> For the complete documentation index, see [llms.txt](https://docs.talus.network/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.talus.network/talus-docs-v2.1.0/reference/move/nexus_tool/finite_credits.md).

# nexus\_tool::finite\_credits

* [Struct `Policy`](#struct-policy)
* [Struct `Config`](#struct-config)
* [Struct `State`](#struct-state)
* [Struct `CreditReserve`](#struct-creditreserve)
* [Struct `CreditsCreatedEvent`](#struct-creditscreatedevent)
* [Struct `CreditOfferChangedEvent`](#struct-creditofferchangedevent)
* [Constants](#constants)
* [Function `enable`](#function-enable)
* [Function `buy`](#function-buy)
* [Function `buy_more`](#function-buy_more)
* [Function `close_issuance`](#function-close_issuance)
* [Function `open_issuance`](#function-open_issuance)
* [Function `update_terms`](#function-update_terms)
* [Function `offer`](#function-offer)
* [Function `issue`](#function-issue)
* [Function `issue_more`](#function-issue_more)
* [Function `get_invocation`](#function-get_invocation)
* [Function `restore_refund`](#function-restore_refund)
* [Function `collect`](#function-collect)
* [Function `share`](#function-share)
* [Function `remaining`](#function-remaining)
* [Function `derive_id`](#function-derive_id)

### Struct `Policy`

Private construction witness for this policy.

```move
public struct Policy has drop
```

<details>

<summary>Fields</summary>

</details>

#### Struct `Config`

Owner configured sale terms for finite credits.

```move
public struct Config has store
```

<details>

<summary>Fields</summary>

`issuance_enabled: boolprice_per_credit: u64minimum_credits: u64maximum_credits: u64`

</details>

#### Struct `State`

Policy state stored in one beneficiary's canonical account.

```move
public struct State has store
```

<details>

<summary>Fields</summary>

[`remaining`](#nexus_tool_finite_credits_remaining)`: u64`

</details>

#### Struct `CreditReserve`

One prepaid unit held by an in flight \[Invocation].

\[CreditReserve] carries no SUI. Payment occurs when credits are purchased; this marker preserves one unit until finalization or refund.

```move
public struct CreditReserve has store
```

<details>

<summary>Fields</summary>

</details>

#### Struct `CreditsCreatedEvent`

Records creation of one canonical finite credit \[PolicyAccount].

```move
public struct CreditsCreatedEvent has copy, drop
```

<details>

<summary>Fields</summary>

`tool: sui::object::IDcashier: sui::object::IDcredits: sui::object::IDbeneficiary:` [`nexus_interface::payment::PaymentSourceKind`](/talus-docs-v2.1.0/reference/move/nexus_interface/payment.md#nexus_interface_payment_PaymentSourceKind)[`remaining`](#nexus_tool_finite_credits_remaining)`: u64`

</details>

#### Struct `CreditOfferChangedEvent`

Records the complete commercial offer for future credit purchases.

```move
public struct CreditOfferChangedEvent has copy, drop
```

<details>

<summary>Fields</summary>

`cashier: sui::object::IDissuance_enabled: boolprice_per_credit: u64minimum_credits: u64maximum_credits: u64`

</details>

#### Constants

```move
#[error]
const ECreditsMismatch: vector<u8> = b"Credits do not authorize this invocation request";
```

```move
#[error]
const EInvalidCreditCount: vector<u8> = b"Credit count is outside the configured range";
```

```move
#[error]
const EInvalidCreditRange: vector<u8> = b"Credit range must start above zero";
```

```move
#[error]
const EInvalidCreditPrice: vector<u8> = b"Credit price must be greater than zero";
```

```move
#[error]
const EIssuanceClosed: vector<u8> = b"Finite credit issuance is closed";
```

```move
#[error]
const ENoCreditsRemaining: vector<u8> = b"No invocation credits remain";
```

```move
#[error]
const ECreditOverflow: vector<u8> = b"Invocation credit count overflow";
```

