diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index 6dd9cf43..982140fe 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Breaking Changes
+
+- **New RPC protocol**: The RPC mode (`--mode rpc`) has been completely redesigned with a new JSON protocol. The old protocol is no longer supported. See [`docs/RPC.md`](docs/RPC.md) for the new protocol documentation and [`test/rpc-example.ts`](test/rpc-example.ts) for a working example. Includes `RpcClient` TypeScript class for easy integration. ([#91](https://github.com/badlogic/pi-mono/issues/91))
+
 ## [0.15.0] - 2025-12-09
 
 ### Changed