> For the complete documentation index, see [llms.txt](https://andrewkimjoseph.gitbook.io/celina-sdk/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://andrewkimjoseph.gitbook.io/celina-sdk/guides/on-chain-attribution.md).

# On-chain attribution

Prepared and AA-submitted calldata carries an **ERC-8021 Schema 0** Celina attribution suffix so indexers and agents can identify app traffic on Celo mainnet.

## Wire format (writes)

Every tagged step appends ERC-8021 only via `appendCelinaCalldataTag` / `toDataSuffix`:

| Layer        | Contents                                                                             |
| ------------ | ------------------------------------------------------------------------------------ |
| **ERC-8021** | Schema 0 codes — always includes platform code `celina`, then lowercase custom codes |

Example: `attributionTags: ["goclaim"]` -> codes `celina`, `goclaim`.

Case rules for **custom tags** (before ERC-8021 lowercasing):

* App tags (e.g. `goclaim`, `celeste_ai`) → uppercase in normalize helpers (`GOCLAIM`, `CELESTE_AI`), then lowercase in ERC-8021 codes
* Celo Builders tags matching `celo_<12 hex>` → lowercase
* Tags are deduped in first-seen order; the literal tag `CELINA` / code `celina` is platform-only

## Where to set tags

| Client                                    | When tags apply                                     |
| ----------------------------------------- | --------------------------------------------------- |
| `createCelinaClient({ attributionTags })` | Every `prepare*` step via `appendCelinaCalldataTag` |
| `createAAClient({ attributionTags })`     | Every step with `data` in `sendPreparedFlow`        |

Omit `attributionTags` on the AA client to **pass step `data` through unchanged** (useful when `prepare*` already tagged). Passing `[]` still applies the platform-only ERC-8021 code `celina`.

Use **one consistent tag list** per send path. Setting different lists on both the Celina client and the AA client can stack or mismatch suffixes.

Hand-built flows (no `prepare*`) that still need tags:

```ts
import { appendCelinaCalldataTag } from "@andrewkimjoseph/celina-sdk";

const data = appendCelinaCalldataTag(encodeFunctionData(...), ["goclaim"]);
```

## Check vs verify

| Tool / API                                                   | Prefer when                                                                               |
| ------------------------------------------------------------ | ----------------------------------------------------------------------------------------- |
| **`check_attribution_tag`** / `checkAttributionInCalldata`   | You want all ERC-8021 `tags` in lowercase (mirrors `erc8021.codes`) or to confirm one tag |
| **`verify_attribution_tag`** / `verifyAttributionInCalldata` | You need the raw ERC-8021 layer                                                           |

See [Configuration](/celina-sdk/getting-started/configuration.md), [Prepared flows](/celina-sdk/concepts/prepared-flows.md), and [Account Abstraction](/celina-sdk/guides/account-abstraction.md).


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