Sell Token

Sells tokens back to the bonding curve in exchange for SOL.

Instruction

SCBondingCurveInstruction::SellToken {
    pda_token_nonce: u8,
    token_to_spend: u64,
    min_sol_to_receive: u64,
    logging_account_bump: u8,
}

Parameters

Parameter	Type	Description
pda_token_nonce	u8	Nonce for the token owner PDA
token_to_spend	u64	Amount of tokens to sell
min_sol_to_receive	u64	Minimum acceptable SOL amount to receive (slippage protection)
logging_account_bump	u8	Bump for the logging authority PDA

Account Setup

#	Account	Description	Derivation
1	Payer account	Transaction signer (User wallet)	-
2	Token program	SPL Token program	TOKEN_PROGRAM_ID
3	Token owner PDA	Bonding curve account	[Buffer.from("token_owner"), mint.toBuffer(), [nonce]]
4	Token mint	Token mint address	Provided by user
5	Owner token account	Token account for PDA	getAssociatedTokenAddress(mint, ownerPDA, true)
6	User token account	User's token account	getAssociatedTokenAddress(mint, userWallet, false)
7	Fee account	Platform fee account	Fixed address (see Reference section)
8	Program account	SC bonding curve program	SC bonding curve program ID
9	Properties account	Platform configuration	[Buffer.from("settings")]
10	Log authority account	For structured logs	[Buffer.from("logging_authority")]

Function Logic

1. Verifies the PDA token owner matches the expected PDA for the token mint

2. Retrieves platform fee from properties account (currently 1%)

3. Verifies the token is not finalized or mark as finalized if migration threshold is crossed

4. Checks if trading is closed for the token

5. Calculates expected SOL return amount using the bonding curve formula

6. Verifies expected SOL amount meets minimum specified (slippage check)

7. Updates pool balances in the bonding curve account

8. Transfers tokens from user to the bonding curve

9. Calculates fee amount and deducts from the SOL return

10. Transfers remaining SOL to the user

11. Transfers fee amount to the fee account

12. Records sell data in logs

Price Calculation

sol_amount = pool_sol_balance * token_amount / (pool_token_balance + token_amount)

Where:

• pool_token_balance = virtual_token + real_token

• pool_sol_balance = virtual_sol + real_sol

• token_amount = amount of tokens being sold

Notes

• The platform fee is deducted from the SOL return amount

• If the sale would leave less than POOL_MIGRATION_RESERVES tokens in the pool, the token is marked as finalized

• Once finalized, a token can no longer be traded on the bonding curve

Example Usage

// Derive PDAs and other accounts
const [tokenOwnerPDA, pdaTokenNonce] = PublicKey.findProgramAddressSync(
  [Buffer.from("token_owner"), tokenMint.toBuffer()],
  SC_BONDING_CURVE_PROGRAM_ID
)

const [propertiesAccount] = PublicKey.findProgramAddressSync(
  [Buffer.from("settings")],
  SC_BONDING_CURVE_PROGRAM_ID
)

const [logAuthority, logAuthorityBump] = PublicKey.findProgramAddressSync(
  [Buffer.from("logging_authority")],
  SC_BONDING_CURVE_PROGRAM_ID
)

// Get token accounts
const ownerTokenAccount = getAssociatedTokenAddressSync(tokenMint, tokenOwnerPDA, true)

const userTokenAccount = getAssociatedTokenAddressSync(tokenMint, wallet.publicKey, false)

// Create instruction data buffer
const data = Buffer.alloc(18)
data.writeUint8(3, 0) // Instruction index for SellToken
data.writeUint8(pdaTokenNonce, 1) // PDA nonce
data.writeBigUInt64LE(tokenToSpend, 2) // Token amount
data.writeBigUInt64LE(minSolToReceive, 10) // Minimum SOL
data.writeUint8(logAuthorityBump, 18) // Log authority bump

const sellTokenIx = new TransactionInstruction({
  programId: SC_BONDING_CURVE_PROGRAM_ID,
  keys: [
    { pubkey: wallet.publicKey, isSigner: true, isWritable: true },
    { pubkey: TOKEN_PROGRAM_ID, isSigner: false, isWritable: false },
    { pubkey: tokenOwnerPDA, isSigner: false, isWritable: true },
    { pubkey: tokenMint, isSigner: false, isWritable: false },
    { pubkey: ownerTokenAccount, isSigner: false, isWritable: true },
    { pubkey: userTokenAccount, isSigner: false, isWritable: true },
    { pubkey: FEE_ACCOUNT, isSigner: false, isWritable: true },
    { pubkey: SC_BONDING_CURVE_PROGRAM_ID, isSigner: false, isWritable: false },
    { pubkey: propertiesAccount, isSigner: false, isWritable: false },
    { pubkey: logAuthority, isSigner: false, isWritable: false },
  ],
  data: data,
})