fix(api): a write that hit a connection failure is still reported, and every failure is reported once

Deep-review round 4, the "one report per failure" contract round 3 introduced.

- `req` marked gateway (502/503/504) and network failures "already reported" because they raise
  the connection notice. But that notice is about connectivity and removes itself on the very next
  answer — which every caller's own resync refetch fetches at once — so a delete that hit a
  keepalive reset flashed the notice and was then reported nowhere, the list still there. Only the
  durable reports (the error dialog, the 401 sign-out) count now; the caller says the action failed.
- A connection notice the user closed swallowed every later one for the rest of the visit; it is
  raised again.
- `req` and `uploadReq` share one failure policy (`reportFailure`). The upload copy had drifted: a
  502 opened the blocking "Server error (502)" dialog and cleared a notice that was still true.
- A taken Plex collection name is a structured 409, localized, and the create/rename calls are
  quiet: it was an English dialog plus a Hungarian toast. `notifyCollectionEditError` is gone.
- The mutation onErrors that toasted unconditionally after a non-quiet request (invite approve /
  deny / add, demo whitelist, audit clear, scheduler, share, full history, edit, config tests, tag
  attach) go through `notifyActionError`; the playlist delete's hand-rolled copy of it too (it takes
  a level now). The user role / suspend / delete actions had no onError at all: a user deleted in
  another tab failed silently and stayed listed — now said, and the list refetched.

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

@@ -0,0 +1,103 @@
+// @vitest-environment jsdom
+//
+// A failed user action is said once, and a user who is gone is not left listed (deep-review round 4).
+// setRole / suspend / delete had no onError at all — "the global error dialog says it" — but a 404
+// (the user was deleted in another tab) gets no dialog, so the click did nothing and the row stayed.
+// And the invite approve/deny toasted unconditionally on top of the dialog `req` opens for a 409.
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { render, cleanup, screen, fireEvent, waitFor } from "@testing-library/react";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+
+vi.mock("react-i18next", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("react-i18next")>();
+  return {
+    ...actual,
+    useTranslation: () => ({ t: (key: string) => key, i18n: { language: "en" } }),
+  };
+});
+vi.mock("../lib/useMe", () => ({
+  useMe: () => ({
+    id: 1,
+    email: "admin@x",
+    role: "admin",
+    pending_invites: 0,
+    pending_activations: 0,
+  }),
+}));
+vi.mock("./ConfirmProvider", () => ({ useConfirm: () => async () => true }));
+const { notify } = vi.hoisted(() => ({
+  notify: vi.fn((_n: { level: string; message: string }) => 0),
+}));
+vi.mock("../lib/notifications", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("../lib/notifications")>()),
+  notify,
+}));
+vi.mock("../lib/errorDialog", () => ({ reportError: vi.fn() }));
+
+import AdminUsers from "./AdminUsers";
+import { api, type AdminUserRow } from "../lib/api";
+import i18n from "../i18n";
+
+const row = {
+  id: 2,
+  email: "gone@x",
+  role: "user",
+  is_suspended: false,
+  is_demo: false,
+  email_verified: true,
+  is_active: true,
+} as unknown as AdminUserRow;
+
+function answer(status: number, detail: unknown) {
+  return new Response(JSON.stringify({ detail }), {
+    status,
+    headers: { "content-type": "application/json" },
+  });
+}
+
+beforeEach(() => {
+  notify.mockClear();
+  localStorage.clear();
+});
+afterEach(() => {
+  cleanup();
+  vi.restoreAllMocks();
+});
+
+function mount() {
+  const users = vi.spyOn(api, "adminUsers").mockResolvedValue([row] as never);
+  render(
+    <QueryClientProvider
+      client={new QueryClient({ defaultOptions: { queries: { retry: false } } })}
+    >
+      <AdminUsers />
+    </QueryClientProvider>,
+  );
+  return users;
+}
+
+describe("a user action that fails", () => {
+  it("says a user who is gone, and refetches the list", async () => {
+    const users = mount();
+    vi.spyOn(globalThis, "fetch").mockResolvedValue(
+      answer(404, { code: "not_found", reason: "user" }),
+    );
+    fireEvent.click(await screen.findByText("users.roles.makeAdmin"));
+    await waitFor(() =>
+      expect(notify).toHaveBeenCalledWith({
+        level: "error",
+        message: i18n.t("errors.notFound.user"), // the request layer localizes a structured detail
+      }),
+    );
+    await waitFor(() => expect(users).toHaveBeenCalledTimes(2));
+  });
+
+  it("is not toasted on top of the error dialog the request already opened", async () => {
+    mount();
+    vi.spyOn(globalThis, "fetch").mockResolvedValue(answer(409, "Cannot demote the last admin"));
+    fireEvent.click(await screen.findByText("users.roles.makeAdmin"));
+    const { reportError } = await import("../lib/errorDialog");
+    await waitFor(() => expect(reportError).toHaveBeenCalled());
+    expect(notify.mock.calls.filter(([n]) => n.level === "error")).toEqual([]);
+  });
+});

