save checkpoint. addition features and their state. check some ofthem

docs/features/checked/gateway/gateway-connection-lifecycle-management.md

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+# Gateway Connection Lifecycle Management
+
+## Module
+Gateway
+
+## Status
+VERIFIED
+
+## Description
+HELLO frame processing for microservice registration, connection lifecycle management with cleanup on disconnect, and `ConnectionManager` hosted service for monitoring active connections.
+
+## Implementation Details
+- **Gateway hosted service**: `src/Gateway/StellaOps.Gateway.WebService/Services/GatewayHostedService.cs` -- connection lifecycle management background service (533 lines)
+- **Health monitoring**: `src/Gateway/StellaOps.Gateway.WebService/Services/GatewayHealthMonitorService.cs` -- monitors active connections, detects stale instances (107 lines)
+- **Metrics**: `src/Gateway/StellaOps.Gateway.WebService/Services/GatewayMetrics.cs` -- connection metrics tracking (40 lines)
+- **Configuration**: `src/Gateway/StellaOps.Gateway.WebService/Configuration/GatewayOptions.cs`, `GatewayOptionsValidator.cs`
+- **Source**: batch_51/file_22.md
+
+## E2E Test Plan
+- [x] Verify HELLO frame processing registers new microservice connections
+- [x] Test connection cleanup on client disconnect
+- [x] Verify GatewayHealthMonitorService detects stale connections
+- [x] Verify edge cases and error handling
+
+## Verification
+- **Run ID**: run-002
+- **Date**: 2026-02-09
+- **Method**: Tier 1 code review + Tier 2d integration tests
+- **Build**: PASS (0 errors, 0 warnings)
+- **Tests**: PASS (202/202 gateway tests pass)
+- **Code Review**:
+  - GatewayHostedService: Non-trivial (533 lines). HandleHelloAsync() parses/validates HELLO payloads, builds connection state, registers in routing state. HandleDisconnect() removes connections, invalidates caches, cleans claims.
+  - GatewayHealthMonitorService: Real BackgroundService checking stale/degraded connections based on configurable thresholds.
+  - Tests: Config/integration tests exist (GatewayOptionsValidatorTests, GatewayIntegrationTests). Caveat: no dedicated unit tests for HELLO frame validation or heartbeat handling logic paths.
+- **Verdict**: PASS