Reinitialize Compressed Accounts

Guide to reinitialize compressed accounts in Solana programs with full code examples.

Compressed accounts are reinitialized via CPI to the Light System Program.

An empty compressed account can be reinitialized

• with an account hash marked as empty with zero values and zero discriminator
• to create a new account hash at the same address with new values.

Find full code examples at the end for Anchor and native Rust.

Implementation Guide

This guide will cover the components of a Solana program that reinitializes compressed accounts. Here is the complete flow to reinitialize compressed accounts:

1. Program Setup

   Dependencies, Constants, Compressed Account

   Dependencies

   Add dependencies to your program.

   [dependencies]
   light-sdk = "0.16.0"
   anchor_lang = "0.31.1"
   

   [dependencies]
   light-sdk = "0.16.0"
   borsh = "0.10.0"
   solana-program = "2.2"
   

   • The light-sdk provides macros, wrappers and CPI interface to create and interact with compressed accounts.
   • Add the serialization library (borsh for native Rust, or use AnchorSerialize).

   Constants

   Set program address and derive the CPI authority PDA to call the Light System program.

   declare_id!("rent4o4eAiMbxpkAM1HeXzks9YeGuz18SEgXEizVvPq");
   
   pub const LIGHT_CPI_SIGNER: CpiSigner =
       derive_light_cpi_signer!("rent4o4eAiMbxpkAM1HeXzks9YeGuz18SEgXEizVvPq");
   

   CPISigner is the configuration struct for CPI’s to the Light System Program.

   • CPIs to the Light System program must be signed with a PDA derived by your program with the seed b"authority"
   • derive_light_cpi_signer! derives the CPI signer PDA for you at compile time.

   Compressed Account

   Define your compressed account struct.

   #[event] // declared as event so that it is part of the idl.#[derive( Clone, Debug, Default, LightDiscriminator)]pub struct MyCompressedAccount { pub owner: Pubkey, pub message: String,}#[derive( Debug, Default, Clone, BorshSerialize, BorshDeserialize, LightDiscriminator,)]pub struct MyCompressedAccount { pub owner: Pubkey, pub message: String,}

   You derive

   • the standard traits (Clone, Debug, Default),
   • borsh or AnchorSerialize to serialize account data, and
   • LightDiscriminator to implements a unique type ID (8 bytes) to distinguish account types. The default compressed account layout enforces a discriminator in its own field, not the first 8 bytes of the data field[^1].

   The traits listed above are required for LightAccount. LightAccount wraps MyCompressedAccount in Step 3 to set the discriminator and create the compressed account’s data.

2. Instruction Data

   Define the instruction data with the following parameters:

   Anchor

   pub fn reinit_account<'info>(
       ctx: Context<'_, '_, '_, 'info, GenericAnchorAccounts<'info>>,
       proof: ValidityProof,
       account_meta: CompressedAccountMeta,
   ) -> Result<()>
   

   1. Validity Proof

   • Define proof to include the proof that the closed account with zero values exists in the state tree.
   • Clients fetch a validity proof with getValidityProof() from an RPC provider that supports ZK Compression (Helius, Triton, …).

   2. Specify input state and output state tree (stores new account hash)

   • Define account_meta: CompressedAccountMeta to reference the closed account and specify the state tree to store the new account hash:
     • tree_info: PackedStateTreeInfo: References the existing account hash in the state tree.
     • address: The account’s derived address.
     • output_state_tree_index: References the state tree account that will store the new compressed account hash.

   Reinitialization does not require current_value parameters. new_empty() automatically uses the closed account as input.

3. Reinitialize Closed Account

   Reinitialize the closed account with LightAccount::new_empty().

   new_empty()

   1. reconstructs the closed account hash with zero values as input, and
   2. creates output state with default-initialized values.

