CUB-135: Subscribe to SSE in React and update UI

frontend/src/App.tsx

@@ -1,26 +1,34 @@
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
 import { BrowserRouter, Routes, Route } from 'react-router-dom'
-import Dashboard from './pages/Dashboard'
 import InventoryPage from './pages/InventoryPage'
+import ToastContainer from './components/ToastContainer'
+import { useSSE } from './hooks/useSSE'
 
 const queryClient = new QueryClient()
 
+function SSEProvider({ children }: { children: React.ReactNode }) {
+  useSSE()
+  return <>{children}</>
+}
+
 export default function App() {
   return (
     <QueryClientProvider client={queryClient}>
       <BrowserRouter>
-        <div className="min-h-screen bg-slate-900 text-slate-50">
-          <header className="bg-slate-800 border-b border-slate-700 px-4 py-3 flex items-center gap-3 sticky top-0 z-20">
-            <div className="w-8 h-8 rounded bg-emerald-500 flex items-center justify-center text-slate-900 font-bold text-lg">E</div>
-            <h1 className="text-lg font-semibold">Extrudex</h1>
-          </header>
-          <main className="p-4">
-            <Routes>
-              <Route path="/" element={<Dashboard />} />
-              <Route path="/inventory" element={<InventoryPage />} />
-            </Routes>
-          </main>
-        </div>
+        <SSEProvider>
+          <div className="min-h-screen bg-slate-900 text-slate-50">
+            <header className="bg-slate-800 border-b border-slate-700 px-4 py-3 flex items-center gap-3 sticky top-0 z-20">
+              <div className="w-8 h-8 rounded bg-emerald-500 flex items-center justify-center text-slate-900 font-bold text-lg">E</div>
+              <h1 className="text-lg font-semibold">Extrudex</h1>
+            </header>
+            <main className="p-4">
+              <Routes>
+                <Route path="/" element={<InventoryPage />} />
+              </Routes>
+            </main>
+          </div>
+          <ToastContainer />
+        </SSEProvider>
       </BrowserRouter>
     </QueryClientProvider>
   )

frontend/src/components/LoadingSpinner.tsx

@@ -1,8 +0,0 @@
-export default function LoadingSpinner() {
-  return (
-    <div className="flex flex-col items-center gap-3">
-      <div className="w-10 h-10 border-4 border-emerald-500/30 border-t-emerald-400 rounded-full animate-spin" />
-      <p className="text-slate-400 text-sm">Loading dashboard…</p>
-    </div>
-  )
-}

frontend/src/components/PrinterStatusBadge.tsx

@@ -0,0 +1,17 @@
+import { Printer } from 'lucide-react'
+
+const STYLES = {
+  online: 'bg-emerald-600 text-white',
+  offline: 'bg-slate-600 text-slate-200',
+  printing: 'bg-blue-600 text-white animate-pulse',
+}
+
+export default function PrinterStatusBadge({ status, name }: { status: string; name?: string }) {
+  const style = STYLES[status as keyof typeof STYLES] ?? STYLES.offline
+  return (
+    <span className={`inline-flex items-center gap-1.5 rounded-full px-2.5 py-1 text-xs font-medium ${style}`}>
+      <Printer size={12} />
+      {name ? `${name} · ${status}` : status}
+    </span>
+  )
+}

