semi implemented and features implemented save checkpoint

docs/features/unchecked/releaseorchestrator/agent-cluster-manager-with-ha-topologies.md

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+# Agent Cluster Manager with HA Topologies
+
+## Module
+ReleaseOrchestrator
+
+## Status
+IMPLEMENTED
+
+## Description
+Agent clustering with support for multiple HA topologies (ActivePassive, ActiveActive, Sharded), leader election, health monitoring, and automatic failover for release orchestrator agents.
+
+## Implementation Details
+- **Modules**: `src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/`
+- **Key Classes**:
+  - `AgentClusterManager` (`src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/AgentClusterManager.cs`) - manages agent clusters with configurable HA topologies
+  - `LeaderElection` (`src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/LeaderElection.cs`) - leader election for ActivePassive topology
+  - `FailoverManager` (`src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/FailoverManager.cs`) - automatic failover when leader becomes unhealthy
+  - `HealthMonitor` (`src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/HealthMonitor.cs`) - monitors cluster member health
+  - `StateSync` (`src/ReleaseOrchestrator/__Agents/StellaOps.Agent.Core/Resilience/StateSync.cs`) - state synchronization between cluster members
+- **Source**: SPRINT_20260117_034
+
+## E2E Test Plan
+- [ ] Configure a 3-node ActivePassive cluster and verify leader election produces a single leader
+- [ ] Verify failover: stop the leader node and confirm a new leader is elected within the timeout
+- [ ] Verify ActiveActive topology: configure two active nodes and confirm both accept tasks
+- [ ] Verify health monitoring: unhealthy node is detected and removed from the active set
+- [ ] Verify state synchronization: cluster state converges after a node rejoins