frontend/src/components/AdminUsers.tsx

@@ -38,6 +38,7 @@ import { useConfirm } from "./ConfirmProvider";
 import Tabs, { usePersistedTab } from "./ui/Tabs";
 import { PageToolbar } from "./ui/PageShell";
 import { useMe } from "../lib/useMe";
+import { notifyActionError } from "../lib/actionErrors";
 
 // Admin-only user & access management: roles, access requests (the Invite whitelist), and the
 // demo whitelist + reset. Each section is its own tab (persisted across reloads); the Access tab
@@ -120,6 +121,13 @@ function UsersRoles({ me }: { me: Me }) {
       n.delete(id);
       return n;
     });
+  // A failed user action: said once (notifyActionError skips what `req` already put in its dialog),
+  // and the list refetched — a user deleted in another tab would otherwise stay listed, every click
+  // on the row doing nothing.
+  const onGoneOrFailed = (e: unknown, fallback: string) => {
+    notifyActionError(e, fallback);
+    qc.invalidateQueries({ queryKey: qk.adminUsers() });
+  };
   const setRole = useMutation({
     mutationFn: ({ id, role }: { id: number; role: "user" | "admin"; email: string }) =>
       api.setUserRole(id, role),
@@ -129,7 +137,9 @@ function UsersRoles({ me }: { me: Me }) {
       notify({ level: "success", message: t("users.roles.updated", { email: vars.email }) });
     },
     onSettled: (_d, _e, vars) => endPending(vars.id),
-    // Errors (e.g. last-admin / self) surface via the global error dialog with the server's detail.
+    // Guards (last admin / self) surface via the global error dialog with the server's detail; what
+    // it does not show (a user deleted meanwhile, a 404) is said here — see onGoneOrFailed.
+    onError: (e) => onGoneOrFailed(e, t("users.roles.failed")),
   });
 
   const suspend = useMutation({
@@ -146,7 +156,8 @@ function UsersRoles({ me }: { me: Me }) {
       });
     },
     onSettled: (_d, _e, vars) => endPending(vars.id),
-    // Guards (demo / self / last admin) surface via the global error dialog.
+    // Guards (demo / self / last admin) surface via the global error dialog; the rest, as above.
+    onError: (e) => onGoneOrFailed(e, t("users.suspend.failed")),
   });
   const del = useMutation({
     mutationFn: ({ id }: { id: number; email: string }) => api.adminDeleteUser(id),
@@ -156,6 +167,7 @@ function UsersRoles({ me }: { me: Me }) {
       notify({ level: "success", message: t("users.delete.done", { email: vars.email }) });
     },
     onSettled: (_d, _e, vars) => endPending(vars.id),
+    onError: (e) => onGoneOrFailed(e, t("users.delete.failed")),
   });
 