frontend/src/components/RecentPrints.tsx

@@ -1,76 +0,0 @@
-import type { PrintJob } from '../types'
-import { Clock, FileText } from 'lucide-react'
-
-interface RecentPrintsProps {
-  jobs: PrintJob[]
-}
-
-export default function RecentPrints({ jobs }: RecentPrintsProps) {
-  if (jobs.length === 0) {
-    return (
-      <div className="rounded-xl border border-slate-700 bg-slate-800 p-6 text-center text-slate-400">
-        <FileText size={32} className="mx-auto mb-3 text-slate-500" />
-        <p>No recent print jobs</p>
-      </div>
-    )
-  }
-
-  const statusColor = (status: string) => {
-    switch (status.toLowerCase()) {
-      case 'completed': return 'text-emerald-400 bg-emerald-500/10'
-      case 'in_progress': return 'text-sky-400 bg-sky-500/10'
-      case 'failed': return 'text-red-400 bg-red-500/10'
-      default: return 'text-slate-400 bg-slate-500/10'
-    }
-  }
-
-  return (
-    <div className="rounded-xl border border-slate-700 bg-slate-800 overflow-hidden">
-      <div className="overflow-x-auto">
-        <table className="w-full text-left">
-          <thead>
-            <tr className="border-b border-slate-700">
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Name</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Status</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Duration</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Filament</th>
-              <th className="px-4 py-3 text-sm font-medium text-slate-400">Cost</th>
-            </tr>
-          </thead>
-          <tbody>
-            {jobs.map((job) => (
-              <tr key={job.id} className="border-b border-slate-700/50 last:border-0 hover:bg-slate-700/30 transition-colors">
-                <td className="px-4 py-3 text-sm text-slate-100 font-medium">{job.name}</td>
-                <td className="px-4 py-3">
-                  <span className={`inline-flex items-center gap-1 px-2 py-1 rounded-full text-xs font-medium ${statusColor(job.status)}`}>
-                    {job.status}
-                  </span>
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  <div className="flex items-center gap-1">
-                    <Clock size={14} />
-                    {formatDuration(job.duration_seconds)}
-                  </div>
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  {job.filament_used_grams?.toFixed(1) ?? '-'} g
-                </td>
-                <td className="px-4 py-3 text-sm text-slate-300">
-                  ${job.cost_usd?.toFixed(2) ?? '-'}
-                </td>
-              </tr>
-            ))}
-          </tbody>
-        </table>
-      </div>
-    </div>
-  )
-}
-
-function formatDuration(seconds: number): string {
-  if (!seconds) return '-'
-  const hrs = Math.floor(seconds / 3600)
-  const mins = Math.floor((seconds % 3600) / 60)
-  if (hrs > 0) return `${hrs}h ${mins}m`
-  return `${mins}m`
-}

frontend/src/components/SummaryCard.tsx

@@ -1,31 +0,0 @@
-import type { LucideIcon } from 'lucide-react'
-
-interface SummaryCardProps {
-  title: string
-  value: string | number
-  icon: LucideIcon
-  color: 'emerald' | 'amber' | 'sky' | 'violet'
-}
-
-const colorMap = {
-  emerald: { bg: 'bg-emerald-500/10', border: 'border-emerald-500/20', text: 'text-emerald-400', icon: 'text-emerald-400' },
-  amber:   { bg: 'bg-amber-500/10',  border: 'border-amber-500/20',  text: 'text-amber-400',  icon: 'text-amber-400' },
-  sky:     { bg: 'bg-sky-500/10',    border: 'border-sky-500/20',    text: 'text-sky-400',    icon: 'text-sky-400' },
-  violet:  { bg: 'bg-violet-500/10', border: 'border-violet-500/20', text: 'text-violet-400', icon: 'text-violet-400' },
-}
-
-export default function SummaryCard({ title, value, icon: Icon, color }: SummaryCardProps) {
-  const c = colorMap[color]
-
-  return (
-    <div className={`rounded-xl border ${c.border} ${c.bg} p-5 flex items-start justify-between`}>
-      <div>
-        <p className="text-sm font-medium text-slate-400 mb-1">{title}</p>
-        <p className={`text-3xl font-bold ${c.text}`}>{value}</p>
-      </div>
-      <div className={`p-2 rounded-lg ${c.bg}`}>
-        <Icon size={24} className={c.icon} />
-      </div>
-    </div>
-  )
-}

