feat(ia): wave 2 — Activity becomes the whole-app pulse; Overview gets the health strip

The Activity tab only knew Celery — the GPU agent (the majority of processing)
and the download pipeline were invisible there. Two new self-polling panels:

- GpuActivityPanel: queue depths + triage verdicts (defects / file-ok /
  unprobed, top reason buckets) with a jump to Maintenance -> Failed
  processing. The triage detail refetches only when the error count moves.
- DownloadsActivityPanel: 24h stat chips + failing-source names with a jump
  into Subscriptions.

Both panels join the Activity tab under Queues+workers AND double as the
Overview health strip (side-by-side grid under the Celery summary) — one
component set, so Overview answers 'is everything healthy?' across all
systems. SystemStatsCards reviewed: content still accurate, left as-is.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CDgx8bQS5YrGRK76v8HUnM

frontend/src/components/settings/DownloadsActivityPanel.vue

@@ -0,0 +1,77 @@
+<template>
+  <v-card class="mb-4">
+    <CardHeading icon="mdi-download" title="Downloads (last 24h)">
+      <v-spacer />
+      <v-btn
+        variant="text" size="small" rounded="pill"
+        to="/subscriptions?tab=downloads"
+      >
+        Open subscriptions
+        <v-icon end size="small">mdi-arrow-right</v-icon>
+      </v-btn>
+    </CardHeading>
+    <v-card-text>
+      <div class="d-flex align-center flex-wrap mb-2" style="gap: 8px">
+        <v-chip size="small" variant="tonal" color="success">
+          {{ stats.ok }} ok
+        </v-chip>
+        <v-chip
+          size="small" variant="tonal"
+          :color="stats.error ? 'error' : undefined"
+        >
+          {{ stats.error }} failed
+        </v-chip>
+        <v-chip v-if="stats.running" size="small" variant="tonal" color="accent">
+          {{ stats.running }} running
+        </v-chip>
+        <v-chip v-if="stats.pending" size="small" variant="tonal">
+          {{ stats.pending }} pending
+        </v-chip>
+        <v-chip v-if="stats.skipped" size="small" variant="tonal">
+          {{ stats.skipped }} skipped
+        </v-chip>
+      </div>
+      <p v-if="!failing.length" class="fc-muted text-body-2 mb-0">
+        All subscription sources healthy.
+      </p>
+      <p v-else class="text-body-2 mb-0">
+        <b class="fc-bad">{{ failing.length }}</b> failing source(s):
+        <span class="fc-muted">{{ failingNames }}</span>
+      </p>
+    </v-card-text>
+  </v-card>
+</template>
+
+<script setup>
+import { computed, onMounted, onUnmounted } from 'vue'
+import { storeToRefs } from 'pinia'
+
+import CardHeading from '../common/CardHeading.vue'
+import { useDownloadsStore } from '../../stores/downloads.js'
+
+const store = useDownloadsStore()
+const { stats, failing } = storeToRefs(store)
+let pollId = null
+
+const failingNames = computed(() => {
+  const names = failing.value.map((s) => s.artist_name || s.url).slice(0, 3)
+  const extra = failing.value.length - names.length
+  return names.join(', ') + (extra > 0 ? ` +${extra} more` : '')
+})
+
+function poll() {
+  store.loadStats(24)
+  store.loadFailing()
+}
+
+onMounted(() => {
+  poll()
+  pollId = setInterval(() => { if (!document.hidden) poll() }, 30000)
+})
+onUnmounted(() => { if (pollId) clearInterval(pollId) })
+</script>
+
+<style scoped>
+.fc-muted { color: rgb(var(--v-theme-on-surface-variant)); }
+.fc-bad { color: rgb(var(--v-theme-error)); }
+</style>

