Biome 2.5.12

Biome 2.5.12 shipped on September 3, 2026, and on the surface it looks like a quiet patch release. Look closer and most of it is Astro-specific parser repair work, plus one new lint rule. That is not a bad thing, but it is not the headline-worthy upgrade some will spin it into.

What Actually Changed

This release is dominated by the formatter handling of Astro expressions. A batch of fixes landed around attribute names being split on colons and periods inside expressions, nested template literals, and expressions whose children contain raw text or HTML comments. Anyone building Astro sites with heavy inline logic will feel these corrections. The rest of the ecosystem will barely notice.

The New Rule

A single nursery rule, useFlatMathMinMax, joins the linter. It flags redundant nesting and flattens Math.max(Math.max(a, b), c) into Math.max(a, b, c). Simple, readable, and low-risk, but it only does anything once you opt in to the nursery.

Where It Helps

noUnresolvedImports no longer reports Bun runtime built-ins such as bun, bun:bundle, and bun:ffi. If you run Biome against Bun projects, that clears a persistent false positive. It is the one change with real everyday payoff.

Worth Upgrading?

If you are already on 2.5.x, the upgrade is safe and worthwhile. Keep expectations in scale though. This is a polish release for parser edge cases, not a feature milestone.