fix(frontend): serve zone detail static export fallback

internal/router/root/frontend.go

@@ -101,7 +101,16 @@ func init() {
 				}
 			}
 
-			// 4. 单页应用（SPA）前端路由兜底：返回 index.html
+			// 4. Next.js static export dynamic route fallback. Runtime IDs cannot be
+			// enumerated at build time, so serve the generated route shell instead of
+			// falling back to the dashboard index.html.
+			if fallbackPath, ok := resolveNextExportDynamicFallback(subFS, cleanPath); ok {
+				if serveFileDirect(c, subFS, fallbackPath) {
+					return
+				}
+			}
+
+			// 5. 单页应用（SPA）前端路由兜底：返回 index.html
 			if serveFileDirect(c, subFS, "index.html") {
 				return
 			}

internal/router/root/frontend_static.go

@@ -0,0 +1,34 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package root
+
+import (
+	"io/fs"
+	"strings"
+)
+
+//nolint:unused // Used by frontend.go in embed_frontend builds; default lint runs without that tag.
+func resolveNextExportDynamicFallback(subFS fs.FS, cleanPath string) (string, bool) {
+	parts := strings.Split(cleanPath, "/")
+	if len(parts) < 2 || parts[0] != "websites" || parts[1] == "" {
+		return "", false
+	}
+
+	var templatePath string
+	switch {
+	case len(parts) == 2 && !strings.Contains(parts[1], "."):
+		templatePath = "websites/1.html"
+	case len(parts) == 2 && strings.HasSuffix(parts[1], ".txt"):
+		templatePath = "websites/1.txt"
+	case len(parts) == 3 && parts[2] != "" && strings.HasPrefix(parts[2], "__next.") && strings.HasSuffix(parts[2], ".txt"):
+		templatePath = "websites/1/" + parts[2]
+	default:
+		return "", false
+	}
+
+	if _, err := fs.Stat(subFS, templatePath); err != nil {
+		return "", false
+	}
+	return templatePath, true
+}

internal/router/root/frontend_static_test.go

@@ -0,0 +1,74 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package root
+
+import (
+	"testing"
+	"testing/fstest"
+)
+
+func TestResolveNextExportDynamicFallbackUsesZoneTemplate(t *testing.T) {
+	subFS := fstest.MapFS{
+		"index.html":      &fstest.MapFile{Data: []byte("dashboard")},
+		"websites/1.html": &fstest.MapFile{Data: []byte("zone detail")},
+		"websites/1.txt":  &fstest.MapFile{Data: []byte("zone flight")},
+		"websites/1/__next.!KG1haW4p.websites.$d$zoneId.__PAGE__.txt": &fstest.MapFile{Data: []byte("zone segment")},
+	}
+
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{name: "html", input: "websites/3", want: "websites/1.html"},
+		{name: "route payload", input: "websites/3.txt", want: "websites/1.txt"},
+		{
+			name:  "segment payload",
+			input: "websites/3/__next.!KG1haW4p.websites.$d$zoneId.__PAGE__.txt",
+			want:  "websites/1/__next.!KG1haW4p.websites.$d$zoneId.__PAGE__.txt",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, ok := resolveNextExportDynamicFallback(subFS, tt.input)
+			if !ok {
+				t.Fatal("expected dynamic websites route fallback")
+			}
+			if got != tt.want {
+				t.Fatalf("expected %q fallback, got %q", tt.want, got)
+			}
+		})
+	}
+}
+
+func TestResolveNextExportDynamicFallbackRejectsNestedOrAssetPath(t *testing.T) {
+	subFS := fstest.MapFS{
+		"websites/1.html": &fstest.MapFile{Data: []byte("zone detail")},
+	}
+
+	tests := []string{
+		"websites",
+		"websites/3/settings",
+		"websites/3.js",
+		"websites/3/",
+		"websites/3/missing.txt",
+	}
+	for _, tt := range tests {
+		t.Run(tt, func(t *testing.T) {
+			if got, ok := resolveNextExportDynamicFallback(subFS, tt); ok {
+				t.Fatalf("expected no fallback, got %q", got)
+			}
+		})
+	}
+}
+
+func TestResolveNextExportDynamicFallbackRequiresGeneratedTemplate(t *testing.T) {
+	subFS := fstest.MapFS{
+		"index.html": &fstest.MapFile{Data: []byte("dashboard")},
+	}
+
+	if got, ok := resolveNextExportDynamicFallback(subFS, "websites/3"); ok {
+		t.Fatalf("expected no fallback without generated template, got %q", got)
+	}
+}