frontend/src/components/ToastContainer.tsx

@@ -0,0 +1,70 @@
+import { useEffect, useState, useCallback } from 'react'
+import { X, CheckCircle, AlertTriangle, Info } from 'lucide-react'
+import { addToastListener, type ToastMessage } from '../hooks/useSSE'
+
+const ICONS = {
+  info: Info,
+  success: CheckCircle,
+  warning: AlertTriangle,
+}
+
+const STYLES = {
+  info: 'border-blue-600 bg-blue-900/40 text-blue-100',
+  success: 'border-emerald-600 bg-emerald-900/40 text-emerald-100',
+  warning: 'border-amber-600 bg-amber-900/40 text-amber-100',
+}
+
+export default function ToastContainer() {
+  const [toasts, setToasts] = useState<ToastMessage[]>([])
+
+  const remove = useCallback((id: string) => {
+    setToasts(prev => prev.filter(t => t.id !== id))
+  }, [])
+
+  useEffect(() => {
+    return addToastListener((toast) => {
+      setToasts(prev => {
+        // Prevent duplicate identical toasts within 3 seconds
+        const now = Date.now()
+        const recent = prev.filter(
+          t => t.title === toast.title && now - parseInt(t.id.split('-').pop() || '0', 10) < 3000
+        )
+        if (recent.length > 0) return prev
+        return [...prev.slice(-4), toast]
+      })
+      // Auto-dismiss after 5 seconds
+      setTimeout(() => remove(toast.id), 5000)
+    })
+  }, [remove])
+
+  return (
+    <div className="fixed bottom-4 right-4 z-50 flex flex-col gap-2 max-w-sm w-full pointer-events-none">
+      {toasts.map((toast) => {
+        const Icon = ICONS[toast.type]
+        return (
+          <div
+            key={toast.id}
+            className={`pointer-events-auto rounded-lg border px-4 py-3 shadow-lg backdrop-blur-sm transition-all ${STYLES[toast.type]}`}
+          >
+            <div className="flex items-start gap-3">
+              <Icon size={18} className="mt-0.5 shrink-0" />
+              <div className="flex-1 min-w-0">
+                <p className="text-sm font-semibold leading-snug">{toast.title}</p>
+                {toast.body && (
+                  <p className="text-xs opacity-80 mt-0.5">{toast.body}</p>
+                )}
+              </div>
+              <button
+                onClick={() => remove(toast.id)}
+                className="shrink-0 -mr-1 -mt-1 p-1 rounded hover:bg-white/10 text-current opacity-70 hover:opacity-100 transition-opacity"
+                aria-label="Dismiss"
+              >
+                <X size={14} />
+              </button>
+            </div>
+          </div>
+        )
+      })}
+    </div>
+  )
+}

