Websockets

docs/openapi.yaml

@@ -8,8 +8,8 @@ info:
     The API is intended for local control tools and the bundled React UI. All mutating
     endpoints return a small action result object.
 
-    WebSocket state streaming is planned for the control UI but is not currently served
-    by RenderCadenceCompositor. Clients should poll `/api/state` until `/ws` is implemented.
+    RenderCadenceCompositor serves `/api/state` for snapshots and `/ws` for local
+    WebSocket state updates consumed by the bundled control UI.
 servers:
   - url: http://127.0.0.1:8080
     description: Default local control server
@@ -179,6 +179,24 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/RuntimeState"
+  /ws:
+    get:
+      tags: [State]
+      summary: Stream runtime state over WebSocket
+      description: |
+        Upgrades to a WebSocket connection. The server sends JSON runtime-state
+        snapshots using the same shape as `GET /api/state` whenever the serialized
+        state changes.
+      operationId: streamRuntimeState
+      responses:
+        "101":
+          description: WebSocket protocol upgrade accepted.
+        "400":
+          description: The request was not a valid WebSocket upgrade.
+          content:
+            text/plain:
+              schema:
+                type: string
   /api/layers/add:
     post:
       tags: [Layers]