fix(plex,channels): deep-review fixes — durable watch-sync + no shared-link clobber

Deep-review of the quickfix batch surfaced two data/preference-loss bugs plus
smaller items; all fixed with tests.

- watch_sync _pull_apply: don't let the Plex-authoritative pull overwrite a DIRTY
  local row (a change whose immediate push failed) — that stranded the value
  forever since _repush_dirty only retries dirty rows. Leave it dirty for re-push.
- PlexProvider / ChannelsProvider: a partial shared link opened in a fresh tab
  persisted mount-time DEFAULTS over the account's stored scope/sort/filters
  (base read before the account was pinned). Persist/keep only URL-present dims;
  re-hydrate the omitted ones from storage.
- playback resume write-back: guard against out-of-order delivery (a superseded
  older push now drops) and evict the throttle map so it can't grow unbounded.
- PlexPlayer: announce mid-playback buffering to assistive tech (role=status +
  sr-only label); new plex.player.buffering (HU+EN).
- columnSort: hoist the shared key:dir sort codec used by both URL-state modules.
- Tests: dirty-guard + flag-settle + per-key throttle scoping + superseded-push
  (backend); hold-repeat/suppress-click/unmount + partial-link no-clobber +
  refetch-doesn't-clobber-undo (frontend). Backend pytest 475, FE vitest 519.

frontend/src/components/ChannelsProvider.dom.test.tsx

@@ -17,6 +17,7 @@ vi.mock("./NavigationProvider", () => ({
 }));
 
 import { ChannelsProvider, useChannels, useChannelsActions } from "./ChannelsProvider";
+import { setActiveAccount } from "../lib/api/core";
 
 const wrapper = ({ children }: { children: ReactNode }) => (
   <ChannelsProvider>{children}</ChannelsProvider>
@@ -99,4 +100,33 @@ describe("ChannelsProvider — S8 shareable URL", () => {
     act(() => result.current.setView("subscribed"));
     expect(new URLSearchParams(window.location.search).has("ctab")).toBe(false);
   });
+
+  it("a PARTIAL shared link (fresh tab) does not clobber the account's stored sort/filters", () => {
+    // Regression: on a fresh tab the account pins AFTER mount, so the seed's base for the OMITTED
+    // dimensions was read as defaults. Persisting the whole seed used to overwrite the account's real
+    // stored sort + filter map. The fix persists ONLY the URL-present dimensions.
+    localStorage.setItem(
+      "siftlode.channelSort.1",
+      JSON.stringify({ key: "subscribers", dir: "desc" }),
+    );
+    localStorage.setItem("siftlode.channelsFilterMap.1", JSON.stringify({ sync: "needsFull" }));
+    sessionStorage.removeItem("siftlode.activeAccount"); // account not pinned yet at mount
+    window.history.replaceState({ sfPage: "channels" }, "", "/?ctab=hidden"); // only the tab in the URL
+
+    const { result } = render();
+    act(() => setActiveAccount(1)); // App pins the account after /api/me
+
+    // The present dim (tab) is adopted from the link...
+    expect(result.current.view).toBe("hidden");
+    // ...but the omitted sort + filters keep the account's real stored values, in state AND storage.
+    expect(result.current.sort).toEqual({ key: "subscribers", dir: "desc" });
+    expect(result.current.filters).toEqual({ sync: "needsFull" });
+    expect(JSON.parse(localStorage.getItem("siftlode.channelSort.1")!)).toEqual({
+      key: "subscribers",
+      dir: "desc",
+    });
+    expect(JSON.parse(localStorage.getItem("siftlode.channelsFilterMap.1")!)).toEqual({
+      sync: "needsFull",
+    });
+  });
 });

