diff --git a/AGENTS.md b/AGENTS.md
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+# Agent Rules
+
+## Feature Parity Update Policy
+
+- If you change implementation status for any feature tracked in `FEATURE_PARITY.md`, update that file in the same branch.
+- Do not open a PR that changes feature behavior without checking `FEATURE_PARITY.md` for needed status updates (`❌`, `🚧`, `✅`, notes, and priorities).
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
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+# Contributing
+
+## Feature Parity Requirement
+
+When your change affects a tracked capability, update `FEATURE_PARITY.md` in the same branch.
+
+### Required before opening a PR
+
+1. Review the relevant parity rows in `FEATURE_PARITY.md`.
+2. Update status/notes if behavior changed.
+3. Include the `FEATURE_PARITY.md` diff in your commit when applicable.