> ## Documentation Index
> Fetch the complete documentation index at: https://docs.stablenet.network/llms.txt
> Use this file to discover all available pages before exploring further.

# Transaction Pool

> How StableNet's mempool validates, stores, and orders transactions before block inclusion — and why your transaction might be pending.

> Transactions sent to StableNet sit in the transaction pool (mempool) until they are included in a block. Understanding the pool explains why a transaction is waiting and how to unstick it.

## Two states: pending and queued

Every transaction in the pool is in one of two states:

| State       | Condition                                     | Included in next block?             |
| ----------- | --------------------------------------------- | ----------------------------------- |
| **Pending** | Nonce matches sender's current on-chain nonce | Yes — eligible immediately          |
| **Queued**  | Nonce is higher than current on-chain nonce   | No — waiting for lower nonces first |

A transaction moves from queued to pending automatically once all preceding nonces from the same sender are confirmed.

## Why your transaction is pending

**The most common reasons:**

1. **Nonce gap** — you sent nonce 5 but nonce 4 is still pending. Nonce 5 sits in the queued state until nonce 4 is included.
2. **Gas tip below minimum** — the governance-enforced minimum `maxPriorityFeePerGas` was not met. The transaction is rejected at submission, not queued.
3. **Insufficient balance** — `balance < value + gasLimit × maxFeePerGas`. The transaction fails validation.
4. **Pool full** — the global pending limit (5,120 slots by default) is reached and your transaction has lower priority than existing ones.

## Gas tip and priority

On StableNet, gas tip competition works differently from Ethereum mainnet.

For **general accounts**, the effective gas tip is fixed by the GovValidator governance contract. All general-account transactions pay the same tip — you cannot outbid other users.

For **authorized accounts** (set by GovCouncil), the `GasTipCap` in the transaction is used as-is, enabling custom priority.

This means pending time is determined almost entirely by nonce order and pool capacity — not by how high you set your tip.

## Replacing a stuck transaction

To replace a pending transaction, submit a new transaction with the same nonce and a gas price at least **10% higher** than the original:

```typescript theme={null}
const replacement = await wallet.sendTransaction({
  to: originalTx.to,
  value: originalTx.value,
  nonce: originalTx.nonce,               // same nonce
  maxPriorityFeePerGas: ethers.parseUnits("30360", "gwei"),  // ≥ 10% above original
  maxFeePerGas: ethers.parseUnits("90000", "gwei"),
});
```

The 10% bump requirement prevents spam-replacement of transactions by trivially higher bids.

## Inspecting the pool

Use the `txpool` namespace to inspect pool state:

```typescript theme={null}
// All pending and queued transactions
const content = await provider.send("txpool_content", []);

// Pending count and queued count
const status = await provider.send("txpool_status", []);
console.log("pending:", parseInt(status.pending, 16));
console.log("queued:", parseInt(status.queued, 16));

// Transactions from a specific address
const mine = await provider.send("txpool_contentFrom", [wallet.address]);
```

## Pool limits

| Limit               | Default     | Description                      |
| ------------------- | ----------- | -------------------------------- |
| Per-account pending | 16 slots    | Max pending txs per sender       |
| Per-account queued  | 64 slots    | Max queued txs per sender        |
| Global pending      | 5,120 slots | Total pending across all senders |
| Global queued       | 1,024 slots | Total queued across all senders  |

When the pool is full, the lowest-priority transactions are evicted first. Locally submitted transactions (via RPC) are protected and evicted last.

## What happens after block inclusion

When a new block is added, the pool:

1. Removes transactions included in the block
2. Promotes queued transactions whose nonce gaps are now filled
3. Re-validates remaining transactions against updated balances
4. Queries GovValidator for the latest gas tip and updates filtering

## Developer benefits

* Pool state is queryable — use `txpool_contentFrom` to monitor your own transactions
* Nonce gaps are the primary cause of stuck transactions — manage nonces carefully in concurrent senders
* Replacement is predictable — 10% price bump guarantees replacement

## Related

* [Gas and Fees](/en/v0.3/learn/gas-and-fees) — governance tip mechanics
* [Architecture Overview](/en/v0.3/learn/architecture-overview) — full transaction lifecycle including pool
* [RPC API Reference](/en/v0.3/reference/rpc-api) — `txpool_content`, `txpool_status`