Biome linter configuration for regional timezone offset validation

Answer first

No. Biome does not provide native timezone offset validation, date-time logic checks, or a biome.json option to normalize timezone data. There is no confirmed Biome roadmap item for a rule that flags native Date usage when timezone awareness is required, nor a built-in rule to enforce the Temporal API.

Biome is a syntax and semantic linter and formatter for JavaScript and TypeScript. It cannot perform runtime temporal calculations or verify correct offset arithmetic.

Confirmed facts

• Biome has no built-in rule for timezone offset validation or date-time manipulation.
• No biome.json configuration exists to normalize timezone data or restrict Date usage to specific temporal-aware libraries.
• Date is a global in JavaScript, so import-based rules do not catch `new Date()` directly.

Likely explanation and practical approximation

Enforcement can be approximated with existing mechanisms, not with native timezone validation.

1. Restrict unwanted date libraries with noRestrictedImports. This steers imports toward a sanctioned library such as Luxon or Day.js, but it does not stop direct use of the global Date.
2. Flag patterns of native Date usage with a GritQL plugin. Biome supports plugins via biome.json plugins. A GritQL pattern can match Date() and new Date() calls and emit a diagnostic.
3. Once Temporal polyfills are common, the same GritQL pattern approach can be repurposed to require Temporal.Now over Date. This is a custom rule, not a core Biome rule.

A robust solution typically combines Biome rules with a type-level wrapper or a small custom lint script, because lint rules alone cannot verify correct offset arithmetic.

Steps needed for this case

• Pin the Biome version in CI and verify plugin support. Run biome --version and check the changelog for your installed version for current GritQL plugin syntax.
• Add import restrictions in biome.json if you want to ban specific libraries.
• Add a GritQL plugin entry that matches new Date() and Date() in the code paths where timezone awareness is required. Scope the plugin to directories if naive timestamps are legitimate elsewhere.
• Test the rule on a sample file and run biome lint to confirm diagnostics fire.

One missing diagnostic detail that changes the recommendation: which Biome version is installed in the project. GritQL plugin syntax and stability have evolved across 1.x releases, so the exact plugin configuration depends on the version.