semi implemented and features implemented save checkpoint

docs/features/unchecked/telemetry/sealed-mode-telemetry.md

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+# Sealed-Mode Telemetry (Offline/Air-Gap)
+
+## Module
+Telemetry
+
+## Status
+IMPLEMENTED
+
+## Description
+Sealed-mode telemetry that writes to local files instead of external endpoints, supporting air-gapped environments.
+
+## Implementation Details
+- **ISealedModeTelemetryService interface**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/ISealedModeTelemetryService.cs` -- `IsSealed`, `EffectiveSamplingRate`, `IsIncidentModeOverrideActive`, `GetSealedModeTags`, `ShouldAllowExporter`; blocks external exporters when sealed
+- **SealedModeTelemetryService**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/SealedModeTelemetryService.cs` -- implementation that disables external exporters and writes to local storage
+- **SealedModeFileExporter**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/SealedModeFileExporter.cs` -- writes telemetry to local files in air-gapped mode
+- **SealedModeTelemetryOptions**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core/SealedModeTelemetryOptions.cs` -- local storage path, file rotation, retention settings
+- **Tests**: `src/Telemetry/StellaOps.Telemetry.Core/StellaOps.Telemetry.Core.Tests/SealedModeTelemetryServiceTests.cs`, `SealedModeFileExporterTests.cs`
+- **Source**: Feature matrix scan
+
+## E2E Test Plan
+- [ ] Verify sealed mode blocks all external telemetry exporters
+- [ ] Test telemetry is written to local files when sealed mode is active
+- [ ] Verify sealed mode tags are added to all telemetry data
+- [ ] Test incident mode can override sealed mode sampling rate
+- [ ] Verify file exporter handles rotation and retention correctly
+- [ ] Test transition between sealed and normal modes preserves data integrity