frontend/src/components/ChannelsProvider.tsx

@@ -73,14 +73,25 @@ function readStoredFilters(): FilterMap {
 // present, the URL wins over this account's stored view — read once at mount and applied over the slice
 // hooks (see the provider). The keys are channels-unique, so their mere presence identifies a shared
 // manager view; no ?page check is needed (the mirror below is page-gated so it never pollutes others).
-function readChannelsUrlSeed(): ChannelsUrlState | null {
+// The seed = the URL-merged state PLUS which dimensions the URL actually carried. `present` matters
+// because the base below is read at MOUNT, before the account is pinned (getAccountRaw returns null),
+// so an OMITTED dimension's base is a default, not this account's stored value. The provider seeds and
+// persists only the PRESENT dimensions and lets the absent ones re-hydrate from storage normally —
+// otherwise a partial shared link silently resets the omitted stored sort / filter map.
+type ChannelsSeedPresent = { view: boolean; sort: boolean; filters: boolean };
+type ChannelsUrlSeed = { state: ChannelsUrlState; present: ChannelsSeedPresent };
+function readChannelsUrlSeed(): ChannelsUrlSeed | null {
   const params = new URLSearchParams(window.location.search);
   if (!hasChannelsParams(params)) return null;
-  return channelsParamsToState(params, {
+  const state = channelsParamsToState(params, {
     view: clampView(getAccountRaw(LS.channelsView)),
     sort: hydrateSort(getAccountRaw(LS.channelSort), [], null),
     filters: readStoredFilters(),
   });
+  return {
+    state,
+    present: { view: params.has("ctab"), sort: params.has("csort"), filters: params.has("cf") },
+  };
 }
 
 type ChannelsState = {
@@ -185,9 +196,13 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
   useLayoutEffect(() => {
     if (!urlSeed || seededRef.current) return;
     seededRef.current = true;
-    if (urlSeed.view !== view) setViewRaw(urlSeed.view);
-    setFilters(urlSeed.filters);
-    setSort(urlSeed.sort);
+    // Only apply the dimensions the URL actually carried. An omitted dimension must NOT go through its
+    // setter (which would markDirty and block the account-pin re-hydrate from loading the stored value)
+    // — leave it to hydrate from storage normally. Fixes a partial link wiping the stored sort/filters.
+    const { state, present } = urlSeed;
+    if (present.view && state.view !== view) setViewRaw(state.view);
+    if (present.filters) setFilters(state.filters);
+    if (present.sort) setSort(state.sort);
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);
 
@@ -198,9 +213,12 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
   useEffect(() => {
     if (!urlSeed || accountId == null || persistedRef.current) return;
     persistedRef.current = true;
-    setAccountRaw(LS.channelsView, urlSeed.view);
-    setAccountRaw(LS.channelsFilterMap, JSON.stringify(urlSeed.filters));
-    setAccountRaw(LS.channelSort, JSON.stringify(urlSeed.sort));
+    // Persist ONLY the URL-present dimensions — the omitted ones were seeded from mount-time defaults
+    // (no account yet), so writing them here would overwrite the account's real stored sort/filter map.
+    const { state, present } = urlSeed;
+    if (present.view) setAccountRaw(LS.channelsView, state.view);
+    if (present.filters) setAccountRaw(LS.channelsFilterMap, JSON.stringify(state.filters));
+    if (present.sort) setAccountRaw(LS.channelSort, JSON.stringify(state.sort));
   }, [urlSeed, accountId]);
 
   // Latest-value ref so the STABLE setView can compare against the current tab without depending on

frontend/src/components/PersonalViewsModal.dom.test.tsx

@@ -80,11 +80,12 @@ function mount() {
   const qc = new QueryClient({ defaultOptions: { queries: { retry: false } } });
   qc.setQueryData(qk.tags(), [{ id: 1, name: "Docu" }]);
   vi.spyOn(api, "tags").mockResolvedValue([{ id: 1, name: "Docu" }] as never);
-  return render(
+  const utils = render(
     <QueryClientProvider client={qc}>
       <PersonalViewsModal />
     </QueryClientProvider>,
   );
+  return { ...utils, qc };
 }
 
