Assets, Vault & Faucet Changes

The asset model was renamed one level down. What was AssetVaultKey is now AssetId, and what was AssetId is now AssetClass. Because the name AssetId survives with a different meaning, a careless search-and-replace will compile and be wrong — do the AssetId → AssetClass rename first. Separately, the single create_fungible_faucet factory split into six auth-specific factories.

Quick Fix

// Before (0.15)
let key: AssetVaultKey = asset.vault_key();
let key = AssetVaultKey::new_fungible(faucet_id, callback_flag);

// After (0.16)
let id: AssetId = asset.id();
let id = AssetId::new_fungible(faucet_id);   // callback flag now lives on the AccountId

If you encounter errors, continue reading for detailed migration steps.

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Summary

The rename reflects a conceptual correction. The per-asset vault key is the thing that actually identifies an asset, so it took the name AssetId; the faucet-level identifier it used to share a name with describes a class of assets, so it became AssetClass.

This is the most dangerous rename in the release precisely because it is not a removal. AssetId still exists after the upgrade, so code referring to it keeps compiling while silently meaning something different. Rename in the right order and let the compiler find the rest.

AssetAmount, AssetComposition, and AssetCallbackFlag all existed in 0.15 and are unchanged. AssetVault::get_balance already returned AssetAmount in 0.15 — only its parameter type was renamed. If you saw AssetAmount described as new, that applies to the client surface, not the protocol.

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AssetVaultKey → AssetId, and AssetId → AssetClass

Summary

The vault key type was renamed to AssetId, the previous AssetId became AssetClass, and Asset::vault_key() became Asset::id(). AssetIdHash is the corresponding hash type.

Affected Code

// Before (0.15)
let key: AssetVaultKey = asset.vault_key();
let balance: AssetAmount = vault.get_balance(vault_key)?;
let key = AssetVaultKey::new_fungible(faucet_id, callback_flag);

// After (0.16)
let id: AssetId = asset.id();
let balance: AssetAmount = vault.get_balance(asset_id)?;
let id = AssetId::new_fungible(faucet_id);
// or, fully explicit:
let id = AssetId::new(asset_class, faucet_id, composition);

Note that AssetId::new_fungible no longer takes a callback flag. Whether a faucet's assets trigger callbacks is encoded in the account ID itself, set at construction time via AccountBuilder::with_asset_callbacks.

Asset itself is unchanged in shape — still an enum with Fungible and NonFungible variants — and FungibleAsset::new(faucet_id, amount) keeps its signature.

Migration Steps

1. Rename AssetId → AssetClass first, throughout your codebase.
2. Then rename AssetVaultKey → AssetId.
3. Replace asset.vault_key() with asset.id().
4. Drop the callback-flag argument from new_fungible calls; set it on the account instead with with_asset_callbacks.
5. Re-index any persisted vault or asset data. Serialized asset identifiers are not compatible across the rename.

Common Errors

Error Message	Cause	Solution
cannot find type AssetVaultKey	Renamed	Use AssetId.
no method named vault_key	Renamed	Use id().
this function takes 1 argument but 2 were supplied on new_fungible	Callback flag removed	Drop it; set with_asset_callbacks on the account.
Type mismatch where AssetId used to work	AssetId now means the vault key	The old meaning is AssetClass.

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Faucet factories split by authentication scheme

Summary

create_fungible_faucet took an AuthMethod and an AccessControl argument and dispatched internally. Since AuthMethod was removed (see Account Changes), the factory split into one function per authentication scheme, each taking a concrete auth component.

Affected Code

// Before (0.15)
pub fn create_fungible_faucet(
    init_seed: [u8; 32],
    faucet: FungibleFaucet,
    account_type: AccountType,
    auth_method: AuthMethod,
    access_control: AccessControl,
    token_policy_manager: TokenPolicyManager,
) -> Result<Account, FungibleFaucetError>

// After (0.16)
pub fn create_singlesig_user_fungible_faucet(
    init_seed: [u8; 32],
    faucet: FungibleFaucet,
    auth_component: AuthSingleSig,
    token_policy_manager: TokenPolicyManager,
    account_type: AccountType,
) -> Result<Account, FungibleFaucetError>

Note that the parameter order changed as well as the parameter list — account_type moved to the end.

The full set of factories:

Faucet kind	v0.16 factory
Fungible, single signature	create_singlesig_user_fungible_faucet
Fungible, multisig	create_multisig_user_fungible_faucet
Fungible, guarded multisig	create_guarded_user_fungible_faucet
Fungible, network account	create_network_fungible_faucet
Non-fungible, user account	create_user_non_fungible_faucet
Non-fungible, network account	create_network_non_fungible_faucet

Non-fungible faucet factories are new in this release; 0.15 shipped only the fungible factory.

Migration Steps

1. Choose the factory matching your authentication scheme and pass a concrete auth component instead of an AuthMethod.
2. Drop the access_control argument. The factories install Authority::AuthControlled and the pausable components for you.
3. Check the argument order — account_type is now last.
4. Expect a different account ID for a faucet rebuilt from the same seed, since the component set and names changed.

Common Errors

Error Message	Cause	Solution
cannot find function create_fungible_faucet	Split into per-scheme factories	Use the matching factory from the table.
cannot find type AuthMethod	Removed	Pass a concrete auth component.
Arguments of the wrong type	Parameter order changed	account_type moved to the end.

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Common Errors

Error Message	Cause	Solution
cannot find type AssetVaultKey	Renamed to AssetId	Rename, after renaming old AssetId to AssetClass.
Silent behaviour change around asset identity	AssetId kept its name with a new meaning	Audit every AssetId reference.
Persisted vault lookups miss after upgrading	Asset identifier serialization changed	Re-index persisted vault data.
cannot find function create_fungible_faucet	Factories split	Use the auth-specific factory.