Passed to PendingItem by ChatModal for each of WSChatContext's
pendingChatMessages.
grouped: boolean
Set when it continues the user's run, which hides the avatar and name.
The signed-in user, who sent it.
onRetry: (nonce: string) => void
onDiscard: (nonce: string) => void
onRestore: (pending: PendingChatMessage) => void
Takes the failed text back into the composer, and discards it.
onJumpTo: (id: string) => void