Tempo Zone Architecture

A Tempo Zone is a dedicated blockchain rooted to Tempo Mainnet where one sequencer controls block production and visibility. No zone data is published on Tempo Mainnet. Instead, the sequencer publishes commitments to the current zone state along with proofs of correct execution. These proofs allow funds to move in and out of the Tempo Zone. This scaling approach is known as a validium.

The sequencer can enable any TIP-20 token on the Tempo Zone. Any enabled TIP-20 with USD currency can pay for zone gas. TIP-20 tokens bridge into the zone nearly instantly and bridge out as soon as a validity proof is posted (targeting under 10 seconds).

Tempo Zones are tightly integrated with Tempo Mainnet. Withdrawals to Tempo Mainnet are processed by the sequencer and can trigger transfers, trades on Tempo's Stablecoin DEX, or deposits into other Tempo Zones, without further interaction from the user.

Tempo Zones are designed for applications that want safe operation guaranteed by validity proofs and privacy from the rest of the world, where users are comfortable trusting a sequencer for liveness and privacy.

System Architecture

Each Tempo Zone runs as a separate Tempo chain with its own Tempo node(s). Tempo Zones are tightly coupled with Tempo Mainnet and have direct, synchronous access to Tempo Mainnet state. Zone contracts can read certain Tempo Mainnet state without any message passing delay, such as deposit queues and TIP-403 policy information.

The sequencer runs a Tempo node with one or more zone nodes attached. Each zone node:

• Synchronizes the zone's view of Tempo Mainnet each time a Tempo Mainnet block finalizes
• Executes zone transactions using privately submitted transactions and the zone's own state
• Produces batches proving state transitions on the zone and posts them to Tempo Mainnet
• Watches for deposits by monitoring Zone Portal events on Tempo Mainnet, and creates corresponding transactions on the zone once the block finalizes
• Watches for withdrawals on the zone and submits transactions to Tempo Mainnet processing them once the batch has been proven

Contract Architecture

The system consists of contracts on both Tempo Mainnet and within each Tempo Zone.

Tempo Contracts

• ZoneFactory deploys new Tempo Zones. Each zone gets its own Zone Portal and Zone Messenger contracts with deterministic addresses.
• ZonePortal is the central bridge contract. It locks all deposited tokens, verifies validity proofs, and processes withdrawals. The Zone Portal contract maintains the authoritative state: which deposits have been made, which batches have been proven, and which withdrawals are pending.
• ZoneMessenger handles withdrawals that include callbacks. When a user wants to withdraw tokens and trigger a contract call atomically, the messenger executes both operations together. If the callback fails, the entire withdrawal reverts and funds bounce back to the zone.

Zone Predeploys

Tempo Zones have four system contract predeploys at fixed addresses:

Creating a Zone

Tempo Zones are created through the ZoneFactory:

1. Choose a TIP-20 token to serve as the zone's initial asset.
2. Select a verifier contract (ZK prover or TEE attestor).
3. Designate a sequencer address.
4. Call ZoneFactory.createZone() with these parameters.

The factory deploys a new ZonePortal and ZoneMessenger for the Tempo Zone. The zone itself runs as a separate chain with the system contracts deployed at genesis. The sequencer can enable additional TIP-20 tokens at any time via ZonePortal.enableToken().

Chain ID

Each Tempo Zone has a unique EIP-155 chain ID derived deterministically from its onchain zone ID:

chain_id = 421700000 + zone_id

The prefix 4217 corresponds to the Tempo Mainnet chain ID. This ensures replay protection between Tempo Zones. A transaction signed for one zone cannot be replayed on another.

Sequencer Transfer

The sequencer can transfer control to a new address via a two-step process on Tempo Mainnet:

1. Current sequencer calls ZonePortal.transferSequencer(newSequencer) to nominate a new sequencer.
2. New sequencer calls ZonePortal.acceptSequencer() to accept the transfer.

Sequencer management occurs on Tempo Mainnet. Zone-side system contracts read the sequencer from Tempo Mainnet via ZoneConfig, which queries TempoState to get the sequencer address from the finalized ZonePortal storage.

Trust Model

Tempo Zones make explicit tradeoffs between trust and performance:

The sequencer cannot steal funds or forge state transitions. Validity proofs prevent this. However, the sequencer can halt the zone entirely, censor specific users, or reorder transactions for MEV.

Failed withdrawals always bounce back to the zone fallbackRecipient, ensuring users retain their funds. TIP-403 policy changes or token pauses on Tempo Mainnet will cause affected withdrawals to bounce back rather than block the queue.