feat(companion): add Biome for linting and formatting

[dhairyashiil]

What does this PR do?

Replaces ESLint and Prettier with Biome for linting and formatting in the companion app. Biome is a fast, all-in-one toolchain that handles both linting and formatting with a single configuration file.

Changes:

• Added biome.json configuration with formatting settings matching previous Prettier config (2 spaces, double quotes, semicolons, trailing commas ES5, line width 100)
• Added Biome scripts to package.json: lint, format, format:check, check, check:ci
• Updated lint-staged to use biome check --write --error-on-warnings for pre-commit (runs both formatting AND linting, fails on warnings)
• Removed ESLint and Prettier dependencies (eslint, eslint-config-expo, eslint-config-prettier, eslint-plugin-prettier, prettier, prettier-plugin-tailwindcss)
• Deleted .prettierrc.js configuration file
• Applied Biome formatting and safe lint fixes to all companion files

Note: Tailwind CSS class sorting is no longer automatically applied since Biome doesn't have a Tailwind plugin. This was a conscious tradeoff for simpler tooling.

Updates since last revision

Enabled noUnusedVariables rule (4 violations fixed):

• AuthTokenProvider.tsx: Prefixed isWebSession with underscore (destructured from useAuth but not used)
• calcom.ts: Prefixed isOrganizer, isHost, isAttendee with underscore (only isParticipating is used for filtering)

Previously enabled lint rules:

• noUnusedFunctionParameters (9 violations): Prefixed unused params with underscore to indicate intentionally unused
• noUnusedVariables (4 violations): Prefixed unused variables with underscore
• noStaticOnlyClass (2 violations): Converted CalComAPIService and WebAuthService from static classes to module-level functions
• noStaticElementInteractions (1 violation): Added role="tooltip" to interactive span in Tooltip.web.tsx
• noNonNullAssertion (7 violations): Added runtime checks in hooks and extension code

Fixed 13 TypeScript errors (all bun typecheck:all errors resolved):

• AuthContext.tsx: Converted checkAuthState, logout, saveOAuthTokens, clearAuth, resetAuthState, handleOAuthAuth, handleWebSessionAuth to useCallback and moved before useEffect
• AvailabilityDetailScreen.tsx: Converted fetchSchedule to useCallback with proper dependencies
• BookingDetailScreen.tsx: Converted fetchBooking to useCallback with proper dependencies
• Header.tsx: Converted fetchUserProfile to useCallback with proper dependencies
• buildPartialUpdatePayload.ts: Added ?? [] fallback for possibly undefined originalMapped array
• oauthService.ts: Removed unused state property assignments (dead code)

Remaining disabled rules for existing codebase:

• noExplicitAny, noArrayIndexKey, useIterableCallbackReturn (suspicious)
• useExhaustiveDependencies (correctness)

Mandatory Tasks (DO NOT REMOVE)

• I have self-reviewed the code (A decent size PR without self-review might be rejected).
• I have updated the developer docs in /docs if this PR makes changes that would require a documentation change. N/A - internal tooling change.
• I confirm automated tests are in place that prove my fix is effective or that my feature works. N/A - tooling setup, verified locally with bun run check and bun run typecheck:all.

How should this be tested?

1. Navigate to the companion folder
2. Run bun install (if needed)
3. Run bun run check - should pass with no errors or warnings
4. Run bun run format:check - should pass (all files formatted)
5. Run bun run typecheck:all - should pass (both app and extension)
6. Test pre-commit hook: Make a change to a companion file, stage it, and commit - Biome should auto-format AND lint, failing if there are any warnings

