fix: don't double-send status to command requester

load_graph/stop_node/start_node each called notify() (push to all
clients) and then sent a direct response — the requesting client
got two identical messages, breaking test recv sequencing.

Use thread_local tl_requester to skip the requesting connection
in the push. notify() is called synchronously from the command,
so the thread_local is visible from the status_cb. Other clients
still receive the push; the requester gets only the direct response.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

studio-manager/main.cpp

@@ -45,11 +45,17 @@ int main(int argc, char* argv[]) {
     std::mutex ws_mutex;
     std::unordered_set<crow::websocket::connection*> clients;
 
-    // Push status to every connected client (called without manager mutex held).
+    // Push status to every connected client except the one whose command triggered
+    // the change — that client gets the direct response from the handler instead.
+    // tl_requester is thread-local: notify() is called synchronously from within
+    // the manager command, so it runs on the same thread as onmessage.
+    thread_local crow::websocket::connection* tl_requester = nullptr;
+
     manager.on_status_change([&](nlohmann::json status) {
         std::lock_guard lk(ws_mutex);
         const std::string msg = status.dump();
-        for (auto* c : clients) c->send_text(msg);
+        for (auto* c : clients)
+            if (c != tl_requester) c->send_text(msg);
     });
 
     CROW_WEBSOCKET_ROUTE(app, "/ws")
@@ -76,6 +82,7 @@ int main(int argc, char* argv[]) {
 
             nlohmann::json response;
             const std::string type = j.value("type", "");
+            tl_requester = &conn;
             try {
                 if      (type == "load_graph") response = manager.load_graph(j.at("graph"));
                 else if (type == "stop_node")  response = manager.stop_node(j.at("id"));
@@ -85,6 +92,7 @@ int main(int argc, char* argv[]) {
             } catch (const std::exception& e) {
                 response = {{"type","error"},{"message", e.what()}};
             }
+            tl_requester = nullptr;
             conn.send_text(response.dump());
         });