diff --git a/frontend/src/components/TopNav.vue b/frontend/src/components/TopNav.vue
index 467278b..8b99c2b 100644
--- a/frontend/src/components/TopNav.vue
+++ b/frontend/src/components/TopNav.vue
@@ -5,9 +5,12 @@
         <img src="/favicon.svg" alt="" class="fc-brand__glyph" width="22" height="22" />
         <span class="fc-brand__text">FabledCurator</span>
       </RouterLink>
-      <span class="fc-health" :title="health.label">
+      <RouterLink
+        :to="{ name: 'system' }" class="fc-health" :title="health.label"
+        :aria-label="`System health: ${health.label}`"
+      >
         <v-icon size="x-small" :color="health.color">{{ health.icon }}</v-icon>
-      </span>
+      </RouterLink>
       <PipelineStatusChip />
     </div>
 
@@ -64,13 +67,15 @@
 </template>
 
 <script setup>
-import { computed, onBeforeUnmount, onMounted, ref } from 'vue'
+import { computed, onBeforeUnmount, onMounted, onUnmounted, ref } from 'vue'
 import { useRoute } from 'vue-router'
 import router, { FRONT_DOOR } from '../router.js'
 import { useSystemStore } from '../stores/system.js'
+import { useSystemHealthStore } from '../stores/systemHealth.js'
 import PipelineStatusChip from './PipelineStatusChip.vue'
 
 const system = useSystemStore()
+const healthStore = useSystemHealthStore()
 
 // Publish the nav's REAL height as --fc-nav-h so full-height workspaces
 // (Explore/Subscriptions) and sticky sub-headers pin to it exactly instead of a
@@ -116,15 +121,55 @@ const settingsRoute = computed(() =>
   navRoutes.value.find(r => r.name === 'settings') || null
 )
 
+// The dot beside the brand, and the only ambient signal that something in the
+// stack has stopped (milestone 365).
+//
+// It used to read /api/health — a no-DB liveness check that proves the WEB
+// container is serving and nothing else. Green there while the worker was dead
+// is exactly what it looked like, and a green dot next to the product name is
+// read as "everything is fine". It now reflects the whole-stack verdict.
+//
+// Deliberately re-using this element rather than adding a second indicator:
+// there were already three partial surfaces (this, the pipeline chip, the
+// Settings Activity tab) and a fourth would have made the question harder to
+// answer, not easier. This is the one that already occupied the slot.
 const health = computed(() => {
-  if (system.healthy === null) {
+  const overall = healthStore.overall
+  if (overall === null) {
     return { icon: 'mdi-circle-outline', color: 'on-surface', label: 'checking…' }
   }
-  if (system.healthy === true) {
-    return { icon: 'mdi-circle', color: 'success', label: 'healthy' }
+  if (overall === 'ok') {
+    return { icon: 'mdi-circle', color: 'success', label: 'All parts running' }
   }
-  return { icon: 'mdi-alert-circle', color: 'error', label: 'unreachable' }
+  // Name what is wrong in the tooltip. "Something is unhealthy" sends someone
+  // hunting; "Scheduler has not checked in for 6 min" does not.
+  const worst = healthStore.problems[0]
+  const others = healthStore.problems.length - 1
+  const suffix = others > 0 ? ` (+${others} more)` : ''
+  if (overall === 'down') {
+    return {
+      icon: 'mdi-alert-circle', color: 'error',
+      label: (worst?.detail || 'A part has stopped') + suffix,
+    }
+  }
+  if (overall === 'stale') {
+    return {
+      icon: 'mdi-alert', color: 'warning',
+      label: (worst?.detail || 'A part is quiet') + suffix,
+    }
+  }
+  return { icon: 'mdi-help-circle-outline', color: 'on-surface', label: 'Health unknown' }
 })
+
+const HEALTH_POLL_MS = 15_000
+let healthTimer = null
+onMounted(() => {
+  healthStore.refresh()
+  healthTimer = setInterval(() => {
+    if (!document.hidden) healthStore.refresh()
+  }, HEALTH_POLL_MS)
+})
+onUnmounted(() => { if (healthTimer) clearInterval(healthTimer) })
 </script>
 
 <style scoped>
@@ -237,7 +282,14 @@ const health = computed(() => {
   display: flex;
   align-items: center;
   flex-shrink: 0;
+  /* A RouterLink since milestone 365 — it is the path to /system, not just an
+     indicator. Reset the anchor so turning a span into a link changed nothing
+     about how the nav reads. */
+  text-decoration: none;
+  color: inherit;
+  border-radius: 50%;
 }
+.fc-health:hover { background: rgb(var(--v-theme-on-surface) / 0.12); }
 .fc-nav-right {
   flex: 1 1 0;
   min-width: 0;
diff --git a/frontend/src/router.js b/frontend/src/router.js
index d4e93c8..64ddb81 100644
--- a/frontend/src/router.js
+++ b/frontend/src/router.js
@@ -1,5 +1,6 @@
 import { createRouter, createWebHistory, createMemoryHistory } from 'vue-router'
 import SettingsView from './views/SettingsView.vue'
+import SystemView from './views/SystemView.vue'
 import GalleryView from './views/GalleryView.vue'
 import ShowcaseView from './views/ShowcaseView.vue'
 import ExploreView from './views/ExploreView.vue'
@@ -45,6 +46,12 @@ const routes = [
 
