V2 Architecture

Detailed system architecture of Kleros V2

Design Principles

Kleros V2 was designed around six key principles:

1. Modularity: Dispute resolution logic is separated into pluggable Dispute Kits
2. Multi-Dispute-Kit Support: Different courts can use different voting, incentive, and appeal mechanisms
3. Fork-Friendly: The protocol supports forking to reduce attack payoffs
4. Lightweight PNK: Simple ERC-20 token (replacing the complex Minime token from V1)
5. Juror Fraud Protection: Mechanisms to detect and penalize pre-reveal, bribery, and cartelling
6. Evidence Spam Protection: Deposit-based evidence submission on L2 where gas is cheap

Component Map

Component	Responsibility
KlerosCore	Dispute creation, period management, appeals, ruling execution, juror rewards
DisputeKitClassic	Plurality voting, commit-reveal, equal-split incentives, asymmetric appeal funding
SortitionModule	Stake-weighted random juror selection via sum trees
DisputeTemplateRegistry	On-chain registry of dispute question/answer templates
PolicyRegistry	Court policy storage (IPFS URIs)
KlerosGovernor	On-chain governance execution (Snapshot → transactions)
Home/Foreign Gateways	Cross-chain dispute relay
Vea Bridge	Optimistic cross-chain message transport

Multi-Chain Vision

The long-term architecture supports Arbitrables on any EVM chain:

• Users interact primarily with the Home chain (Arbitrum) for most operations
• Evidence can be submitted from foreign chains for convenience
• Gateways and the Vea bridge abstract away bridging complexity
• Each supported foreign chain has its own Foreign Gateway deployment

Dispute Kit System

Courts can support multiple dispute kits, enabling different:

• Drawing methods: PNK-weighted, Proof-of-Humanity-based, etc.
• Voting systems: Plurality, Condorcet-IRV, etc.
• Incentive models: Equal split, weighted functions, etc.
• Appeal systems: Fund-2-only, fund-multiple, stake-based, etc.

Currently, DisputeKitClassic (PNK drawing + plurality voting + equal split + fund-2-only appeals) is the only deployed kit and is mandatorily supported by all courts.

Security Model

• Cryptoeconomic: Jurors stake PNK; incoherent voters lose stake
• Random Selection: Prevents manipulation of juror composition
• Appeal Escalation: Exponentially increasing cost to sustain an attack
• Emergency Controls: Guardian pause + Governor unpause for rapid response
• Fork Mechanism: Ultimate defense: honest minority can fork the protocol