refactor(ui): consolidates timeInfo memo and adds boundary test

Author: wgordon17

src/app/components/dashboard/ItemRow.tsx

@@ -33,12 +33,14 @@ export default function ItemRow(props: ItemRowProps) {
     const updated = shortRelativeTime(props.updatedAt);
     const createdLabel = `Created ${relativeTime(props.createdAt)}`;
     const updatedLabel = `Updated ${relativeTime(props.updatedAt)}`;
-    return { created, updated, createdLabel, updatedLabel };
+    const createdTitle = `Created: ${new Date(props.createdAt).toLocaleString()}`;
+    const updatedTitle = `Updated: ${new Date(props.updatedAt).toLocaleString()}`;
+    const diffMs = Date.parse(props.updatedAt) - Date.parse(props.createdAt);
+    return { created, updated, createdLabel, updatedLabel, createdTitle, updatedTitle, diffMs };
   });
   const hasUpdate = createMemo(() => {
-    const diff = new Date(props.updatedAt).getTime() - new Date(props.createdAt).getTime();
-    if (diff <= 60_000) return false;
-    const { created, updated } = timeInfo();
+    const { diffMs, created, updated } = timeInfo();
+    if (diffMs <= 60_000) return false;
     return created !== "" && updated !== "" && created !== updated;
   });
 
@@ -121,15 +123,15 @@ export default function ItemRow(props: ItemRowProps) {
         </Show>
         <span class="inline-flex items-center gap-1 whitespace-nowrap">
           <span
-            title={`Created: ${new Date(props.createdAt).toLocaleString()}`}
+            title={timeInfo().createdTitle}
             aria-label={timeInfo().createdLabel}
           >
             {timeInfo().created}
           </span>
           <Show when={hasUpdate()}>
             <span aria-hidden="true">{"\u00B7"}</span>
             <span
-              title={`Updated: ${new Date(props.updatedAt).toLocaleString()}`}
+              title={timeInfo().updatedTitle}
               aria-label={timeInfo().updatedLabel}
             >
               {timeInfo().updated}

tests/components/ItemRow.test.tsx

@@ -49,7 +49,7 @@ describe("ItemRow", () => {
     // Should show compact format like "2h"
     const timeEl = screen.getByTitle(`Created: ${new Date(defaultProps.createdAt).toLocaleString()}`);
     expect(timeEl).toBeDefined();
-    expect(timeEl.textContent).toMatch(/^\d+h$/);
+    expect(timeEl.textContent).toBe("2h");
   });
 
   it("renders children slot when provided", () => {
@@ -198,6 +198,18 @@ describe("ItemRow", () => {
     expect(screen.queryByTitle(`Updated: ${new Date("2026-03-30T11:59:30Z").toLocaleString()}`)).toBeNull();
   });
 
+  it("shows single date when updatedAt is exactly 60s after createdAt", () => {
+    const { container } = render(() => (
+      <ItemRow
+        {...defaultProps}
+        createdAt="2026-03-30T11:59:00Z"
+        updatedAt="2026-03-30T12:00:00Z"
+      />
+    ));
+    // diff === 60_000ms, condition is <=, so still suppressed
+    expect(container.querySelector('span[aria-hidden="true"]')).toBeNull();
+  });
+
   it("shows single date when both compact values are identical (display-equality guard)", () => {
     // Both 3 days ago — createdAt 3d+2min ago, updatedAt exactly 3d ago, both display "3d"
     const createdAt = new Date(MOCK_NOW - (3 * 24 * 60 * 60 + 2 * 60) * 1000).toISOString();