> ## Documentation Index
> Fetch the complete documentation index at: https://ouroborai.xyz/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# TimeBoost
> 200ms express lane priority for Arbitrum transactions
TimeBoost is Arbitrum's priority sequencing auction that grants the winner a **200ms express lane advantage** over the public mempool. This is a key differentiator for the platform -- the agent can bid for express lane access, execute priority trades, and resell unused capacity for profit.
## What Is TimeBoost?
TimeBoost is Arbitrum's answer to MEV. Instead of a first-come-first-served mempool, Arbitrum runs a sealed-bid, second-price auction every 60 seconds. The winner of each round becomes the **express lane controller** and can submit transactions that get sequenced 200 milliseconds before any public mempool transactions.
Each auction round lasts 60 seconds. Bids must be submitted at least 15 seconds before the round starts.
Bids are private. You pay the second-highest bid, not your own -- incentivizing truthful bidding.
The express lane controller's transactions are sequenced 200ms ahead of public mempool transactions.
## Why It Matters
The 200ms priority window creates a structural advantage for:
* **DEX arbitrage**: capture price discrepancies across Uniswap, Camelot, and other DEXs before other traders
* **Liquidations**: be first to liquidate undercollateralized lending positions on Aave, Radiant, etc.
* **Backrunning**: execute profitable backrun trades on large public mempool transactions
* **Priority execution**: ensure your time-sensitive trades execute before competitors
On Arbitrum, TimeBoost replaces traditional block builder MEV extraction. The revenue goes to the Arbitrum DAO treasury rather than to individual block builders, making it a fairer system overall.
## How the Bidder Works
The `TimeBoostBidder` class manages the full lifecycle of express lane participation.
### Bid Loop
When started, the bidder runs a continuous loop:
1. **Detect round transition** -- polls the auctioneer for the current round number
2. **Estimate round value** -- calculates expected MEV profit from available strategies
3. **Compare against threshold** -- skips rounds where expected profit is below `minProfitThresholdWei`
4. **Fetch auctioneer stats** -- gets the average winning bid to avoid overbidding
5. **Submit bid** -- places a bid at 80% of expected profit, capped at 90% of the average winning bid
6. **Wait for result** -- if won, emits `roundWon` event; otherwise emits `roundLost`
### Bid Submission
Bids are submitted via JSON-RPC to the autonomous auctioneer:
```
Method: auctioneer_submitBid
Params: {
chainId,
expressLaneController,
auctionContractAddress,
round,
amount
}
```
The auctioneer only considers the most recent bid per address, so the bidder can update its bid as new information arrives before the auction closes.
### Express Lane Transactions
When the bidder wins a round, it can submit transactions via the express lane:
```
Method: timeboost_sendExpressLaneTransaction
Params: {
round,
sequenceNumber,
transaction,
auctionContractAddress,
signature
}
```
These transactions are sequenced by the Arbitrum sequencer with 200ms priority over the public mempool.
## MEV Estimation
The bidder estimates the expected value of each round using a per-strategy model with historical calibration.
### Strategy Values
| Strategy | Estimated Value | Description |
| ------------- | --------------- | ----------------------------------- |
| `arb` | \~0.002 ETH | Cross-DEX arbitrage opportunities |
| `liquidation` | \~0.005 ETH | Lending protocol liquidation profit |
| `sandwich` | \~0.0015 ETH | Sandwich trading (higher risk) |
| `backrun` | \~0.0008 ETH | Backrunning large transactions |
| `resale` | \~0.003 ETH | Express lane resale revenue |
### Historical Calibration
The bidder maintains a rolling history of the last 100 round outcomes. This history adjusts the estimation multiplier:
| History Signal | Multiplier | Effect |
| -------------------------- | ---------- | --------------------------- |
| \< 5 rounds of data | 1.0x | Neutral (no data) |
| Average profit negative | 0.6x | Reduce bid aggressiveness |
| Average profit > 0.005 ETH | 1.2x | Increase bid aggressiveness |
| Otherwise | 1.0x | No adjustment |
The bidder also subtracts estimated gas costs (\~0.00002 ETH on Arbitrum) from the total expected value before placing a bid.
Call `bidder.recordRoundResult(round, profitWei)` after each won round to feed the historical calibration system. More data leads to more accurate bid sizing.
## Express Lane Resale
A key revenue multiplier: if you win a round but do not need the full 60 seconds of express lane access, you can resell capacity to other searchers.
### How Resale Works
1. Win an express lane round for cost X
2. Other searchers pay you USDC via x402 micropayments for sub-round access
3. The `resellExpressLane(buyer, pricePaidUsdc)` method grants the buyer express lane forwarding rights for the remainder of the round
4. Multiple resale slots can be active simultaneously within a single round
### Revenue Model
The total revenue from a won round can come from three sources:
Profit from executing priority arbitrage, liquidations, and backruns during the 200ms window.
USDC payments from other searchers who buy sub-round express lane access.
Other agents pay USDC to use the express lane as a paid skill via the MCP server.
## TimeBoost Vault Contract
The **TimeBoostVault** Stylus contract manages the financial infrastructure for bidding and resale:
* **Bid funding**: agents deposit ETH or USDC that the vault uses for auction bids
* **Resale payments**: authorized buyers pay USDC to the vault in exchange for express lane transaction forwarding
* **Earnings tracking**: the contract tracks `total_resale_earnings` and `total_bid_cost` for P\&L calculation
* **Owner withdrawal**: accumulated profits can be withdrawn by the vault owner
The TimeBoostVault is a Stylus contract written in Rust. It manages the USDC payment flow for resale but does not directly interact with the auctioneer. The off-chain `TimeBoostBidder` handles bid submission.
## Auctioneer Stats
The bidder can query aggregate auction statistics to inform bidding strategy:
```typescript theme={"theme":{"light":"dracula","dark":"dracula"}}
const stats = await bidder.refreshAuctioneerStats();
// stats.avgWinningBidWei — average winning bid over recent rounds
// stats.recentRounds — number of rounds in the sample
// stats.winRate — our win rate percentage
```
Stats are cached for 5 minutes to avoid excessive RPC calls.
## Risk Factors
TimeBoost bidding involves real financial risk. Consider these factors before enabling automated bidding.
| Risk | Description |
| ------------------ | ------------------------------------------------------------- |
| **Overbidding** | Bidding more than the MEV you can extract leads to losses |
| **Execution risk** | Winning the round does not guarantee profitable MEV execution |
| **Competition** | Sophisticated searchers dominate most rounds |
| **Capital lockup** | Bid capital is committed for the round duration |
| **Gas costs** | Failed strategies still consume gas |
## Configuration
The `TimeBoostBidder` accepts these configuration options:
| Option | Type | Default | Description |
| ----------------------- | -------- | -------------------------------------- | ----------------------------------------- |
| `privateKey` | `Hex` | Required | Signing key for bids and express lane txs |
| `rpcUrl` | `string` | Arbitrum One public RPC | Arbitrum RPC endpoint |
| `auctioneerUrl` | `string` | `https://arb1-auctioneer.arbitrum.io/` | TimeBoost auctioneer RPC endpoint |
| `minProfitThresholdWei` | `bigint` | `0n` | Minimum expected profit to place a bid |
## Example Usage
```
Enable TimeBoost bidding with a 0.001 ETH minimum profit threshold
```
```
What's the current express lane status?
```
```
How many TimeBoost rounds have we won this session?
```
```
Resell express lane access at 5 USDC per slot
```