   const onToggle = async (u: AdminUserRow) => {
@@ -518,7 +530,7 @@ function AdminInvites() {
       refresh();
       notify({ level: "success", message: t("settings.invites.approved", { email: vars.email }) });
     },
-    onError: () => notify({ level: "error", message: t("settings.invites.approveFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.invites.approveFailed")),
   });
   const deny = useMutation({
     mutationFn: (id: number) => api.denyInvite(id),
@@ -526,7 +538,7 @@ function AdminInvites() {
       refresh();
       notify({ level: "success", message: t("settings.invites.denied") });
     },
-    onError: () => notify({ level: "error", message: t("settings.invites.denyFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.invites.denyFailed")),
   });
   const onDeny = async (i: { id: number; email: string }) => {
     const ok = await confirm({
@@ -630,7 +642,7 @@ function AdminInvites() {
       refresh();
       notify({ level: "success", message: t("settings.invites.addedToWhitelist", { email }) });
     },
-    onError: () => notify({ level: "error", message: t("settings.invites.addFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.invites.addFailed")),
   });
 
   const list = invites.data ?? [];
@@ -780,7 +792,7 @@ function AdminDemo() {
       qc.invalidateQueries({ queryKey: qk.demoWhitelist() });
       notify({ level: "success", message: t("settings.demo.added", { email }) });
     },
-    onError: () => notify({ level: "error", message: t("settings.demo.addFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.demo.addFailed")),
   });
   const remove = useMutation({
     mutationFn: (id: number) => api.removeDemoWhitelist(id),
@@ -788,7 +800,7 @@ function AdminDemo() {
       qc.invalidateQueries({ queryKey: qk.demoWhitelist() });
       notify({ level: "success", message: t("settings.demo.removed") });
     },
-    onError: () => notify({ level: "error", message: t("settings.demo.removeFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.demo.removeFailed")),
   });
   const onRemove = async (r: { id: number; email: string }) => {
     const ok = await confirm({
@@ -806,7 +818,7 @@ function AdminDemo() {
         level: "success",
         message: t("settings.demo.resetDone", { count: r.playlists_seeded }),
       }),
-    onError: () => notify({ level: "error", message: t("settings.demo.resetFailed") }),
+    onError: (e) => notifyActionError(e, t("settings.demo.resetFailed")),
   });
 
   const rows = list.data ?? [];

frontend/src/components/AuditLog.tsx

@@ -12,6 +12,7 @@ import { useConfirm } from "./ConfirmProvider";
 import DataTable from "./ui/DataTable";
 import { LoadingState, StateMessage } from "./ui/QueryState";
 import { auditColumns } from "./auditColumns";
+import { notifyActionError } from "../lib/actionErrors";
 
 // Admin-only audit trail: an append-only who/what/when log of admin actions + scheduler run
 // summaries (never per-row). Read-only apart from Clear. Client-side sort/filter/paginate via
@@ -36,7 +37,7 @@ export default function AuditLog() {
       qc.invalidateQueries({ queryKey: qk.adminAudit() });
       notify({ level: "success", message: t("audit.cleared", { count: r.cleared }) });
     },
-    onError: () => notify({ level: "error", message: t("audit.clearFailed") }),
+    onError: (e) => notifyActionError(e, t("audit.clearFailed")),
   });
   const onClear = async () => {
     if (

