Why SMS replies should feel like texts
When a character lives in iMessage or SMS, the bar is different. You’re not staring at a chat product UI. You’re in the same place you text friends. If the reply feels like a support bot, the whole thing falls apart.
So the north star for SMS is simple: it should feel like texts. Short when short makes sense. Natural rhythm. Not a three-paragraph essay for “hey.” Not performative chaos either. Just a person on the other side of the bubble.
The surface is the product
Save the Vibeside number. Start a character with a short START code (or a QR). From there it’s Messages. Blue or green bubbles. Typing happens in the app you already open a hundred times a day.
That context changes everything. People skim. They reply while walking. They send one-liners. A character that answers every ping with a scene description and five questions doesn’t belong here.
What “good” looks like
Good SMS replies match the energy of the thread. If you send something light, they don’t over-explain. If you open up, they don’t bounce off it with a joke that misses. They notice the vibe of the last few messages and answer like someone who’s actually in the conversation.
Texture matters too. Real texts have little irregularities. Timing. Length that varies. Reactions that feel specific. We’re picky about replies that feel flat, and equally picky about replies that try too hard to sound “random” or “quirky.”
What we’re avoiding
Essay-bot energy. Fake therapist mode when you didn’t ask. Stage directions that belong in a roleplay window, not a text thread. Claiming to be your person out of nowhere. And the classic chatbot tell: answering a simple check-in with a wall of options.
We’re also careful about commands people need. HELP should help. STOP should stop outbound texts. The product stuff has to stay clear even when the character voice is strong.
Always improving the feel
This isn’t a one-time prompt tweak and done. We keep pressure-testing SMS chats the way you’d vibe-check a friend’s texting style. Does it still feel human after twenty turns? Does it stay itself? Does it get boring or weird?
You’ll see that work show up as better day-to-day replies, not as a feature checklist. If you’re already texting characters, keep going. If you haven’t tried it, grab the number from explore, send START, and see whether it feels like a real thread.
Multi-turn is the real test
One clever reply is easy. Twenty turns is the product. Does the character still sound like themselves? Do they notice what you said three messages ago without dragging the whole history into every bubble? That’s the bar we care about for SMS.
If a thread gets weird, start another one. If a character stays good across a long night of short texts, that’s the signal we’re chasing.
Web and phone can both matter
Some people start on the web and continue on their phone. The SMS feel still has to hold. Same character energy. Same texting instincts. Different glass, same person on the other side.