diff --git a/cmd/migrate/migration/version/1786700001000_demo_menu.go b/cmd/migrate/migration/version/1786700001000_demo_menu.go
index 193fdbcb..4e00a477 100644
--- a/cmd/migrate/migration/version/1786700001000_demo_menu.go
+++ b/cmd/migrate/migration/version/1786700001000_demo_menu.go
@@ -56,7 +56,10 @@ func _1786700001000DemoMenu(db *gorm.DB, version string) error {
 		dir := models.SysMenu{
 			MenuId: demoMenuId, MenuName: "Demo", Title: "示例模块", Icon: "example",
 			Path: "/demo", Paths: "/0/9000", MenuType: "M", ParentId: 0,
-			Component: "Layout", Sort: 900, Visible: "0", IsFrame: "1",
+			// sort is `gorm:"size:4"`, which MySQL builds as a tinyint - anything
+			// over 127 is rejected outright. The seeded menus run to 100, so 110
+			// still puts this last.
+			Component: "Layout", Sort: 110, Visible: "0", IsFrame: "1",
 		}
 		if err := upsert(tx, &models.SysMenu{}, "menu_id = ?", dir.MenuId, &dir); err != nil {
 			return err
diff --git a/cmd/migrate/migration/version/column_width_test.go b/cmd/migrate/migration/version/column_width_test.go
new file mode 100644
index 00000000..99bd4623
--- /dev/null
+++ b/cmd/migrate/migration/version/column_width_test.go
@@ -0,0 +1,82 @@
+package version
+
+import (
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"math"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+)
+
+// Fields tagged gorm:"size:4" become a tinyint on MySQL, which holds -128..127.
+// sqlite ignores the width, so a value that overflows passes every local test
+// and fails on a real install - and because the migration is not transactional,
+// it fails partway, leaving later migrations unapplied.
+//
+// That is what happened: a seeded menu with Sort: 900 stopped the run at
+// 1786700001000, so the soft-delete conversion never ran, deleted_at stayed
+// NULL, and nobody could log in.
+var narrowColumns = map[string]struct{ min, max int64 }{
+	"Sort":   {math.MinInt8, math.MaxInt8},
+	"Status": {math.MinInt8, math.MaxInt8},
+}
+
+func TestSeededValuesFitTheirColumns(t *testing.T) {
+	dir, err := os.Getwd()
+	if err != nil {
+		t.Fatal(err)
+	}
+	files, err := filepath.Glob(filepath.Join(dir, "*.go"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	checked := 0
+	for _, path := range files {
+		if strings.HasSuffix(path, "_test.go") {
+			continue
+		}
+		fset := token.NewFileSet()
+		f, err := parser.ParseFile(fset, path, nil, 0)
+		if err != nil {
+			t.Fatalf("parse %s: %v", path, err)
+		}
+		ast.Inspect(f, func(n ast.Node) bool {
+			kv, ok := n.(*ast.KeyValueExpr)
+			if !ok {
+				return true
+			}
+			key, ok := kv.Key.(*ast.Ident)
+			if !ok {
+				return true
+			}
+			limits, watched := narrowColumns[key.Name]
+			if !watched {
+				return true
+			}
+			lit, ok := kv.Value.(*ast.BasicLit)
+			if !ok || lit.Kind != token.INT {
+				return true
+			}
+			v, err := strconv.ParseInt(lit.Value, 10, 64)
+			if err != nil {
+				return true
+			}
+			checked++
+			if v < limits.min || v > limits.max {
+				t.Errorf("%s:%d: %s: %d does not fit a tinyint (%d..%d);\n"+
+					"    MySQL rejects it with Error 1264 and the migration stops there",
+					filepath.Base(path), fset.Position(lit.Pos()).Line, key.Name, v, limits.min, limits.max)
+			}
+			return true
+		})
+	}
+
+	if checked == 0 {
+		t.Fatal("no seeded values were examined; the scan is broken, not the code")
+	}
+}