feat(frontend): the folders are layers — an import only goes down, a module is reached through its index.ts

`local/layers` (eslint.config.js) resolves every import to its file and refuses one that goes up
(lib/ → components/ui/ → features/ → modules/ → shell/) or that reaches into another module's own
files. A module's index.ts is its public face: the stores, mounted at the root and read app-wide,
which features/ may read too; a page is still opened lazily by import(). Its contract test probes
every edge, and three mutants of the rule (off, no face check, a door for everyone) each turn it red.

Six modules got that face; the shared channel UI (about, tags, tag manager) moved to
features/channel, the filter chips and the saved-views context to features/filters, and the prefs
store's controller type moved next to the store instead of importing it from its own page. The
header's per-module controls and the eagerly loaded rails keep eight inline suppressions, each
naming why: they go when the header gets slots and every rail loads lazily.

`chunkGuard` fails the production build when a lazily imported module lands in a boot chunk (the
entry, the shell, what they import) — e.g. a page re-exported from an index.ts, which makes its
import() a silent no-op. Proved on a build with that mutant; today's build has none.

frontend/src/shell/App.tsx

@@ -21,8 +21,12 @@ import { LS } from "../lib/storage";
 import { usePref } from "../lib/usePref";
 import { useVerifyEntry } from "../lib/useVerifyEntry";
 import { useNavigation, useNavigationActions } from "../features/navigation/navigationContext";
-import { useFeedFilters, useFeedFiltersActions } from "../modules/feed/feedFiltersContext";
-import { useFeedView, useFeedViewActions } from "../modules/feed/feedViewContext";
+import {
+  useFeedFilters,
+  useFeedFiltersActions,
+  useFeedView,
+  useFeedViewActions,
+} from "../modules/feed";
 import { moduleOrder } from "../lib/modules";
 import { PAGE_CONTENT, PAGE_RAIL, preloadPages } from "./moduleRegistry";
 import { lazyWithPreload } from "../lib/lazyWithPreload";

frontend/src/shell/AppCommandPalette.dom.test.tsx

@@ -57,7 +57,7 @@ vi.mock("../modules/playlists/playlistsContext", () => ({
 vi.mock("../features/prefs/prefsContext", () => ({
   usePrefs: () => ({ theme: { scheme: "default" }, setTheme: vi.fn() }),
 }));
-vi.mock("../modules/feed/savedViewsContext", () => ({
+vi.mock("../features/filters/savedViewsContext", () => ({
   useSavedViews: () => ({ views: [], apply: vi.fn() }),
 }));
 const requestSurprise = vi.fn();

frontend/src/shell/AppCommandPalette.tsx

@@ -24,9 +24,9 @@ import { requestLinkBox } from "../lib/downloadIntake";
 import { openRecorderStart } from "../lib/debugRecorder";
 import { useDebugRecording } from "../features/diagnostics/useDebugRecording";
 import { useNavigationActions } from "../features/navigation/navigationContext";
-import { usePlaylistsActions } from "../modules/playlists/playlistsContext";
+import { usePlaylistsActions } from "../modules/playlists";
 import { usePrefs } from "../features/prefs/prefsContext";
-import { useSavedViews } from "../modules/feed/savedViewsContext";
+import { useSavedViews } from "../features/filters/savedViewsContext";
 
 // What Ctrl/Cmd+K can reach. The generic list/filter/keyboard shell is `ui/CommandPalette`; this is
 // the domain half — the layer boundary says a primitive may not import `lib/api` or a module.