 beforeEach(() => {
@@ -92,6 +93,8 @@ beforeEach(() => {
   h.saveCurrent.mockClear();
   h.rename.mockClear();
   h.activeViewId = null;
+  // Fresh baseline each test — one test mutates CTX.views to simulate a refetch.
+  CTX.views = [{ id: 5, name: "Docs", filters: VIEW_FILTERS, position: 0, is_default: false }];
 });
 afterEach(() => {
   cleanup();
@@ -119,6 +122,39 @@ describe("PersonalViewsModal — S7 editable detail pane", () => {
     expect(h.updateFilters.mock.calls[1]![1]).toMatchObject({ tags: [1] });
   });
 
+  it("a same-view refetch (new-identity filters) does not wipe the undo history", async () => {
+    // Guards the [selectedId]-only re-seed effect (its exhaustive-deps disable): after a chip prune the
+    // real provider refetches and hands back the SAME view id with a fresh-identity filters object. The
+    // draft must NOT re-seed on that (it would destroy the undo history and the Undo control). A deps
+    // regression that added selected.filters would make this fail.
+    const { rerender, qc } = mount();
+    fireEvent.click(await screen.findByLabelText("feed.chips.remove"));
+    await waitFor(() => expect(h.updateFilters).toHaveBeenCalledTimes(1));
+    expect(await screen.findByLabelText("common.undo")).toBeTruthy();
+
+    // Simulate the post-write refetch: same id 5, new object identity, carrying the pruned value.
+    CTX.views = [
+      {
+        id: 5,
+        name: "Docs",
+        filters: { ...VIEW_FILTERS, tags: [] },
+        position: 0,
+        is_default: false,
+      },
+    ];
+    rerender(
+      <QueryClientProvider client={qc}>
+        <PersonalViewsModal />
+      </QueryClientProvider>,
+    );
+
+    // Undo history survived the refetch — the control is still there and still re-persists on click.
+    const undo = await screen.findByLabelText("common.undo");
+    fireEvent.click(undo);
+    await waitFor(() => expect(h.updateFilters).toHaveBeenCalledTimes(2));
+    expect(h.updateFilters.mock.calls[1]![1]).toMatchObject({ tags: [1] });
+  });
+
   it("Save-current stores the live filters into the view when it isn't already the active one", async () => {
     mount();
     fireEvent.click(await screen.findByText("views.saveCurrent"));

frontend/src/components/PlexPlayer.tsx

@@ -760,13 +760,24 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
           mid-playback stall or in-flight seek (see the state); `loadError` surfaces a fatal failure so
           it can't hide behind a running video. Spinner on load/stall, error text otherwise. */}
       {(!ready || buffering || loadError) && (
-        <div className="absolute inset-0 grid place-items-center px-6 text-center text-sm pointer-events-none">
+        <div
+          role="status"
+          aria-live="polite"
+          className="absolute inset-0 grid place-items-center px-6 text-center text-sm pointer-events-none"
+        >
           {loadError ? (
             <span className="max-w-md text-danger">{loadError}</span>
           ) : (
             <div className="flex flex-col items-center gap-3 text-white/80">
               <Loader2 className="w-10 h-10 animate-spin" aria-hidden />
-              {!ready && <span>{t("plex.player.loading")}</span>}
+              {/* Announce the stall to assistive tech. Initial load shows visible text; a mid-playback
+                  rebuffer/seek (ready, no error) has no visible label, so give it an sr-only one via the
+                  aria-live region so a screen reader distinguishes "buffering" from a frozen frame. */}
+              {!ready ? (
+                <span>{t("plex.player.loading")}</span>
+              ) : buffering ? (
+                <span className="sr-only">{t("plex.player.buffering")}</span>
+              ) : null}
             </div>
           )}
         </div>