   // Settings — config, pinned to the right of the nav (TopNav special-cases it).
   { path: '/settings', name: 'settings', component: SettingsView, meta: { title: 'Settings', stickyChrome: true } },
+  // Deliberately NO meta.title: TopNav builds its nav row from routes that
+  // have one, and this is reached from the health indicator beside the
+  // brand — the place someone already looks when they suspect something is
+  // wrong. A sixth top-level tab for a page you visit twice a year would
+  // cost more attention than it returns.
+  { path: '/system', name: 'system', component: SystemView },
 
   // The old standalone paths now redirect into the Browse hub, preserving any
   // deep-link query (e.g. /posts?post_id=N → /browse?tab=posts&post_id=N). The
diff --git a/frontend/src/stores/system.js b/frontend/src/stores/system.js
index eae4059..ce62f9c 100644
--- a/frontend/src/stores/system.js
+++ b/frontend/src/stores/system.js
@@ -4,7 +4,12 @@ import { useApi } from '../composables/useApi.js'
 
 export const useSystemStore = defineStore('system', () => {
   const api = useApi()
-  const healthy = ref(null)  // null=unknown, true=ok, false=down
+  // NOT what the nav dot reads any more (milestone 365): that is the
+  // whole-stack verdict in systemHealth.js. /api/health only proves the web
+  // container is serving, which is why a green dot here sat happily beside a
+  // dead worker. refreshHealth() is still called — it is also how build/version
+  // info arrives — so this stays as its by-product rather than its purpose.
+  const healthy = ref(null)
   // What the instance says it is. Since milestone 318 stopped publishing
   // version image tags, this is the only answer to "which build is this?" —
   // there is no registry name left to check it against.
diff --git a/frontend/src/stores/systemHealth.js b/frontend/src/stores/systemHealth.js
new file mode 100644
index 0000000..fafe016
--- /dev/null
+++ b/frontend/src/stores/systemHealth.js
@@ -0,0 +1,49 @@
+import { defineStore } from 'pinia'
+import { computed, ref } from 'vue'
+
+import { useApi } from '../composables/useApi.js'
+
+// Whole-stack health: is every part of FabledCurator running (milestone 365)?
+//
+// Distinct from `system.js`, which polls /api/health — a no-DB liveness check
+// that only proves the web container is serving. That endpoint answers "can I
+// reach the API"; this one answers "is anything broken", which is the question
+// a green dot beside the brand was already being read as answering.
+//
+// Also distinct from `systemActivity.js`, which is about what the pipeline is
+// DOING — queue depths, running tasks, failures. Running and alive are
+// different questions and they fail independently: a perfectly idle stack with
+// a dead worker looks identical to a healthy one on the activity surfaces.
+export const useSystemHealthStore = defineStore('systemHealth', () => {
+  const api = useApi()
+
+  const overall = ref(null)      // null until the first answer: unknown ≠ ok
+  const parts = ref([])
+  const checkedAt = ref(null)
+  const thresholds = ref(null)   // server-owned, so the UI keeps no second copy
+  const lastError = ref(null)
+
+  async function refresh() {
+    try {
+      const body = await api.get('/api/system/health')
+      overall.value = body.overall
+      parts.value = body.parts || []
+      checkedAt.value = body.checked_at
+      thresholds.value = body.thresholds || null
+      lastError.value = null
+    } catch (e) {
+      // The endpoint is built never to fail because a dependency failed, so a
+      // throw here means the API itself is unreachable — which is its own kind
+      // of unhealthy and must not be shown as "ok".
+      lastError.value = e.message
+      overall.value = 'unknown'
+    }
+    return overall.value
+  }
+
+  // The parts worth naming in a tooltip — everything that is not ok, worst
+  // first. The endpoint already sorts that way.
+  const problems = computed(() => parts.value.filter(p => p.state !== 'ok'))
+
+  return { overall, parts, checkedAt, thresholds, lastError, problems, refresh }
+})
diff --git a/frontend/src/views/SystemView.vue b/frontend/src/views/SystemView.vue
new file mode 100644
index 0000000..18ead8a
--- /dev/null
+++ b/frontend/src/views/SystemView.vue
@@ -0,0 +1,129 @@
+<template>
+  <v-container class="py-6" style="max-width: 900px">
+    <div class="d-flex align-center mb-1">
+      <h1 class="text-h5">System</h1>
+      <v-spacer />
+      <span class="fc-sys__checked">
+        {{ store.checkedAt ? `checked ${formatRelative(store.checkedAt)}` : 'checking…' }}