frontend/src/shell/Header.palette.dom.test.tsx

@@ -0,0 +1,77 @@
+// @vitest-environment jsdom
+//
+// Ctrl/Cmd+K had no visible entry point (debt burn B28). The owner's pick: a key cap in the header's
+// search field, and a "Jump to…" pill in its place on a page that has no search field.
+import { describe, it, expect, vi, afterEach } from "vitest";
+import { render, screen, fireEvent, cleanup, act } from "@testing-library/react";
+
+vi.mock("react-i18next", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("react-i18next")>()),
+  useTranslation: () => ({ t: (k: string) => k, i18n: { language: "en" } }),
+}));
+
+let page = "home";
+vi.mock("../features/navigation/navigationContext", () => ({ useNavigation: () => ({ page }) }));
+vi.mock("../modules/feed/feedFiltersContext", () => ({
+  useFeedFilters: () => ({ q: "", sort: "newest" }),
+  useFeedFiltersActions: () => ({ setFilters: vi.fn() }),
+}));
+vi.mock("../modules/playlists/playlistsContext", () => ({
+  usePlaylists: () => ({ search: "" }),
+  usePlaylistsActions: () => ({ setSearch: vi.fn() }),
+}));
+vi.mock("../modules/channels/channelsContext", () => ({
+  useChannels: () => ({ search: "" }),
+  useChannelsActions: () => ({ setSearch: vi.fn(), goToFullHistory: vi.fn() }),
+}));
+vi.mock("../modules/channels/SyncStatus", () => ({ default: () => null }));
+
+import Header from "./Header";
+import { closePalette, usePaletteOpen } from "../lib/keymap";
+import type { Me } from "../lib/api";
+
+afterEach(() => {
+  cleanup();
+  act(() => closePalette());
+});
+
+function mount() {
+  let open = false;
+  function Probe() {
+    open = usePaletteOpen();
+    return null;
+  }
+  render(
+    <>
+      <Header me={{ plex_enabled: false } as Me} onYtSearch={() => {}} />
+      <Probe />
+    </>,
+  );
+  return () => open;
+}
+
+describe("the command palette's visible entry", () => {
+  it("is a key cap inside the search field, naming the chord the palette row binds", () => {
+    page = "feed";
+    const isOpen = mount();
+    const cap = screen.getByRole("button", { name: /^palette\.open \((Ctrl|⌘) K\)$/ });
+    // Label in Name: the name carries what the cap shows, so "click Ctrl K" finds it.
+    expect(cap.getAttribute("aria-label")).toContain(cap.textContent);
+    // …and a tooltip equal to that name, so a screen reader does not read it again as a description.
+    expect(cap.getAttribute("title")).toBe(cap.getAttribute("aria-label"));
+    expect(screen.getByRole("textbox")).toBeTruthy();
+    fireEvent.click(cap);
+    expect(isOpen()).toBe(true);
+  });
+
+  it("is a Jump-to pill on a page with no search field", () => {
+    page = "home";
+    const isOpen = mount();
+    expect(screen.queryByRole("textbox")).toBeNull();
+    // Named by what it shows ("Jump to…" and its key cap), not by a label that replaced it.
+    const pill = screen.getByRole("button", { name: /^palette\.title ?(Ctrl|⌘) K$/ });
+    expect(pill.getAttribute("title")).toBe("palette.open");
+    fireEvent.click(pill);
+    expect(isOpen()).toBe(true);
+  });
+});

frontend/src/shell/Header.tsx

@@ -3,16 +3,21 @@ import { useTranslation } from "react-i18next";
 import { YouTubeIcon } from "../lib/brandIcons";
 import type { Me } from "../lib/api";
 import SearchBar from "../features/header/SearchBar";
-import { useFiles, useFilesActions } from "../modules/files/filesContext";
+import { useFiles, useFilesActions } from "../modules/files";
+// eslint-disable-next-line local/layers -- the header still hosts this module's control; it goes once each page renders its own controls into the header's slots.
 import PlexSearchBox from "../modules/plex/PlexSearchBox";
+// eslint-disable-next-line local/layers -- the header still hosts this module's control; it goes once each page renders its own controls into the header's slots.
 import PlexScopeToggle from "../modules/plex/PlexScopeToggle";
+// eslint-disable-next-line local/layers -- the header still hosts this module's control; it goes once each page renders its own controls into the header's slots.
 import PlexViewToggle from "../modules/plex/PlexViewToggle";
+// eslint-disable-next-line local/layers -- the header still hosts this module's control; it goes once each page renders its own controls into the header's slots.
 import FeedScopeToggle from "../modules/feed/FeedScopeToggle";
+// eslint-disable-next-line local/layers -- the header still hosts this module's control; it goes once each page renders its own controls into the header's slots.
 import SyncStatus from "../modules/channels/SyncStatus";
 import { useNavigation } from "../features/navigation/navigationContext";
-import { useFeedFilters, useFeedFiltersActions } from "../modules/feed/feedFiltersContext";
-import { usePlaylists, usePlaylistsActions } from "../modules/playlists/playlistsContext";
-import { useChannels, useChannelsActions } from "../modules/channels/channelsContext";
+import { useFeedFilters, useFeedFiltersActions } from "../modules/feed";
+import { usePlaylists, usePlaylistsActions } from "../modules/playlists";
+import { useChannels, useChannelsActions } from "../modules/channels";
 import { PaletteLauncher } from "../features/header/PaletteLauncher";
 
 // The floating top header: a row of glass pills over the content — the module's SearchBar where it

frontend/src/shell/moduleRegistry.tsx

@@ -2,8 +2,11 @@ import type { ComponentType } from "react";
 import { lazyWithPreload, type PreloadableComponent } from "../lib/lazyWithPreload";
 import type { Page } from "../lib/urlState";
 import type { PanelId, PanelLayout } from "../lib/panelLayout";
+// eslint-disable-next-line local/layers -- a rail (or the feed page's wrapper) the shell still loads eagerly; it goes once every rail loads lazily, like the pages.
 import Sidebar from "../modules/feed/Sidebar";
+// eslint-disable-next-line local/layers -- a rail (or the feed page's wrapper) the shell still loads eagerly; it goes once every rail loads lazily, like the pages.
 import PlaylistsRail from "../modules/playlists/PlaylistsRail";
+// eslint-disable-next-line local/layers -- a rail (or the feed page's wrapper) the shell still loads eagerly; it goes once every rail loads lazily, like the pages.
 import { Feed, FeedPage } from "../modules/feed/modulePages";
 
 // The RENDER half of the module registry: which component (and side rail) each page renders. The