frontend/src/components/Channels.tsx

@@ -6,6 +6,7 @@ import { Ban, Eye, EyeOff, History, LayoutGrid, Pencil, RefreshCw, Table, X } fr
 import ExcludedChannelList from "./ExcludedChannelList";
 import { api, NO_TAG_SENTINEL, type ManagedChannel } from "../lib/api";
 import { Sparkles } from "lucide-react";
+import { notifyActionError } from "../lib/actionErrors";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { accountKey, LS } from "../lib/storage";
 import { buildChannelColumns, applySyncFilter } from "./channelColumns";
@@ -182,10 +183,10 @@ export default function Channels() {
     // suggestions: acceptSuggestion optimistically dropped the channel from that cache, and on
     // failure the tag never actually attached — so the server still suggests it and the ghost chips
     // must come back rather than leaving an empty cell (honest states). Surface the write failure too.
-    onError: () => {
+    onError: (e) => {
       qc.invalidateQueries({ queryKey: qk.channels() });
       qc.invalidateQueries({ queryKey: qk.tagSuggestions() });
-      notify({ level: "error", message: t("channels.tags.updateFailed") });
+      notifyActionError(e, t("channels.tags.updateFailed"));
     },
   });
   // --- Suggested tags (E8·S4): learned from the user's own manual-tag pattern, shown as accept/dismiss

frontend/src/components/ConfigPanel.tsx

@@ -14,6 +14,7 @@ import { PageToolbar } from "./ui/PageShell";
 import { Switch } from "./ui/form";
 import { DraftSaveBar, type SaveState } from "./ui/DraftSaveBar";
 import { LS } from "../lib/storage";
+import { notifyActionError } from "../lib/actionErrors";
 
 // Admin Configuration page: edit DB-overridable operational settings (registry-driven from the
 // backend — adding a key there makes it appear here automatically). Edits are drafted and
@@ -125,7 +126,7 @@ export default function ConfigPanel() {
   const testEmail = useMutation({
     mutationFn: () => api.testEmail(),
     onSuccess: (r) => notify({ level: "success", message: t("config.testSent", { to: r.to }) }),
-    onError: () => notify({ level: "error", message: t("config.testFailed") }),
+    onError: (e) => notifyActionError(e, t("config.testFailed")),
   });
 
   // Plex "Test connection": verifies the server URL + token and returns the library sections,
@@ -138,9 +139,9 @@ export default function ConfigPanel() {
       setPlexResult(r);
       notify({ level: "success", message: t("config.plexTestOk", { name: r.server_name }) });
     },
-    onError: () => {
+    onError: (e) => {
       setPlexResult(null);
-      notify({ level: "error", message: t("config.plexTestFailed") });
+      notifyActionError(e, t("config.plexTestFailed"));
     },
   });
   const plexLibs = (draft["plex_libraries"] ?? "")

frontend/src/components/PlexCollectionEditor.tsx

@@ -4,7 +4,7 @@ import { useTranslation } from "react-i18next";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { Check, Plus } from "lucide-react";
 import { api } from "../lib/api";
-import { notifyCollectionEditError } from "../lib/actionErrors";
+import { notifyActionError } from "../lib/actionErrors";
 import { useScrollFade } from "../lib/useScrollFade";
 import { Button } from "./ui/Button";
 import Modal from "./ui/Modal";
@@ -103,9 +103,9 @@ export default function PlexCollectionEditor({
       setMembers((prev) => new Set(prev).add(col.id));
       refresh();
     } catch (e) {
-      // The backend rejects a duplicate name with 409 (Plex conflates same names) — localize it to
-      // nameTaken rather than surfacing the server's raw English detail.
-      notifyCollectionEditError(e, t("plex.collection.editFailed"), t("plex.collection.nameTaken"));
+      // The backend rejects a duplicate name with 409 (Plex conflates same names), structured — so
+      // it reads in the reader's language (see localizeDetail).
+      notifyActionError(e, t("plex.collection.editFailed"));
     } finally {
       setBusy(null);
     }

