Add read-only OS package update status (apt) on the About page

New system package checks `apt list --upgradable` against the current
package index (no apt update triggered) and the reboot-required marker
file. Read-only - never installs or upgrades anything. Shown as a card
on the About page with a manual "Check now" refresh.

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

handler/routes.go

@@ -29,6 +29,7 @@ import (
 	"github.com/ngoduykhanh/wireguard-ui/firewall"
 	"github.com/ngoduykhanh/wireguard-ui/model"
 	"github.com/ngoduykhanh/wireguard-ui/store"
+	"github.com/ngoduykhanh/wireguard-ui/system"
 	"github.com/ngoduykhanh/wireguard-ui/telegram"
 	"github.com/ngoduykhanh/wireguard-ui/util"
 )
@@ -1770,3 +1771,11 @@ func AboutPage() echo.HandlerFunc {
 		})
 	}
 }
+
+// GetSystemUpdateStatus reports pending OS package updates (Debian/Ubuntu
+// via apt), read-only - nothing is installed or upgraded.
+func GetSystemUpdateStatus() echo.HandlerFunc {
+	return func(c echo.Context) error {
+		return c.JSON(http.StatusOK, system.CheckAptUpdates())
+	}
+}

main.go

@@ -236,6 +236,7 @@ func main() {
 
 	app.GET(util.BasePath+"/test-hash", handler.GetHashesChanges(db), handler.ValidSession)
 	app.GET(util.BasePath+"/about", handler.AboutPage())
+	app.GET(util.BasePath+"/system/update-status", handler.GetSystemUpdateStatus(), handler.ValidSession, handler.NeedsAdmin)
 	app.GET(util.BasePath+"/_health", handler.Health())
 	app.GET(util.BasePath+"/favicon", handler.Favicon())
 	app.POST(util.BasePath+"/new-client", handler.NewClient(db), handler.ValidSession, handler.ContentTypeJson)

system/updates.go

@@ -0,0 +1,63 @@
+// Package system checks the host OS for pending package updates. It never
+// installs or upgrades anything - read-only status only, using the
+// existing apt package index (no "apt update" is run automatically, since
+// that touches network/package state on every page load).
+package system
+
+import (
+	"bufio"
+	"context"
+	"os"
+	"os/exec"
+	"strings"
+	"time"
+)
+
+// UpdateStatus summarizes pending OS package updates on a Debian/Ubuntu host.
+type UpdateStatus struct {
+	Supported       bool     `json:"supported"` // false if apt isn't available (e.g. non-Debian host)
+	UpgradableCount int      `json:"upgradable_count"`
+	Packages        []string `json:"packages"`
+	RebootRequired  bool     `json:"reboot_required"`
+	CheckedAt       time.Time `json:"checked_at"`
+	Error           string   `json:"error,omitempty"`
+}
+
+// CheckAptUpdates lists upgradable packages from the current apt index
+// (`apt list --upgradable`) without refreshing it, and checks for the
+// standard Debian/Ubuntu reboot-required marker file.
+func CheckAptUpdates() UpdateStatus {
+	status := UpdateStatus{CheckedAt: time.Now().UTC()}
+
+	if _, err := exec.LookPath("apt"); err != nil {
+		status.Supported = false
+		return status
+	}
+	status.Supported = true
+
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+	defer cancel()
+
+	cmd := exec.CommandContext(ctx, "apt", "list", "--upgradable")
+	out, err := cmd.Output()
+	if err != nil {
+		status.Error = "cannot list upgradable packages: " + err.Error()
+		return status
+	}
+
+	scanner := bufio.NewScanner(strings.NewReader(string(out)))
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if line == "" || strings.HasPrefix(line, "Listing...") {
+			continue
+		}
+		status.Packages = append(status.Packages, line)
+	}
+	status.UpgradableCount = len(status.Packages)
+
+	if _, err := os.Stat("/var/run/reboot-required"); err == nil {
+		status.RebootRequired = true
+	}
+
+	return status
+}

templates/about.html

@@ -45,6 +45,25 @@ About
                 </div>
                 <!-- /.card -->
             </div>
+
+            <!-- right column -->
+            <div class="col-md-6">
+                <div class="card card-info">
+                    <div class="card-header">
+                        <h3 class="card-title">System Updates (OS packages)</h3>
+                    </div>
+                    <div class="card-body">
+                        <p class="text-muted">Read-only check against the current apt package index. Nothing is installed automatically.</p>
+                        <div id="_update_status_summary">Checking...</div>
+                        <div id="_update_status_reboot" style="display:none;" class="text-danger mt-2">
+                            <i class="fas fa-exclamation-triangle"></i> A reboot is required to apply already-installed updates.
+                        </div>
+                        <pre id="_update_status_packages" style="max-height: 30vh; overflow:auto; margin-top: 10px;"></pre>
+                        <button type="button" class="btn btn-outline-secondary btn-sm" id="btn_check_updates">Check now</button>
+                    </div>
+                </div>
+                <!-- /.card -->
+            </div>
         </div>
         <!-- /.row -->
     </div>
@@ -52,4 +71,47 @@ About
 {{ end }}
 
 {{ define "bottom_js"}}
+<script>
+    function loadUpdateStatus() {
+        $("#_update_status_summary").text("Checking...");
+        $("#_update_status_packages").text("");
+        $("#_update_status_reboot").hide();
+        $.ajax({
+            cache: false,
+            method: 'GET',
+            url: '{{.basePath}}/system/update-status',
+            dataType: 'json',
+            success: function (data) {
+                if (!data.supported) {
+                    $("#_update_status_summary").text("Not supported on this host (apt not found).");
+                    return;
+                }
+                if (data.error) {
+                    $("#_update_status_summary").text("Error: " + data.error);
+                    return;
+                }
+                if (data.upgradable_count === 0) {
+                    $("#_update_status_summary").html('<span class="text-success"><i class="fas fa-check-circle"></i> System is up to date.</span>');
+                } else {
+                    $("#_update_status_summary").html('<span class="text-warning"><i class="fas fa-arrow-circle-up"></i> ' +
+                        data.upgradable_count + ' package(s) can be upgraded.</span>');
+                    $("#_update_status_packages").text((data.packages || []).join("\n"));
+                }
+                if (data.reboot_required) {
+                    $("#_update_status_reboot").show();
+                }
+            },
+            error: function () {
+                $("#_update_status_summary").text("Could not check update status.");
+            }
+        });
+    }
+
+    $(document).ready(function () {
+        loadUpdateStatus();
+        $("#btn_check_updates").click(function () {
+            loadUpdateStatus();
+        });
+    });
+</script>
 {{ end }}