css.at-rules.supports.at-rule - missing compat data for @supports at-rule()

What type of issue is this?

Missing compatibility data

What information was incorrect, unhelpful, or incomplete?

BCD has data for @supports in css/at-rules/supports.json, including subfeatures for selector(), font-tech(), and font-format().

It does not currently have data for the new at-rule() support condition function used inside @supports, for example:

@supports at-rule(@starting-style) {}

Proposed BCD path: css.at-rules.supports.at-rule

What browsers does this problem apply to, if applicable?

Chromium (Chrome, Edge 79+, Opera, Samsung Internet)

What did you expect to see?

I expected BCD to have a subfeature under css.at-rules.supports for the at-rule() support condition function, similar to the existing selector(), font-tech(), and font-format() subfeatures.

Did you test this? If so, how?

I checked the current BCD source file:
https://github.com/mdn/browser-compat-data/blob/main/css/at-rules/supports.json

WPT:
https://github.com/web-platform-tests/wpt/blob/master/css/css-conditional/js/supports-at-rule.html

Can you link to any release notes, bugs, pull requests, or MDN pages related to this?

No response

Do you have anything more you want to share?

• Spec: https://drafts.csswg.org/css-conditional-5/#typedef-supports-at-rule-fn
• WPT: https://github.com/web-platform-tests/wpt/blob/master/css/css-conditional/js/supports-at-rule.html
• Edge explainer: https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/AtRuleFeatureDetection/explainer.md

MDN URL

No response

MDN metadata

No response

Open css/at-rules/supports.json and compare the existing selector(), font-tech(), and font-format() subfeatures. Use the linked WPT supports-at-rule.html and the reported browser versions to add the at-rule() compatibility entry at css.at-rules.supports.at-rule. Done means the data matches the proposed path and passes the repository's validation checks.