Human Review Checklist

• Review unused variables in calcom.ts - isOrganizer, isHost, isAttendee are destructured but only isParticipating is used for filtering bookings. Verify this is intentional vs. incomplete filtering logic
• Review isWebSession in AuthTokenProvider.tsx - Verify this unused variable isn't needed for conditional token handling logic
• Review unused parameters in BookingModals.tsx - 5 reschedule-related props are unused. Verify this is intentional (reschedule modal moved elsewhere) vs incomplete implementation that should be cleaned up
• Review unused parameters in iOS components - BookingListItem.ios.tsx and EventTypeListItem.ios.tsx have unused props that are part of shared interfaces but not needed for iOS context menu implementation
• Review useCallback dependency arrays - Verify the dependency arrays in AuthContext.tsx, AvailabilityDetailScreen.tsx, BookingDetailScreen.tsx, and Header.tsx include all necessary dependencies and won't cause stale closures
• Review CalComAPIService conversion - Verify the conversion from static class to module functions maintains all functionality. The file is 1500+ lines with 40+ methods
• Review WebAuthService conversion - Same pattern as above, verify all internal references were updated correctly
• Review removal of state property in oauthService.ts - The state was being assigned but never read for CSRF verification. Confirm this dead code removal is safe
• Verify biome.json configuration matches team coding standards
• Confirm the team is okay with losing Tailwind class sorting (no Biome plugin available)

Checklist

• I have read the contributing guide
• My code follows the style guidelines of this project
• I have checked if my changes generate no new warnings

---

Link to Devin run: https://app.devin.ai/sessions/464fb766dbb547958648f4c98afa3622
Requested by: Dhairyashil Shinde (@dhairyashiil)

[devin-ai-integration]

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3 Skipped Deployments

Project	Deployment	Review	Updated (UTC)
cal	Ignored		Dec 27, 2025 11:09am
cal-companion	Ignored	Preview	Dec 27, 2025 11:09am
cal-eu	Ignored		Dec 27, 2025 11:09am

[cubic-dev-ai]

1 issue found across 33 files

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="companion/components/booking-modals/BookingModals.tsx">

<violation number="1" location="companion/components/booking-modals/BookingModals.tsx:237">
P1: Using `&amp;apos;` in React Native `&lt;Text&gt;` will render as literal &quot;&amp;apos;&quot; instead of an apostrophe. React Native doesn&#39;t decode HTML entities like web browsers. Use a JavaScript string instead.</violation>
</file>

_{Reply to cubic to teach it or ask questions. Tag @cubic-dev-ai to re-run a review.}

[volnei]

@dhairyashiil we're going to use biome instead eslint/prettier... 🙂

[cubic-dev-ai]

3 issues found across 106 files

Note: This PR contains a large number of files. cubic only reviews up to 75 files per PR, so some files may not have been reviewed.

Prompt for AI agents (all issues)

Check if these issues are valid — if so, understand the root cause of each and fix them.


<file name="companion/components/Tooltip.web.tsx">

<violation number="1" location="companion/components/Tooltip.web.tsx:22">
P2: The `role=&quot;tooltip&quot;` is applied to the wrong element. According to WAI-ARIA, this role should be on the popup content (the inner span that displays `{text}`), not the container/trigger element. Screen readers may incorrectly interpret the entire wrapper as a tooltip.

Consider moving the role to the inner span and using `role=&quot;presentation&quot;` or no role on the outer span, or restructuring to use a semantically appropriate element for the trigger.</violation>
</file>

<file name="companion/components/screens/AvailabilityDetailScreen.tsx">

<violation number="1" location="companion/components/screens/AvailabilityDetailScreen.tsx:602">
P2: The key `${slot.startTime}-${slot.endTime}` may produce duplicate keys if multiple time slots have identical times. Include `slotIndex` in the key to guarantee uniqueness.</violation>
</file>

<file name="companion/components/event-type-detail/utils/buildPartialUpdatePayload.ts">

<violation number="1" location="companion/components/event-type-detail/utils/buildPartialUpdatePayload.ts:263">
P1: Key mismatch bug: `originalLimits` uses uppercase keys (`PER_DAY`, `PER_WEEK`, etc.) but `currentLimits` uses lowercase keys from `parseFrequencyUnit()` (`day`, `week`, etc.). This will cause the function to always return `true` (changed) even when values haven&#39;t changed.</violation>
</file>

_{Reply to cubic to teach it or ask questions. Tag @cubic-dev-ai to re-run a review.}