Rent and reclaimable rent

minimum_balance(data_len) = (ACCOUNT_STORAGE_OVERHEAD + data_len) × lamports_per_byte

excess = (128 + data_len) × (old_rate − new_rate)

/// This instruction is to be used to rescue SOL sent to any TokenProgram
/// owned account by sending them to any other account, leaving behind only
/// lamports for rent exemption.
///
/// 0. `[writable]` Source Account owned by the token program
/// 1. `[writable]` Destination account
/// 2. `[signer]` Authority
/// 3. `..3+M` `[signer]` M signer accounts
WithdrawExcessLamports,

// packages/spl-token/src/instructions/types.ts
export enum TokenInstruction {
    // ...
    TransferHookExtension = 36,
    // ConfidentialTransferFeeExtension = 37,
    // WithdrawalExcessLamports = 38,   // ← not exposed
    MetadataPointerExtension = 39,
    // ...
}

import { PublicKey, TransactionInstruction } from "@solana/web3.js";

export function createWithdrawExcessLamportsInstruction(params: {
  source: PublicKey;        // the token account holding excess lamports
  destination: PublicKey;   // where the excess goes — usually the wallet itself
  authority: PublicKey;     // owner of `source`, or the multisig account
  multiSigners?: PublicKey[];
  programId: PublicKey;     // TOKEN_PROGRAM_ID or TOKEN_2022_PROGRAM_ID
}): TransactionInstruction {
  const { source, destination, authority, multiSigners = [], programId } = params;
  return new TransactionInstruction({
    programId,
    keys: [
      { pubkey: source, isSigner: false, isWritable: true },
      { pubkey: destination, isSigner: false, isWritable: true },
      { pubkey: authority, isSigner: !multiSigners.length, isWritable: false },
      ...multiSigners.map((pubkey) => ({ pubkey, isSigner: true, isWritable: false })),
    ],
    data: Buffer.from([38]),
  });
}

const [tokenResp, token2022Resp] = await Promise.all([
  connection.getTokenAccountsByOwner(owner, { programId: TOKEN_PROGRAM_ID }),
  connection.getTokenAccountsByOwner(owner, { programId: TOKEN_2022_PROGRAM_ID }),
]);
const raw = [...tokenResp.value, ...token2022Resp.value];

// one lookup per distinct account size — a wallet normally has two or three
const spaces = Array.from(new Set(raw.map(({ account }) => account.data.length)));
const minimums = new Map(
  await Promise.all(
    spaces.map(async (space) => [space, await connection.getMinimumBalanceForRentExemption(space)] as const),
  ),
);

const reclaimable = raw.filter(({ account }) => {
  // wrapped SOL carries its token balance as lamports — both programs refuse it.
  // The `is_native` COption tag sits at offset 109 in the token account layout,
  // which Token-2022 preserves before its extension data.
  if (account.data.readUInt32LE(109) === 1) return false;
  return account.lamports > minimums.get(account.data.length)!;
});

# read-only: what can this wallet reclaim, and what would it be worth after all five steps
yarn dev src/rent/checkReclaimableRent.ts
yarn dev src/rent/checkReclaimableRent.ts <any wallet address>

# build, simulate (DRY_RUN = true by default), then send the batched sweep
yarn dev src/rent/reclaimRent.ts

const batches = chunk(report.accounts, ACCOUNTS_PER_TX);

const builtTxs = await Promise.all(
  batches.map(async (batch) => {
    const builder = new TxBuilder({
      connection,
      feePayer: owner.publicKey,
      cluster: raydium.cluster,
      owner: raydium.owner,
    });
    builder.addInstruction({
      instructions: batch.map((account) =>
        createWithdrawExcessLamportsInstruction({
          source: account.pubkey,
          destination: owner.publicKey,
          authority: owner.publicKey,
          programId: account.programId,
        }),
      ),
    });
    return builder.versionBuild({ txVersion });
  }),
);

// versionMultiBuild puts the calling builder's transaction first and appends
// extraPreBuildData after it, so batch 1 drives and batches 2..n follow in order
const [firstTx, ...restTxs] = builtTxs;
const { execute } = await firstTx.builder.versionMultiBuild({ txVersion, extraPreBuildData: restTxs });
const { txIds } = await execute({ sequentially: true });