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+# API Deprecation Policy
+
+## Overview
+
+This document defines how deprecated endpoints and fields are announced and eventually removed from the Notify-Chain API.
+
+## Deprecation Metadata
+
+### Response Headers
+
+Deprecated endpoints and fields will include the following response header:
+
+```
+Deprecation: true
+```
+
+Additional metadata will be provided in a custom header:
+
+```
+X-API-Deprecation: version=2.0.0; sunset=2027-04-17; link="https://github.com/coderolisa/Notify-Chain/blob/main/docs/API_MIGRATION_GUIDES.md"
+```
+
+**Header Fields:**
+- `version`: The API version where the deprecation was introduced
+- `sunset`: The date when the endpoint/field will be removed (RFC 3339 format)
+- `link`: URL to migration documentation
+
+## Status
+
+🚧 **Work in Progress** - This is a foundational document (1% complete)
+
+---
+
+*Last updated: 2026-10-17*