fix: preserve booker timezone selection

[Aamod007]

Description

Fix timezone handling for bookings when lockTimeZone is not enabled

Changes

• Added logic to preserve auto-detected timezone
• Created getInitialTimezone() function to handle timezone selection
• Ensures booker's timezone is not overwritten by default

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[coderabbitai]

Walkthrough

• EventMeta.tsx: Added an internal comment in useEffect clarifying that when lockTimeZone is false, the booker’s auto-detected timezone is preserved rather than defaulting to the event owner’s timezone. No logic changes.
• timePreferences.ts: Introduced internal helper getInitialTimezone() to read a saved timezone from localStorage and fall back to CURRENT_TIMEZONE. Updated timePreferencesStore initialization to use this helper. No changes to exported/public APIs; behavior remains the same with persistence only on setTimezone.

Possibly related PRs

• feat: Ability to set a locked timezone for event type #22531: Adjusts timezone handling related to EventMeta and initialization in timePreferences, overlapping with this PR’s timezone preservation and store setup.

Pre-merge checks (3 passed)

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title Check	✅ Passed	The title "fix: preserve booker timezone selection" succinctly and accurately captures the primary change—preserving the booker's auto-detected timezone when lockTimeZone is disabled—which matches the modifications described in EventMeta.tsx and timePreferences.ts. It is a single clear sentence and uses a conventional commit prefix that aids history scanning. Therefore it satisfies the criteria for a concise, relevant PR title.
Description Check	✅ Passed	The PR description clearly states the intent ("Fix timezone handling...") and enumerates the key changes (preserve auto-detected timezone, create getInitialTimezone, ensure booker's timezone not overwritten), which aligns with the provided file summaries. It is directly related to the changeset and not off-topic, meeting the lenient criteria for this check. Thus the description passes.
Docstring Coverage	✅ Passed	No functions found in the changes. Docstring coverage check skipped.

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Actionable comments posted: 0

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

packages/features/bookings/Booker/components/EventMeta.tsx (1)

245-248: Fix mismatch: fallback should include schedule.timeZone when lockedTimeZone is absent

When the event is locked but lockedTimeZone is null/empty while schedule.timeZone exists, the effect sets the store to schedule.timeZone, yet the select renders CURRENT_TIMEZONE, causing a visible discrepancy (and it’s disabled, so the user can’t correct it).

Apply:

-                    value={
-                      event.lockTimeZoneToggleOnBookingPage
-                        ? event.lockedTimeZone || CURRENT_TIMEZONE
-                        : timezone
-                    }
+                    value={
+                      event.lockTimeZoneToggleOnBookingPage
+                        ? event.lockedTimeZone || event.schedule?.timeZone || CURRENT_TIMEZONE
+                        : timezone
+                    }

🧹 Nitpick comments (3)

packages/features/bookings/Booker/components/EventMeta.tsx (2)

118-125: Keep BookerStore timezone in sync when enforcing a locked TZ

You set only timePreferences here. If other parts rely on the Booker store’s timezone, they may drift.

Proposed tweak:

   if (event?.lockTimeZoneToggleOnBookingPage) {
     const timezone = event.lockedTimeZone || event.schedule?.timeZone;
     if (timezone) {
       setTimezone(timezone);
+      setBookerStoreTimezone(timezone);
     }
   }

---

148-153: Guard navigator for SSR safety

Accessing navigator.language can throw during SSR if locale is null.

Apply:

-  const userLocale = locale ?? navigator.language;
+  const userLocale =
+    locale ?? (typeof navigator !== "undefined" ? navigator.language : i18n.language);

packages/features/bookings/lib/timePreferences.ts (1)

16-31: Validate stored timezone; fall back when invalid

If localStorage contains an invalid/old IANA TZ, downstream formatting can break. Validate before using; otherwise use CURRENT_TIMEZONE. Also good to keep SSR-safety via the webstorage wrapper (please confirm).

Apply:

 /**
  * Get the initial timezone for the booker, ensuring it's auto-detected from the browser
  * if not previously set by the user.
  */
-const getInitialTimezone = () => {
-  const savedTimezone = localStorage.getItem(timezoneLocalStorageKey);
-
-  // If user has previously set a timezone preference, use that
-  if (savedTimezone) {
-    return savedTimezone;
-  }
-
-  // Auto-detect timezone from browser - don't save to localStorage yet
-  // Only save when user explicitly changes timezone
-  return CURRENT_TIMEZONE;
-};
+const isValidTimezone = (tz: string) => {
+  try {
+    // Throws if tz is not a valid IANA zone
+    new Intl.DateTimeFormat(undefined, { timeZone: tz });
+    return true;
+  } catch {
+    return false;
+  }
+};
+
+const getInitialTimezone = () => {
+  const savedTimezone = localStorage.getItem(timezoneLocalStorageKey) ?? undefined;
+  if (savedTimezone && isValidTimezone(savedTimezone)) return savedTimezone;
+  // Auto-detect from browser; don't persist until user changes explicitly
+  return CURRENT_TIMEZONE;
+};

Verification ask: confirm @calcom/lib/webstorage is SSR-safe (no direct window.localStorage access on server).

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📥 Commits

Reviewing files that changed from the base of the PR and between a62c74f and 3223625.

📒 Files selected for processing (2)

• packages/features/bookings/Booker/components/EventMeta.tsx (1 hunks)
• packages/features/bookings/lib/timePreferences.ts (2 hunks)

🧰 Additional context used

📓 Path-based instructions (4)

**/*.tsx

📄 CodeRabbit inference engine (.cursor/rules/review.mdc)

Always use t() for text localization in frontend code; direct text embedding should trigger a warning

Files:

• packages/features/bookings/Booker/components/EventMeta.tsx

**/*.{ts,tsx}

📄 CodeRabbit inference engine (.cursor/rules/review.mdc)

Flag excessive Day.js use in performance-critical code; prefer native Date or Day.js .utc() in hot paths like loops

Files:

• packages/features/bookings/Booker/components/EventMeta.tsx
• packages/features/bookings/lib/timePreferences.ts

**/*.{ts,tsx,js,jsx}

⚙️ CodeRabbit configuration file

Flag default exports and encourage named exports. Named exports provide better tree-shaking, easier refactoring, and clearer imports. Exempt main components like pages, layouts, and components that serve as the primary export of a module.

Files:

• packages/features/bookings/Booker/components/EventMeta.tsx
• packages/features/bookings/lib/timePreferences.ts

**/*.ts

📄 CodeRabbit inference engine (.cursor/rules/review.mdc)

**/*.ts: For Prisma queries, only select data you need; never use include, always use select
Ensure the credential.key field is never returned from tRPC endpoints or APIs

Files:

• packages/features/bookings/lib/timePreferences.ts

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🔇 Additional comments (2)

packages/features/bookings/Booker/components/EventMeta.tsx (1)

126-128: Comment clarifies intent—good

Clear note prevents future regressions when lock is off.

packages/features/bookings/lib/timePreferences.ts (1)

44-45: Helper extraction LGTM

Switching init to getInitialTimezone() improves readability and centralizes behavior.

[kart1ka]

Could you please mention the exact issue this PR is resolving? We are also going to need a loom video that shows this fixes the bug.

[github-actions]

This PR is being marked as stale due to inactivity.

[keithwillcode]

Appreciate the contribution @Aamod007 but this PR's code results in no change. Closing for now.