fix(web): stop reading anchor from undoing a pending scroll; drop duplicated settings spec

tests/web/provider-settings-page.spec.ts

@@ -1561,78 +1561,6 @@ it("restores sliders to persisted values when a direct save fails", async () =>
   );
 });
 
-it("saves every result display and footer control through presentation preferences, with failed saves preserving the canonical value", async () => {
-  const fetcher = settingsFetcher();
-  vi.stubGlobal("fetch", fetcher);
-  const configure = vi.fn(async () => true);
-  renderSettings({ onConfigureOpenPi: configure });
-  await screen.findByText(i18n.t("agentBehavior"));
-  for (const label of ["subagentResults", "bashOperations", "fileMutations"]) {
-    const select = screen.getByRole<HTMLButtonElement>("button", {
-      name: i18n.t(label),
-    });
-    fireEvent.click(select);
-    fireEvent.click(
-      screen.getByRole("menuitemradio", {
-        name: i18n.t("detailDisplay_full"),
-      }),
-    );
-    await waitFor(() =>
-      expect(select.textContent).toBe(i18n.t("detailDisplay_full")),
-    );
-    await waitFor(() => expect(select.disabled).toBe(false));
-  }
-  fireEvent.click(
-    screen.getByRole("button", { name: i18n.t("terminalFooterStyle") }),
-  );
-  fireEvent.click(
-    screen.getByRole("menuitemradio", { name: "Powerline Mono" }),
-  );
-  const footerStyle = screen.getByRole<HTMLButtonElement>("button", {
-    name: i18n.t("terminalFooterStyle"),
-  });
-  await waitFor(() => expect(footerStyle.textContent).toBe("Powerline Mono"));
-  fireEvent.click(
-    screen.getByRole("switch", { name: i18n.t("terminalFooter") }),
-  );
-  await waitFor(() =>
-    expect(
-      screen.getByRole<HTMLButtonElement>("button", {
-        name: i18n.t("terminalFooterStyle"),
-      }).disabled,
-    ).toBe(true),
-  );
-  expect(configure).not.toHaveBeenCalled();
-  expect(
-    fetcher.mock.calls.filter(([input]) =>
-      String(input).includes("/api/settings/preferences"),
-    ),
-  ).toHaveLength(5);
-  vi.stubGlobal(
-    "fetch",
-    vi.fn(
-      async () =>
-        new Response(JSON.stringify({ error: "read-only configuration" }), {
-          status: 422,
-        }),
-    ),
-  );
-  fireEvent.click(
-    screen.getByRole("button", { name: i18n.t("bashOperations") }),
-  );
-  fireEvent.click(
-    screen.getByRole("menuitemradio", {
-      name: i18n.t("detailDisplay_compact"),
-    }),
-  );
-  await screen.findByText(i18n.t("settingsPreferencesSaveFailed"));
-  expect(
-    screen.getByRole<HTMLButtonElement>("button", {
-      name: i18n.t("bashOperations"),
-    }).textContent,
-  ).toBe(i18n.t("detailDisplay_full"));
-});
-
 it("routes agent controls through canonical setup and waits for a save receipt", async () => {
   const fetcher = settingsFetcher();
   vi.stubGlobal("fetch", fetcher);
@@ -1667,6 +1595,8 @@ it("routes agent controls through canonical setup and waits for a save receipt",
       i18n.t("setupRequestLimits", { concurrency: 9, calls: 64 }),
     ),
   );
+  // The display change saved through preferences, never through setup.
+  expect(configure).toHaveBeenCalledTimes(1);
   expect(
     fetcher.mock.calls.filter(([input]) =>
       String(input).includes("/api/settings/preferences"),

tests/web/reading-anchor.spec.ts

@@ -71,3 +71,32 @@ it("drops an old anchor when its message disappears or the Session changes", ()
   act(() => result.current.restore());
   expect(root.scrollTop).toBe(0);
 });
+
+it("keeps a reader scroll that lands before its scroll event when rows re-render", () => {
+  const root = document.createElement("div");
+  const row = document.createElement("article");
+  row.dataset.historyEntry = "row";
+  root.append(row);
+  document.body.append(root);
+  let offset = 400;
+  root.getBoundingClientRect = () => new DOMRect(0, 0, 800, 600);
+  row.getBoundingClientRect = () =>
+    new DOMRect(0, offset - root.scrollTop, 800, 100);
+  row.getClientRects = () =>
+    [row.getBoundingClientRect()] as unknown as DOMRectList;
+  root.scrollTop = 300;
+  const pinned = { current: false };
+  const lastScrollTop = { current: 300 };
+  const { rerender } = renderHook(() =>
+    useReadingAnchor({ current: root }, pinned, "session", lastScrollTop),
+  );
+  // Rows above the anchor grow without reader input: keep the same row put.
+  offset = 450;
+  rerender();
+  expect(root.scrollTop).toBe(350);
+  // The reader jumps to the top; a commit runs before the scroll event.
+  root.scrollTop = 0;
+  offset = 470;
+  rerender();
+  expect(root.scrollTop).toBe(0);
+});

web/dist/build-info.json

@@ -1,5 +1,5 @@
 {
   "version": "1.2.0",
-  "id": "a283f2f3abe8a99a97b970b6ba20529713876fa5ae2e52ab8c14ee238c0907a5",
+  "id": "e1964cd252b1b17f3806b49b43e02c5e4b33b5a99f1d70301c5f2830cb45a9fd",
   "mode": "production"
 }

web/ui/src/features/transcript/use-reading-anchor.ts

@@ -15,6 +15,7 @@ export function useReadingAnchor(
     scope: string;
     element: HTMLElement;
     offset: number;
+    scrollTop: number;
   } | null>(null);
   const capture = useCallback(() => {
     const root = viewport.current;
@@ -59,6 +60,7 @@ export function useReadingAnchor(
           scope,
           element,
           offset: element.getBoundingClientRect().top - bounds.top,
+          scrollTop: root.scrollTop,
         }
       : null;
   }, [viewport, pinned, scope]);
@@ -73,6 +75,11 @@ export function useReadingAnchor(
       saved.current = null;
       return;
     }
+    // The reader (or the browser) moved this scrollport after the anchor was
+    // captured, and its scroll event has not been dispatched yet. The anchor
+    // describes a position the reader already left; restoring it would undo
+    // their scroll. The layout effect captures the new position instead.
+    if (Math.abs(root.scrollTop - anchor.scrollTop) > 0.5) return;
     const delta =
       anchor.element.getBoundingClientRect().top -
       root.getBoundingClientRect().top -