> ## Documentation Index
> Fetch the complete documentation index at: https://sequence-0fb8d9e6-api_docs.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# How to Configure a ERC1155Pack Contract in Sequence Builder

> Learn how ERC1155Pack works in Builder, including commit-reveal mechanics, and publishing pack contents.

Use this guide to configure packs in your ERC1155Pack contract in Sequence Builder. The `ERC1155Pack` contract extends ERC1155Items to add a pack-opening flow powered by a commit-reveal scheme.

<Warning>
  Prerequisite: Deploy Contracts and Items

  Make sure you have [created a project](/solutions/builder/getting-started), deployed your ERC1155Pack contract, and deployed the ERC1155 or ERC721 contracts/collections whose items you want inside each pack.
</Warning>

## Step 1: Open your ERC1155Pack contract

From your project dashboard, select the PACK contract you want to configure, then open the `Pack` tab to manage its contents. Confirm you are on the correct network and linked collection before editing.

<Frame>
  <img src="https://mintcdn.com/sequence-0fb8d9e6-api_docs/vDTbCJ2IwBHOse5J/images/builder/builder-packs-1.png?fit=max&auto=format&n=vDTbCJ2IwBHOse5J&q=85&s=6733a2f43c03d234e456e8fbfff0f73b" alt="Pack contract overview" width="1944" height="1532" data-path="images/builder/builder-packs-1.png" />
</Frame>

## Step 2: Choose or add a pack to edit

Use the pack selector to pick the pack you want to update, or click `Add new pack` to create another pack entry. The table lists each pack's underlying token address, type, IDs, and amounts that will be included when a pack is opened.

<Frame>
  <img src="https://mintcdn.com/sequence-0fb8d9e6-api_docs/vDTbCJ2IwBHOse5J/images/builder/builder-packs-2.png?fit=max&auto=format&n=vDTbCJ2IwBHOse5J&q=85&s=eae32feb9fe39f69ee744295d2e00f96" alt="Select pack and review contents" width="1960" height="1720" data-path="images/builder/builder-packs-2.png" />
</Frame>

## Step 3: Upload pack contents via CSV

Click `Add New Pack` or `Update Pack Contents` to open the CSV uploader. Enter the `Pack ID` you want to modify, set the `Supply` for how many packs can be opened, and upload a CSV with one row per pack content.

Each row must include:

* `Pack Content ID`
* For each item: `Token Address`, `Token Type` (1155/721), `Token IDs`, and `Amounts`

e.g.

```
Pack Content ID, Item 1 Token Addr, Item 1 Token Type, Item 1 Token IDs, Item 1 Amounts, Item 2 Token Addr, Item 2 Token Type, Item 2 Token IDs, Item 2 Amounts
1,0x3a6a8f4091b705fe1241c47e2532d45a6dff5a85,721,"1200","1",0xa558419686308ce836c36a5c44eeeb4b0916ca7b,1155,"5,6","7,3"
2,0x3a6a8f4091b705fe1241c47e2532d45a6dff5a85,721,"1201","1",0xa558419686308ce836c36a5c44eeeb4b0916ca7b,1155,"9,10","7,9"
3,0x3a6a8f4091b705fe1241c47e2532d45a6dff5a85,721,"1202","1",0xa558419686308ce836c36a5c44eeeb4b0916ca7b,1155,"7,8","4,8"
4,0x3a6a8f4091b705fe1241c47e2532d45a6dff5a85,721,"1203","1",0xa558419686308ce836c36a5c44eeeb4b0916ca7b,1155,"9","7"
5,0x3a6a8f4091b705fe1241c47e2532d45a6dff5a85,721,"1204","1",0xa558419686308ce836c36a5c44eeeb4b0916ca7b,1155,"9,10","5,4"

```

<Frame>
  <img src="https://mintcdn.com/sequence-0fb8d9e6-api_docs/vDTbCJ2IwBHOse5J/images/builder/builder-packs-3.png?fit=max&auto=format&n=vDTbCJ2IwBHOse5J&q=85&s=7f086e91d3e5ccad057913b6b3acfeb9" alt="Upload CSV for pack contents" width="1474" height="1286" data-path="images/builder/builder-packs-3.png" />
</Frame>

<Warning>
  The CSV replaces all existing contents for the selected Pack ID, and resets pack distribution tracking.

  If you have already distributed packs for a specific ID, we recommend you do not change the CSV, as this resets which packs have been opened.

  If a 721 item was already distributed in a previous pack, and it is in a new pack CSV, it will fail to mint when a user opens that pack.
</Warning>

## Step 4: Give the pack contract a Minter role on your item collection

For packs to mint items when opened, grant the ERC1155Pack contract address the `Minter` role on the ERC1155 collection you're using for pack contents. Open that item contract’s `Settings > Permissions`, add the pack contract address, and assign `Minter`, then sign the transaction.

## Step 5: Review and publish

After the CSV is processed you will see a preview of the parsed Pack Content rows. Verify the token addresses, IDs, amounts, and totals, then click `Create Pack Contents` to save. Your pack is now ready to be opened by players.

<Frame>
  <img src="https://mintcdn.com/sequence-0fb8d9e6-api_docs/vDTbCJ2IwBHOse5J/images/builder/builder-packs-4.png?fit=max&auto=format&n=vDTbCJ2IwBHOse5J&q=85&s=33ab6ad317493452199d4f9a248bfc57" alt="Preview processed pack contents and publish" width="1472" height="1628" data-path="images/builder/builder-packs-4.png" />
</Frame>

Looking for a frontend to open packs? Check out our react boilerplate at [https://github.com/0xsequence-demos/pack-opening-boilerplate/](https://github.com/0xsequence-demos/pack-opening-boilerplate/).

## How ERC1155Pack works

Pack contents are managed by addresses with `PACK_ADMIN_ROLE` using `setPacksContent(bytes32 _merkleRoot, uint256 _supply, uint256 packId)`. The merkle root encodes every possible pack content, and `supply` defines how many packs can be opened for that ID. Builder handles the root creation from your CSV so you can focus on content.

Flow (on-chain):

* User calls `commit(packId)` to burn their pack and create a commitment.
* After at least one block, anyone can call `reveal(user, packContent, proof, packId)` with a merkle proof for the selected content; the contract verifies and mints the items. The Sequence API will do this automatically.
* If reveal is not called before the commitment block hash expires (30 minutes), `refundPack(user, packId)` returns the pack.

Randomization:

* Commitment records `block.number + 1` for randomness.
* Reveal derives `randomSeed = keccak256(abi.encode(blockHash, user))`.
* The contract picks `randomSeed % remainingSupply[packId]`, using a Fisher–Yates-style `_availableIndices` map so each content can only be revealed once and stays uniformly random.
* The merkle leaf is `keccak256(abi.encode(revealIdx, packContent))`, matched by the supplied proof.

<Warning>
  Validators or miners controlling sequential blocks could bias block hashes. Allowing anyone to call `reveal` helps ensure committed packs are revealed before block hashes expire.
</Warning>