agentpay

    let new_today = spent_today        .checked_add(amount).ok_or(VaultError::Overflow)?;    require!(new_today <= max_per_day, VaultError::ExceedsDailyLimit);     // ---- Phase 2: CPI with fee split ----    let bump_arr = [bump];    let seeds: &[&[u8]] = &[b"vault", agent_key.as_ref(), &bump_arr];    let signer_seeds = &[seeds];     // Calculate fee (fee_bps = 30 means 0.3%)    let fee_amount: u64 = if fee_bps > 0 {        (amount as u128)            .checked_mul(fee_bps as u128).ok_or(VaultError::Overflow)?            .checked_div(10_000).ok_or(VaultError::Overflow)? as u64    } else {        0    };    let net_amount = amount.checked_sub(fee_amount).ok_or(VaultError::Overflow)?;     // Main transfer: vault → recipient (net_amount)    token::transfer(        CpiContext::new_with_signer(            ctx.accounts.token_program.to_account_info(),            Transfer {

1. Line 146 .checked_add(amount).ok_or(VaultError::Overflow)?;: Uses checked arithmetic so overflow fails instead of wrapping.
2. Line 147 require!(new_today <= max_per_day, VaultError::ExceedsDailyLimit);: An explicit validation that aborts the instruction with an error.
3. Line 150 let bump_arr = [bump];: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.
4. Line 152 let signer_seeds = &[seeds];: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
5. Line 165 token::transfer(: An SPL token transfer through the Token Program.
6. Line 166 CpiContext::new_with_signer(: Makes a CPI signed by a PDA. The signer seeds prove the program controls that address.

    let signer_seeds = &[seeds];     token::transfer(        CpiContext::new_with_signer(            ctx.accounts.token_program.to_account_info(),            Transfer {                from: ctx.accounts.vault_ata.to_account_info(),                to: ctx.accounts.owner_ata.to_account_info(),                authority: ctx.accounts.vault.to_account_info(),            },            signer_seeds,        ),        amount,    )?;     emit!(EmergencyWithdrawEvent {        vault: ctx.accounts.vault.key(),        owner: ctx.accounts.owner.key(),        amount,        ts: Clock::get()?.unix_timestamp,    });     Ok(())}

1. Line 37 let signer_seeds = &[seeds];: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
2. Line 39 token::transfer(: An SPL token transfer through the Token Program.
3. Line 40 CpiContext::new_with_signer(: Makes a CPI signed by a PDA. The signer seeds prove the program controls that address.
4. Line 52 emit!(EmergencyWithdrawEvent {: Emits an Anchor event that clients can parse from the logs.
5. Line 56 ts: Clock::get()?.unix_timestamp,: Reads on-chain time from the Clock sysvar.

use anchor_lang::prelude::*;use crate::state::*;use crate::errors::VaultError; #[derive(Accounts)]pub struct UpdatePolicy<'info> {    pub owner: Signer<'info>,    #[account(        mut,        seeds = [b"vault", vault.authority.as_ref()],        bump = vault.bump,        has_one = owner @ VaultError::Unauthorized,    )]    pub vault: Account<'info, AgentVault>,} pub fn handler(ctx: Context<UpdatePolicy>, new_policy: SpendingPolicy) -> Result<()> {    require!(new_policy.allowlist.len() <= 16, VaultError::AllowlistFull);    ctx.accounts.vault.policy = new_policy;    Ok(())}

1. Line 7 pub owner: Signer<'info>,: Requires this account to have signed the transaction.
2. Line 10 seeds = [b"vault", vault.authority.as_ref()],: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
3. Line 11 bump = vault.bump,: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.
4. Line 12 has_one = owner @ VaultError::Unauthorized,: Checks that a stored pubkey field matches the passed account.
5. Line 18 require!(new_policy.allowlist.len() <= 16, VaultError::AllowlistFull);: An explicit validation that aborts the instruction with an error.

use anchor_lang::prelude::*;use anchor_spl::token::{Token, TokenAccount};use anchor_spl::associated_token::AssociatedToken;use anchor_spl::token::Mint;use crate::state::FeeCollector; #[derive(Accounts)]pub struct InitializeFeeCollector<'info> {    #[account(mut)]    pub payer: Signer<'info>,     /// Fee collector authority (protocol team controls this)    /// CHECK: Only storing pubkey, no type validation needed    pub fee_authority: UncheckedAccount<'info>,     pub mint: Account<'info, Mint>,     #[account(        init,        payer = payer,        space = FeeCollector::LEN,        seeds = [FeeCollector::SEEDS],        bump    )]

1. Line 10 pub payer: Signer<'info>,: Requires this account to have signed the transaction.
2. Line 19 init,: Creates and pays for a new account. Space and payer must be specified.
3. Line 22 seeds = [FeeCollector::SEEDS],: Declares the PDA seeds. Anchor re-derives the address and rejects the account if it doesn't match.
4. Line 23 bump: Uses the bump seed, the extra byte that pushes the derived address off the ed25519 curve.