accounts.mdx

Accounts

Everything in Evolve is an account. This account-centric model is the foundation of the entire system.

What is an Account?

An account has three components:

Component	Description
Identity	Unique AccountId (u128)
Code	Implementation of the AccountCode trait
State	Isolated storage namespace

The AccountCode Trait

Every account implements the AccountCode trait:

pub trait AccountCode: Send + Sync {
    fn execute(
        &self,
        env: &mut dyn Environment,
        request: InvokeRequest,
    ) -> SdkResult<Vec<u8>>;

    fn query(
        &self,
        env: &dyn EnvironmentQuery,
        request: InvokeRequest,
    ) -> SdkResult<Vec<u8>>;
}

The #[account_impl] macro generates this implementation for you.

System Accounts

Reserved AccountId values with special behavior:

ID	Name	Purpose
0	RUNTIME_ACCOUNT_ID	Account creation, migrations
1	STORAGE_ACCOUNT_ID	Storage read/write operations
2	EVENT_HANDLER_ACCOUNT_ID	Event emission
5	UNIQUE_HANDLER_ACCOUNT_ID	Unique ID generation

System accounts have hardcoded handlers in the invoker.

Inter-Account Calls

Accounts communicate through message passing:

// Account A calls Account B
env.do_exec(account_b_id, &message, funds)?;

// Internally:
// 1. Invoker creates checkpoint
// 2. Funds are transferred (if any)
// 3. Account B's code executes
// 4. On error: checkpoint restored
// 5. On success: changes committed

Message Dispatch

The #[account_impl] macro generates:

1. Message structs for each function
2. Function IDs from SHA-256 of function name
3. Dispatch logic in AccountCode::execute/query

Storage Isolation

Each account's storage is prefixed by its AccountId:

[AccountId][FieldPrefix][Key] => Value

Example:
[0x0A][0x01][alice] => 1000  // Account 10, field 1, key "alice"

This prevents accounts from accidentally (or maliciously) accessing each other's state.