solana-tx-building

Solana Transaction Building

This skill covers how to construct, simulate, and inspect Solana transactions programmatically. It addresses the full anatomy of a Solana transaction — from raw instruction encoding to versioned transaction formats, compute budget management, priority fees, and address lookup tables.

Safety: This skill is for transaction construction and analysis only. Scripts in this skill NEVER sign or submit real transactions. Always simulate before sending. Never auto-sign.

Transaction Anatomy

A Solana transaction consists of:

1. Signatures: One or more Ed25519 signatures (64 bytes each)
2. Message: The serializable payload containing:
   • Header: Counts of required signers, read-only signers, read-only non-signers
   • Account keys: Array of all pubkeys referenced by instructions
   • Recent blockhash: 32-byte hash for replay protection (expires ~60-90 seconds)
   • Instructions: Array of program calls

Transaction Size Limit

The hard limit is 1232 bytes for the entire serialized transaction. This constrains how many instructions and accounts you can include. Strategies to stay within the limit:

• Use versioned transactions with Address Lookup Tables (ALTs)
• Minimize the number of accounts per instruction
• Combine related operations into single instructions where supported
• Split complex operations across multiple transactions

Instruction Format

Each instruction contains three fields:

Instruction {
    program_id_index: u8,      // Index into the account keys array
    accounts: [u8],            // Indices into account keys array
    data: [u8],                // Opaque byte array interpreted by the program
}

Account Meta

Every account referenced in an instruction has metadata:

AccountMeta {
    pubkey: Pubkey,            // 32-byte public key
    is_signer: bool,           // Must sign the transaction
    is_writable: bool,         // Will be written to by this instruction
}