Simulating Transactions

Q: How does this apply on Agave 4.1.1?

Agave 4.1.1 RPC simulateTransaction runs the same Sealevel path as real execution, minus persistence and fees.

Q: What Solana CLI version should I use?

Use Solana CLI 3.0.10, which pairs with Agave 4.1.1. Install with agave-install init 4.1.1 (or your team's pin file), then verify with solana --version and agave-install --version.

Q: Should I use @solana/kit or web3.js?

Use @solana/kit 7.0.0 for new TypeScript—typed RPC methods, smaller API surface, and examples on this page already use Kit. Keep web3.js only for legacy codebases; migrate RPC calls and transaction building incrementally.

Q: What commitment level is recommended?

Simulate at confirmed, then poll getSignatureStatuses at confirmed for speed. Use finalized before treating token movements as settled.

Q: How do I debug related failures?

Always read err, logs, and unitsConsumed. Match account list and signers exactly—simulation succeeds but send fails when blockhash or fees differ.

Q: Does this work on devnet?

Yes—point CLI and RPC to https://api.devnet.solana.com. Behavior matches mainnet; only account data and economics differ.

Q: How do compute units affect this?

Simulation returns CU usage—use it to set SetComputeUnitLimit with ~10% headroom.

Q: What is the Anchor 0.32.1 pattern?

Anchor 0.32.1 uses #[program], Context, and #[derive(Accounts)] with explicit mut/signer constraints—run anchor build and anchor test on 0.32.1 via avm use 0.32.1.

Q: How do I test with Surfpool 0.12.0?

Run anchor test with Surfpool 0.12.0 to simulate full transactions against a mainnet fork—especially priority-fee and v0/ALT paths.

Q: Can LiteSVM 0.6.x cover this?

LiteSVM is a local simulator; use RPC simulateTransaction when you need exact cluster account state.

Pre-flight simulation and error decoding. This guide targets Agave 4.1.1 validators, Solana CLI 3.0.10, Anchor 0.32.1, and @solana/kit 7.0.0 clients.

Recipe

Quick-reference recipe card.

solana config set --url devnet
solana balance

import { createSolanaRpc } from "@solana/kit";
const rpc = createSolanaRpc("https://api.devnet.solana.com");

When to reach for this:

Implementing or debugging simulating transactions in production paths
Teaching the concept to engineers new to Solana
Auditing whether your stack matches Agave 4.1 era behavior

Working Example

import { createSolanaRpc, address } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.devnet.solana.com");
const slot = await rpc.getSlot().send();
 
const sig = "PASTE_SIGNATURE_AFTER_YOUR_TX";
const tx = await rpc
  .getTransaction(sig, { encoding: "json", maxSupportedTransactionVersion: 0 })
  .send();
 
console.log({ slot, err: tx?.meta?.err, cu: tx?.meta?.computeUnitsConsumed });

use anchor_lang::prelude::*;
#[program]
pub mod demo {
    use super::*;
    pub fn log_slot(_ctx: Context<LogSlot>) -> Result<()> {
        let clock = Clock::get()?;
        msg!("slot: {}", clock.slot);
        Ok(())
    }
}
#[derive(Accounts)]
pub struct LogSlot {}

What this demonstrates:

RPC access patterns with @solana/kit 7.0.0
Reading execution metadata (errors, CU) from confirmed transactions
On-chain sysvar access in Anchor 0.32.1 programs

Deep Dive

How It Works

Pre-flight simulation and error decoding.
Solana's account model requires explicit account lists per instruction
Sealevel executes non-conflicting transactions in parallel

Agave 4.1.1 Notes

Confirmation semantics follow TowerBFT voting with PoH ordering
Alpenglow (Votor + Rotor) is rolling out for faster finality - see Consensus section
Local development: Surfpool 0.12.0 and LiteSVM 0.6.x

Rust Notes

// Use checked math and explicit constraints in programs
require!(amount > 0, MyError::InvalidAmount);

Gotchas

Legacy web3.js v1 snippets - API differs from Kit. Fix: use @solana/kit 7.0.0.
Wrong cluster - devnet vs mainnet mismatch. Fix: align CLI, RPC, wallet, explorer.
Float SOL amounts - precision loss. Fix: bigint lamports end-to-end.
Expired blockhash - dropped txs. Fix: re-fetch blockhash and re-sign.
Insufficient CU - OOM or budget exceeded. Fix: optimize program + set Compute Budget.
Missing owner checks - writable account exploits. Fix: Anchor constraints on every mut account.

