Manage agenda and backlog items in a meeting. Use this when the user wants to add, update, remove, or schedule an agenda or backlog item. Do not use it to manage the meeting itself, participants, or action items — those are handled by separate tools. Set `backlog` to select the variant and `action` to one of: assign, create, delete, update. Then provide the fields for the selected combination. backlog=false, action=create: Add an item to a meeting's agenda. Use this when the user wants to schedule an agenda item. `meeting_id`, `title`, and `item_type` are required. A 409 means the meeting has already ended and cannot accept more agenda items; do not retry. The 201 body returns the created item `id`. Use an `Idempotency-Key` to prevent duplicates. backlog=false, action=delete: Remove an item from a meeting's agenda. Use this when the user wants to delete an agenda item. Deletes an agenda item in the caller's workspace, keyed by the `{id}` from v1ListAgendaItems; requires the `meetings:write` scope. Returns 204 No Content on success with no body. Deleting an unknown id or one outside the caller's workspace returns 404. The operation is effectively idempotent — a repeat delete of the same id simply 404s — so retries after a network error are safe. backlog=false, action=update: Modify an agenda item in a meeting. Use this when the user wants to change an item's title, description, or time allocation. Partial update (PATCH) of an agenda item. Requires `meetings:write` and the `id` from v1ListAgendaItems. 404 for unknown/cross-workspace ids. Not idempotent — re-read before retrying. `DEFERRED` skips the item in the current run; it does NOT move to the backlog. To move to backlog, delete and create a backlog item. backlog=true, action=assign: Schedule an unscheduled agenda item onto a meeting. Use this when the user wants to move a backlog item onto a meeting's agenda. Schedules an active backlog item onto a meeting. Requires `meeting_id` body field and `meetings:write` scope. Returns the new `agenda_item_id`; the backlog item is closed out and moves to v1ListBacklogItemHistory. Edit the created agenda item with v1UpdateAgendaItem. 404 unknown/out-of-workspace meeting, 400 missing `meeting_id`. backlog=true, action=create: Capture an unscheduled agenda item in the backlog. Use this when the user wants to save an item for later without putting it on a meeting. `title` and `item_type` are required; valid values are `DISCUSSION`, `QUESTIONS_TO_ANSWER`, `BREAK`, and `ADJOURN`. No `meeting_id` is used; assign to a meeting later with v1AssignBacklogItem. The 201 body returns the new `id`; use an `Idempotency-Key` to avoid duplicates. backlog=true, action=delete: Discard an unscheduled agenda item from the backlog. Use this when the user wants to permanently remove a backlog item. Soft-deletes the active backlog item keyed by `{id}`; removed items move to v1ListBacklogItemHistory with `deleted_at` set. Returns 204. There is no restore operation. The call is effectively idempotent: a repeat delete 404s, so retries are safe. backlog=true, action=update: Edit an unscheduled agenda item in the backlog. Use this when the user wants to change a backlog item's content. Partial update (PATCH) of an active backlog item. Omitted fields are left as-is; empty values clear the field. `item_type` is restricted to `DISCUSSION`, `QUESTIONS_TO_ANSWER`, `BREAK`, and `ADJOURN`. Already-assigned or deleted items return 404; find them in v1ListBacklogItemHistory.