serial numbers

Frontend/erp-system/hooks/use-tracking-settings.ts

@@ -0,0 +1,36 @@
+"use client"
+
+import { useEffect, useState } from "react"
+
+import { trackingApi } from "@/lib/api/tracking"
+import { TrackingSettings } from "@/types/tracking"
+
+// One request per page load, shared by every component that asks; the Product Configuration
+// page calls invalidateTrackingSettings() after a toggle so the next read is fresh.
+let cached: Promise<TrackingSettings> | null = null
+
+function load(): Promise<TrackingSettings> {
+  // A failed read falls back to the server's own default (serial numbers on).
+  cached ??= trackingApi.settings().catch(() => ({ serialNumbersEnabled: true }))
+  return cached
+}
+
+export function invalidateTrackingSettings() {
+  cached = null
+}
+
+/**
+ * Product Configuration tracking switches (docs/ITEM_TRACKING_PLAN.md §8). `serialNumbersEnabled`
+ * is null until loaded — callers treat that like "on", the server default.
+ */
+export function useTrackingSettings(): { serialNumbersEnabled: boolean | null } {
+  const [settings, setSettings] = useState<TrackingSettings | null>(null)
+
+  useEffect(() => {
+    let cancelled = false
+    load().then((s) => { if (!cancelled) setSettings(s) })
+    return () => { cancelled = true }
+  }, [])
+
+  return { serialNumbersEnabled: settings?.serialNumbersEnabled ?? null }
+}