[Intermediate]: Add `minNodeReadmitTime` and `maxNodeReadmitTime` getters and setters

[rwalworth]

🧩 Intermediate Friendly

This issue is a good fit for contributors who are already familiar with the Hiero Swift SDK and feel comfortable navigating the codebase.

Intermediate Issues often involve:

• Exploring existing implementations
• Understanding how different components work together
• Making thoughtful changes that follow established patterns

The goal is to support deeper problem-solving while keeping the task clear, focused, and enjoyable to work on.

🐞 Problem Description

The Client class has no way to configure how long a node remains excluded after experiencing errors. Currently, in Sources/Hiero/Client/NodeHealth.swift, the timing is hardcoded:

/// Duration to keep circuit open before testing recovery (5 minutes)
private static let circuitOpenDurationNanos: UInt64 = TimeInterval(5 * 60).nanoseconds

Other Hiero SDKs (Java, Go, C++) provide configurable node readmit times:

• getMinNodeReadmitTime() / setMinNodeReadmitTime() - Minimum time before reconsidering a failed node
• getMaxNodeReadmitTime() / setMaxNodeReadmitTime() - Maximum time a node can be excluded

This allows users to tune node recovery behavior based on their network conditions and reliability requirements.

Relevant files:

• Sources/Hiero/Client/Client.swift - Main client class
• Sources/Hiero/Client/NodeHealth.swift - Circuit breaker with hardcoded recovery duration
• Sources/Hiero/Client/ConsensusNetwork.swift - Uses NodeHealth for node management

💡 Expected Outcome

Add configurable node readmit time settings:

1. getMinNodeReadmitTime() -> TimeInterval - Returns the minimum readmit time
2. setMinNodeReadmitTime(_ time: TimeInterval) - Sets the minimum readmit time
3. getMaxNodeReadmitTime() -> TimeInterval - Returns the maximum readmit time
4. setMaxNodeReadmitTime(_ time: TimeInterval) - Sets the maximum readmit time

The implementation should:

• Replace the hardcoded circuitOpenDurationNanos with configurable values
• minNodeReadmitTime maps to when unhealthy nodes can be reconsidered
• maxNodeReadmitTime maps to the circuit breaker recovery period
• Store configuration in the Client
• Default to current behavior (reasonable defaults)

🧠 Implementation Notes

Understanding the mapping:

In the Swift SDK's circuit breaker pattern:

• Unhealthy state: Node is temporarily excluded with exponential backoff
• Circuit open state: Node is excluded for a fixed recovery period (currently 5 minutes)

The readmit times in other SDKs map to:

• minNodeReadmitTime: Initial/minimum backoff before retrying a failed node
• maxNodeReadmitTime: Maximum time before forcing a retry (circuit open duration)

Suggested approach:

1. Add private properties to Client:

   private let _minNodeReadmitTime: NIOLockedValueBox<TimeInterval>
   private let _maxNodeReadmitTime: NIOLockedValueBox<TimeInterval>

2. Initialize with current defaults:

   self._minNodeReadmitTime = .init(0.25)      // 250ms (current initialBackoffInterval)
   self._maxNodeReadmitTime = .init(5 * 60)    // 5 minutes (current circuitOpenDuration)

3. Add public getter/setter methods to Client

4. Modify NodeHealth to accept these values instead of using hardcoded constants:

   • Pass values when creating ConsensusNetwork
   • Or create a NodeHealthConfig struct

5. Update markUnhealthy() and circuit breaker logic to use the configured values

Key considerations:

• The circuitOpenDurationNanos constant needs to become configurable
• Consider how this interacts with the existing backoff intervals
• Thread safety when values are changed at runtime
• Changes span Client.swift, NodeHealth.swift, and possibly ConsensusNetwork.swift

Reference implementations:

• Java: Client.getMinNodeReadmitTime() / setMinNodeReadmitTime(Duration) - stored in Network
• Go: Client.GetMinNodeReadmitTime() / SetMinNodeReadmitTime(Duration)
• C++: Client.getMinNodeReadmitTime() / setMinNodeReadmitTime(duration)

✅ Acceptance Criteria

To help get this change merged smoothly:

• Four methods added: getMinNodeReadmitTime, setMinNodeReadmitTime, getMaxNodeReadmitTime, setMaxNodeReadmitTime
• Hardcoded values in NodeHealth.swift replaced with configurable values
• Default behavior unchanged
• Follow existing project conventions
• Avoid breaking public APIs
• Include tests where appropriate
• Pass all CI checks

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📚 Additional Context or Resources

If you have questions, the community is happy to help:

https://discord.com/channels/905194001349627914/1337424839761465364

Useful files to review:

• Sources/Hiero/Client/NodeHealth.swift - Circuit breaker implementation
• Sources/Hiero/ExponentialBackoff.swift - Backoff algorithm
• Sources/Hiero/Client/ConsensusNetwork.swift - How NodeHealth is used