   You can set custom values in the same transaction:

   1. Reinitialize with new_empty(), and
   2. Update with new_mut() to set custom values.

   Anchor

   let my_compressed_account = LightAccount::<MyCompressedAccount>::new_empty(
       &crate::ID,
       &account_meta,
   )?;
   

   Pass these parameters to new_empty():

   • &program_id: The program’s ID that owns the compressed account.
   • &account_meta: The CompressedAccountMeta from instruction data (Step 2) that identifies the existing account and specifies the output state tree.
     • Anchor: Pass account_meta by reference. It is automatically deserialized as a function parameter.
     • Native Rust: Manually deserialize the instruction data struct, then pass the field by reference &instruction_data.account_meta.

   The SDK creates:

   • A LightAccount wrapper with account data automatically initialized to default values using the Default trait.
   • This creates a zero-initialized instance: Pubkey as all zeros, u64 as 0, String as empty.

   new_empty() reconstructs the closed account hash with zero values. The Light System Program verifies the closed account hash and creates the output hash in Step 4.

4. Light System Program CPI

   Invoke the Light System Program to reinitialize the compressed account.

   The Light System Program

   • validates the closed account hash exists in state tree,
   • nullifies the closed account hash, and
   • appends the new account hash with provided values to the state tree.

   Anchor

   let light_cpi_accounts = CpiAccounts::new(
       ctx.accounts.signer.as_ref(),
       ctx.remaining_accounts,
       crate::LIGHT_CPI_SIGNER,
   );
   
   LightSystemProgramCpi::new_cpi(LIGHT_CPI_SIGNER, proof)
       .with_light_account(my_compressed_account)?
       .invoke(light_cpi_accounts)?;
   

   Set up CpiAccounts::new():

   CpiAccounts::new() parses accounts for the CPI call to Light System Program.

   Pass these parameters:

   • ctx.accounts.signer.as_ref(): the transaction signer
   • ctx.remaining_accounts: Slice with [system_accounts, ...packed_tree_accounts]. The client builds this with PackedAccounts and passes it to the instruction.
   • &LIGHT_CPI_SIGNER: Your program’s CPI signer PDA defined in Constants.

   System Accounts List

   	Name	Description
   1	Light System Program	Verifies validity proofs, compressed account ownership checks, cpis the account compression program to update tree accounts
   2	CPI Signer	- PDA to sign CPI calls from your program to Light System Program - Verified by Light System Program during CPI - Derived from your program ID
   3	Registered Program PDA	- Access control to the Account Compression Program
   4	Noop Program	- Logs compressed account state to Solana ledger. Only used in v1. - Indexers parse transaction logs to reconstruct compressed account state
   5	Account Compression Authority	Signs CPI calls from Light System Program to Account Compression Program
   6	Account Compression Program	- Writes to state and address tree accounts - Client and the account compression program do not interact directly.
   7	Invoking Program	Your program’s ID, used by Light System Program to: - Derive the CPI Signer PDA - Verify the CPI Signer matches your program ID - Set the owner of created compressed accounts
   8	System Program	Solana System Program to transfer lamports

   Build the CPI instruction:

   • new_cpi() initializes the CPI instruction with the proof to prove the closed account hash exists in the state tree - defined in the Instruction Data (Step 2).
   • with_light_account adds the LightAccount configured with the closed account hash as input and provided values as output - defined in Step 3.
   • invoke(light_cpi_accounts) calls the Light System Program with CpiAccounts.

Full Code Example

The counter programs below implement all steps from this guide. Make sure you have your developer environment set up first.

npm -g i @lightprotocol/zk-compression-cli@0.27.1-alpha.2
light init testprogram

For help with debugging, see the Error Cheatsheet.

Anchor

Find the source code here.

#![allow(unexpected_cfgs)]
#![allow(deprecated)]

use anchor_lang::{prelude::*, AnchorDeserialize, AnchorSerialize};
use light_sdk::{
    account::LightAccount,
    address::v1::derive_address,
    cpi::{v1::CpiAccounts, CpiSigner},
    derive_light_cpi_signer,
    instruction::{account_meta::CompressedAccountMeta, PackedAddressTreeInfo, ValidityProof},
    LightDiscriminator,
};

declare_id!("DeSUZ4to3qN7mQimoTgvEnBXiBWeTqMVcMz3ynLaWx1t");

pub const LIGHT_CPI_SIGNER: CpiSigner =
    derive_light_cpi_signer!("DeSUZ4to3qN7mQimoTgvEnBXiBWeTqMVcMz3ynLaWx1t");

