Upcoming changes to web-features

[ddbeck]

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[ddbeck]

This month, we're expecting to ship a breaking release (v3.0.0). We're planning to make the following breaking changes:

• Changes to the schema to handle redirecting from one ID to one other ID (a feature move) and from one ID to many IDs (a feature split). Starting with v3.0.0, if you look up a feature by ID, then you might not get regular feature data. Use the new kind property to check whether a given ID is a redirect to one or more other features.
• Simplifications to the types in the existing schema. Previously, some fields could be a string or an array of strings. Starting with v3.0.0 only arrays of strings are allowed.
• Removing some features that should not have been created or were minted prematurely. These will be named in the release notes. There are no longer any planned feature removals.

For more information, see #3269.

[ddbeck]

In a probable June 2026 release, we're expecting to relax an undocumented constraint on feature definitions and browser compatibility data.

Presently, @mdn/browser-compat-data (BCD) keys are associated with only one feature entry at a time. To calculate more accurate and consistent statuses, we're planning to allow some BCD keys to be shared between features. For example, the api.HTMLMediaElement BCD key could be shared between the feature entries for the <video> and <audio> HTML element features, since both features depend on a shared interface. If you depend on BCD keys being associated with one feature only, then you may need to change how you handle web-features data in the near future.

For more information, see #4034.