# Check a group offer

Validate a grouped seller challenge from the live wire. Send caps, not a merchant profile.

Canonical: https://402signal.com/developers/check-group-offer

## Check a group offer

Use this when a seller challenge describes a grouped settlement, session, native charge, atomic group or invoice. Send the exact HTTPS GET `url`, `buyer_limits` caps and `require_route_binding: true`. Do not pass `merchant_profile`. The server auto-selects a codec from the live wire: `exact`, `sess`, `mpp`, `atom` or `inv`. Unknown or ambiguous challenges fail closed.

The HTTP result and `compared[]` name the short codes `job` (`chk_grp`) and `codec`. `label` is optional debug. The public receipt leaf stays commitment-only. This is a short-lived observation, not permission to deposit, issue vouchers or sign an arbitrary transaction.

Hosted enablement is operator-controlled. An ordinary exact-payment receipt does not authorize this job. After a qualifying observation, use the matching session or manifest guide before funding.

```
curl -sS -D - https://402signal.com/route \
  -H 'Content-Type: application/json' \
  --data '{"url":"https://merchant.example/batch","buyer_limits":{"network":"eip155:8453","asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","recipient":"0x2222222222222222222222222222222222222222","receiver_authorizer":"0x3721824a31197dcDD2984cF43b92B6cc8A87c0Fb","withdraw_delay_seconds":900,"max_call_amount_atomic":"1000","max_cumulative_amount_atomic":"4000","max_capital_atomic":"4000"},"require_route_binding":true}'
```

Caps select a codec before the probe. The live challenge must speak that codec. Empty or unknown caps are refused. A qualifying observation costs $0.003 USDC; seller charges remain separate.

[Check group offer contract](https://github.com/402signalhq/402signal/blob/main/docs/batch-observation-v1.md) · [Fund a session or invoice after the observation](/developers/sessions-and-invoices).

Give this task to your coding agent

```
Add a Check group offer observation. Read https://402signal.com/developers/check-group-offer and docs/batch-observation-v1.md. POST url, buyer_limits and require_route_binding:true. Do not send merchant_profile. Expect job chk_grp, a detected codec and label Check group offer. Unknown wires must fail closed. Do not treat the observation as signing or funding authority.
```

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