feat(shell): add global keyboard shortcuts and their help dialog

g then d/m/l/t/i/c/s opens a page through the same visible-destination
lists the navigation renders, so a switched-off module, a Coach without a
provider or a door a shared record does not cover stays shut. n opens the
capture picker, [ and ] step the open day, ? lists everything. Keys typed
into a field, held with Cmd/Ctrl/Alt, or pressed while a dialog or menu is
open are left alone; [ and ] still act over the day sheet and when the
layout needs Alt or AltGr to type them. The list is also reachable from
the sidebar account menu.

CHANGELOG.md

@@ -98,6 +98,9 @@ an earlier fold computed from part of a day.
   `REINDEX INDEX CONCURRENTLY` per index, largest first.
 - **Query statistics.** The bundled database loads `pg_stat_statements`;
   `CREATE EXTENSION` once to read it (`docs/ops/query-statistics.md`).
+- **Keyboard shortcuts.** `g` then `d`, `m`, `l`, `t`, `i`, `c` or `s` opens
+  a page, `n` the add menu, `[` and `]` step the open day, and `?` (or the
+  account menu) lists them; ignored while typing in a field.
 
 ### Changed
 

e2e/keyboard-shortcuts.spec.ts

@@ -0,0 +1,214 @@
+import AxeBuilder from "@axe-core/playwright";
+import type { Page } from "@playwright/test";
+
+import { mockDay } from "./setup/day-mock";
+import { STORAGE_STATE_PATH } from "./setup/global-setup";
+import { expect, test } from "./setup/test";
+import { mockTimeline } from "./utils/mock-timeline";
+
+/**
+ * v1.42 — the keyboard shortcuts.
+ *
+ *   - `g t` opens the timeline while its module is on, and does nothing while
+ *     it is off;
+ *   - keys typed into a field stay in the field;
+ *   - `?` opens the list: a titled dialog that keeps focus inside and closes
+ *     on Escape; the account menu opens the same list;
+ *   - `n` opens the add menu;
+ *   - `[` and `]` step the open day, never past today.
+ *
+ * The module map is the account's real `/api/auth/me` with only `timeline`
+ * rewritten, so the switch is never moved on a shared account. Desktop only:
+ * a phone has no keyboard to press these on.
+ */
+
+test.use({ storageState: STORAGE_STATE_PATH });
+
+const TODAY = new Intl.DateTimeFormat("en-CA", {
+  timeZone: "Europe/Berlin",
+  year: "numeric",
+  month: "2-digit",
+  day: "2-digit",
+}).format(new Date());
+
+function shiftDay(key: string, delta: number): string {
+  const d = new Date(`${key}T12:00:00Z`);
+  d.setUTCDate(d.getUTCDate() + delta);
+  return d.toISOString().slice(0, 10);
+}
+
+async function withTimelineModule(page: Page, on: boolean): Promise<void> {
+  await page.route("**/api/auth/me", async (route) => {
+    const res = await route.fetch();
+    const json = await res.json().catch(() => null);
+    if (!json?.data?.modules) return route.fulfill({ response: res });
+    json.data.modules.timeline = on;
+    return route.fulfill({
+      response: res,
+      body: JSON.stringify(json),
+      headers: { ...res.headers(), "content-type": "application/json" },
+    });
+  });
+}
+
+/** The shell is up and its listener registered. */
+async function shellReady(page: Page): Promise<void> {
+  await expect(page.locator("#main-content")).toBeVisible({ timeout: 20_000 });
+  await expect(page.locator('[data-slot="top-bar"]')).toBeVisible();
+}
+
+const helpDialog = (page: Page) =>
+  page.getByRole("dialog", { name: "Keyboard shortcuts" });
+
+test.describe("keyboard shortcuts", () => {
+  test.beforeEach(async ({ context }, testInfo) => {
+    test.skip(
+      testInfo.project.name !== "chromium-desktop",
+      "keyboard journeys run on the desktop project",
+    );
+    const baseURL = testInfo.project.use.baseURL ?? "http://localhost:3000";
+    await context.addCookies([
+      { name: "healthlog-locale", value: "en", url: baseURL },
+    ]);
+  });
+
+  test("g t opens the timeline while its module is on", async ({ page }) => {
+    await withTimelineModule(page, true);
+    await mockTimeline(page, "ready", TODAY);
+    await page.goto("/");
+    await shellReady(page);
+    await page.keyboard.press("g");
+    await page.keyboard.press("t");
+    await expect(page).toHaveURL(/\/timeline$/);
+  });
+
+  test("g t does nothing while the timeline module is off", async ({
+    page,
+  }) => {
+    await withTimelineModule(page, false);
+    // Every client navigation, in order, so "nothing happened" is a fact
+    // rather than a wait.
+    await page.addInitScript(() => {
+      const log: string[] = [];
+      (window as unknown as { __pushed: string[] }).__pushed = log;
+      const push = history.pushState.bind(history);
