Message Ordering Guarantees with Optional Salted ICA Routing

[XxAxe1xX]

Problem

Is your feature request related to a problem? Please describe.

Currently, Hyperlane message senders have no protocol-level ordering guarantees, which creates challenges for:

• Middleware contracts using ICAs requiring differential permissioning on destination chains
• Applications needing to segment state and control message execution order
• Dependent message processing requiring specific sequencing

Solution

Describe the solution you'd like

Implement an opt-in message ordering system through:

1. Ordering Hook Mechanism

• Allow message senders to specify an ordering hook with customizable nonce/salt
• Hook sends a message to an ordering ISM with commitment to:
  • Original message ID
  • Custom nonce
  • Application-specific metadata

2. ICA Router Enhancement

• Add optional salt parameter for ICA derivation
• Salt becomes part of the unique identifier for message ordering
• Enables fine-grained control over message sequencing

3. Ordering ISM

• New ISM type specifically for enforcing message ordering
• Validates and maintains ordering commitments
• Allows different ordering rules per application logic

Technical Implementation Details

• Extend ICARouter interface to accept salt parameter
• Create new OrderingHook contract for commitment management
• Implement OrderingISM with configurable ordering rules
• Add ordering metadata to message processing pipeline
• Optimize gas costs for ordering verification

Benefits

• Opt-in nature preserves existing functionality
• Flexible ordering rules per application needs
• Better support for complex middleware architectures
• Enhanced state management capabilities

Additional Context

• Related to issue Dependent messages #5352 (Dependent messages)
• Builds on existing ICA infrastructure
• Maintains composability with other Hyperlane features