frontend/src/components/PlexCollectionView.tsx

@@ -5,7 +5,7 @@ import { Play, Shuffle, Pencil, Trash2, Plus, X, Lock, Check, Search } from "luc
 import { qk } from "../lib/queryKeys";
 import { api, isIntrinsicReadOnly, type PlexCard, type PlexCollectionDetail } from "../lib/api";
 import { formatRuntime } from "../lib/format";
-import { notifyActionError, notifyCollectionEditError } from "../lib/actionErrors";
+import { notifyActionError } from "../lib/actionErrors";
 import { notify } from "../lib/notifications";
 import { showEpisodeKeys } from "../lib/plexQueue";
 import { healPlexSort, plexSortOptions } from "../lib/plexSort";
@@ -187,8 +187,8 @@ export default function PlexCollectionView({
       invalidate();
       setRenaming(false);
     } catch (e) {
-      // The backend enforces per-library name uniqueness — localize its 409 to nameTaken.
-      notifyCollectionEditError(e, t("plex.collection.editFailed"), t("plex.collection.nameTaken"));
+      // The backend enforces per-library name uniqueness — a taken name comes back localized.
+      notifyActionError(e, t("plex.collection.editFailed"));
     } finally {
       setBusy(false);
     }

frontend/src/components/Scheduler.tsx

@@ -25,6 +25,7 @@ import { useConfirm } from "./ConfirmProvider";
 import { relativeTime } from "../lib/format";
 import { notify } from "../lib/notifications";
 import Tooltip from "./ui/Tooltip";
+import { notifyActionError } from "../lib/actionErrors";
 
 const POLL_MS = 4000;
 // While any job is running, poll faster so short scheduled runs aren't missed between ticks.
@@ -375,14 +376,14 @@ export default function Scheduler() {
   const pauseResume = useMutation({
     mutationFn: (paused: boolean) => (paused ? api.resumeSync() : api.pauseSync()),
     onSuccess: () => qc.invalidateQueries({ queryKey: qk.scheduler() }),
-    onError: () => notify({ level: "error", message: t("scheduler.toggleFailed") }),
+    onError: (e) => notifyActionError(e, t("scheduler.toggleFailed")),
   });
 
   const intervalMut = useMutation({
     mutationFn: (v: { jobId: string; minutes: number }) =>
       api.updateSchedulerJob(v.jobId, v.minutes),
     onSuccess: () => qc.invalidateQueries({ queryKey: qk.scheduler() }),
-    onError: () => notify({ level: "error", message: t("scheduler.intervalFailed") }),
+    onError: (e) => notifyActionError(e, t("scheduler.intervalFailed")),
   });
 
   // Manual "run now" triggers. The wrapper runs in a background thread server-side; the

frontend/src/components/ShareDialog.tsx

@@ -7,6 +7,7 @@ import clsx from "clsx";
 import Modal from "./ui/Modal";
 import { useConfirm } from "./ConfirmProvider";
 import { notify } from "../lib/notifications";
+import { notifyActionError } from "../lib/actionErrors";
 import { copyText } from "../lib/clipboard";
 import { api, type DownloadJob, type ShareLink } from "../lib/api";
 import { inputCls } from "./ui/form";
@@ -39,7 +40,7 @@ function UserShare({ job }: { job: DownloadJob }) {
       setQ("");
       setOpen(false);
     },
-    onError: () => notify({ level: "error", message: t("downloads.share.failed") }),
+    onError: (e) => notifyActionError(e, t("downloads.share.failed")),
   });
 
   return (

frontend/src/components/Stats.tsx

@@ -15,6 +15,7 @@ import FilterChipGroup from "./ui/FilterChipGroup";
 import Tabs from "./ui/Tabs";
 import { Section, SettingRow } from "./ui/form";
 import { useMe } from "../lib/useMe";
+import { notifyActionError } from "../lib/actionErrors";
 
 const RANGES = [7, 30, 90] as const;
 type StatsTab = "overview" | "system";
@@ -85,7 +86,7 @@ function Overview({ me }: { me: Me }) {
         message: t("stats.sync.fullHistoryRequested", { count: r.updated ?? 0 }),
       });
     },
-    onError: () => notify({ level: "error", message: t("stats.sync.fullHistoryFailed") }),
+    onError: (e) => notifyActionError(e, t("stats.sync.fullHistoryFailed")),
   });
 
   return (

frontend/src/components/VideoEditor.tsx

@@ -10,6 +10,7 @@ import { api, type DownloadJob, type EditSpec } from "../lib/api";
 import { contentRect, cropToSourcePx, type Frac } from "../lib/cropGeometry";
 import { inputCls, btnCls } from "./ui/form";
 import { Button } from "./ui/Button";
+import { notifyActionError } from "../lib/actionErrors";
 
