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htmx 4.0 shipped after eight months and makes attribute inheritance opt-in, breaking every existing app
bigskysoftware/htmx tagged v4.0.0 on 2026-08-28T13:00 (49,061 stars, previous tag was v4.0.0-beta6 on 2026-07-23) and the announcement hit HN at 691 points. Attribute inheritance flips from implicit to explicit via an :inherited suffix, which the team itself calls the largest upgrade burden; events are renamed to htmx:phase:action, htmx:xhr:* is gone, localStorage history caching is removed, and idiomorph morphing plus an <hx-partial> tag land natively. Notably the release ships four skills files aimed at LLMs — guidance, debugging, extension authoring, and 2.x upgrading — and 2.x stays `latest` on npm until early 2027.
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