+      history.pushState = (state, unused, url) => {
+        if (url != null) log.push(String(url));
+        push(state, unused, url);
+      };
+    });
+    await page.goto("/insights");
+    await shellReady(page);
+    await page.keyboard.press("g");
+    await page.keyboard.press("t");
+    // The positive control: the same reader opens a page that is on.
+    await page.keyboard.press("g");
+    await page.keyboard.press("d");
+    await expect(page).toHaveURL(/\/$/);
+    const pushed = await page.evaluate(
+      () => (window as unknown as { __pushed: string[] }).__pushed,
+    );
+    expect(pushed.some((url) => url.includes("/timeline"))).toBe(false);
+  });
+
+  test("keys typed into a field stay in the field", async ({ page }) => {
+    await withTimelineModule(page, true);
+    await page.goto("/");
+    await shellReady(page);
+    // A plain field in the page: the rule is about the focused element, not
+    // about which page carries it.
+    await page.evaluate(() => {
+      const field = document.createElement("input");
+      field.setAttribute("data-testid", "probe-field");
+      field.setAttribute("aria-label", "Probe");
+      document.getElementById("main-content")?.prepend(field);
+    });
+    const field = page.getByTestId("probe-field");
+    await field.focus();
+    await page.keyboard.type("gt n ? [");
+    await expect(field).toHaveValue("gt n ? [");
+    await expect(page).toHaveURL(/\/$/);
+    await expect(helpDialog(page)).toHaveCount(0);
+    await expect(page.getByTestId("capture-picker-options")).toHaveCount(0);
+  });
+
+  test("? opens a titled list that keeps focus and closes on Escape", async ({
+    page,
+  }) => {
+    await page.goto("/");
+    await shellReady(page);
+    await page.keyboard.press("Shift+?");
+    const dialog = helpDialog(page);
+    await expect(dialog).toBeVisible();
+    await expect(
+      dialog.locator('[data-slot="keyboard-shortcuts"] [data-group]'),
+    ).toHaveCount(3);
+    await expect(dialog.locator('[data-shortcut="go-d"] kbd')).toHaveText([
+      "g",
+      "d",
+    ]);
+
+    // Focus trap: Tab and Shift+Tab never leave the dialog.
+    for (const step of ["Tab", "Tab", "Tab", "Shift+Tab", "Shift+Tab"]) {
+      await page.keyboard.press(step);
+      expect(
+        await dialog.evaluate((el) => el.contains(document.activeElement)),
+      ).toBe(true);
+    }
+
+    // While the list is open, the page's shortcuts are off.
+    await page.keyboard.press("g");
+    await page.keyboard.press("i");
+    await expect(page).toHaveURL(/\/$/);
+
+    const axe = await new AxeBuilder({ page })
+      .include('[role="dialog"]')
+      .withTags(["wcag2a", "wcag2aa", "wcag21a", "wcag21aa"])
+      .analyze();
+    expect(axe.violations).toEqual([]);
+
+    await page.keyboard.press("Escape");
+    await expect(dialog).toHaveCount(0);
+  });
+
+  test("the account menu opens the same list", async ({ page }) => {
+    await page.goto("/");
+    await shellReady(page);
+    await page
+      .getByRole("button", { name: "User menu" })
+      .locator("visible=true")
+      .first()
+      .click();
+    await page.locator('[data-slot="open-keyboard-shortcuts"]').click();
+    await expect(helpDialog(page)).toBeVisible();
+  });
+
+  test("n opens the add menu", async ({ page }) => {
+    await page.goto("/insights");
+    await shellReady(page);
+    await page.keyboard.press("n");
+    await expect(page.getByTestId("capture-picker-options")).toBeVisible();
+    await page.keyboard.press("Escape");
+    await expect(page.getByTestId("capture-picker-options")).toHaveCount(0);
+  });
+
+  test("[ and ] step the open day, never past today", async ({ page }) => {
+    await page.setViewportSize({ width: 1440, height: 900 });
+    await mockDay(page);
+    const yesterday = shiftDay(TODAY, -1);
+    await page.goto(`/insights?day=${yesterday}`);
+    await shellReady(page);
+    const panel = page.locator('[data-slot="day-panel"]');
+    await expect(panel).toHaveAttribute("data-shell", "docked");
+    // Focus on the page, not in the panel: docked, the keys still reach it.
+    await page.locator("#main-content").focus();
+
+    await page.keyboard.press("[");
+    await expect(page).toHaveURL(new RegExp(`[?&]day=${shiftDay(TODAY, -2)}`));
+    await page.keyboard.press("]");
+    await page.keyboard.press("]");
+    await expect(page).toHaveURL(new RegExp(`[?&]day=${TODAY}`));
+    await page.keyboard.press("]");
+    await expect(page).toHaveURL(new RegExp(`[?&]day=${TODAY}`));
+  });
+});

