Light PDA

Create PDA accounts with sponsored rent-exemption for Anchor programs. Works with your existing Anchor implementations.

Light-PDAs are Solana PDAs with sponsored rent-exemption. Programs create them using Anchor #[account(init)] with #[light_account(init)].

	Regular PDA	Light-PDA
100-byte account	~1,600,000 lamports	~11,500 lamports

What changes

Area	Change
State struct	Derive LightAccount, add compression_info: CompressionInfo
Accounts struct	Derive LightAccounts, add #[light_account] on init accounts
Program module	Add #[light_program] above #[program]
Instructions (reads, updates, closes)	No program changes. Client prepends a load instruction if account is cold.

Audit overhead is minimal as your program logic is mostly untouched. The rest is macro-generated.

---

Step 1: Dependencies

[dependencies]
light-account = { version = "0.20.0", features = ["anchor"] }
light-sdk = { version = "0.20.0", features = ["anchor", "v2", "cpi-context"] }
anchor-lang = "0.31"

Step 2: State struct

Add compression_info field and derive LightAccount:

use light_account::{CompressionInfo, LightAccount};

#[derive(Default, Debug, InitSpace, LightAccount)]
#[account]
pub struct Counter {
    /// Add this:
    pub compression_info: CompressionInfo,

    pub owner: Pubkey,
    pub count: u64,
}

Step 3: Program module

Add #[light_program] above #[program]. Define the CPI signer constant with your program ID:

use light_account::{derive_light_cpi_signer, light_program, CpiSigner};

pub const LIGHT_CPI_SIGNER: CpiSigner =
    derive_light_cpi_signer!("YourProgramId11111111111111111111111111111111");

#[light_program]
#[program]
pub mod counter {
    use super::*;

    pub fn create_counter<'info>(
        ctx: Context<'_, '_, '_, 'info, CreateCounter<'info>>,
        params: CreateCounterParams,
    ) -> Result<()> {
        ctx.accounts.counter.owner = ctx.accounts.owner.key();
        ctx.accounts.counter.count = params.count;
        Ok(())
    }

    /// Standard Anchor — no Light-specific changes.
    pub fn increment(ctx: Context<Increment>) -> Result<()> {
        ctx.accounts.counter.count = ctx.accounts.counter.count.checked_add(1).unwrap();
        Ok(())
    }

    /// Standard Anchor — no Light-specific changes.
    pub fn close_counter(_ctx: Context<CloseCounter>) -> Result<()> {
        Ok(())
    }
}

Step 4: Accounts struct

Derive LightAccounts on your Accounts struct and add #[light_account(...)] next to #[account(...)].

Only the init struct derives LightAccounts. The increment and close structs are standard Anchor:

use light_account::{CreateAccountsProof, LightAccounts};

#[derive(AnchorSerialize, AnchorDeserialize, Clone)]
pub struct CreateCounterParams {
    pub create_accounts_proof: CreateAccountsProof,
    pub count: u64,
}

#[derive(Accounts, LightAccounts)]
#[instruction(params: CreateCounterParams)]
pub struct CreateCounter<'info> {
    #[account(mut)]
    pub fee_payer: Signer<'info>,

    /// CHECK: Read-only, used for PDA derivation.
    pub owner: AccountInfo<'info>,

    /// CHECK: Validated by Light Protocol CPI.
    pub compression_config: AccountInfo<'info>,

    /// CHECK: PDA rent sponsor for compression rent reimbursement.
    #[account(mut)]
    pub pda_rent_sponsor: AccountInfo<'info>,

    #[account(
        init,
        payer = fee_payer,
        space = 8 + <Counter as anchor_lang::Space>::INIT_SPACE,
        seeds = [COUNTER_SEED, owner.key().as_ref()],
        bump,
    )]
    #[light_account(init)]
    pub counter: Account<'info, Counter>,

    pub system_program: Program<'info, System>,
}

Full Example

Program

lib.rs

use anchor_lang::prelude::*;
use light_account::{
    CompressionInfo, LightAccount, LightAccounts, CreateAccountsProof,
    derive_light_cpi_signer, light_program, CpiSigner,
};

declare_id!("YourProgramId11111111111111111111111111111111");

pub const LIGHT_CPI_SIGNER: CpiSigner =
    derive_light_cpi_signer!("YourProgramId11111111111111111111111111111111");

pub const COUNTER_SEED: &[u8] = b"counter";

#[derive(Default, Debug, InitSpace, LightAccount)]
#[account]
pub struct Counter {
    pub compression_info: CompressionInfo,
    pub owner: Pubkey,
    pub count: u64,
}