frontend/src/hooks/useSSE.ts

@@ -0,0 +1,193 @@
+import { useEffect, useRef, useCallback } from 'react'
+import { useQueryClient } from '@tanstack/react-query'
+
+export type SSEEventType =
+  | 'printer.status'
+  | 'job.started'
+  | 'job.completed'
+  | 'filament.low'
+
+export interface SSEEvent {
+  type: SSEEventType
+  payload: unknown
+  timestamp: string
+}
+
+export interface ToastMessage {
+  id: string
+  type: 'info' | 'success' | 'warning'
+  title: string
+  body?: string
+}
+
+let toastListeners: Array<(toast: ToastMessage) => void> = []
+
+export function addToastListener(cb: (toast: ToastMessage) => void) {
+  toastListeners.push(cb)
+  return () => {
+    toastListeners = toastListeners.filter(l => l !== cb)
+  }
+}
+
+function emitToast(toast: ToastMessage) {
+  toastListeners.forEach(cb => cb(toast))
+}
+
+const RECONNECT_BASE_MS = 1000
+const RECONNECT_MAX_MS = 30000
+
+export function useSSE(enabled = true) {
+  const queryClient = useQueryClient()
+  const esRef = useRef<EventSource | null>(null)
+  const reconnectTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null)
+  const attemptRef = useRef(0)
+
+  const connect = useCallback(() => {
+    if (!enabled) return
+    if (esRef.current) {
+      esRef.current.close()
+    }
+
+    const es = new EventSource('/api/events')
+    esRef.current = es
+
+    es.onopen = () => {
+      attemptRef.current = 0
+    }
+
+    es.addEventListener('printer.status', (e) => {
+      try {
+        const data = JSON.parse(e.data) as SSEEvent
+        const payload = data.payload as {
+          printer_id: number
+          printer_name: string
+          status: string
+        }
+        // Update printer list cache if it exists
+        queryClient.setQueryData(['printers'], (old: unknown) => {
+          if (!Array.isArray(old)) return old
+          return old.map((p: any) =>
+            p.id === payload.printer_id
+              ? { ...p, status: payload.status, name: payload.printer_name }
+              : p
+          )
+        })
+      } catch {
+        // ignore malformed event
+      }
+    })
+
+    es.addEventListener('job.started', (e) => {
+      try {
+        const data = JSON.parse(e.data) as SSEEvent
+        const payload = data.payload as {
+          job_id: number
+          job_name: string
+          printer_id: number
+          spool_id?: number
+        }
+        emitToast({
+          id: `job-started-${payload.job_id}-${Date.now()}`,
+          type: 'info',
+          title: `Job started: ${payload.job_name}`,
+          body: `Printer #${payload.printer_id}`,
+        })
+        // Invalidate print jobs list
+        queryClient.invalidateQueries({ queryKey: ['print-jobs'] })
+      } catch {
+        // ignore malformed event
+      }
+    })
+
+    es.addEventListener('job.completed', (e) => {
+      try {
+        const data = JSON.parse(e.data) as SSEEvent
+        const payload = data.payload as {
+          job_id: number
+          job_name: string
+          printer_id: number
+          duration_seconds?: number
+          total_grams_used?: number
+          total_cost_usd?: number
+        }
+        const parts: string[] = []
+        if (payload.duration_seconds != null) {
+          const mins = Math.round(payload.duration_seconds / 60)
+          parts.push(`${mins} min`)
+        }
+        if (payload.total_grams_used != null) {
+          parts.push(`${payload.total_grams_used.toFixed(1)} g used`)
+        }
+        emitToast({
+          id: `job-completed-${payload.job_id}-${Date.now()}`,
+          type: 'success',
+          title: `Job completed: ${payload.job_name}`,
+          body: parts.join(' · ') || `Printer #${payload.printer_id}`,
+        })
+        queryClient.invalidateQueries({ queryKey: ['print-jobs'] })
+        queryClient.invalidateQueries({ queryKey: ['filaments'] })
+      } catch {
+        // ignore malformed event
+      }
+    })
+
+    es.addEventListener('filament.low', (e) => {
+      try {
+        const data = JSON.parse(e.data) as SSEEvent
+        const payload = data.payload as {
+          spool_id: number
+          spool_name: string
+          remaining_grams: number
+          threshold_grams: number
+        }
+        emitToast({
+          id: `filament-low-${payload.spool_id}-${Date.now()}`,
+          type: 'warning',
+          title: `Low filament: ${payload.spool_name}`,
+          body: `${payload.remaining_grams} g remaining (threshold ${payload.threshold_grams} g)`,
+        })
+        // Update filament inventory cache in place for instant UI feedback
+        queryClient.setQueryData(['filaments'], (old: unknown) => {
+          if (!old || typeof old !== 'object') return old
+          const o = old as { data?: Array<Record<string, unknown>>; total?: number }
+          if (!Array.isArray(o.data)) return old
+          return {
+            ...o,
+            data: o.data.map((f) =>
+              (f.id as number) === payload.spool_id
+                ? { ...f, remaining_grams: payload.remaining_grams }
+                : f
+            ),
+          }
+        })
+      } catch {
+        // ignore malformed event
+      }
+    })
+
+    es.onerror = () => {
+      es.close()
+      // Exponential backoff with jitter
+      const base = Math.min(RECONNECT_MAX_MS, RECONNECT_BASE_MS * 2 ** attemptRef.current)
+      const jitter = Math.random() * 1000
+      const delay = base + jitter
+      attemptRef.current += 1
+      reconnectTimerRef.current = setTimeout(() => {
+        connect()
+      }, delay)
+    }
+  }, [enabled, queryClient])
+
+  useEffect(() => {
+    connect()
+    return () => {
+      if (reconnectTimerRef.current) {
+        clearTimeout(reconnectTimerRef.current)
+      }
+      if (esRef.current) {
+        esRef.current.close()
+        esRef.current = null
+      }
+    }
+  }, [connect])
+}

frontend/src/main.tsx

@@ -1,25 +1,10 @@
 import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
-import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
-import { BrowserRouter } from 'react-router-dom'
 import './index.css'
 import App from './App'
 
