test(work-orders): cover missing checklist completedBy provenance

Regression: null/empty/whitespace completedBy shows Unknown, never the viewer.

src/test/app/(protected)/workorders/dispatch-checklist-section.test.tsx

@@ -0,0 +1,58 @@
+import { render, screen } from "@testing-library/react";
+import { describe, expect, it, vi } from "vitest";
+import { DispatchChecklistSection } from "@/app/(protected)/workorders/_components/dispatch/dispatch-detail/dispatch-checklist-section";
+import type { DispatchChecklistItem } from "@/domain/work-orders/types/work-order";
+
+const VIEWER_NAME = "Alice Viewer";
+
+function renderChecklist(items: DispatchChecklistItem[]) {
+  return render(
+    <DispatchChecklistSection
+      items={items}
+      isLocked={false}
+      isUpdating={false}
+      newItem=""
+      onNewItemChange={vi.fn()}
+      onToggleItem={vi.fn()}
+      onAddItem={vi.fn()}
+    />,
+  );
+}
+
+describe("DispatchChecklistSection completedBy provenance", () => {
+  it.each([
+    { label: "null", completedBy: null },
+    { label: "empty", completedBy: "" },
+    { label: "whitespace", completedBy: "   " },
+  ])("shows Unknown (never the viewer) when completedBy is $label", ({ completedBy }) => {
+    renderChecklist([
+      {
+        id: 1,
+        itemText: "Verify site access",
+        isCompleted: true,
+        completedBy,
+        completedAt: "2026-07-01T15:30:00Z",
+      },
+    ]);
+
+    expect(screen.getByText(/Unknown/)).toBeInTheDocument();
+    expect(screen.queryByText(VIEWER_NAME)).not.toBeInTheDocument();
+    expect(screen.queryByText(/Alice/)).not.toBeInTheDocument();
+  });
+
+  it("renders the recorded completedBy when present", () => {
+    renderChecklist([
+      {
+        id: 2,
+        itemText: "Collect photos",
+        isCompleted: true,
+        completedBy: "Jordan Tech",
+        completedAt: "2026-07-01T15:30:00Z",
+      },
+    ]);
+
+    expect(screen.getByText(/Jordan Tech/)).toBeInTheDocument();
+    expect(screen.queryByText(/Unknown/)).not.toBeInTheDocument();
+    expect(screen.queryByText(VIEWER_NAME)).not.toBeInTheDocument();
+  });
+});