> For the complete documentation index, see [llms.txt](https://docs.sail.money/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sail.money/protocol/architecture.md).

# Architecture

Sail draws a hard line between a small **trusted core** and an open, **untrusted periphery**. The security analysis lives entirely in the core; everything outside it is contained by the [four evaluation guarantees](/protocol/concepts/evaluation-guarantees.md).

## Trusted core vs. periphery

|                     | Contracts                                                  | Trust                                                                                                                                      |
| ------------------- | ---------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| **Trusted core**    | `SailKernel`, `SailGovernance`, `TimelockController`       | Audited; their correctness is assumed. The kernel and governance are the only contracts that can move Safe assets or change parameters.    |
| **Trusted helpers** | `SafeModuleEnabler`, `MandateFactory`, `StandardFeePolicy` | Constrained by construction: the enabler is stateless, the factory holds no privilege, and fee policies must be on a governance allowlist. |
| **Periphery**       | Permission templates, custom fee policies, oracles         | User-deployed, unaudited by default. A bug here affects only the accounts that opted into it. The kernel never trusts them.                |

> **Blast radius.** A bug in a permission template affects only accounts that registered it; a bug in a fee policy affects only accounts using it. Nothing in the periphery can compromise the kernel or another account.

## Component map

| Component            | Responsibility                                                                                                                | Page                                                               |
| -------------------- | ----------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------ |
| `SailKernel`         | Account registration, permission registry, EIP-712 verification, single & batch dispatch, fee accounting, principal tracking. | [SailKernel](/protocol/architecture/kernel.md)                     |
| `SailGovernance`     | Constitutional caps + tunable parameters behind a 48h timelock; emergency pause; trusted allowlists.                          | [Governance](/protocol/architecture/governance.md)                 |
| `TimelockController` | Standalone 48h timelock, injected into governance and validated at construction.                                              | [Governance](/protocol/architecture/governance.md)                 |
| `MandateFactory`     | Bundles configure → register into one transaction. No privilege.                                                              | [MandateFactory](/protocol/architecture/mandate-factory.md)        |
| `SafeModuleEnabler`  | Enables the kernel as a Safe module during account creation.                                                                  | [SafeModuleEnabler](/protocol/architecture/safe-module-enabler.md) |
| `StandardFeePolicy`  | Reference 2-and-20 fee policy.                                                                                                | [Fee model](/protocol/fees-and-governance/fees.md)                 |

## Dependency direction

```
SailKernel ── reads params, cut, caps, allowlists ──▶ SailGovernance ──▶ TimelockController
SailKernel ── computeFee / recordCollection ────────▶ IFeePolicy (StandardFeePolicy or custom)
SailKernel ── evaluate / evaluateBatch (staticcall) ▶ IPermission / IBatchPermission (periphery)
SailKernel ── execTransactionFromModule ───────────▶ ISafe (the SMA)
```

The kernel inherits OpenZeppelin's `EIP712` and `ReentrancyGuard`. It reads — but never writes — governance state, and it calls out to fee policies and permissions only through tightly bounded paths (`recordCollection` after a CEI-ordered fee split; `evaluate` under `staticcall` + gas cap).

## Two dispatch paths

* **Single dispatch** (`dispatch`) — one call, gated by one named permission.
* **Batch dispatch** (`dispatchBatch`) — an ordered array of calls executed atomically, gated by one named batch-aware permission.

Both follow selective authorization. See [single & batch dispatch](/protocol/architecture/dispatch.md).


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