Set a boundary in writing

Messages at midnight, creeping scope, or a pattern you need to name once.

Help me write a message that sets a boundary and keeps the relationship.

First tell me whether this needs to name the pattern or only correct this instance. Naming a pattern is a bigger move and should be deliberate.

The message should:
1. State the boundary as a fact about how I work, not as a request for permission. "I pick up messages from nine" beats "would it be okay if...".
2. Give one reason at most, and no apology for having limits.
3. Say what I will still do, so it reads as a shape rather than a refusal.
4. Define the genuine exception tightly, if there is one.
5. Stay short. Length signals negotiability.

Flag every hedge, softener, and conditional that would let this be quietly ignored.

Situation:

Hard news and conflict. Bad news, apologies, angry replies, boundaries and feedback that has to survive in writing.