diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 06c0b5409..5aa7afeed 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -72,6 +72,10 @@ jobs:
         if: matrix.runtime == 'node'
         run: pnpm build
 
+      - name: Protocol check (node)
+        if: matrix.runtime == 'node'
+        run: pnpm protocol:check
+
       - name: Lint (bun)
         if: matrix.runtime == 'bun'
         run: bunx biome check src
diff --git a/docs/control-api.md b/docs/control-api.md
index 9f2dd2ca3..a56414e27 100644
--- a/docs/control-api.md
+++ b/docs/control-api.md
@@ -1,5 +1,7 @@
 # Control channel API (newline-delimited JSON)
 
+**Deprecated:** superseded by the WebSocket Gateway protocol (`clawdis gateway`, see `docs/architecture.md` and `docs/gateway.md`). Use only for legacy builds predating the Gateway rollout.
+
 Endpoint: `127.0.0.1:18789` (TCP, localhost only). Clients reach it via SSH port forward in remote mode.
 
 ## Frame format