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Mist can use AI models from several providers. Each chat has its own model, which you choose from the model picker in the chat box. Auto is the default, and it picks a model for you on every message.

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Choose a model for a chat

1

Open the model picker

In the chat box, click the model name.
2

Find a model

Models are grouped by provider, such as OpenAI or xAI. Type in Search models… to filter the list. Each model shows its context size and its price per million output tokens.
3

Pick it

Click the model. The chat uses it from your next message.
To go back to automatic choice, pick Auto, under Default.

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How Auto works

Before each message, Auto asks a small, fast model which of three tiers the message needs. It’s told to pick the cheapest tier that will still do the job well. Auto also follows these rules:
  • If it isn’t confident about a tier, it moves up one tier.
  • A message with several tasks, or with text files attached, uses at least the standard tier.
  • A message that’s likely to change production, such as publishing, deploying, writing through the Fluid API, issuing a refund, writing to a database or deleting something, uses the complex tier.
  • In a long chat that was active in the last 5 minutes, it doesn’t drop to a cheaper model than the one it used last. There, a cheaper model would cost more, because it can’t reuse the chat the current model has already cached.
  • If it can’t choose within about 2.5 seconds, or the choice fails, it uses Claude Opus 5.5.
So Auto saves cost on simple messages, and uses the most capable model where a mistake would matter most.

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Set the default model for new chats

1

Open Preferences

Click your name at the bottom of the sidebar, then click Preferences.
2

Choose the default

Under Default chat model, pick a model, or Auto — Mist recommended.
New chats on this computer use this model. Chats you already have keep their own model. If you haven’t set a default, a new chat uses the model you picked most recently, or Auto.

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Frequently asked questions

Yes. Each model has its own price, which the picker shows. Your company pays for Mist’s AI usage, up to a daily cap. See your company’s usage under Settings > AI usage in Mist, or on AI Spend in the admin.
The model you picked is no longer available. Mist moves the chat to Auto when that happens.
Mist stops answering and tells you why, for example “Your company is out of AI credits.” or “Your company’s AI spend limit is reached.” An admin can check Billing in the admin.