Deposit (Trader Collateral)

This instruction allows a trader to deposit collateral into their UserAccount for trading futures.

Instruction: Deposit
Discriminator: 0

---

Overview

The Deposit instruction:

• Transfers tokens from trader → pool vault
• Credits trader collateral inside UserAccount
• Updates protocol accounting
• Enables futures trading

Collateral is written as u128 in E18 precision format.

---

Account Order (Strict)

Index	Account	Signer	Writable
0	Trader (user)	✅	✅
1	UserAccount PDA	❌	✅
2	Trader Token Account (source)	❌	✅
3	Pool Token Account (vault)	❌	✅
4	Token Program	❌	❌
5	ConfigCore PDA	❌	✅
6	Token Mint	❌	❌

⚠️ Account ordering must exactly match the on-chain processor.

---

Instruction Data Layout

u8     discriminator (0)
u128   amount (E18 precision)

• amount is serialized little-endian (16 bytes)
• Must match Rust u128 layout exactly

---

U128 Encoding Helper

function writeU128LE(value: string): Buffer {
  const bn = BigInt(value);
  const buf = Buffer.alloc(16);
  let remaining = bn;

  for (let i = 0; i < 16; i++) {
    buf[i] = Number(remaining & BigInt(0xff));
    remaining = remaining >> BigInt(8);
  }

  return buf;
}

---

TypeScript Instruction Builder

const DEPOSIT_TAG = 0;

function createDepositInstruction(
  programId: PublicKey,
  user: PublicKey,
  userAccountPda: PublicKey,
  userTokenAccount: PublicKey,
  poolTokenAccount: PublicKey,
  configPda: PublicKey,
  tokenMint: PublicKey,
  amount: string
): TransactionInstruction {

  const data = Buffer.concat([
    Buffer.from([DEPOSIT_TAG]),
    writeU128LE(amount),
  ]);

  return new TransactionInstruction({
    keys: [
      { pubkey: user, isSigner: true, isWritable: true },
      { pubkey: userAccountPda, isSigner: false, isWritable: true },
      { pubkey: userTokenAccount, isSigner: false, isWritable: true },
      { pubkey: poolTokenAccount, isSigner: false, isWritable: true },
      { pubkey: TOKEN_PROGRAM_ID, isSigner: false, isWritable: false },
      { pubkey: configPda, isSigner: false, isWritable: true },
      { pubkey: tokenMint, isSigner: false, isWritable: false },
    ],
    programId,
    data,
  });
}

---

Execution Flow

1. Trader initializes UserAccount (if not already)
2. Trader approves token transfer
3. Deposit instruction:
   • Moves tokens → pool vault
   • Increments user collateral balance
   • Updates config accounting

---

Example Usage

const depositIx = createDepositInstruction(
  PROGRAM_ID,
  trader.publicKey,
  userAccountPda,
  traderTokenAccount,
  poolTokenAccount,
  configCorePDA,
  mintKeypair.publicKey,
  "1000000000000000000" // 1 token in E18
);

const depositTx = new Transaction().add(depositIx);

const depositSig = await sendAndConfirmTransaction(
  connection,
  depositTx,
  [trader],
  { commitment: 'confirmed' }
);

console.log("Deposit successful:", depositSig);

---

On-Chain Effects

After execution:

• Trader token balance decreases
• Pool vault balance increases
• UserAccount.collateral increases (u128)
• Trader can now open leveraged positions

---

Precision Model

• SPL Token → 9 decimals (example)
• Internal protocol math → E18 precision
• Always convert correctly before sending deposit amount

Example:

1 token → "1000000000000000000"

Mismatch between SPL decimals and E18 math will cause incorrect margin accounting.

Deposit is mandatory before any futures position can be opened.