#[derive(AnchorSerialize, AnchorDeserialize, Clone)]
pub struct CreateCounterParams {
    pub create_accounts_proof: CreateAccountsProof,
    pub count: u64,
}

#[light_program]
#[program]
pub mod counter {
    use super::*;

    pub fn create_counter<'info>(
        ctx: Context<'_, '_, '_, 'info, CreateCounter<'info>>,
        params: CreateCounterParams,
    ) -> Result<()> {
        ctx.accounts.counter.owner = ctx.accounts.owner.key();
        ctx.accounts.counter.count = params.count;
        Ok(())
    }

    /// Standard Anchor — no Light-specific changes.
    pub fn increment(ctx: Context<Increment>) -> Result<()> {
        ctx.accounts.counter.count = ctx.accounts.counter.count.checked_add(1).unwrap();
        Ok(())
    }

    /// Standard Anchor — no Light-specific changes.
    pub fn close_counter(_ctx: Context<CloseCounter>) -> Result<()> {
        Ok(())
    }
}

#[derive(Accounts, LightAccounts)]
#[instruction(params: CreateCounterParams)]
pub struct CreateCounter<'info> {
    #[account(mut)]
    pub fee_payer: Signer<'info>,

    /// CHECK: Read-only, used for PDA derivation.
    pub owner: AccountInfo<'info>,

    /// CHECK: Validated by Light Protocol CPI.
    pub compression_config: AccountInfo<'info>,

    /// CHECK: PDA rent sponsor for compression rent reimbursement.
    #[account(mut)]
    pub pda_rent_sponsor: AccountInfo<'info>,

    #[account(
        init,
        payer = fee_payer,
        space = 8 + <Counter as anchor_lang::Space>::INIT_SPACE,
        seeds = [COUNTER_SEED, owner.key().as_ref()],
        bump,
    )]
    #[light_account(init)]
    pub counter: Account<'info, Counter>,

    pub system_program: Program<'info, System>,
}

/// Standard Anchor
#[derive(Accounts)]
pub struct Increment<'info> {
    pub owner: Signer<'info>,

    #[account(
        mut,
        seeds = [COUNTER_SEED, owner.key().as_ref()],
        bump,
        has_one = owner,
    )]
    pub counter: Account<'info, Counter>,
}

/// Standard Anchor close
#[derive(Accounts)]
pub struct CloseCounter<'info> {
    #[account(mut)]
    pub fee_payer: Signer<'info>,

    pub owner: Signer<'info>,

    #[account(
        mut,
        close = fee_payer,
        seeds = [COUNTER_SEED, owner.key().as_ref()],
        bump,
        has_one = owner,
    )]
    pub counter: Account<'info, Counter>,
}

Client

counter.rs

//! Light-PDA lifecycle test: create → increment → close.

use anchor_lang::{InstructionData, ToAccountMetas};
use light_client::interface::{
    get_create_accounts_proof, CreateAccountsProofInput, InitializeRentFreeConfig,
};
use light_program_test::{
    program_test::{setup_mock_program_data, LightProgramTest},
    ProgramTestConfig, Rpc,
};
use light_token::instruction::RENT_SPONSOR;
use solana_instruction::Instruction;
use solana_keypair::Keypair;
use solana_pubkey::Pubkey;
use solana_signer::Signer;

const PROGRAM_ID: Pubkey = counter::ID;

/// Setup: create test RPC and initialize rent-free config for the counter program.
async fn setup() -> (LightProgramTest, Keypair, Pubkey) {
    let config = ProgramTestConfig::new_v2(true, Some(vec![("counter", PROGRAM_ID)]));
    let mut rpc = LightProgramTest::new(config).await.unwrap();
    let payer = rpc.get_payer().insecure_clone();

    let program_data_pda = setup_mock_program_data(&mut rpc, &payer, &PROGRAM_ID);

    // Register this program for rent-free accounts. One-time setup per program.
    let (init_config_ix, compression_config) = InitializeRentFreeConfig::new(
        &PROGRAM_ID,
        &payer.pubkey(),
        &program_data_pda,
        RENT_SPONSOR,
        payer.pubkey(),
    )
    .build();

    rpc.create_and_send_transaction(&[init_config_ix], &payer.pubkey(), &[&payer])
        .await
        .expect("initialize rent-free config");

    (rpc, payer, compression_config)
}

#[tokio::test]
async fn test_counter_lifecycle() {
    let (mut rpc, payer, compression_config) = setup().await;

