Feishu Calendar

This is a comprehensive Feishu (Lark) calendar integration that handles meeting creation, attendee management, and free/busy queries. The documentation is unusually thorough about implementation gotchas: it explains why you must pass user_open_id even though the calendar already uses user identity (so the creator appears in the attendee list), clarifies that meeting room booking is async so you need to poll for confirmation, and warns that the instances action only works on recurring events. Fixed to Asia/Shanghai timezone with ISO 8601 formatting. If you're building Feishu workflow automation in Chinese markets, the detailed constraint documentation here will save you from common mistakes around attendee permissions and ID format confusion between ou_xxx and user_xxx identifiers.