Tuesday's rehearsal moved to Wednesday. You posted in the cast chat. Six people liked it. The two who have the scene are on a show tonight and have not opened the app. On Wednesday you will have a room and no scene.
A schedule change is a decision with a call time. It is not a vibe. The people who have to walk into a room need the old time, the changed time, the scenes, and a yes that belongs to them.
One call, one yes
"Can you make Wednesday 7:00–9:30pm at the black box, scenes 4 and 7, call 6:45, yes or no by Monday 6pm." That is a decision. "Rehearsal update — please read" is a newsletter.
If tech week and a rehearsal both moved, that is two briefings. A pile gets the easier yes.
Write the old call so a cold reader can see what changed. Write who is called — names they answer to, not your private nicknames. Write what happens if they cannot: an understudy, a later slot, or you hold the scene.
Set a deadline they can meet after work, not during a show. "If I do not hear by Monday 6pm, I will call the understudy and release you from Wednesday." A default that assumes silence is attendance is how you light an empty mark.
They will answer from email
Actors are not connecting an assistant to a community theater. They do not have to. The briefing arrives as mail and a page. They reply from either. You approve the wording. The stage manager's assistant does not speak as the production.
If you use Claude and a director uses ChatGPT, the cast reads one package. Their chats stay put.
No conflict-calendar file. Write the one night. If the season grid already lives on a page the company uses, name that page.
One person per send. Twelve people in the scene is twelve approvals of the same ask. Slower than a company blast, and that is why the blast fails: the two you need will assume the twelve already answered.
What a sufficient reply is
"Yes." "No — I can do Thursday." "Yes if I can leave at 9." One line. Say that is enough. A note about character work can wait until they are in the room.
If someone says no, you still have Monday evening. That is the point of the deadline.
What this is not
It is not notes. Notes belong in the room, or in a separate message after the run, with a different ask.
It is not a place to process whether a person is committed. A no to Wednesday is a no to Wednesday. If a pattern needs a conversation, have the conversation. Do not hide it under a call time.
If your assistant already has the grid, let it draft the change. You read the names and the clock. Then the people who must be there can answer from a phone.