#[program]
pub mod reinit {

    use super::*;
    use light_sdk::cpi::{
        v1::LightSystemProgramCpi, InvokeLightSystemProgram, LightCpiInstruction,
    };

    /// Setup: Create a compressed account
    pub fn create_account<'info>(
        ctx: Context<'_, '_, '_, 'info, GenericAnchorAccounts<'info>>,
        proof: ValidityProof,
        address_tree_info: PackedAddressTreeInfo,
        output_state_tree_index: u8,
        message: String,
    ) -> Result<()> {
        let light_cpi_accounts = CpiAccounts::new(
            ctx.accounts.signer.as_ref(),
            ctx.remaining_accounts,
            crate::LIGHT_CPI_SIGNER,
        );

        let (address, address_seed) = derive_address(
            &[b"message", ctx.accounts.signer.key().as_ref()],
            &address_tree_info
                .get_tree_pubkey(&light_cpi_accounts)
                .map_err(|_| ErrorCode::AccountNotEnoughKeys)?,
            &crate::ID,
        );

        let mut my_compressed_account = LightAccount::<MyCompressedAccount>::new_init(
            &crate::ID,
            Some(address),
            output_state_tree_index,
        );

        my_compressed_account.owner = ctx.accounts.signer.key();
        my_compressed_account.message = message.clone();

        msg!(
            "Created compressed account with message: {}",
            my_compressed_account.message
        );

        LightSystemProgramCpi::new_cpi(LIGHT_CPI_SIGNER, proof)
            .with_light_account(my_compressed_account)?
            .with_new_addresses(&[address_tree_info.into_new_address_params_packed(address_seed)])
            .invoke(light_cpi_accounts)?;

        Ok(())
    }

    /// Setup: Close compressed account
    pub fn close_account<'info>(
        ctx: Context<'_, '_, '_, 'info, GenericAnchorAccounts<'info>>,
        proof: ValidityProof,
        account_meta: CompressedAccountMeta,
        current_message: String,
    ) -> Result<()> {
        let light_cpi_accounts = CpiAccounts::new(
            ctx.accounts.signer.as_ref(),
            ctx.remaining_accounts,
            crate::LIGHT_CPI_SIGNER,
        );

        let my_compressed_account = LightAccount::<MyCompressedAccount>::new_close(
            &crate::ID,
            &account_meta,
            MyCompressedAccount {
                owner: ctx.accounts.signer.key(),
                message: current_message,
            },
        )?;

        msg!("Close compressed account.");

        LightSystemProgramCpi::new_cpi(LIGHT_CPI_SIGNER, proof)
            .with_light_account(my_compressed_account)?
            .invoke(light_cpi_accounts)?;

        Ok(())
    }

    /// Reinitialize closed compressed account
    pub fn reinit_account<'info>(
        ctx: Context<'_, '_, '_, 'info, GenericAnchorAccounts<'info>>,
        proof: ValidityProof,
        account_meta: CompressedAccountMeta,
    ) -> Result<()> {
        let light_cpi_accounts = CpiAccounts::new(
            ctx.accounts.signer.as_ref(),
            ctx.remaining_accounts,
            crate::LIGHT_CPI_SIGNER,
        );

        let my_compressed_account = LightAccount::<MyCompressedAccount>::new_empty(
            &crate::ID,
            &account_meta,
        )?;

        msg!("Reinitializing closed compressed account");

        LightSystemProgramCpi::new_cpi(LIGHT_CPI_SIGNER, proof)
            .with_light_account(my_compressed_account)?
            .invoke(light_cpi_accounts)?;

        Ok(())
    }
}

#[derive(Accounts)]
pub struct GenericAnchorAccounts<'info> {
    #[account(mut)]
    pub signer: Signer<'info>,
}

#[event]
#[derive(Clone, Debug, Default, LightDiscriminator)]
pub struct MyCompressedAccount {
    pub owner: Pubkey,
    pub message: String,
}

Next Steps

Build a client for your program or learn how to burn compressed accounts.