messages/de.json

@@ -12554,6 +12554,22 @@
       "body": "Titel und Notiz sind danach nicht mehr da."
     }
   },
+  "shortcuts": {
+    "title": "Tastenkürzel",
+    "description": "Tasten, die überall in der App funktionieren, außer während du in ein Feld tippst.",
+    "menuEntry": "Tastenkürzel",
+    "then": "dann",
+    "help": "Diese Liste zeigen",
+    "close": "Dialog oder Bereich schließen",
+    "previousDay": "Vorheriger Tag",
+    "nextDay": "Nächster Tag",
+    "dayHint": "Während ein Tag geöffnet ist.",
+    "groups": {
+      "navigation": "Navigation",
+      "actions": "Aktionen",
+      "day": "Tag"
+    }
+  },
   "aboutPage": {
     "eyebrow": "Info",
     "title": "Über HealthLog",

messages/en.json

@@ -12554,6 +12554,22 @@
       "body": "Its title and note will be gone."
     }
   },
+  "shortcuts": {
+    "title": "Keyboard shortcuts",
+    "description": "Keys that work anywhere in the app, except while you type in a field.",
+    "menuEntry": "Keyboard shortcuts",
+    "then": "then",
+    "help": "Show this list",
+    "close": "Close a dialog or panel",
+    "previousDay": "Previous day",
+    "nextDay": "Next day",
+    "dayHint": "While a day is open.",
+    "groups": {
+      "navigation": "Navigation",
+      "actions": "Actions",
+      "day": "Day"
+    }
+  },
   "aboutPage": {
     "eyebrow": "About",
     "title": "About HealthLog",

messages/es.json

@@ -12554,6 +12554,22 @@
       "body": "Su título y su nota desaparecerán."
     }
   },
+  "shortcuts": {
+    "title": "Atajos de teclado",
+    "description": "Teclas que funcionan en toda la aplicación, salvo mientras escribes en un campo.",
+    "menuEntry": "Atajos de teclado",
+    "then": "luego",
+    "help": "Mostrar esta lista",
+    "close": "Cerrar un diálogo o panel",
+    "previousDay": "Día anterior",
+    "nextDay": "Día siguiente",
+    "dayHint": "Mientras hay un día abierto.",
+    "groups": {
+      "navigation": "Navegación",
+      "actions": "Acciones",
+      "day": "Día"
+    }
+  },
   "aboutPage": {
     "eyebrow": "Información",
     "title": "Acerca de HealthLog",

messages/fr.json

@@ -12554,6 +12554,22 @@
       "body": "Son titre et sa note disparaîtront."
     }
   },
+  "shortcuts": {
+    "title": "Raccourcis clavier",
+    "description": "Des touches qui fonctionnent partout dans l’application, sauf pendant la saisie dans un champ.",
+    "menuEntry": "Raccourcis clavier",
+    "then": "puis",
+    "help": "Afficher cette liste",
+    "close": "Fermer une boîte de dialogue ou un panneau",
+    "previousDay": "Jour précédent",
+    "nextDay": "Jour suivant",
+    "dayHint": "Lorsqu’un jour est ouvert.",
+    "groups": {
+      "navigation": "Navigation",
+      "actions": "Actions",
+      "day": "Jour"
+    }
+  },
   "aboutPage": {
     "eyebrow": "À propos",
     "title": "À propos de HealthLog",