+      </span>
+    </div>
+
+    <p class="fc-sys__lede text-body-2 mb-5">
+      Every moving part of FabledCurator and whether it is still checking in.
+      Parts are learned as they appear, so anything that has run at least once
+      stays listed — that is what lets a stopped one be noticed rather than
+      simply vanishing.
+    </p>
+
+    <v-alert
+      v-if="store.lastError" type="error" variant="tonal" density="compact" class="mb-4"
+    >
+      Could not reach FabledCurator: {{ store.lastError }}
+    </v-alert>
+
+    <v-card v-else variant="flat" class="fc-sys__card">
+      <div v-if="!store.parts.length" class="pa-6 text-center fc-sys__muted">
+        Still gathering — this fills in on the first check.
+      </div>
+
+      <div
+        v-for="part in store.parts" :key="part.key"
+        class="fc-sys__row" :class="`fc-sys__row--${part.state}`"
+      >
+        <span class="fc-sys__dot" :class="`fc-sys__dot--${part.state}`" />
+
+        <div class="fc-sys__body">
+          <div class="fc-sys__name">
+            {{ part.name }}
+            <span class="fc-sys__kind">{{ kindLabel(part.kind) }}</span>
+          </div>
+          <!-- The sentence, not just a chip. At the moment someone is deciding
+               whether to go and open Portainer, "has not checked in for 6 min"
+               is the thing that answers them. -->
+          <div class="fc-sys__detail">{{ part.detail }}</div>
+        </div>
+
+        <div class="fc-sys__meta">
+          <div v-if="part.last_seen_at" :title="part.last_seen_at">
+            seen {{ formatRelative(part.last_seen_at) }}
+          </div>
+          <div v-if="part.latency_ms != null">{{ part.latency_ms }} ms</div>
+          <div v-if="part.queues?.length" class="fc-sys__queues">{{ part.queues.join(', ') }}</div>
+        </div>
+      </div>
+    </v-card>
+
+    <p v-if="store.thresholds" class="fc-sys__foot text-caption mt-4">
+      A part is called stale after
+      {{ Math.round(store.thresholds.stale_after_seconds / 60) }} min without a
+      check-in and treated as stopped after
+      {{ Math.round(store.thresholds.down_after_seconds / 60) }} min. The window
+      is deliberately wide: a rolling deploy briefly runs two of a service and
+      then neither, and an indicator that reddened on every update would stop
+      being read.
+    </p>
+  </v-container>
+</template>
+
+<script setup>
+import { onMounted, onUnmounted } from 'vue'
+
+import { useSystemHealthStore } from '../stores/systemHealth.js'
+import { formatRelative } from '../utils/date.js'
+
+const store = useSystemHealthStore()
+
+// Slower than the pipeline chip's 8s: liveness changes on the scale of
+// container restarts, not task starts, and this page is open while someone
+// watches it.
+const POLL_MS = 10_000
+let timer = null
+
+function kindLabel(kind) {
+  if (kind === 'celery') return 'background worker'
+  if (kind === 'agent') return 'GPU agent'
+  if (kind === 'datastore') return 'datastore'
+  return kind
+}
+
+onMounted(() => {
+  store.refresh()
+  timer = setInterval(() => { if (!document.hidden) store.refresh() }, POLL_MS)
+})
+onUnmounted(() => { if (timer) clearInterval(timer) })
+</script>
+
+<style scoped>
+.fc-sys__lede, .fc-sys__muted, .fc-sys__checked, .fc-sys__foot {
+  color: rgb(var(--v-theme-on-surface) / 0.66);
+}
+.fc-sys__checked { font-size: 0.78rem; }
+.fc-sys__card { background: rgb(var(--v-theme-on-surface) / 0.04); }
+
+.fc-sys__row {
+  display: flex; align-items: center; gap: 12px;
+  padding: 12px 16px;
+  border-bottom: 1px solid rgb(var(--v-theme-on-surface) / 0.08);
+}
+.fc-sys__row:last-child { border-bottom: 0; }
+
+.fc-sys__dot { width: 9px; height: 9px; border-radius: 50%; flex: 0 0 auto; }
+.fc-sys__dot--ok      { background: rgb(var(--v-theme-success)); }
+.fc-sys__dot--stale   { background: rgb(var(--v-theme-warning)); }
+.fc-sys__dot--down    { background: rgb(var(--v-theme-error)); }
+.fc-sys__dot--unknown { background: rgb(var(--v-theme-on-surface) / 0.35); }
+
+.fc-sys__body { min-width: 0; flex: 1 1 auto; }
+.fc-sys__name { font-weight: 600; }
+.fc-sys__kind {
+  margin-left: 8px; font-weight: 400; font-size: 0.72rem; text-transform: uppercase;
+  letter-spacing: 0.04em; color: rgb(var(--v-theme-on-surface) / 0.5);
+}
+.fc-sys__detail { font-size: 0.82rem; color: rgb(var(--v-theme-on-surface) / 0.72); }
+
+.fc-sys__meta {
+  text-align: right; font-size: 0.75rem; flex: 0 0 auto;
+  font-variant-numeric: tabular-nums; color: rgb(var(--v-theme-on-surface) / 0.6);
+}
+.fc-sys__queues { opacity: 0.75; }
+</style>