fix(web): stabilize homepage live status

apps/web/src/components/dashboard/flywheel-kpi-card.tsx

@@ -5,7 +5,7 @@
  *
  * 飛輪健康度 KPI 面板。
  * C2: 初始載入 GET /api/v1/stats/summary（HTTP fallback）
- * C3: WebSocket /api/v1/stats/flywheel/ws 即時推送（10s 更新）
+ * C3: WebSocket /api/v1/stats/flywheel/ws 即時推送（旗標開啟時）
  *
  * 2026-04-12 ogt (ADR-073-C C2 + C3)
  */
@@ -16,6 +16,7 @@ import { FlywheelDiagram, type FlowItem } from './flywheel-diagram'
 const API_BASE = process.env.NEXT_PUBLIC_API_URL ?? ''
 // ws(s):// mirror of NEXT_PUBLIC_API_URL
 const WS_BASE = API_BASE.replace(/^https/, 'wss').replace(/^http/, 'ws')
+const ENABLE_FLYWHEEL_WS = process.env.NEXT_PUBLIC_ENABLE_FLYWHEEL_WS === 'true'
 
 interface FlywheelSummary {
   playbook_count: number
@@ -37,23 +38,29 @@ export function FlywheelKPICard() {
   const [error, setError] = useState(false)
   const wsRef = useRef<WebSocket | null>(null)
 
-  // C2: HTTP fallback (initial load + 30s poll when WS unavailable)
+  // C2: HTTP fallback (initial load + 30s poll)
   useEffect(() => {
     let cancelled = false
     let pollId: ReturnType<typeof setInterval> | null = null
 
-    const load = () => {
+    const loadSummary = () => {
       fetch(`${API_BASE}/api/v1/stats/summary`)
         .then(r => r.ok ? r.json() : Promise.reject(r.status))
         .then(d => { if (!cancelled) { setData(d); setError(false) } })
         .catch(() => { if (!cancelled) setError(true) })
     }
 
-    // 載入飛輪節點狀態（C4 用）
-    fetch(`${API_BASE}/api/v1/stats/flywheel`)
-      .then(r => r.ok ? r.json() : null)
-      .then(d => { if (!cancelled && d) setFlowData(d) })
-      .catch(() => {})
+    const loadFlow = () => {
+      fetch(`${API_BASE}/api/v1/stats/flywheel`)
+        .then(r => r.ok ? r.json() : null)
+        .then(d => { if (!cancelled && d) setFlowData(d) })
+        .catch(() => {})
+    }
+
+    const load = () => {
+      loadSummary()
+      loadFlow()
+    }
 
     load()
 
@@ -63,7 +70,7 @@ export function FlywheelKPICard() {
     let wsRetryTimer: ReturnType<typeof setTimeout> | null = null
 
     const connectWS = () => {
-      if (!WS_BASE || cancelled) return
+      if (!ENABLE_FLYWHEEL_WS || !WS_BASE || cancelled) return
       const ws = new WebSocket(`${WS_BASE}/api/v1/stats/flywheel/ws`)
       wsRef.current = ws
 
@@ -94,7 +101,7 @@ export function FlywheelKPICard() {
     }
 
     connectWS()
-    // Also start polling as backup until WS opens
+    // Production default: HTTP polling stays authoritative unless WS is enabled explicitly.
     pollId = setInterval(load, 30_000)
 
     return () => {