Program Implementation

Program-side guide to building with Magic Actions

---

Quick Access

Magic Actions Example

Explore reference implementation on GitHub

---

1) Create action instruction

The instruction update_leaderboard runs on the base layer immediately after the commit lands. The #[action] attribute on its accounts context marks it as callable from a post-commit action.

// program instruction
pub fn update_leaderboard(ctx: Context<UpdateLeaderboard>) -> Result<()> {
    let leaderboard = &mut ctx.accounts.leaderboard;
    let counter_info = &mut ctx.accounts.counter.to_account_info();
    let mut data: &[u8] = &counter_info.try_borrow_data()?;
    let counter = Counter::try_deserialize(&mut data)?;

    if counter.count > leaderboard.high_score {
        leaderboard.high_score = counter.count;
    }

    msg!(
        "Leaderboard updated! High score: {}",
        leaderboard.high_score
    );
    Ok(())
}

// instruction context
#[action]
#[derive(Accounts)]
pub struct UpdateLeaderboard<'info> {
    #[account(mut, seeds = [LEADERBOARD_SEED], bump)]
    pub leaderboard: Account<'info, Leaderboard>,
    /// CHECK: PDA owner depends on: 1) Delegated: Delegation Program; 2) Undelegated: Your program ID
    pub counter: UncheckedAccount<'info>,
}

2) Build the commit instruction with the action

The commit instruction commit_and_update_leaderboard runs on the ER. It uses MagicIntentBundleBuilder to schedule both the commit and the post-commit action onto magic_context — both are applied together when the ER transaction is sealed back to the base layer.

// commit action instruction on ER
pub fn commit_and_update_leaderboard(ctx: Context<CommitAndUpdateLeaderboard>) -> Result<()> {
    // Build the post-commit action that updates the leaderboard on base layer
    let instruction_data =
        anchor_lang::InstructionData::data(&crate::instruction::UpdateLeaderboard {});
    let action_args = ActionArgs::new(instruction_data);
    let action_accounts = vec![
        ShortAccountMeta {
            pubkey: ctx.accounts.leaderboard.key(),
            is_writable: true,
        },
        ShortAccountMeta {
            pubkey: ctx.accounts.counter.key(),
            is_writable: false,
        },
    ];
    let action = CallHandler {
        destination_program: crate::ID,
        accounts: action_accounts,
        args: action_args,
        // Signer that pays transaction fees for the action from its escrow PDA
        escrow_authority: ctx.accounts.payer.to_account_info(),
        compute_units: 200_000,
    };

    // Schedule commit + post-commit action on magic_context
    MagicIntentBundleBuilder::new(
        ctx.accounts.payer.to_account_info(),
        ctx.accounts.magic_context.to_account_info(),
        ctx.accounts.magic_program.to_account_info(),
    )
    .commit(&[ctx.accounts.counter.to_account_info()])
    .add_post_commit_actions([action])
    .build_and_invoke()?;

    Ok(())
}

// commit action context on ER
#[commit]
#[derive(Accounts)]
pub struct CommitAndUpdateLeaderboard<'info> {
    #[account(mut)]
    pub payer: Signer<'info>,

    #[account(mut, seeds = [COUNTER_SEED], bump)]
    pub counter: Account<'info, Counter>,

    /// CHECK: Leaderboard PDA - not mut here, writable set in handler
    #[account(seeds = [LEADERBOARD_SEED], bump)]
    pub leaderboard: UncheckedAccount<'info>,

    /// CHECK: Your program ID
    pub program_id: AccountInfo<'info>,
}

Execute multiple actions

You can commit multiple accounts and chain several actions in one call. Actions execute sequentially in the order they’re passed to add_post_commit_actions.

// Chain several actions — they execute sequentially on base layer after the commit lands.
MagicIntentBundleBuilder::new(
    ctx.accounts.payer.to_account_info(),
    ctx.accounts.magic_context.to_account_info(),
    ctx.accounts.magic_program.to_account_info(),
)
.commit(&[
    ctx.accounts.counter.to_account_info(),
    // ... additional committed accounts
])
.add_post_commit_actions([action_1, action_2, action_3])
.build_and_invoke()?;

Undelegate with actions

Actions can also be chained onto an undelegation — the counter commits, undelegates, and the actions run, all atomically in one ER transaction.

// Commit, undelegate, AND execute actions — all atomically on base layer after the ER transaction seals.
MagicIntentBundleBuilder::new(
    ctx.accounts.payer.to_account_info(),
    ctx.accounts.magic_context.to_account_info(),
    ctx.accounts.magic_program.to_account_info(),
)
.commit_and_undelegate(&[ctx.accounts.counter.to_account_info()])
.add_post_commit_actions([action])
.build_and_invoke()?;

---