frontend/src/components/PlexProvider.tsx

@@ -131,15 +131,31 @@ function readPlexFilters(): PlexFilters {
     return EMPTY_PLEX_FILTERS;
   }
 }
-function readPlexUrlSeed(): PlexUrlState | null {
+// A shared-link seed = the URL-merged state PLUS which dimensions the URL actually carried. `present`
+// matters because the base below is read at MOUNT, before the account is pinned (getAccountRaw returns
+// null then), so the base for an OMITTED dimension is a hard default, NOT this account's stored value.
+// The provider must therefore persist/keep only the PRESENT dimensions on account-pin and re-read the
+// account's real stored value for the absent ones — otherwise a partial link silently resets them.
+type PlexSeedPresent = { scope: boolean; sort: boolean; show: boolean; filters: boolean };
+type PlexUrlSeed = { state: PlexUrlState; present: PlexSeedPresent };
+function readPlexUrlSeed(): PlexUrlSeed | null {
   const params = new URLSearchParams(window.location.search);
   if (!hasPlexParams(params)) return null;
-  return plexParamsToState(params, {
+  const state = plexParamsToState(params, {
     scope: readPlexScope(),
     sort: readPlexSort(),
     show: readPlexShow(),
     filters: readPlexFilters(),
   });
+  return {
+    state,
+    present: {
+      scope: params.has("pscope"),
+      sort: params.has("psort"),
+      show: params.has("pshow"),
+      filters: params.has("pf"),
+    },
+  };
 }
 
 export function PlexProvider({ children }: { children: ReactNode }) {
@@ -148,12 +164,12 @@ export function PlexProvider({ children }: { children: ReactNode }) {
   const [urlSeed] = useState(readPlexUrlSeed);
   // The former per-library picker is now a cross-library SCOPE: movie | show | both (unified library).
   // (Reuses the old LS.plexLibrary key; an old stored library-id value falls back to "both".)
-  const [scope, setScopeState] = useState<string>(() => urlSeed?.scope ?? readPlexScope());
-  const [show, setShowState] = useState<string>(() => urlSeed?.show ?? readPlexShow());
-  const [sort, setSortState] = useState<SortState>(() => urlSeed?.sort ?? readPlexSort());
+  const [scope, setScopeState] = useState<string>(() => urlSeed?.state.scope ?? readPlexScope());
+  const [show, setShowState] = useState<string>(() => urlSeed?.state.show ?? readPlexShow());
+  const [sort, setSortState] = useState<SortState>(() => urlSeed?.state.sort ?? readPlexSort());
   // The expanded Plex filters live as one JSON blob (the string-only account store serializes it).
   const [filtersRaw, setFiltersRaw] = useState<string>(() =>
-    urlSeed ? JSON.stringify(urlSeed.filters) : readPlexFiltersRaw(),
+    urlSeed ? JSON.stringify(urlSeed.state.filters) : readPlexFiltersRaw(),
   );
   const filters = useMemo<PlexFilters>(() => {
     try {
@@ -180,10 +196,20 @@ export function PlexProvider({ children }: { children: ReactNode }) {
   // non-shared slices (q/field) from storage. Mirrors FeedFiltersProvider's initialHadUrlFilters branch.
   const markDirty = useAccountRehydrate(() => {
     if (urlSeed) {
-      setAccountRaw(LS.plexLibrary, urlSeed.scope);
-      setAccountRaw(LS.plexShow, urlSeed.show);
-      setAccountRaw(LS.plexSort, JSON.stringify(urlSeed.sort));
-      setAccountRaw(LS.plexFilters, JSON.stringify(urlSeed.filters));
+      // Per dimension: a dimension the URL carried (present) is the shared view — adopt it and persist
+      // it to this now-pinned account (so it wins and survives a later plain reload). A dimension the
+      // URL OMITTED was seeded from a mount-time default (no account yet), so do NOT persist that
+      // default over the account's real stored value — re-read the stored value instead, exactly like a
+      // normal load. This is the fix for a partial shared link silently resetting the omitted slices.
+      const { state, present } = urlSeed;
+      if (present.scope) setAccountRaw(LS.plexLibrary, state.scope);
+      else setScopeState(readPlexScope());
+      if (present.show) setAccountRaw(LS.plexShow, state.show);
+      else setShowState(readPlexShow());
+      if (present.sort) setAccountRaw(LS.plexSort, JSON.stringify(state.sort));
+      else setSortState(readPlexSort());
+      if (present.filters) setAccountRaw(LS.plexFilters, JSON.stringify(state.filters));
+      else setFiltersRaw(readPlexFiltersRaw());
       setQState(readPlexQ());
       setFieldState(readPlexField());
       return;

