feat(dashboard): add failure-threshold computeds backed by settings store

frontend/src/views/Dashboard.vue

@@ -300,12 +300,14 @@ import { useSourcesStore } from '../stores/sources'
 import { useDownloadsStore } from '../stores/downloads'
 import { useCredentialsStore } from '../stores/credentials'
 import { useNotificationStore } from '../stores/notifications'
+import { useSettingsStore } from '../stores/settings'
 import { settingsApi, downloadsApi } from '../services/api'
 
 const sourcesStore = useSourcesStore()
 const downloadsStore = useDownloadsStore()
 const credentialsStore = useCredentialsStore()
 const notifications = useNotificationStore()
+const settingsStore = useSettingsStore()
 
 // Supported platforms for credential status
 const supportedPlatforms = ['patreon', 'subscribestar', 'hentaifoundry', 'discord', 'pixiv', 'deviantart']
@@ -326,6 +328,41 @@ let refreshInterval = null
 const stats = computed(() => downloadsStore.stats)
 const recentActivity = computed(() => downloadsStore.recentActivity)
 
+// Fixed display order for platform health bars
+const PLATFORM_ORDER = [
+  'patreon', 'subscribestar', 'hentaifoundry',
+  'discord', 'pixiv', 'deviantart',
+]
+
+// Read threshold from settings, default 5 if unset
+const failureThreshold = computed(() =>
+  settingsStore.settings?.['dashboard.failure_threshold'] ?? 5
+)
+
+// Per-platform health for platforms with ≥1 enabled source
+const platformHealth = computed(() => {
+  const enabled = sourcesStore.sources.filter(s => s.enabled)
+  return PLATFORM_ORDER
+    .map(platform => {
+      const sources = enabled.filter(s => s.platform === platform)
+      if (sources.length === 0) return null
+      const failing = sources.filter(
+        s => (s.error_count || 0) >= failureThreshold.value
+      ).length
+      return { platform, total: sources.length, failing }
+    })
+    .filter(Boolean)
+})
+
+// Sources currently in failing state, most-recent-check first
+const failingSources = computed(() => {
+  return sourcesStore.sources
+    .filter(s => s.enabled && (s.error_count || 0) >= failureThreshold.value)
+    .sort((a, b) => new Date(b.last_check || 0) - new Date(a.last_check || 0))
+})
+
+const totalFailingCount = computed(() => failingSources.value.length)
+
 // Sources with recent failures - derived from recent activity
 // Only shows sources where a recent download failed (not cumulative error_count)
 const sourcesWithErrors = computed(() => {
@@ -369,6 +406,7 @@ function loadDashboardData() {
   // Each section handles its own loading state
   sourcesStore.fetchSources().catch(e => console.error('Failed to fetch sources:', e))
   credentialsStore.fetchCredentials().catch(e => console.error('Failed to fetch credentials:', e))
+  settingsStore.fetchSettings().catch(e => console.error('Failed to fetch settings:', e))
 
   downloadsStore.fetchStats()
     .catch(e => console.error('Failed to fetch stats:', e))