Phase 8D - massive refactor and admin functions / admin shell in

webinterface. Memory and cross-origin problems.

src/session_broker.h

@@ -130,6 +130,14 @@ esp_err_t session_broker_disconnect(session_broker_client_id_t client_id);
 esp_err_t session_broker_request_writer(session_broker_client_id_t client_id);
 esp_err_t session_broker_release_writer(session_broker_client_id_t client_id);
 esp_err_t session_broker_force_writer(session_broker_client_id_t client_id);
+/*
+ * Atomically replace exactly the expected current writer with a connected target.
+ * expected_writer_id may be zero; target_client_id must identify a live client.
+ * A changed current writer returns ESP_ERR_INVALID_STATE without altering the lease.
+ */
+esp_err_t session_broker_compare_exchange_writer(
+    session_broker_client_id_t expected_writer_id,
+    session_broker_client_id_t target_client_id);
 /* Revoke only if the expected client still owns the writer lease. */
 esp_err_t session_broker_force_release_writer(session_broker_client_id_t expected_writer_id);
 session_broker_client_id_t session_broker_get_writer_id(void);