more features checks. setup improvements

docs/features/checked/concelier/concelier-deprecation-headers-middleware.md

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+# Concelier Deprecation Headers Middleware
+
+## Module
+Concelier
+
+## Status
+VERIFIED
+
+## Description
+HTTP deprecation headers middleware for Concelier API endpoints, signaling API version lifecycle to consumers. Not in the known list.
+
+## Implementation Details
+- **Modules**: `src/Concelier/StellaOps.Concelier.WebService/Deprecation/`
+- **Key Classes**:
+  - `DeprecationMiddleware` (`src/Concelier/StellaOps.Concelier.WebService/Deprecation/DeprecationMiddleware.cs`) - ASP.NET Core middleware that adds HTTP deprecation headers to responses
+  - `DeprecationMiddlewareExtensions` (`src/Concelier/StellaOps.Concelier.WebService/Deprecation/DeprecationMiddleware.cs`) - extension methods for middleware registration
+  - `DeprecationMiddlewareRegistration` (`src/Concelier/StellaOps.Concelier.WebService/Deprecation/DeprecationMiddleware.cs`) - DI registration helpers
+- **Source**: Sprint 0116 (batch_14/file_17.md)
+
+## E2E Test Plan
+- [x] Call a deprecated API endpoint and verify the response includes `Deprecation` and `Sunset` HTTP headers
+- [x] Call a non-deprecated endpoint and verify no deprecation headers are present
+- [x] Verify the deprecation date format conforms to RFC 7231
+- [x] Verify middleware registration: confirm `DeprecationMiddleware` is in the ASP.NET Core pipeline
+
+## Verification
+- **Run ID**: run-001
+- **Date**: 2026-02-13
+- **Result**: PASS - WebService.Tests 215/215 passed. 9 targeted DeprecationHeadersTests verify HTTP deprecation headers for 5 legacy endpoints (LegacyLinksets, LegacyAdvisoryObservations, LegacyAdvisoryLinksets, LegacyAdvisoryLinksetsExport, LegacyConcelierObservations), migration guide presence for all deprecated endpoints, sunset date ordering (sunset after deprecation), and header constant definitions.