messages/it.json

@@ -12554,6 +12554,22 @@
       "body": "Titolo e nota non ci saranno più."
     }
   },
+  "shortcuts": {
+    "title": "Scorciatoie da tastiera",
+    "description": "Tasti che funzionano ovunque nell’app, tranne mentre scrivi in un campo.",
+    "menuEntry": "Scorciatoie da tastiera",
+    "then": "poi",
+    "help": "Mostra questo elenco",
+    "close": "Chiudi una finestra o un pannello",
+    "previousDay": "Giorno precedente",
+    "nextDay": "Giorno successivo",
+    "dayHint": "Quando un giorno è aperto.",
+    "groups": {
+      "navigation": "Navigazione",
+      "actions": "Azioni",
+      "day": "Giorno"
+    }
+  },
   "aboutPage": {
     "eyebrow": "Informazioni",
     "title": "Informazioni su HealthLog",

messages/ko.json

@@ -12554,6 +12554,22 @@
       "body": "제목과 메모가 사라져요."
     }
   },
+  "shortcuts": {
+    "title": "키보드 단축키",
+    "description": "입력란에 입력하는 중이 아니면 앱 어디에서나 작동하는 키입니다.",
+    "menuEntry": "키보드 단축키",
+    "then": "다음",
+    "help": "이 목록 보기",
+    "close": "대화 상자나 패널 닫기",
+    "previousDay": "이전 날",
+    "nextDay": "다음 날",
+    "dayHint": "하루가 열려 있을 때.",
+    "groups": {
+      "navigation": "탐색",
+      "actions": "작업",
+      "day": "하루"
+    }
+  },
   "aboutPage": {
     "eyebrow": "정보",
     "title": "HealthLog 정보",

messages/pl.json

@@ -12554,6 +12554,22 @@
       "body": "Tytuł i notatka znikną."
     }
   },
+  "shortcuts": {
+    "title": "Skróty klawiszowe",
+    "description": "Klawisze działające w całej aplikacji, z wyjątkiem pisania w polu.",
+    "menuEntry": "Skróty klawiszowe",
+    "then": "potem",
+    "help": "Pokaż tę listę",
+    "close": "Zamknij okno lub panel",
+    "previousDay": "Poprzedni dzień",
+    "nextDay": "Następny dzień",
+    "dayHint": "Gdy otwarty jest dzień.",
+    "groups": {
+      "navigation": "Nawigacja",
+      "actions": "Akcje",
+      "day": "Dzień"
+    }
+  },
   "aboutPage": {
     "eyebrow": "Informacje",
     "title": "O HealthLog",

