> For the complete documentation index, see [llms.txt](https://docs.vault.ky/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.vault.ky/smart-contracts/overview.md).

# Program overview

Vault runs on two Anchor programs deployed to Solana.

| Program        | Responsibility                                                                    |
| -------------- | --------------------------------------------------------------------------------- |
| `vault-core`   | Global configuration, shared types, and the campaign state machine definition.    |
| `vault-escrow` | Campaign creation, contributions, tips, settlement, refunds, and treasury sweeps. |

Splitting configuration from execution keeps the escrow program's surface narrow. Global parameters live in one account that the escrow program reads but does not own.

## Design constraints

**Financial math uses `u128` intermediates.** Fee and refund calculations are performed in wider precision before narrowing, so lamport arithmetic cannot silently overflow.

**No oracle at execution time.** Values that would otherwise need a live price feed — the refund fee cap and the tip threshold — are converted to lamports once, at campaign creation, and stored on the campaign account. Settlement and refunds never consult an external price source.

**A narrow state machine.** There is no milestone system, no voting, no partial execution, and no discretionary withdrawal path. A campaign moves through a fixed set of states and terminates.

**Permissionless progression.** The instructions that advance a campaign and process refunds do not require Vault's signature. Anyone can submit them.

## What the programs do not do

The programs hold and move SOL according to campaign rules. They do not perform off-chain fulfillment, custody assets other than SOL, or bridge value to another chain.

Fulfillment happens off-chain after settlement. That boundary is described in [Trust boundary](/smart-contracts/trust-boundary.md).


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