Alternatives

Alternative	Use When	Don't Use When
@solana/kit 7.0.0	New TypeScript clients	Maintaining legacy code temporarily
Solana CLI 3.0.10	Ops and quick probes	Production transaction signing at scale
Surfpool 0.12.0	Anchor integration tests	Production deployment
LiteSVM 0.6.x	Fast unit tests	Full network behavior validation

FAQs

How does this apply on Agave 4.1.1?

Agave 4.1.1 RPC simulateTransaction runs the same Sealevel path as real execution, minus persistence and fees.

What Solana CLI version should I use?

Use Solana CLI 3.0.10, which pairs with Agave 4.1.1. Install with agave-install init 4.1.1 (or your team's pin file), then verify with solana --version and agave-install --version.

Should I use @solana/kit or web3.js?

Use @solana/kit 7.0.0 for new TypeScript—typed RPC methods, smaller API surface, and examples on this page already use Kit. Keep web3.js only for legacy codebases; migrate RPC calls and transaction building incrementally.

What commitment level is recommended?

Simulate at confirmed, then poll getSignatureStatuses at confirmed for speed. Use finalized before treating token movements as settled.

How do I debug related failures?

Always read err, logs, and unitsConsumed. Match account list and signers exactly—simulation succeeds but send fails when blockhash or fees differ.

Does this work on devnet?

Yes—point CLI and RPC to https://api.devnet.solana.com. Behavior matches mainnet; only account data and economics differ.

How do compute units affect this?

Simulation returns CU usage—use it to set SetComputeUnitLimit with ~10% headroom.

What is the Anchor 0.32.1 pattern?

Anchor 0.32.1 uses #[program], Context<T>, and #[derive(Accounts)] with explicit mut/signer constraints—run anchor build and anchor test on 0.32.1 via avm use 0.32.1.

How do I test with Surfpool 0.12.0?

Run anchor test with Surfpool 0.12.0 to simulate full transactions against a mainnet fork—especially priority-fee and v0/ALT paths.

Can LiteSVM 0.6.x cover this?

LiteSVM is a local simulator; use RPC simulateTransaction when you need exact cluster account state.

What changed in the Agave era?

The validator client rebranded to Agave (4.1.1), CLI 3.0.10 aligns with it, and Alpenglow work is changing finality—pin versions and read release notes each upgrade.

Where do I find related RPC methods?

simulateTransaction with sigVerify: true for production parity; getAccountInfo to seed missing accounts.

Browse other pages in the transactions-instructions-fees section for complementary topics
Solana Basics - account and transaction orientation

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Recipe

Quick-reference recipe card.

solana config set --url devnet
solana balance

import { createSolanaRpc } from "@solana/kit";
const rpc = createSolanaRpc("https://api.devnet.solana.com");

When to reach for this:

Implementing or debugging simulating transactions in production paths
Teaching the concept to engineers new to Solana
Auditing whether your stack matches Agave 4.1 era behavior

Working Example

import { createSolanaRpc, address } from "@solana/kit";
 
const rpc = createSolanaRpc("https://api.devnet.solana.com");
const slot = await rpc.getSlot().send();
 
const sig = "PASTE_SIGNATURE_AFTER_YOUR_TX";
const tx = await rpc
  .getTransaction(sig, { encoding: "json", maxSupportedTransactionVersion: 0 })
  .send();
 
console.log({ slot, err: tx?.meta?.err, cu: tx?.meta?.computeUnitsConsumed });

use anchor_lang::prelude::*;
#[program]
pub mod demo {
    use super::*;
    pub fn log_slot(_ctx: Context<LogSlot>) -> Result<()> {
        let clock = Clock::get()?;
        msg!("slot: {}", clock.slot);
        Ok(())
    }
}
#[derive(Accounts)]
pub struct LogSlot {}