    // ── Create ───────────────────────────────────────────────────────────
    let (counter_pda, _) = Pubkey::find_program_address(
        &[counter::COUNTER_SEED, payer.pubkey().as_ref()],
        &PROGRAM_ID,
    );

    let proof_result = get_create_accounts_proof(
        &rpc,
        &PROGRAM_ID,
        vec![CreateAccountsProofInput::pda(counter_pda)],
    )
    .await
    .unwrap();

    let create_accounts = counter::accounts::CreateCounter {
        fee_payer: payer.pubkey(),
        owner: payer.pubkey(),
        compression_config,
        counter: counter_pda,
        system_program: solana_sdk::system_program::ID,
    };

    let create_data = counter::instruction::CreateCounter {
        params: counter::CreateCounterParams {
            create_accounts_proof: proof_result.create_accounts_proof,
            count: 0,
        },
    };

    let create_ix = Instruction {
        program_id: PROGRAM_ID,
        accounts: [
            create_accounts.to_account_metas(None),
            proof_result.remaining_accounts,
        ]
        .concat(),
        data: create_data.data(),
    };

    rpc.create_and_send_transaction(&[create_ix], &payer.pubkey(), &[&payer])
        .await
        .expect("create_counter");

    // Verify initial state.
    let account = rpc.get_account(counter_pda).await.unwrap().unwrap();
    let ctr: counter::Counter =
        anchor_lang::AccountDeserialize::try_deserialize(&mut account.data.as_slice()).unwrap();
    assert_eq!(ctr.count, 0);
    assert_eq!(ctr.owner, payer.pubkey());

    // ── Increment (standard Anchor) ────────────────────────────
    let inc_accounts = counter::accounts::Increment {
        owner: payer.pubkey(),
        counter: counter_pda,
    };
    let inc_data = counter::instruction::Increment {};
    let inc_ix = Instruction {
        program_id: PROGRAM_ID,
        accounts: inc_accounts.to_account_metas(None),
        data: inc_data.data(),
    };

    rpc.create_and_send_transaction(&[inc_ix], &payer.pubkey(), &[&payer])
        .await
        .expect("increment");

    let account = rpc.get_account(counter_pda).await.unwrap().unwrap();
    let ctr: counter::Counter =
        anchor_lang::AccountDeserialize::try_deserialize(&mut account.data.as_slice()).unwrap();
    assert_eq!(ctr.count, 1);

    // ── Close (standard Anchor) ────────────────────────────────
    let close_accounts = counter::accounts::CloseCounter {
        fee_payer: payer.pubkey(),
        owner: payer.pubkey(),
        counter: counter_pda,
    };
    let close_data = counter::instruction::CloseCounter {};
    let close_ix = Instruction {
        program_id: PROGRAM_ID,
        accounts: close_accounts.to_account_metas(None),
        data: close_data.data(),
    };

    rpc.create_and_send_transaction(&[close_ix], &payer.pubkey(), &[&payer])
        .await
        .expect("close_counter");

    // Account should no longer exist.
    let account = rpc.get_account(counter_pda).await.unwrap();
    assert!(account.is_none(), "counter should be closed");
}

View counter example on Github: counter

---

How it works

The SDK pays the rent-exemption cost. After extended inactivity, cold accounts auto-compress. Your program only ever interacts with hot accounts. Clients can safely load cold accounts back into the onchain Solana account space when needed via create_load_instructions.

	Hot (active)	Cold (inactive)
Storage	On-chain	Compressed
Latency/CU	No change	+load instruction
Your program code	No change	No change

FAQ

How does it prevent re-init attacks?

When creating an account for the first time, the SDK provides a proof that the account doesn’t exist in the cold address space. The SVM already verifies this for the onchain space. Both address spaces are checked before creation, preventing re-init attacks, even if the account is currently cold.

Who triggers compression?

Miners (Forester nodes) compress accounts that have been inactive for an extended period of time (when their virtual rent balance drops below threshold). In practice, having to load cold accounts should be rare. The common path (hot) has no extra overhead and does not increase CU or txn size.

How is the SDK able to sponsor rent exemption?

When accounts compress after extended inactivity, the on-chain rent-exemption is released back to the rent sponsor. This creates a revolving lifecycle: active “hot” accounts hold a rent-exempt lamports balance, inactive “cold” accounts release it back. The rent sponsor must be derived from the program owner. For all mint, ATA, and token accounts, the Light Token Program is the rent sponsor. For your own program-owned PDAs, the SDK derives a rent sponsor address automatically.

Do rent-free accounts increase CU?

Hot path (e.g. reads, updates, closes): No. Active accounts do not add CU overhead to your instructions.

First time init + loading cold accounts: Yes, adds up to 15k-400k CU, depending on number and type of accounts being initialized or loaded.

---

API is in Beta and subject to change.

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