src/components/layout/__tests__/keyboard-shortcuts-dialog.test.tsx

@@ -0,0 +1,114 @@
+import { describe, expect, it, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+import { I18nProvider } from "@/lib/i18n/context";
+
+// The sheet primitive portals through Radix, which renders nothing on the
+// server; this stand-in keeps its contract (title + description name the
+// surface) so the list itself can be read. Focus trap and Escape are the
+// primitive's and are proven in `e2e/keyboard-shortcuts.spec.ts`.
+vi.mock("@/components/ui/responsive-sheet", () => ({
+  ResponsiveSheet: ({
+    open,
+    title,
+    description,
+    children,
+  }: {
+    open: boolean;
+    title: React.ReactNode;
+    description?: React.ReactNode;
+    children: React.ReactNode;
+  }) =>
+    open ? (
+      <section role="dialog" aria-label={String(title)}>
+        <h2>{title}</h2>
+        <p>{description}</p>
+        {children}
+      </section>
+    ) : null,
+}));
+
+import { KeyboardShortcutsDialog } from "../keyboard-shortcuts-dialog";
+
+const EVERYTHING = {
+  navHrefs: ["/", "/medications", "/labs", "/timeline", "/insights", "/coach"],
+  settingsHref: "/settings/account",
+};
+
+function render(
+  props: Partial<React.ComponentProps<typeof KeyboardShortcutsDialog>> = {},
+  locale = "en",
+) {
+  return renderToStaticMarkup(
+    <I18nProvider initialLocale={locale as "en"}>
+      <KeyboardShortcutsDialog
+        open
+        onOpenChange={() => undefined}
+        offer={EVERYTHING}
+        canCapture
+        {...props}
+      />
+    </I18nProvider>,
+  );
+}
+
+describe("<KeyboardShortcutsDialog>", () => {
+  it("renders nothing while closed", () => {
+    expect(render({ open: false })).toBe("");
+  });
+
+  it("is titled and lists three groups", () => {
+    const html = render();
+    expect(html).toContain('aria-label="Keyboard shortcuts"');
+    expect(html).toContain('data-group="navigation"');
+    expect(html).toContain('data-group="actions"');
+    expect(html).toContain('data-group="day"');
+  });
+
+  it("shows every destination as g then its key, in kbd", () => {
+    const html = render();
+    for (const k of ["d", "m", "l", "t", "i", "c", "s"]) {
+      expect(html).toContain(`data-shortcut="go-${k}"`);
+    }
+    expect(html).toMatch(/<kbd[^>]*>g<\/kbd>/);
+    expect(html).toContain(">then<");
+    expect(html).toMatch(/<kbd[^>]*>\?<\/kbd>/);
+    expect(html).toMatch(/<kbd[^>]*>\[<\/kbd>/);
+    expect(html).toMatch(/<kbd[^>]*>\]<\/kbd>/);
+    expect(html).toMatch(/<kbd[^>]*>Esc<\/kbd>/);
+  });
+
+  it("drops a destination the session does not offer", () => {
+    const html = render({
+      offer: { navHrefs: ["/", "/insights"], settingsHref: null },
+    });
+    expect(html).toContain('data-shortcut="go-d"');
+    expect(html).toContain('data-shortcut="go-i"');
+    for (const k of ["m", "l", "t", "c", "s"]) {
+      expect(html).not.toContain(`data-shortcut="go-${k}"`);
+    }
+  });
+
+  it("drops n where there is nothing to log", () => {
+    expect(render({ canCapture: false })).not.toContain(
+      'data-shortcut="capture"',
+    );
+    expect(render()).toContain('data-shortcut="capture"');
+  });
+
+  it("uses token classes for the keys, no raw colour", () => {
+    const kbd = render().match(/<kbd class="([^"]+)"/)?.[1] ?? "";
+    expect(kbd).toContain("bg-muted");
+    expect(kbd).toContain("text-foreground");
+    expect(kbd).not.toMatch(/#[0-9a-f]{3,6}|dracula|\[/i);
+  });
+
+  it.each(["de", "es", "fr", "it", "pl", "ko"])(
+    "is translated in %s",
+    (locale) => {
+      const html = render({}, locale);
+      expect(html).not.toContain('aria-label="Keyboard shortcuts"');
+      expect(html).not.toContain("shortcuts.");
+    },
+  );
+});

src/components/layout/auth-shell.tsx

@@ -24,6 +24,7 @@ import { CoachLaunchProvider } from "@/lib/insights/coach-launch-context";
 import { isManageDelegateSettingsDestination } from "@/lib/record-settings/classification";
 import { isDestinationInSharedRecord } from "./nav-model";
 import { BottomNav } from "./bottom-nav";
+import { GlobalShortcuts } from "./global-shortcuts";
 import { DemoBanner } from "./demo-banner";
 import { OfflineBanner } from "./offline-banner";
 import { SharedRecordBanner } from "./shared-record-banner";
@@ -579,6 +580,10 @@ export function AuthShell({
           got a raw 403. Demo is read-only by design; the FAB has no job
           here, so it's mounted only outside demo mode. */}
       {!demoMode && !inSharedRecord && <LayoutCoachFab />}
+      {/* v1.42 — the keyboard shortcuts (`g d`, `n`, `?` …) and their list.
+          Mounted here and only here, so they never run on the sign-in pages
+          or in the setup flow, which return above. */}
+      <GlobalShortcuts />
     </CoachLaunchProvider>
   );
 }