frontend/src/components/settings/GpuActivityPanel.vue

@@ -0,0 +1,110 @@
+<template>
+  <v-card class="mb-4">
+    <CardHeading icon="mdi-expansion-card" title="GPU agent pipeline">
+      <v-spacer />
+      <v-btn
+        variant="text" size="small" rounded="pill"
+        @click="$emit('open-maintenance')"
+      >
+        Open maintenance
+        <v-icon end size="small">mdi-arrow-right</v-icon>
+      </v-btn>
+    </CardHeading>
+    <v-card-text>
+      <div class="fc-cells mb-2">
+        <div class="fc-cell">
+          <div class="fc-cell__n">{{ q.pending }}</div>
+          <div class="fc-cell__l">pending</div>
+        </div>
+        <div class="fc-cell">
+          <div class="fc-cell__n">{{ q.leased }}</div>
+          <div class="fc-cell__l">in flight</div>
+        </div>
+        <div class="fc-cell">
+          <div class="fc-cell__n fc-good">{{ q.done }}</div>
+          <div class="fc-cell__l">done</div>
+        </div>
+        <div class="fc-cell">
+          <div class="fc-cell__n" :class="q.error ? 'fc-bad' : ''">{{ q.error }}</div>
+          <div class="fc-cell__l">errored</div>
+        </div>
+      </div>
+      <p v-if="!q.error" class="fc-muted text-body-2 mb-0">
+        No failed jobs — the pipeline is clean. Work drains whenever the
+        desktop agent is running.
+      </p>
+      <p v-else class="text-body-2 mb-0">
+        Triage: <b>{{ triage.defect }}</b> defective file(s) ·
+        {{ triage.file_ok }} file-ok · {{ triage.unclassified }} unprobed
+        <span v-if="reasonSummary" class="fc-muted">— {{ reasonSummary }}</span>
+        <br>
+        <span class="fc-muted text-caption">
+          Recover defective files from Maintenance → Failed processing.
+        </span>
+      </p>
+    </v-card-text>
+  </v-card>
+</template>
+
+<script setup>
+import { computed, onMounted, onUnmounted, ref } from 'vue'
+
+import CardHeading from '../common/CardHeading.vue'
+import { useGpuStore } from '../../stores/gpu.js'
+
+defineEmits(['open-maintenance'])
+
+const store = useGpuStore()
+const q = ref({ pending: 0, leased: 0, done: 0, error: 0 })
+const triage = ref({ defect: 0, file_ok: 0, unclassified: 0 })
+const byClass = ref({})
+let pollId = null
+let lastErrorCount = -1
+
+const reasonSummary = computed(() =>
+  Object.entries(byClass.value)
+    .sort((a, b) => b[1] - a[1])
+    .slice(0, 3)
+    .map(([k, n]) => `${k.replaceAll('_', ' ')} ${n}`)
+    .join(' · '))
+
+async function poll() {
+  try {
+    q.value = await store.status()
+    // The triage detail is only worth a second call when the error count
+    // actually moved (it's a 500-row join server-side).
+    if (q.value.error !== lastErrorCount) {
+      lastErrorCount = q.value.error
+      if (q.value.error > 0) {
+        const body = await store.errors()
+        triage.value = body.triage
+        byClass.value = body.by_class
+      } else {
+        triage.value = { defect: 0, file_ok: 0, unclassified: 0 }
+        byClass.value = {}
+      }
+    }
+  } catch { /* non-fatal — panel just shows the last snapshot */ }
+}
+
+onMounted(() => {
+  poll()
+  pollId = setInterval(() => { if (!document.hidden) poll() }, 5000)
+})
+onUnmounted(() => { if (pollId) clearInterval(pollId) })
+</script>
+
+<style scoped>
+.fc-muted { color: rgb(var(--v-theme-on-surface-variant)); }
+.fc-cells { display: flex; gap: 28px; }
+.fc-cell__n {
+  font-size: 20px; font-weight: 700; line-height: 1.1;
+  font-family: 'JetBrains Mono', monospace;
+}
+.fc-cell__l {
+  font-size: 11px; text-transform: uppercase; letter-spacing: 0.04em;
+  color: rgb(var(--v-theme-on-surface-variant));
+}
+.fc-good { color: rgb(var(--v-theme-success)); }
+.fc-bad { color: rgb(var(--v-theme-error)); }
+</style>

frontend/src/components/settings/SystemActivityTab.vue

@@ -17,6 +17,12 @@
       </v-card-text>
     </v-card>
 
+    <!-- The non-Celery halves of the app (2026-07-02): the GPU agent does the
+         majority of processing and downloads feed the library — Activity is
+         the whole-app pulse, not just the worker queues. -->
+    <GpuActivityPanel @open-maintenance="$emit('open-maintenance')" />
+    <DownloadsActivityPanel />
+
     <!-- Recent failures pane -->
     <v-card class="mb-4">
       <CardHeading icon="mdi-alert-circle-outline" title="Recent failures (last 24h)">
@@ -167,6 +173,10 @@ import { formatRelative as fmtRelative } from '../../utils/date.js'
 import ErrorDetailModal from '../common/ErrorDetailModal.vue'
 import QueuesTable from './QueuesTable.vue'
 import CardHeading from '../common/CardHeading.vue'
+import GpuActivityPanel from './GpuActivityPanel.vue'
+import DownloadsActivityPanel from './DownloadsActivityPanel.vue'
+
+defineEmits(['open-maintenance'])
 
 // Click-to-open modal for full error text. Replaces the unusable
 // :title="..." tooltip (operator-flagged 2026-05-26: SQLAlchemy

frontend/src/views/SettingsView.vue

@@ -28,6 +28,13 @@
           class="mt-4"
           @open-activity="tab = 'activity'"
         />
+        <!-- Health strip (2026-07-02): the same GPU + downloads panels the
+             Activity tab uses — Overview answers "is everything healthy?"
+             across ALL systems, not just the Celery queues above. -->
+        <div class="fc-health-row mt-4">
+          <GpuActivityPanel @open-maintenance="tab = 'maintenance'" />
+          <DownloadsActivityPanel />
+        </div>
         <v-alert
           v-if="system.stats && (system.stats.tasks.pending + system.stats.tasks.queued) > 0"
           type="info" variant="tonal" class="mt-4" closable
@@ -38,7 +45,7 @@
       </v-window-item>
 
       <v-window-item value="activity">
-        <SystemActivityTab />
+        <SystemActivityTab @open-maintenance="tab = 'maintenance'" />
       </v-window-item>
 
       <v-window-item value="cleanup">
@@ -58,6 +65,8 @@ import { useSystemStore } from '../stores/system.js'
 import SystemStatsCards from '../components/settings/SystemStatsCards.vue'
 import SystemActivitySummary from '../components/settings/SystemActivitySummary.vue'
 import SystemActivityTab from '../components/settings/SystemActivityTab.vue'
+import GpuActivityPanel from '../components/settings/GpuActivityPanel.vue'
+import DownloadsActivityPanel from '../components/settings/DownloadsActivityPanel.vue'
 import MaintenancePanel from '../components/settings/MaintenancePanel.vue'
 import CleanupView from './CleanupView.vue'
 import { useMLStore } from '../stores/ml.js'
@@ -93,4 +102,13 @@ watch(tab, (t) => {
 .fc-settings {
   max-width: 1140px;
 }
+/* Overview health strip: the two pulse panels side by side, stacking on
+   narrow screens. Cancel the panels' own bottom margin — the row owns gaps. */
+.fc-health-row {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(340px, 1fr));
+  gap: 16px;
+  align-items: start;
+}
+.fc-health-row :deep(.v-card) { margin-bottom: 0 !important; }
 </style>