Constant IDLE 

pub const IDLE: u8 = 29;

INVOKED: what the shards have left to do, sent once before the worker closes the connection: count u32, then per shard shard u32, epoch u64, flags u8 (bit 0: busy, bit 1: the budget ended), due_in_ms u64 (u64::MAX: nothing due), steps u64, open_us u64, types u32, then each type as bytes (workflow types with runs this worker had no code for). Not answered.