diff --git a/assets/sai.js b/assets/sai.js
index 3331b95..9248896 100644
--- a/assets/sai.js
+++ b/assets/sai.js
@@ -1,3 +1,5 @@
+const SAI_JS_API_VERSION = 2;
+
 (function() {
 
 /*
@@ -1033,6 +1035,7 @@ function ws_open_sai()
 				 
 				 sai.send("{\"schema\":" +
 				 	  "\"com.warmcat.sai.taskinfo\"," +
+					  "\"js_api_version\": " + SAI_JS_API_VERSION + "," +
 				 	  "\"logs\": 1," +
 				 	  "\"task_hash\":" +
 				 	  JSON.stringify(tid) + "}");
@@ -1051,7 +1054,8 @@ function ws_open_sai()
 				 
 				 sai.send("{\"schema\":" +
 				 	  "\"com.warmcat.sai.eventinfo\"," +
-				 	  "\"event_hash\":" +
+					  "\"js_api_version\": " + SAI_JS_API_VERSION + "," +
+					  "\"event_hash\":" +
 				 	  JSON.stringify(eid) + "}");
 				 	  
 				 return;
@@ -1062,7 +1066,7 @@ function ws_open_sai()
 			 */
 			
 			 sai.send("{\"schema\":" +
-			 	  "\"com.warmcat.sai.taskinfo\"}");
+			 	  "\"com.warmcat.sai.taskinfo\", \"js_api_version\": " + SAI_JS_API_VERSION + "}");
 		};
 
 		sai.onmessage = function got_packet(msg) {
@@ -1113,6 +1117,12 @@ function ws_open_sai()
 				}
 			}
 
+			if (jso.api_version && jso.api_version !== SAI_JS_API_VERSION) {
+				console.warn(`Sai JS API version mismatch. Client: ${SAI_JS_API_VERSION}, Server: ${jso.api_version}. Reloading page.`);
+				location.reload(true); // Force a hard reload
+				return; // Stop processing this old message
+			}
+
 			switch (jso.schema) {
 
 			case "com.warmcat.sai.builders":
diff --git a/src/common/include/private.h b/src/common/include/private.h
index 5291eed..d6a75f2 100644
--- a/src/common/include/private.h
+++ b/src/common/include/private.h
@@ -421,6 +421,7 @@ typedef struct sai_browse_rx_evinfo {
 typedef struct sai_browse_rx_taskinfo {
 	char		task_hash[65];
 	unsigned int	log_start;
+	unsigned int	js_api_version;
 	uint8_t		logs;
 } sai_browse_rx_taskinfo_t;
 
diff --git a/src/web/w-private.h b/src/web/w-private.h
index 9fbef99..4c88487 100644
--- a/src/web/w-private.h
+++ b/src/web/w-private.h
@@ -23,6 +23,8 @@
 #include <sqlite3.h>
 #include <sys/stat.h>
 
+#define SAIW_API_VERSION 2
+
 struct sai_plat;
 
 typedef struct sai_platm {
@@ -167,6 +169,7 @@ struct pss {
 	int			log_cache_size;
 	int			authorized;
 	int			specificity;
+	unsigned int		js_api_version;
 	unsigned long		expiry_unix_time;
 
 	/* notification hmac information */
@@ -318,7 +321,7 @@ saiw_sched_destroy(struct lws_dll2 *d, void *user);
 
 
 void
-saiw_ws_broadcast_raw(struct vhd *vhd, const void *buf, size_t len);
+saiw_ws_broadcast_raw(struct vhd *vhd, const void *buf, size_t len, unsigned int min_api_version);
 
 void
 saiw_browser_state_changed(struct pss *pss, int established);
diff --git a/src/web/w-websrv.c b/src/web/w-websrv.c
index ced0742..9c75049 100644
--- a/src/web/w-websrv.c
+++ b/src/web/w-websrv.c
@@ -117,7 +117,7 @@ saiw_lp_rx(void *userobj, const uint8_t *buf, size_t len, int flags)
 		m->a.ac = NULL;
 		vhd->builders_owner =
 				&((sai_plat_owner_t *)m->a.dest)->plat_owner;
-		saiw_ws_broadcast_raw(vhd, buf, len);
+		saiw_ws_broadcast_raw(vhd, buf, len, 0);
 		break;
 
 	case SAIS_WS_WEBSRV_RX_OVERVIEW:
@@ -150,7 +150,7 @@ saiw_lp_rx(void *userobj, const uint8_t *buf, size_t len, int flags)
                /* A builder sent a load report, forward to all browsers */
                lwsl_notice("%s: ===== Received load report, broadcasting to %d browsers\n",
                            __func__, (int)vhd->browsers.count);
-               saiw_ws_broadcast_raw(vhd, buf, len);
+               saiw_ws_broadcast_raw(vhd, buf, len, 2);
 		break;
 	}
 