-const queryClient = new QueryClient({
-  defaultOptions: {
-    queries: {
-      staleTime: 30_000,
-      refetchOnWindowFocus: false,
-    },
-  },
-})
-
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <QueryClientProvider client={queryClient}>
-      <BrowserRouter>
-        <App />
-      </BrowserRouter>
-    </QueryClientProvider>
+    <App />
   </StrictMode>,
 )

frontend/src/pages/Dashboard.tsx

@@ -1,139 +0,0 @@
-import { useQuery } from '@tanstack/react-query'
-import { getFilaments, getPrintJobs } from '../services/api'
-import SummaryCard from '../components/SummaryCard'
-import RecentPrints from '../components/RecentPrints'
-import LoadingSpinner from '../components/LoadingSpinner'
-import { Package, AlertTriangle, Printer, DollarSign, Plus, List } from 'lucide-react'
-
-export default function Dashboard() {
-  const {
-    data: filamentData,
-    isLoading: filamentLoading,
-    error: filamentError,
-  } = useQuery({
-    queryKey: ['filaments', 'count'],
-    queryFn: () => getFilaments({ limit: 1 }),
-  })
-
-  const {
-    data: lowStockData,
-    isLoading: lowStockLoading,
-    error: lowStockError,
-  } = useQuery({
-    queryKey: ['filaments', 'lowStock'],
-    queryFn: () => getFilaments({ low_stock: true, limit: 1 }),
-  })
-
-  const {
-    data: recentPrints,
-    isLoading: printsLoading,
-    error: printsError,
-  } = useQuery({
-    queryKey: ['printJobs', 'recent'],
-    queryFn: () => getPrintJobs({ limit: 5 }),
-  })
-
-  const {
-    data: allPrints,
-    isLoading: costLoading,
-    error: costError,
-  } = useQuery({
-    queryKey: ['printJobs', 'all'],
-    queryFn: () => getPrintJobs({ limit: 1000 }),
-  })
-
-  const totalSpools = filamentData?.total ?? 0
-  const lowStockCount = lowStockData?.total ?? 0
-  const recentPrintJobs = recentPrints?.data ?? []
-
-  // Calculate cost this month from all print jobs
-  const now = new Date()
-  const currentMonth = now.getMonth()
-  const currentYear = now.getFullYear()
-  const monthlyCost =
-    allPrints?.data
-      .filter((job) => {
-        const d = new Date(job.started_at)
-        return d.getMonth() === currentMonth && d.getFullYear() === currentYear
-      })
-      .reduce((sum, job) => sum + (job.cost_usd ?? 0), 0) ?? 0
-
-  const isLoading = filamentLoading || lowStockLoading || printsLoading || costLoading
-  const error = filamentError || lowStockError || printsError || costError
-
-  if (isLoading) {
-    return (
-      <div className="min-h-screen flex items-center justify-center bg-slate-900">
-        <LoadingSpinner />
-      </div>
-    )
-  }
-
-  if (error) {
-    return (
-      <div className="min-h-screen flex items-center justify-center bg-slate-900">
-        <div className="p-6 rounded-lg bg-red-900/30 border border-red-500 text-red-200 max-w-md">
-          <h2 className="text-xl font-bold mb-2">Error</h2>
-          <p className="text-sm">{(error as Error).message || 'Failed to load dashboard data.'}</p>
-        </div>
-      </div>
-    )
-  }
-
-  return (
-    <div className="min-h-screen bg-slate-900 p-4 md:p-8">
-      <div className="max-w-6xl mx-auto">
-        <header className="mb-8">
-          <h1 className="text-3xl font-bold text-emerald-400 mb-2">Dashboard</h1>
-          <p className="text-slate-400">Overview of your Extrudex inventory and prints</p>
-        </header>
-
-        {/* Summary Cards Grid */}
-        <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-4 gap-4 mb-8">
-          <SummaryCard
-            title="Total Spools"
-            value={totalSpools}
-            icon={Package}
-            color="emerald"
-          />
-          <SummaryCard
-            title="Low Stock"
-            value={lowStockCount}
-            icon={AlertTriangle}
-            color={lowStockCount > 0 ? 'amber' : 'emerald'}
-          />
-          <SummaryCard
-            title="Recent Prints"
-            value={recentPrintJobs.length}
-            icon={Printer}
-            color="sky"
-          />
-          <SummaryCard
-            title="Cost This Month"
-            value={`$${monthlyCost.toFixed(2)}`}
-            icon={DollarSign}
-            color="violet"
-          />
-        </div>
-
-        {/* Quick Actions */}
-        <div className="flex flex-wrap gap-3 mb-8">
-          <button className="flex items-center gap-2 px-4 py-2 rounded-lg bg-emerald-600 hover:bg-emerald-500 text-white font-medium transition-colors active:scale-95 touch-manipulation">
-            <Plus size={18} />
-            Add Spool
-          </button>
-          <button className="flex items-center gap-2 px-4 py-2 rounded-lg bg-slate-700 hover:bg-slate-600 text-slate-100 font-medium transition-colors active:scale-95 touch-manipulation">
-            <List size={18} />
-            View Inventory
-          </button>
-        </div>
-
-        {/* Recent Prints Section */}
-        <section>
-          <h2 className="text-xl font-semibold text-slate-100 mb-4">Recent Prints</h2>
-          <RecentPrints jobs={recentPrintJobs} />
-        </section>
-      </div>
-    </div>
-  )
-}

