips using HEAD requests just to retrieve Content-Length when generating HTML reports.

I wonder, can we find common ground here and consider making this part of the standard?

Checklist

• Sign Allure CLA
• Provide unit tests