What this demonstrates:

RPC access patterns with @solana/kit 7.0.0
Reading execution metadata (errors, CU) from confirmed transactions
On-chain sysvar access in Anchor 0.32.1 programs

Deep Dive

How It Works

Pre-flight simulation and error decoding.
Solana's account model requires explicit account lists per instruction
Sealevel executes non-conflicting transactions in parallel

Agave 4.1.1 Notes

Confirmation semantics follow TowerBFT voting with PoH ordering
Alpenglow (Votor + Rotor) is rolling out for faster finality - see Consensus section
Local development: Surfpool 0.12.0 and LiteSVM 0.6.x

Rust Notes

// Use checked math and explicit constraints in programs
require!(amount > 0, MyError::InvalidAmount);

Gotchas

Legacy web3.js v1 snippets - API differs from Kit. Fix: use @solana/kit 7.0.0.
Wrong cluster - devnet vs mainnet mismatch. Fix: align CLI, RPC, wallet, explorer.
Float SOL amounts - precision loss. Fix: bigint lamports end-to-end.
Expired blockhash - dropped txs. Fix: re-fetch blockhash and re-sign.
Insufficient CU - OOM or budget exceeded. Fix: optimize program + set Compute Budget.
Missing owner checks - writable account exploits. Fix: Anchor constraints on every mut account.

Alternatives

Alternative	Use When	Don't Use When
@solana/kit 7.0.0	New TypeScript clients	Maintaining legacy code temporarily
Solana CLI 3.0.10	Ops and quick probes	Production transaction signing at scale
Surfpool 0.12.0	Anchor integration tests	Production deployment
LiteSVM 0.6.x	Fast unit tests	Full network behavior validation

FAQs

How does this apply on Agave 4.1.1?

Agave 4.1.1 RPC simulateTransaction runs the same Sealevel path as real execution, minus persistence and fees.

What Solana CLI version should I use?

Use Solana CLI 3.0.10, which pairs with Agave 4.1.1. Install with agave-install init 4.1.1 (or your team's pin file), then verify with solana --version and agave-install --version.

Should I use @solana/kit or web3.js?

What commitment level is recommended?

Simulate at confirmed, then poll getSignatureStatuses at confirmed for speed. Use finalized before treating token movements as settled.

How do I debug related failures?

Always read err, logs, and unitsConsumed. Match account list and signers exactly—simulation succeeds but send fails when blockhash or fees differ.

Does this work on devnet?

Yes—point CLI and RPC to https://api.devnet.solana.com. Behavior matches mainnet; only account data and economics differ.

How do compute units affect this?

Simulation returns CU usage—use it to set SetComputeUnitLimit with ~10% headroom.

What is the Anchor 0.32.1 pattern?

Anchor 0.32.1 uses #[program], Context<T>, and #[derive(Accounts)] with explicit mut/signer constraints—run anchor build and anchor test on 0.32.1 via avm use 0.32.1.

How do I test with Surfpool 0.12.0?

Run anchor test with Surfpool 0.12.0 to simulate full transactions against a mainnet fork—especially priority-fee and v0/ALT paths.

Can LiteSVM 0.6.x cover this?

LiteSVM is a local simulator; use RPC simulateTransaction when you need exact cluster account state.

What changed in the Agave era?

The validator client rebranded to Agave (4.1.1), CLI 3.0.10 aligns with it, and Alpenglow work is changing finality—pin versions and read release notes each upgrade.

Where do I find related RPC methods?

simulateTransaction with sigVerify: true for production parity; getAccountInfo to seed missing accounts.

Browse other pages in the transactions-instructions-fees section for complementary topics
Solana Basics - account and transaction orientation

Stack versions: This page was written for Agave 4.1.1, Solana CLI 3.0.10, Anchor 0.32.1, anchor-lang 0.32.1, Rust 1.91.1, @solana/kit 7.0.0, Surfpool 0.12.0, and LiteSVM 0.6.x.

Simulating Transactions

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Simulating Transactions