frontend/src/services/api.ts

@@ -1,19 +0,0 @@
-import axios from 'axios'
-import type { ListResponse, FilamentSpool, PrintJob } from '../types'
-
-const api = axios.create({
-  baseURL: '/api',
-  headers: { 'Content-Type': 'application/json' },
-})
-
-export async function getFilaments(params?: { low_stock?: boolean; limit?: number; offset?: number }) {
-  const res = await api.get<ListResponse<FilamentSpool>>('/filaments', { params })
-  return res.data
-}
-
-export async function getPrintJobs(params?: { limit?: number; offset?: number }) {
-  const res = await api.get<ListResponse<PrintJob>>('/print-jobs', { params })
-  return res.data
-}
-
-export default api

frontend/src/types/index.ts

@@ -1,42 +0,0 @@
-export interface FilamentSpool {
-  id: number;
-  name: string;
-  material_base_id: number;
-  material_finish_id: number;
-  material_modifier_id: number;
-  color_hex: string;
-  brand: string;
-  diameter_mm: number;
-  initial_grams: number;
-  remaining_grams: number;
-  spool_weight_grams: number;
-  cost_usd: number;
-  low_stock_threshold_grams: number;
-  notes: string;
-  barcode: string;
-  created_at: string;
-  updated_at: string;
-  deleted_at: string | null;
-}
-
-export interface PrintJob {
-  id: number;
-  name: string;
-  printer_id: number;
-  filament_id: number;
-  status: string;
-  duration_seconds: number;
-  filament_used_grams: number;
-  cost_usd: number;
-  started_at: string;
-  completed_at: string | null;
-  created_at: string;
-  updated_at: string;
-}
-
-export interface ListResponse<T> {
-  data: T[];
-  total: number;
-  limit: number;
-  offset: number;
-}

frontend/tsconfig.json

@@ -15,7 +15,6 @@
     "noUnusedLocals": true,
     "noUnusedParameters": true,
     "noFallthroughCasesInSwitch": true,
-    "ignoreDeprecations": "5.0",
     "baseUrl": ".",
     "paths": {
       "@/*": ["src/*"]