fix(nav): an item Back finds in another list is brought into view

frontend/src/lib/listNav.restoreMoved.dom.test.tsx

@@ -5,7 +5,7 @@
 // sits in the stream below. The restore matched the unnamed list by its place, missed the name there
 // and fell back to the saved index — the focus landed on the neighbour, and Enter opened the wrong
 // notification. Its own file: listNav keeps module-level state.
-import { afterEach, describe, expect, it } from "vitest";
+import { afterEach, describe, expect, it, vi } from "vitest";
 import { act, cleanup, render } from "@testing-library/react";
 import { useRef } from "react";
 
@@ -72,4 +72,21 @@ describe("Back to an item that moved to another list", () => {
     ]);
     expect(focused()).toBe("download");
   });
+
+  it("brings an item found in another list into view; one in its own list stays put", async () => {
+    // The scroll restore put the page where the item WAS: found elsewhere, it would hold the focus
+    // off screen.
+    const reveal = vi.fn();
+    Element.prototype.scrollIntoView = reveal;
+    await leaveAndReturn([["subscribed", "download"], ["older"]], "subscribed", [
+      ["download"],
+      ["subscribed", "older"],
+    ]);
+    expect(reveal).toHaveBeenCalledTimes(1);
+    cleanup();
+    reveal.mockClear();
+    await leaveAndReturn([["subscribed", "download"]], "download", [["download", "subscribed"]]);
+    expect(focused()).toBe("download");
+    expect(reveal).not.toHaveBeenCalled();
+  });
 });

frontend/src/lib/listNav.ts

@@ -492,7 +492,8 @@ function restoreTarget(
  *  list N may be another list, and <body> is the honest outcome — unless the item's name is the
  *  page's alone (`restoreTarget`). Gives up when the time is up, and at
  *  once when focus is already somewhere (the reader moved on, a dialog took it). The item is focused
- *  where the scroll restore put it, never scrolled to. (A stand-in the focus keeper placed when the view
+ *  where the scroll restore put it, never scrolled to — but one found in another list is brought into
+ *  view. (A stand-in the focus keeper placed when the view
  *  it held was swapped away counts as untouched, like <body>.) Returns a cancel. */
 export function restoreNavPosition(pos: NavPosition): () => void {
   const deadline = Date.now() + RESTORE_MS;
@@ -512,7 +513,9 @@ export function restoreNavPosition(pos: NavPosition): () => void {
     // nearest one: names repeat (a log console's `http.request GET /api/feed 200` lines, two
     // downloads of one video), and the first of them is rarely the one left behind.
     const el = restoreTarget(all, list, pos);
-    if (el) return focusItem(el, false);
+    // Where the scroll restore put it — unless it is found in another list than the one it was left
+    // in: the restored scroll is the old place's, and the item would hold the focus off screen.
+    if (el) return focusItem(el, !list?.el.contains(el));
     if (Date.now() < deadline) timer = setTimeout(attempt, RESTORE_POLL_MS);
   };
   // Not inside the popstate dispatch that landed: a sub-view's own listener (`useHistorySubview`)