skip refreshes while offline, catch up when the connection returns

brew outdated never touches the network: offline, a refresh silently
succeeded on stale local tap data and reported "all up to date". An
NWPathMonitor now gates refreshAll — offline shows a dedicated status
instead, and every offline→online transition triggers a refresh, which
covers the launch refresh, scheduled refreshes skipped during an
outage, and clearing the offline status when the connection returns.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

BrewBar/BrewBarApp.swift

@@ -1,4 +1,5 @@
 import Cocoa
+import Network
 import UserNotifications
 
 @main
@@ -43,6 +44,11 @@ class AppDelegate: NSObject, NSApplicationDelegate {
     var cachedOutdated: OutdatedPackages = .none
     var lastNotifiedOutdated: Set<String> = []
 
+    let pathMonitor = NWPathMonitor()
+    /// false until the monitor's first update, so the launch refresh waits
+    /// until the network state is actually known. Main-queue only.
+    var isOnline = false
+
     // MARK: - Menu
 
     func applicationDidFinishLaunching(_: Notification) {
@@ -91,7 +97,16 @@ class AppDelegate: NSObject, NSApplicationDelegate {
 
         statusItem.menu = menu
 
-        refreshAll()
+        // no refreshAll() here: the monitor fires once immediately after
+        // start(), and the first online update triggers the launch refresh
+        pathMonitor.pathUpdateHandler = { path in
+            // updates arrive on the monitor's queue; hop to main for AppKit
+            DispatchQueue.main.async {
+                self.networkPathChanged(online: path.status == .satisfied)
+            }
+        }
+        pathMonitor.start(queue: DispatchQueue(label: "fr.socheleau.BrewBar.network"))
+
         refreshBrewVersion()
 
         refreshTimer = Timer.scheduledTimer(withTimeInterval: refreshInterval, repeats: true) { _ in
@@ -431,7 +446,30 @@ class AppDelegate: NSObject, NSApplicationDelegate {
         }
     }
 
+    /// Refreshing offline would silently succeed on stale data: brew update
+    /// fails but its exit code was never checked, and brew outdated compares
+    /// against the local taps without touching the network — so the app
+    /// claimed "all up to date" no matter what. Every offline→online
+    /// transition refreshes, which also covers the refreshes skipped below.
+    func networkPathChanged(online: Bool) {
+        let wasOnline = isOnline
+        isOnline = online
+
+        guard online else {
+            statusMenuItem.title = "📡 Offline"
+            return
+        }
+        if !wasOnline {
+            refreshAll()
+        }
+    }
+
     func refreshAll() {
+        guard isOnline else {
+            statusMenuItem.title = "📡 Offline"
+            return
+        }
+
         statusMenuItem.title = "Updating..."
 
         runBrew("update") { _ in