diff --git a/src/web/w-ws-browser.c b/src/web/w-ws-browser.c
index 18995f9..9a44614 100644
--- a/src/web/w-ws-browser.c
+++ b/src/web/w-ws-browser.c
@@ -35,17 +35,25 @@
  * all connected browsers, eg, for load reports.
  */
 void
-saiw_ws_broadcast_raw(struct vhd *vhd, const void *buf, size_t len)
+saiw_ws_broadcast_raw(struct vhd *vhd, const void *buf, size_t len, unsigned int api_ver_min)
 {
+	int eff = 0;
 	// lwsl_err("%s: sai-web broadcasting to browsers\n", __func__);
 	// lwsl_hexdump_err(buf, len);
 
 	lws_start_foreach_dll(struct lws_dll2 *, p, vhd->browsers.head) {
 		struct pss *pss = lws_container_of(p, struct pss, same);
 
-		if (lws_buflist_append_segment(&pss->raw_tx, buf, len) >= 0)
-			lws_callback_on_writable(pss->wsi);
+		if (pss->js_api_version >= api_ver_min) {
+			eff++;
+			if (lws_buflist_append_segment(&pss->raw_tx, buf, len) >= 0)
+				lws_callback_on_writable(pss->wsi);
+		}
+
 	} lws_end_foreach_dll(p);
+
+	lwsl_notice("%s: broadcast to %d / %d browsers\n", __func__,
+		        eff, (int)vhd->browsers.count);	
 }
 
 extern const lws_struct_map_t lsm_load_report_members[2]; 
@@ -63,11 +71,11 @@ static lws_struct_map_t lsm_browser_taskreset[] = {
 };
 
 static lws_struct_map_t lsm_browser_taskinfo[] = {
-	LSM_CARRAY	(sai_browse_rx_taskinfo_t, task_hash,	"task_hash"),
-	LSM_UNSIGNED	(sai_browse_rx_taskinfo_t, logs,	"logs"),
+	LSM_CARRAY	(sai_browse_rx_taskinfo_t, task_hash,		"task_hash"),
+	LSM_UNSIGNED	(sai_browse_rx_taskinfo_t, logs,		"logs"),
+	LSM_UNSIGNED    (sai_browse_rx_taskinfo_t, js_api_version,	"js_api_version"),
 };
 
-
 /*
  * Schema list so lws_struct can pick the right object to create based on the
  * incoming schema name
@@ -97,6 +105,7 @@ enum {
 	SAIM_WS_BROWSER_RX_EVENTRESET,
 	SAIM_WS_BROWSER_RX_EVENTDELETE,
 	SAIM_WS_BROWSER_RX_TASKCANCEL,
+	SAIM_WS_BROWSER_RX_JS_HELLO,
 };
 
 
@@ -425,6 +434,10 @@ saiw_ws_json_rx_browser(struct vhd *vhd, struct pss *pss, uint8_t *buf,
 	int m, ret = -1;
 
 	memset(&a, 0, sizeof(a));
+	/*
+	 * pss->js_api_version defaults to 1 (from ESTABLISHED callback).
+	 * A new client will update it by sending a js-hello message.
+	 */
 	a.map_st[0] = lsm_schema_json_map_bwsrx;
 	a.map_entries_st[0] = LWS_ARRAY_SIZE(lsm_schema_json_map_bwsrx);
 	a.map_entries_st[1] = LWS_ARRAY_SIZE(lsm_schema_json_map_bwsrx);
@@ -460,6 +473,9 @@ saiw_ws_json_rx_browser(struct vhd *vhd, struct pss *pss, uint8_t *buf,
 			 */
 			// lwsl_warn("%s: SAIM_WS_BROWSER_RX_TASKINFO: doing WSS_PREPARE_BUILDER_SUMMARY\n", __func__);
 
+			if (ti->js_api_version)
+				pss->js_api_version = ti->js_api_version;
+
 			saiw_alloc_sched(pss, WSS_PREPARE_OVERVIEW);
 			saiw_alloc_sched(pss, WSS_PREPARE_BUILDER_SUMMARY);
 			ret = 0;
@@ -790,11 +806,13 @@ again:
 
 		p += lws_snprintf((char *)p, lws_ptr_diff_size_t(end, p),
 			"{\"schema\":\"sai.warmcat.com.overview\","
+			" \"api_version\":%u,"
 			" \"alang\":\"%s\","
 			" \"authorized\": %d,"
 			" \"auth_secs\": %ld,"
 			" \"auth_user\": \"%s\","
 			"\"overview\":[",
+			SAIW_API_VERSION,
 			lws_json_purify(esc, pss->alang, sizeof(esc) - 1, &iu),
 			pss->authorized, pss->authorized ? pss->expiry_unix_time - lws_now_secs() : 0,
 			lws_json_purify(esc1, pss->auth_user, sizeof(esc1) - 1, &iu)