semi implemented and features implemented save checkpoint

docs/features/unchecked/releaseorchestrator/a-b-testing-experiment-engine.md

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+# A/B Testing Experiment Engine
+
+## Module
+ReleaseOrchestrator
+
+## Status
+IMPLEMENTED
+
+## Description
+A/B testing experiment engine with deterministic variant assignment, p-value statistical analysis, and experiment lifecycle management for controlled rollouts.
+
+## Implementation Details
+- **Modules**: `src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Progressive/`, `src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.ProgressiveDelivery/`
+- **Key Classes**:
+  - `AbReleaseManager` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Progressive/AbRelease/AbReleaseManager.cs`) - experiment lifecycle management with variant assignment
+  - `CanaryController` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.ProgressiveDelivery/CanaryController.cs`) - statistical analysis and auto-advance logic for experiments
+  - `TrafficManager` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.ProgressiveDelivery/TrafficManager.cs`) - manages traffic distribution between experiment variants
+  - `FeatureFlagBridge` (`src/ReleaseOrchestrator/__Libraries/StellaOps.ReleaseOrchestrator.Progressive/FeatureFlags/FeatureFlagBridge.cs`) - bridges feature flags with experiment variants
+- **Source**: SPRINT_20260117_035
+
+## E2E Test Plan
+- [ ] Create an experiment with control and treatment variants and verify deterministic variant assignment
+- [ ] Verify statistical analysis: collect metrics during experiment and verify p-value calculation
+- [ ] Verify experiment lifecycle: create, start, observe, conclude experiment through full lifecycle
+- [ ] Verify early stopping: trigger statistical significance threshold and verify auto-conclusion
+- [ ] Verify `FeatureFlagBridge` maps experiment variants to feature flag states