 // mm:ss.d timecode <-> seconds.
 function tc(s: number): string {
@@ -322,7 +323,7 @@ export default function VideoEditor({ job, onClose }: { job: DownloadJob; onClos
       notify({ level: "success", message: t("editor.created", { count: files }) });
       onClose();
     },
-    onError: () => notify({ level: "error", message: t("editor.failed") }),
+    onError: (e) => notifyActionError(e, t("editor.failed")),
   });
 
   const sel = segments.find((s) => s.id === selId) ?? segments[0];

frontend/src/components/plexBrowseLists.tsx

@@ -6,7 +6,7 @@ import { Check, ListMusic, Lock, Plus, Search, X } from "lucide-react";
 import { qk } from "../lib/queryKeys";
 import { api, isIntrinsicReadOnly, type PlexCard, type PlexCollection } from "../lib/api";
 import { formatRuntime } from "../lib/format";
-import { notifyCollectionEditError } from "../lib/actionErrors";
+import { notifyActionError } from "../lib/actionErrors";
 import { useDebounced } from "../lib/useDebounced";
 import { LoadingState, StateMessage } from "./ui/QueryState";
 import PosterTile from "./PosterTile";
@@ -95,8 +95,9 @@ function NewCollectionPanel({
       const col = await api.plexCreateCollection("", trimmed, card.id); // backend derives the library
       onCreated(col.id);
     } catch (e) {
-      // The backend is authoritative on per-library name uniqueness — its 409 is localized to nameTaken.
-      notifyCollectionEditError(e, t("plex.collection.editFailed"), t("plex.collection.nameTaken"));
+      // The backend is authoritative on per-library name uniqueness — a taken name comes back
+      // structured, and so localized (see localizeDetail).
+      notifyActionError(e, t("plex.collection.editFailed"));
       setBusy(false);
     }
   }

frontend/src/components/usePlaylistActions.ts

@@ -1,8 +1,8 @@
 import { useQueryClient } from "@tanstack/react-query";
 import { useTranslation } from "react-i18next";
 import { qk } from "../lib/queryKeys";
-import { alreadyReported, api, HttpError, type Playlist } from "../lib/api";
-import { notify } from "../lib/notifications";
+import { api, type Playlist } from "../lib/api";
+import { notifyActionError } from "../lib/actionErrors";
 import { notifyYouTubeActionError } from "../lib/youtubeErrors";
 import { playlistName } from "../lib/playlistName";
 import { useChoice } from "./ConfirmProvider";
@@ -71,14 +71,12 @@ export function usePlaylistActions() {
     } catch (err) {
       // Prefer the server's specific reason (e.g. a local vs YouTube-side failure) over a blanket
       // "couldn't delete on YouTube" that misleads when the failure wasn't the YouTube side — unless
-      // `req` already put it on screen (the error dialog, the connection notice): not twice.
-      if (!alreadyReported(err))
-        notify({
-          level: "warning",
-          message:
-            (err instanceof HttpError && err.detail) ||
-            (onYoutube ? t("playlists.deleteYtFailed") : t("playlists.deleteFailed")),
-        });
+      // `req` already put it in its error dialog: not twice (notifyActionError checks).
+      notifyActionError(
+        err,
+        onYoutube ? t("playlists.deleteYtFailed") : t("playlists.deleteFailed"),
+        "warning",
+      );
     }
     qc.removeQueries({ queryKey: qk.playlist(pl.id) });
     qc.invalidateQueries({ queryKey: qk.playlists() });