#### Function `enable`

Enables finite credit admission and sales.

```move
public fun enable(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>, price_per_credit: u64, minimum_credits: u64, maximum_credits: u64)
```

#### Function `buy`

Purchases credits, shares the canonical policy account, and transfers prepaid SUI to the cashier inbox. The public call returns only the deposit ID.

```move
public fun buy(cashier: &mut nexus_tool::tool_cashier::ToolCashier, pay_with: &mut sui::coin::Coin<sui::sui::SUI>, beneficiary: nexus_interface::payment::PaymentSourceKind, credits: u64, ctx: &mut sui::tx_context::TxContext): sui::object::ID
```

#### Function `buy_more`

Purchases units for an existing canonical credit account.

```move
public fun buy_more(cashier: &nexus_tool::tool_cashier::ToolCashier, credits: &mut nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>, pay_with: &mut sui::coin::Coin<sui::sui::SUI>, additional_credits: u64, ctx: &mut sui::tx_context::TxContext): sui::object::ID
```

#### Function `close_issuance`

Stops purchases and owner issuance without invalidating existing accounts.

```move
public fun close_issuance(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>)
```

#### Function `open_issuance`

Resumes purchases and owner issuance for canonical credit accounts.

```move
public fun open_issuance(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>)
```

#### Function `update_terms`

Replaces the sale terms used only for future purchases and grants.

```move
public fun update_terms(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>, price_per_credit: u64, minimum_credits: u64, maximum_credits: u64)
```

#### Function `offer`

Returns the current finite credit offer.

```move
public fun offer(cashier: &nexus_tool::tool_cashier::ToolCashier): (bool, u64, u64, u64)
```

#### Function `issue`

Issues credits under Tool owner authority.

```move
public fun issue(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>, beneficiary: nexus_interface::payment::PaymentSourceKind, credits: u64, ctx: &mut sui::tx_context::TxContext): nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>
```

#### Function `issue_more`

Adds an owner granted amount to an existing canonical credit account.

```move
public fun issue_more(cashier: &nexus_tool::tool_cashier::ToolCashier, credits: &mut nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>, additional_credits: u64)
```

#### Function `get_invocation`

Decrements \[State] and creates an \[Invocation] holding one prepaid unit.

The held \[CreditReserve] is a unit marker, not an execution payment reserve. The Invocation therefore records zero SUI and names \[credits] as its exact accounting source.

```move
public fun get_invocation(cashier: &nexus_tool::tool_cashier::ToolCashier, credits: &mut nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>, request: nexus_interface::payment::InvocationRequest, ctx: &mut sui::tx_context::TxContext): nexus_tool::invocation::Invocation
```

#### Function `restore_refund`

Restores one exact refunded unit to its canonical credit account.

```move
public fun restore_refund(credits: &mut nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>, receiving: sui::transfer::Receiving<nexus_tool::invocation::Invocation>)
```

#### Function `collect`

Collects finalized credit Invocations and consumes their reserved units.

```move
public fun collect(cashier: &mut nexus_tool::tool_cashier::ToolCashier, owner_cap: &nexus_primitives::owner_cap::CloneableOwnerCap<nexus_tool::tool_cashier::OverToolCashier>, invocations: vector<sui::transfer::Receiving<nexus_tool::invocation::Invocation>>): sui::balance::Balance<sui::sui::SUI>
```

#### Function `share`

Shares a canonical credit \[PolicyAccount] for runtime admission.

```move
public fun share(credits: nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>)
```

#### Function `remaining`

Returns the units currently available in \[self].

```move
public fun remaining(self: &nexus_tool::tool_cashier::PolicyAccount<nexus_tool::finite_credits::Policy, nexus_tool::finite_credits::State>): u64
```

#### Function `derive_id`

Derives the canonical finite credit account for \[beneficiary].

```move
public fun derive_id(cashier: sui::object::ID, beneficiary: nexus_interface::payment::PaymentSourceKind): sui::object::ID
```


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