The chat app

Choosing a model

The picker in the header lists every model Katara can serve. Each entry is a bundle (see Models and bundles). The default is a managed model that always answers; marketplace models may be cheaper or faster when providers are online.

What a reply costs

Under every reply is its settled cost in USDC and, on hover, who served it. Replies from the managed fallback are marked. Costs are also in your usage history.

The balance

The header shows your spendable balance. Click it to open the wallet panel. When something needs doing before you can chat, the header says so: create a wallet, approve spending, or add funds.

The wallet panel

Under Account → Wallet:

• Balance and next step. Spendable, your wallet balance, your prepaid balance, and the amount you approved; your address with a copy button; the spending approval and when it ends; a withdrawal button for the prepaid balance.
• Add funds. The test faucet on the public test network; your address and a QR code for transfers; card purchases when enabled.
• Budget. Follow the balance, or cap the approved amount. The approval period is 30 days, 6 months, or a year.

Desktop and phone

The desktop app has the same wallet panel under Settings → Wallet, and the same cost line under each reply.

On the phone, the wallet card under Settings shows the balance, claims test funds, and sets the budget. Creating a wallet and approving spending need your passkey, which lives in the browser, so those two buttons open the portal; come back to the app when you are done.

Errors you may see

• Chat is paused until you approve spending. Open the wallet panel and approve.
• Your spendable balance is below this request’s maximum charge. Add funds or raise the cap. Long prompts and large max_tokens raise the maximum.
• No provider can take this request right now. Try again shortly. Models with a fallback rarely show this.