Apply all settings and alerts live without Save buttons

Auto-persist client preferences on change with footer feedback, and
apply server alert engine settings/channels/rules immediately.

server/services/alerts.js

@@ -1154,6 +1154,7 @@ function armPoll() {
     clearInterval(pollTimer)
     pollTimer = null
   }
+  if (!config.enabled) return
   const ms = config.pollIntervalMs || DEFAULT_POLL_MS
   pollTimer = setInterval(() => {
     pollHealth().catch((err) => {
@@ -1163,14 +1164,36 @@ function armPoll() {
   if (typeof pollTimer.unref === 'function') pollTimer.unref()
 }
 
+/**
+ * Apply in-memory config to runtime (poll timer, etc.) without restart.
+ * Called after every config mutation so enable/disable and intervals are live.
+ */
+function applyRuntimeConfig({ kickPoll = false } = {}) {
+  armPoll()
+  if (kickPoll && config.enabled) {
+    pollHealth().catch((err) => {
+      logger.debug('alerts: kick poll failed', { error: err.message })
+    })
+  }
+  logger.info('alerts: runtime config applied', {
+    enabled: config.enabled,
+    pollIntervalMs: config.pollIntervalMs,
+    minSeverity: config.minSeverity,
+    rateLimitPerMinute: config.rateLimitPerMinute,
+    quietHours: Boolean(config.quietHours?.enabled),
+    channels: config.channels.filter((c) => c.enabled).length,
+    rules: config.rules.filter((r) => r.enabled).length,
+  })
+}
+
 export function startAlerts() {
   if (started) return
   started = true
   loadDisk()
-  armPoll()
-  // Initial poll shortly after boot
+  applyRuntimeConfig({ kickPoll: false })
+  // Initial poll shortly after boot (only if enabled)
   setTimeout(() => {
-    pollHealth().catch(() => {})
+    if (config.enabled) pollHealth().catch(() => {})
   }, 5_000)
   logger.info('Alerts engine started', {
     channels: config.channels.length,
@@ -1216,6 +1239,7 @@ export function getAlertsConfigRaw() {
  * @param {{ replace?: boolean }} [opts]
  */
 export function updateAlertsConfig(partial, opts = {}) {
+  const wasEnabled = config.enabled
   if (opts.replace) {
     config = normalizeConfig(partial)
   } else {
@@ -1237,7 +1261,10 @@ export function updateAlertsConfig(partial, opts = {}) {
   }
   config.updatedAt = new Date().toISOString()
   saveDisk()
-  armPoll()
+  // Live apply: poll interval, enable/disable — no process restart
+  applyRuntimeConfig({
+    kickPoll: config.enabled && (!wasEnabled || partial.pollIntervalMs != null),
+  })
   return getAlertsConfig()
 }
 
@@ -1258,6 +1285,12 @@ export function upsertAlertChannel(input) {
     config.channels.push(ch)
   }
   scheduleSave()
+  // Channel list is read on each fire — already live; log for ops clarity
+  logger.debug('alerts: channel upserted live', {
+    id: ch.id,
+    enabled: ch.enabled,
+    type: ch.type,
+  })
   return redactChannel(ch)
 }
 
@@ -1280,6 +1313,11 @@ export function upsertAlertRule(input) {
   if (idx >= 0) config.rules[idx] = rule
   else config.rules.push(rule)
   scheduleSave()
+  logger.debug('alerts: rule upserted live', {
+    id: rule.id,
+    enabled: rule.enabled,
+    kind: rule.kind,
+  })
   return rule
 }