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Overview

Traditional blockchain architecture assumes you’re dealing with a single network. In the Agglayer ecosystem, you’re dealing with multiple sovereign chains that each have their own block times, execution environments, and state management. AggKit provides the synchronization layer that keeps all of them coordinated.

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The Three-Tier Architecture

AggKit’s architecture has three distinct tiers, each with a specific purpose:

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Tier 1: Your Chain’s Domain

At the foundation, you have your L2 chain doing what it does best – processing transactions, executing smart contracts, maintaining state. This is your domain, where you have full sovereignty and control. When users perform bridge operations on your chain, several things happen simultaneously: bridge contracts emit events, state gets updated, and your chain needs to communicate these changes to the broader ecosystem. This is where AggKit steps in.

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Tier 2: The AggKit Synchronization Layer

In the middle tier, AggKit components work together to maintain synchronization. Each component has a specialized role: Aggkit Figure 1: The three-tier architecture – your chain, AggKit synchronization, and the broader ecosystem

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Tier 3: The Unified Ecosystem

At the top tier, you have the broader Agglayer ecosystem – Agglayer itself, Ethereum L1, and all the other chains connected to the network. This is where the global state lives, where final settlement happens, and where the unified liquidity that makes everything possible is maintained.

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Data Flow Architecture

AggKit handles two directions of communication that keep chain state synchronized with Agglayer:

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Upward Flow: L2 → Agglayer

Purpose: Submits L2 state transitions to Agglayer for validation and proof generation. Components Involved:
  • BridgeSync: Captures bridge events from L2 contracts
  • L1InfoTreeSync: Provides L1 verification data and Merkle proofs
  • AggSender: Packages data into signed certificates and submits to Agglayer

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Downward Flow: Agglayer → L2

Purpose: Propagates global state updates from Agglayer/L1 to L2 chains for claim verification. Components Involved:
  • L1InfoTreeSync: Monitors L1 for Global Exit Root updates
  • AggOracle: Propagates GER updates to L2 contracts (with v0.3.5 committee security)
  • L2GERSync: Indexes and manages GER state locally on L2

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Component Interaction Patterns

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Certificate Generation Pattern

Figure 2: Certificate generation and submission pattern

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Oracle Propagation Pattern

Figure 3: GER propagation with v0.3.5 committee security

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v0.3.5 Security Enhancements

The major architectural improvement in v0.3.5 is the elimination of single-address vulnerabilities:

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Before v0.3.5: Single Point of Failure

Risk: Single compromised address could steal funds or mint unauthorized assets.

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After v0.3.5: Distributed Security

Security: Multiple parties must agree before any GER injection, eliminating single points of failure.