fix: handle collective multiple host on destinationCalendar

[zaibkhan]

No description provided.

[codoki-pr-intelligence]

Codoki PR Review

Summary: Support multiple destination calendars, update types
What’s good: Type updates align with the PR goal: destinationCalendar now supports multiple hosts, and schedulingType and externalId add clarity for downstream consumers.
Review Status: ❌ Requires changes
Overall Priority: High
Review Update:
• Coverage: Reviewed all 22 files across 3 batches

Issues (Critical & High only)

Severity	Issue	Why it matters
High	Correctness — Null access on mainHostDestinationCalendar.integraton cau...	…/core/EventManager.ts mainHostDestinationCalendar can be undefined when there is no destinationCalendar; accessing mainHostDestinationCalendar.integration below will throw at runtime, causing booking creation to fail. Guard this access before comparing against 'google_calendar'.
High	Correctness — Missing calendarId fallback in Google updateEvent leads t...	…/lib/CalendarService.ts When externalCalendarId is null/undefined, this expression resolves to undefined (find() compares against null/undefined), causing calendarId to be undefined in the update call and leading to Google API errors. Provide a safe fallback to the main host's calendar or 'primary'.

Showing top 2 issues. Critical: 0, High: 2. See inline suggestions for more.

Key Feedback (click to expand)

• Needs improvement: Changing Calendar.createEvent to require credentialId and making destinationCalendar an array are breaking changes; consider a backward-compatible path (e.g., optional parameter, overloads, or transitional typedefs) and ensure all implementations are updated.
• Testing: Add tests covering: (1) createEvent with multiple destination calendars to ensure all hosts receive events, (2) regression where a single destination calendar is passed (ensure array handling or validation), and (3) createEvent callers that omit credentialId (if any legacy paths exist) to fail fast or auto-infer correctly.
• Documentation: Document the migration: destinationCalendar is now an array and Calendar.createEvent now requires credentialId; include examples and a short guide for updating integrators (Google/Lark/etc.).
• Compatibility: These type changes are potentially breaking for all Calendar implementations and callsites. Provide an interim compatibility layer (optional param, overload, or wrapper) or a codemod guide and a clear version note.
• Performance: No clear performance impact from the type changes; if createAllCalendarEvents fans out to multiple destination calendars, ensure batching/rate-limiting in implementations to avoid provider throttling.
• Security: No new security surface evident in the provided diffs. Verify that any expanded fan-out to multiple calendars preserves existing permission checks per credential.
• Open questions: Should credentialId live on CalendarEvent (to simplify callsites) or remain a separate param? Do we guarantee all CalendarService implementations now accept destinationCalendar[] and not a single object?

Confidence: 3/5 — Needs work before merge (2 high · status: Requires changes · scope: large PR (22 files))

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[codoki-pr-intelligence]

⚠️ High: mainHostDestinationCalendar can be undefined when there is no destinationCalendar; accessing mainHostDestinationCalendar.integration below will throw at runtime, causing booking creation to fail. Guard this access before comparing against 'google_calendar'.

Suggested change

	const [mainHostDestinationCalendar] = evt.destinationCalendar ?? [];
	if (evt.location === MeetLocationType && (mainHostDestinationCalendar?.integration !== "google_calendar")) {
	evt["location"] = "integrations:daily";
	}

[codoki-pr-intelligence]

⚠️ High: When externalCalendarId is null/undefined, this expression resolves to undefined (find() compares against null/undefined), causing calendarId to be undefined in the update call and leading to Google API errors. Provide a safe fallback to the main host's calendar or 'primary'.

Suggested change

	const [mainHostDestinationCalendar] = event.destinationCalendar ?? [];
	const selectedCalendar = externalCalendarId || mainHostDestinationCalendar?.externalId || "primary";

[codoki-pr-intelligence]

🔷 Medium: updateAllCalendarEvents builds an array of Promises via result.push(updateEvent(...)) but does not clearly await them before returning; this can lead to unhandled promise behavior and incomplete updates. Ensure the function returns Promise.all(result) to resolve all update operations.

[codoki-pr-intelligence]

🔷 Medium: Changing the empty case to [] alters truthiness (an empty array is truthy), which can cause downstream checks like if (evt.destinationCalendar) to behave as if a calendar is present. To avoid subtle bugs across consumers, return null when there is no destination calendar or ensure all consumers check .length > 0.

Suggested change

	destinationCalendar: booking.destinationCalendar || user.destinationCalendar,
	destinationCalendar: selectedDestinationCalendar ? [selectedDestinationCalendar] : null,