tributary

        authority: authority_info.clone(),    };    let cpi_ctx = match authority_mode {        AuthorityMode::Direct => CpiContext::new(token_program.key(), cpi_accounts),        AuthorityMode::PdaSigner(seeds) => {            CpiContext::new_with_signer(token_program.key(), cpi_accounts, seeds)        }    };    token_interface::transfer_checked(cpi_ctx, reward, mint_decimals)?;     let mut referral_account = referral_loader.load_mut()?;    referral_account.total_earned = referral_account        .total_earned        .checked_add(reward)        .ok_or(TributaryError::ArithmeticOverflow)?;     Ok(())} // ──────────────────────────────────────────────────────────────────// C-02: referral chain topology validation// ──────────────────────────────────────────────────────────────────#[cfg(test)]mod tests {

1. Line 424 AuthorityMode::Direct => CpiContext::new(token_program.key(), cpi_accounts),: Makes a cross-program invocation into another program.
2. Line 426 CpiContext::new_with_signer(token_program.key(), cpi_accounts, seeds): Makes a CPI signed by a PDA. The signer seeds prove the program controls that address.
3. Line 429 token_interface::transfer_checked(cpi_ctx, reward, mint_decimals)?;: A checked token transfer, which also verifies the mint and decimals.
4. Line 434 .checked_add(reward): Uses checked arithmetic so overflow fails instead of wrapping.

use crate::{error::TributaryError, state::*, CONFIG_SEED};use anchor_lang::prelude::*; #[derive(Accounts)]pub struct Initialize<'info> {    #[account(mut)]    pub authority: Signer<'info>,     #[account(mut)]    pub admin: Signer<'info>,     #[account(        init,        payer = admin,        space = ProgramConfig::SIZE,        seeds = [CONFIG_SEED],        bump    )]    pub config: Account<'info, ProgramConfig>,     /// CHECK: Program data account containing upgrade authority info.    /// Enforces that only the upgrade authority can initialize the protocol.    #[account(constraint = program_data.upgrade_authority_address == Some(authority.key()) @ TributaryError::UnauthorizedInitializer)]    pub program_data: Account<'info, ProgramData>,

1. Line 7 pub authority: Signer<'info>,: Requires this account to have signed the transaction.
2. Line 13 init,: Creates and pays for a new account. Space and payer must be specified.
3. Line 16 seeds = [CONFIG_SEED],: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
4. Line 17 bump: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.

    #[account(        mut,        seeds = [CONFIG_SEED],        bump = config.bump,        constraint = config.admin == admin.key() @ TributaryError::Unauthorized    )]    pub config: Account<'info, ProgramConfig>,} impl<'info> ChangeProgramAuthority<'info> {    /// Rotate the protocol admin. Existing admin must sign; new admin is    /// recorded for future admin-gated calls. `fee_recipient` is untouched.    pub fn handler_change_program_authority(ctx: Context<ChangeProgramAuthority>) -> Result<()> {        let config = &mut ctx.accounts.config;        let old_admin = config.admin;        config.admin = ctx.accounts.new_admin.key();         emit!(ProgramAuthorityChanged {            old_admin,            new_admin: config.admin,        });         msg!(            "Program authority rotated from {:?} to {:?}",

1. Line 15 seeds = [CONFIG_SEED],: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
2. Line 16 bump = config.bump,: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.
3. Line 30 emit!(ProgramAuthorityChanged {: Emits an Anchor event that clients can parse from the logs.
4. Line 35 msg!(: Logs to the program log, which is visible in explorers and the test output.

use crate::{constants::*, error::TributaryError, state::*};use anchor_lang::prelude::*; #[derive(Accounts)]pub struct CreatePaymentGateway<'info> {    #[account(mut)]    pub admin: Signer<'info>,     /// CHECK: The authority that will own the gateway    pub authority: UncheckedAccount<'info>,     #[account(        init,        payer = admin,        space = PaymentGateway::SIZE,        seeds = [GATEWAY_SEED, authority.key().as_ref()],        bump    )]    pub gateway: Account<'info, PaymentGateway>,     #[account(        seeds = [CONFIG_SEED],        bump = config.bump,        constraint = config.admin == admin.key(),

1. Line 7 pub admin: Signer<'info>,: Requires this account to have signed the transaction.
2. Line 13 init,: Creates and pays for a new account. Space and payer must be specified.
3. Line 16 seeds = [GATEWAY_SEED, authority.key().as_ref()],: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
4. Line 17 bump: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.