sync: add cross-subsystem event bus for config consistency

Add EventBus with loop guards to keep firewall, dnsmasq, wireguard,
and network configs consistent. Handlers emit SyncEvent after mutations;
subscribers compute diffs and write JSON without manual cascade loops.

webui/static/hoover/api.js

@@ -238,7 +238,13 @@ export function apiSubmit(opts) {
                 }
                 const res = await apiFetch(url, { method, body: b });
                 if (res.ok) {
-                    toast(successMsg, 'success');
+                    const synced = res.data?.synced;
+                    let msg = successMsg;
+                    if (synced && synced.length) {
+                        msg += ' (auto-synced: ' + synced.join(', ') + ')';
+                        synced.forEach(s => modelFetch(s));
+                    }
+                    toast(msg, 'success');
                     if (closeModal) closeModal();
                     if (refresh) {
                         const models = Array.isArray(refresh) ? refresh : [refresh];

webui/static/hoover/components/data.js

@@ -64,6 +64,9 @@ export function Card(props = {}) {
 
 /**
  * A Remove button that confirms, deletes via API, toasts, and refreshes models.
+ * When the response includes a ``synced`` array (list of subsystem names
+ * that were auto-updated), shows a secondary toast and refreshes those
+ * models.
  *
  * @param {object} props
  * @param {string} props.url       - API DELETE URL
@@ -81,7 +84,13 @@ export function ConfirmDelete(props = {}) {
             if (!confirm(props.message)) return;
             const r = await apiFetch(props.url, opts);
             if (r.ok) {
-                toast(props.success || 'Removed', 'success');
+                const synced = r.data?.synced;
+                let msg = props.success || 'Removed';
+                if (synced && synced.length) {
+                    msg += ' (auto-synced: ' + synced.join(', ') + ')';
+                    synced.forEach(s => modelFetch(s));
+                }
+                toast(msg, 'success');
                 if (props.refresh) {
                     const names = Array.isArray(props.refresh) ? props.refresh : [props.refresh];
                     names.forEach(n => modelFetch(n));
@@ -95,6 +104,9 @@ export function ConfirmDelete(props = {}) {
 /**
  * An action button that POSTs to an API endpoint, toasts on result,
  * and optionally refreshes models. Supports toggle labels for on/off buttons.
+ * When the response includes a ``synced`` array (list of subsystem names
+ * that were auto-updated), shows a secondary toast and refreshes those
+ * models.
  *
  * @param {object} props
  * @param {string} props.url            - API URL
@@ -125,7 +137,14 @@ export function ActionButton(props = {}) {
             if (body !== undefined) opts.body = body;
             const resp = await apiFetch(props.url, opts);
             if (resp.ok) {
-                if (props.successMsg) toast(props.successMsg, 'success');
+                const synced = resp.data?.synced;
+                let msg = props.successMsg || '';
+                if (synced && synced.length) {
+                    if (msg) msg += ' ';
+                    msg += '(auto-synced: ' + synced.join(', ') + ')';
+                    synced.forEach(s => modelFetch(s));
+                }
+                if (msg) toast(msg, 'success');
                 if (props.refresh) {
                     const names = Array.isArray(props.refresh) ? props.refresh : [props.refresh];
                     names.forEach(n => modelFetch(n));

webui/static/pages/dhcp.js

@@ -182,7 +182,13 @@ export default definePage({
                     'on:click': async () => {
                         const res = await apiFetch('/api/dhcp/apply', { method: 'POST' });
                         if (res.ok) {
-                            toast('dnsmasq applied', 'success');
+                            const synced = res.data?.synced;
+                            let msg = 'dnsmasq applied';
+                            if (synced && synced.length) {
+                                msg += ' (auto-synced: ' + synced.join(', ') + ')';
+                                synced.forEach(s => modelFetch(s));
+                            }
+                            toast(msg, 'success');
                             modelFetch('dnsmasq');
                         } else {
                             toast(res.error || 'Apply failed', 'error');