fix(feed): an optimistic write outlives only the server answers older than it

A reset wrote a position mask over the cached list, so a replay's saved position stayed hidden: a reopen resumed at 0 and its first checkpoint wrote over the progress. The reset now writes 0 into the cache, where the player's closing patch writes the next one. Overrides carry their write order, and a landing refetch drops only those written before it set out. The player session ends after the modal unmounts, so a clip auto-marked watched as it closes still refetches the list.
2026-10-09 22:01:27 +02:00
parent 942154cf49
commit 568bf93510
4 changed files with 327 additions and 71 deletions
@@ -0,0 +1,177 @@
+// @vitest-environment jsdom
+//
+// The feed's optimistic layer: a card shows what was just written to it until the server's own answer
+// lands. Which answers count is the rule pinned here: a refetch that LANDS (for what was written
+// before it set out), a filter change; never an append of the next page. A mark made while a refetch
+// was in flight is newer than its answer, and dropping it put a card marked watched back into an
+// Unwatched view. The grid is a stub that shows what Feed hands it.
+import { describe, it, expect, vi, beforeAll, afterEach } from "vitest";
+import { render, screen, fireEvent, waitFor, cleanup, act } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+
+vi.mock("react-i18next", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("react-i18next")>()),
+  useTranslation: () => ({ t: (key: string) => key, i18n: { language: "en" } }),
+}));
+vi.mock("./wizardContext", () => ({ useWizard: () => ({ openWizard: vi.fn() }) }));
+vi.mock("./VirtualFeed", () => ({
+  default: ({
+    items,
+    onState,
+    fetchNextPage,
+  }: {
+    items: { id: string; status: string }[];
+    onState: (id: string, status: string) => void;
+    fetchNextPage: (o: object) => unknown;
+  }) => (
+    <ol aria-label="results">
+      {items.map((v) => (
+        <li key={v.id}>
+          <span>{`${v.id}:${v.status}`}</span>
+          <button onClick={() => onState(v.id, "watched")}>watch {v.id}</button>
+        </li>
+      ))}
+      <button onClick={() => void fetchNextPage({})}>more</button>
+    </ol>
+  ),
+}));
+
+import Feed from "./Feed";
+import { api, DEFAULT_TAG_MODES, type FeedFilters, type Video } from "../lib/api";
+import { qk } from "../lib/queryKeys";
+
+beforeAll(() => {
+  class Stub {
+    observe() {}
+    unobserve() {}
+    disconnect() {}
+    takeRecords() {
+      return [];
+    }
+  }
+  globalThis.ResizeObserver ??= Stub as unknown as typeof ResizeObserver;
+  globalThis.IntersectionObserver ??= Stub as unknown as typeof IntersectionObserver;
+});
+afterEach(() => {
+  cleanup();
+  vi.restoreAllMocks();
+});
+
+const FILTERS: FeedFilters = {
+  tags: [],
+  tagModes: DEFAULT_TAG_MODES,
+  channelIds: [],
+  q: "",
+  sort: "newest",
+  scope: "my",
+  includeNormal: true,
+  includeShorts: false,
+  includeLive: false,
+  show: "all",
+};
+
+const video = (id: string) =>
+  ({
+    id,
+    title: id,
+    channel_id: "UCx",
+    channel_title: "Channel",
+    status: "new",
+    position_seconds: 0,
+    duration_seconds: 600,
+    published_at: "2026-01-01T00:00:00Z",
+    watch_url: `https://www.youtube.com/watch?v=${id}`,
+  }) as unknown as Video;
+
+// The server never takes the mark in these tests: whatever a list shows as "watched" is the override.
+const page = (ids: string[], next: string | null = null) =>
+  ({ items: ids.map(video), next_cursor: next }) as never;
+
+function mount(feed: ReturnType<typeof vi.fn>) {
+  vi.spyOn(api, "feed").mockImplementation(feed as never);
+  vi.spyOn(api, "feedSummary").mockResolvedValue({ count: 1, facets: {} } as never);
+  vi.spyOn(api, "setState").mockResolvedValue({ ok: true } as never);
+  const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  qc.setQueryData(qk.me(), { id: 1, can_write: true, prefs: {} });
+  const ui = (filters: FeedFilters) => (
+    <QueryClientProvider client={qc}>
+      <Feed
+        filters={filters}
+        setFilters={() => {}}
+        view="cards"
+        setView={() => {}}
+        canRead
+        ytSearch={null}
+        onYtSearch={() => {}}
+        onExitYtSearch={() => {}}
+      />
+    </QueryClientProvider>
+  );
+  const r = render(ui(FILTERS));
+  return { qc, rerender: (f: FeedFilters) => r.rerender(ui(f)) };
+}
+
+const settle = () => act(() => new Promise((r) => setTimeout(r, 20)));
+
+describe("Feed — optimistic overrides", () => {
+  it("give way to a refetch that lands after them", async () => {
+    let answer: (v: unknown) => void = () => {};
+    const feed = vi
+      .fn()
+      .mockResolvedValueOnce(page(["v1"]))
+      .mockImplementationOnce(() => new Promise((r) => (answer = r)));
+    const { qc } = mount(feed);
+    fireEvent.click(await screen.findByText("watch v1"));
+    await screen.findByText("v1:watched");
+    act(() => void qc.invalidateQueries({ queryKey: qk.feed() }));
+    await waitFor(() => expect(feed).toHaveBeenCalledTimes(2));
+    await settle();
+    await act(async () => answer(page(["v1"])));
+    await waitFor(() => expect(screen.getByText("v1:new")).toBeTruthy());
+  });
+
+  it("keep a mark made while the refetch was in flight", async () => {
+    let answer: (v: unknown) => void = () => {};
+    const feed = vi
+      .fn()
+      .mockResolvedValueOnce(page(["v1"]))
+      .mockImplementationOnce(() => new Promise((r) => (answer = r)));
+    const { qc } = mount(feed);
+    await screen.findByText("v1:new");
+    act(() => void qc.invalidateQueries({ queryKey: qk.feed() }));
+    await waitFor(() => expect(feed).toHaveBeenCalledTimes(2));
+    await settle();
+    fireEvent.click(screen.getByText("watch v1"));
+    await screen.findByText("v1:watched");
+    // The answer the server gave before it heard of the mark.
+    await act(async () => answer(page(["v1"])));
+    await settle();
+    expect(screen.getByText("v1:watched")).toBeTruthy();
+  });
+
+  it("survive an append of the next page", async () => {
+    let answer: (v: unknown) => void = () => {};
+    const feed = vi
+      .fn()
+      .mockResolvedValueOnce(page(["v1"], "c1"))
+      .mockImplementationOnce(() => new Promise((r) => (answer = r)));
+    mount(feed);
+    fireEvent.click(await screen.findByText("watch v1"));
+    await screen.findByText("v1:watched");
+    fireEvent.click(screen.getByText("more"));
+    await waitFor(() => expect(feed).toHaveBeenCalledTimes(2));
+    await settle();
+    await act(async () => answer(page(["v2"])));
+    await screen.findByText("v2:new");
+    await settle();
+    expect(screen.getByText("v1:watched")).toBeTruthy();
+  });
+
+  it("are dropped by a change of the filters", async () => {
+    const { rerender } = mount(vi.fn().mockResolvedValue(page(["v1"])));
+    fireEvent.click(await screen.findByText("watch v1"));
+    await screen.findByText("v1:watched");
+    rerender({ ...FILTERS });
+    await waitFor(() => expect(screen.getByText("v1:new")).toBeTruthy());
+  });
+});