frontend/src/components/PriorityStepper.dom.test.tsx

@@ -12,7 +12,10 @@ vi.mock("react-i18next", async (importOriginal) => {
   return { ...actual, useTranslation: () => ({ t: (key: string) => key }) };
 });
 
-afterEach(cleanup);
+afterEach(() => {
+  cleanup();
+  vi.useRealTimers(); // any fake-timer test resets here so it can't leak into the next
+});
 
 const raise = () => screen.getByRole("button", { name: "channels.row.raisePriority" });
 const lower = () => screen.getByRole("button", { name: "channels.row.lowerPriority" });
@@ -78,4 +81,57 @@ describe("PriorityStepper", () => {
     fireEvent.click(raise());
     expect(onPriority).toHaveBeenCalledWith(1);
   });
+
+  it("holding a step button auto-repeats (accelerating) and suppresses the trailing click", () => {
+    vi.useFakeTimers();
+    const onPriority = vi.fn();
+    render(<PriorityStepper priority={0} onPriority={onPriority} onSet={vi.fn()} />);
+
+    fireEvent.pointerDown(raise());
+    vi.advanceTimersByTime(349);
+    expect(onPriority).not.toHaveBeenCalled(); // a tap below the 350ms threshold doesn't repeat
+    vi.advanceTimersByTime(1); // cross the threshold → first auto-repeat tick
+    expect(onPriority).toHaveBeenCalledTimes(1);
+
+    vi.advanceTimersByTime(1000); // several accelerating repeats while held
+    const heldCount = onPriority.mock.calls.length;
+    expect(heldCount).toBeGreaterThan(3);
+    expect(onPriority.mock.calls.every(([d]) => d === 1)).toBe(true);
+
+    fireEvent.pointerUp(raise());
+    vi.advanceTimersByTime(1000);
+    expect(onPriority.mock.calls.length).toBe(heldCount); // stops repeating on release
+
+    fireEvent.click(raise()); // the click that trails a hold is swallowed (no double-count)
+    expect(onPriority.mock.calls.length).toBe(heldCount);
+  });
+
+  it("a quick tap (released before the hold threshold) still nudges exactly once", () => {
+    vi.useFakeTimers();
+    const onPriority = vi.fn();
+    render(<PriorityStepper priority={0} onPriority={onPriority} onSet={vi.fn()} />);
+
+    fireEvent.pointerDown(lower());
+    vi.advanceTimersByTime(100); // below the threshold → no auto-repeat armed
+    fireEvent.pointerUp(lower());
+    fireEvent.click(lower()); // the tap's click is NOT suppressed
+    expect(onPriority.mock.calls).toEqual([[-1]]);
+  });
+
+  it("clears the auto-repeat timer on unmount (no fire after the row is gone)", () => {
+    vi.useFakeTimers();
+    const onPriority = vi.fn();
+    const { unmount } = render(
+      <PriorityStepper priority={0} onPriority={onPriority} onSet={vi.fn()} />,
+    );
+
+    fireEvent.pointerDown(raise());
+    vi.advanceTimersByTime(350); // repeat armed + first tick
+    const before = onPriority.mock.calls.length;
+    expect(before).toBeGreaterThan(0);
+
+    unmount();
+    vi.advanceTimersByTime(1000);
+    expect(onPriority.mock.calls.length).toBe(before); // no post-unmount timer fire
+  });
 });