Track the current Biome release

[sehkone]

Background

biomejs/setup-biome@v2 pins version: 2.4.9, while the rest of the organisation tracks latest (2.5.7 today). Biome runs here with --error-on-warnings, so simply moving the pin turns CI red: 2.5.7 reports eleven findings that 2.4.9 did not.

They are worth fixing rather than pinning away.

lint/correctness/noUnsafeOptionalChaining — 4 occurrences. Two each in src/lib/dashboard/analytics.ts and src/lib/dashboard/attention.ts, all the same shape:

Array.isArray(config?.excluded_user_ids)
  ? (config?.excluded_user_ids as string[]).filter(...)
  : []

The Array.isArray guard already establishes that the value is an array, so the code is safe in practice — but the optional chain is re-evaluated inside the branch, and the linter cannot see the narrowing through ?. plus the cast. If config were nullish the member access would throw.

lint/complexity/useOptionalChain — 7 occurrences. All !x || x.y !== "literal", which reads more directly as x?.y !== "literal".

Configuration deprecations — 2. The declared $schema is 2.4.9 while a newer Biome runs, and linter.rules.recommended is deprecated in favour of preset; it is removed in Biome 3.x.

Scope

• .github/workflows/ci.yml: change the Biome pin from 2.4.9 to latest.
• src/lib/dashboard/analytics.ts, src/lib/dashboard/attention.ts: hoist each optional access into a local before the Array.isArray guard, so the branch no longer re-evaluates the optional chain. The as string[] cast stays, so inference is untouched and behaviour is identical.
• Six files: apply the useOptionalChain rewrite. Every case compares against a string literal and every subject is an object from a GraphQL or database result, so !x and x?. cover the same inputs.
• biome.json, via biome migrate --write: schema to 2.5.7, recommended to preset.

Acceptance criteria

• CI installs Biome latest.
• biome ci --error-on-warnings . passes with no warnings and no deprecation notices.
• tsc --noEmit still passes.

Verification already done

• biome ci --error-on-warnings . at 2.5.7 on this change: exit 0, Checked 412 files, no findings.
• pnpm run typecheck (tsc --noEmit): exit 0.
• Before the change, the same command at 2.5.7 exited 1 with 7 warnings, 4 correctness findings and 2 deprecation notices.