# Route with Enso

URL: https://docs.hanzo.ai/docs/guides/cookbook/route

> Send model auto, cap the price of each call, read which model answered, and tell the router how it went.

**One request shape for every model.** Enso picks per request; you bound what it
may spend and grade what it picked.

## Send `auto`, capped

```bash
curl -s https://api.hanzo.ai/v1/chat/completions \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -H "X-Max-Cost: 0.002" \
  -D headers.txt -o answer.json \
  -d '{"model": "auto", "messages": [{"role": "user", "content": "Rewrite this SQL to use a join: SELECT * FROM a WHERE id IN (SELECT a_id FROM b)"}]}'

grep -i '^x-routed-model' headers.txt
jq -r '.model, .choices[0].message.content' answer.json
```

`X-Max-Cost` is a ceiling in USD per 1,000 tokens; models priced above it are
not eligible. `X-Max-Latency-Ms` bounds latency the same way. The routed model
is in the header and in `.model`, and it is what you are billed for.

## Tell it how it went

```bash
curl -s https://api.hanzo.ai/v1/ai/feedback \
  -H "Authorization: Bearer $HANZO_API_KEY" \
  -H "Content-Type: application/json" \
  -d "$(jq -n --arg id "$(jq -r .id answer.json)" '{request_id: $id, signal: "accept"}')"
```

`accept` and `up` record 1, `regenerate` 0.25, `down`, `switch`, `abandon` and
`revert` 0; `dismiss` records nothing. Send the signal your product already has
— the user kept the answer, re-rolled it, or switched model — and the router
learns from ordinary use. No prompt text is sent or stored.

## The same from Python

```python
import os
from openai import OpenAI

client = OpenAI(api_key=os.environ["HANZO_API_KEY"], base_url="https://api.hanzo.ai/v1")

raw = client.chat.completions.with_raw_response.create(
    model="auto",
    messages=[{"role": "user", "content": "Rewrite this SQL to use a join: ..."}],
    extra_headers={"X-Max-Cost": "0.002"},
)
answer = raw.parse()
print(raw.headers.get("x-routed-model"), answer.id)
print(answer.choices[0].message.content)
```

**Why it pays:** most requests are easy, and a router that sends easy ones to a
small model spends the large one's price only where it buys something. How the
pick is made: [Enso](https://docs.hanzo.ai/docs/models/enso#how-it-picks).