fix(ui): a read-ahead waits out a background refetch, and a revealed row is mounted before it is focused

NEXT_PAGE joins ANY fetch in flight: a read-ahead during an invalidation or a poll joined that refetch and appended no page, and nothing asked again until the reader moved the range (the channel page during a backfill). The read-ahead now waits while the list fetches anything (mayReadAhead, re-run on isFetching); a Load older click cancels a poll instead (nextPageOnClick). A page turn to a revealed row restarted the progressive mount at 30 rows; Channels focuses that row in the next commit, and at index 40 of a 50-row page it was not there, so focus fell to <body>. The mount now reaches through the revealed row.
2026-10-02 23:42:31 +02:00
parent ac53a3b757
commit 15ec67b029
11 changed files with 165 additions and 28 deletions
@@ -100,4 +100,28 @@ describe("DataTable — a long page mounts in steps", () => {
    expect(bodyRows()).toBe(FIRST_ROWS);
    await waitFor(() => expect(bodyRows()).toBe(150));
  });
+
+  // E31 S5: Channels turns the page to the row a priority pick moved and focuses it in the commit
+  // that follows. That row was at index 40 of a 50-row page: not mounted yet, focus fell to <body>.
+  it("mounts a revealed row in the render that turns to its page", () => {
+    host = document.createElement("div");
+    document.body.appendChild(host);
+    root = createRoot(host);
+    const rows = many(100);
+    const draw = (reveal: { key: string; seq: number } | null) =>
+      flushSync(() =>
+        root!.render(
+          <DataTable
+            rows={rows}
+            columns={plain}
+            rowKey={(x) => x.id}
+            pageSize={50}
+            reveal={reveal}
+          />,
+        ),
+      );
+    draw(null);
+    draw({ key: "r90", seq: 1 });
+    expect(host.querySelector("tbody")?.textContent).toContain("r 90");
+  });
 });