src/components/layout/global-shortcuts.tsx

@@ -0,0 +1,185 @@
+"use client";
+
+import { useRouter } from "next/navigation";
+import {
+  useEffect,
+  useMemo,
+  useRef,
+  useState,
+  useSyncExternalStore,
+} from "react";
+
+import { stepDay, useOpenDay } from "@/components/day/day-layer-controller";
+import { useTodayKey } from "@/components/day/use-today-key";
+import {
+  CAPTURE_KIND_ORDER,
+  CapturePicker,
+  visibleCaptureKinds,
+} from "@/components/layout/capture-picker";
+import { KeyboardShortcutsDialog } from "@/components/layout/keyboard-shortcuts-dialog";
+import {
+  isSettingsUtilityDestination,
+  visibleNavDestinations,
+  visibleUtilityDestinations,
+} from "@/components/layout/nav-model";
+import { useAuth } from "@/hooks/use-auth";
+import { useNavModules } from "@/hooks/use-nav-modules";
+import { useRecordCapabilities } from "@/hooks/use-record-capabilities";
+import {
+  createShortcutReader,
+  resolveGoTo,
+  shortcutScope,
+  type ShortcutOffer,
+} from "@/lib/keyboard/global-shortcuts";
+
+/**
+ * The app-wide keyboard shortcuts, mounted once by the authenticated shell
+ * (never on the sign-in pages or in the setup flow, which the shell renders
+ * without it).
+ *
+ * `g` + a key opens a page, `n` the add menu, `[` / `]` step the open day,
+ * `?` the list of all of them. Which key does what, and when a key is not
+ * ours, is decided in `src/lib/keyboard/global-shortcuts.ts`; this component
+ * reads the page's state and carries the action out. A destination comes from
+ * the same lists the navigation renders, so `g t` with the timeline module
+ * off, or `g c` without an AI provider, does nothing at all.
+ *
+ * The account menu opens the list too (`openShortcutsHelp`), for anyone who
+ * does not know there is a `?` to press.
+ */
+
+let helpOpen = false;
+const helpListeners = new Set<() => void>();
+
+function setShortcutsHelpOpen(open: boolean): void {
+  if (helpOpen === open) return;
+  helpOpen = open;
+  for (const listener of helpListeners) listener();
+}
+
+function subscribeHelp(listener: () => void): () => void {
+  helpListeners.add(listener);
+  return () => helpListeners.delete(listener);
+}
+
+/** Open the shortcut list from anywhere inside the signed-in shell. */
+export function openShortcutsHelp(): void {
+  setShortcutsHelpOpen(true);
+}
+
+function useShortcutOffer(): ShortcutOffer & { canCapture: boolean } {
+  const { user } = useAuth();
+  const navModules = useNavModules();
+  const capabilities = useRecordCapabilities();
+  const { inSharedRecord, sections, recordKind, level } = capabilities;
+  const manageableDomains = user?.accountAccess?.active?.manageableDomains;
+  const canCapture =
+    visibleCaptureKinds(capabilities, CAPTURE_KIND_ORDER, user?.modules)
+      .length > 0;
+  const navHrefs = useMemo(
+    () =>
+      visibleNavDestinations(navModules, true, inSharedRecord, sections).map(
+        (d) => d.href,
+      ),
+    [navModules, inSharedRecord, sections],
+  );
+  const settingsHref = useMemo(
+    () =>
+      visibleUtilityDestinations({
+        record: inSharedRecord
+          ? { recordKind, level, manageableDomains: manageableDomains ?? [] }
+          : null,
+      }).find(isSettingsUtilityDestination)?.href ?? null,
+    [inSharedRecord, recordKind, level, manageableDomains],
+  );
+  return { navHrefs, settingsHref, canCapture };
+}
+
+export function GlobalShortcuts() {
+  const router = useRouter();
+  const open = useSyncExternalStore(
+    subscribeHelp,
+    () => helpOpen,
+    () => false,
+  );
+  const [captureOpen, setCaptureOpen] = useState(false);
+  const offer = useShortcutOffer();
+  const openDay = useOpenDay();
+  const today = useTodayKey();
+
+  // The listener is registered once; it reads the current state from here.
+  const latest = useRef({ offer, openDay, today, router });
+  useEffect(() => {
+    latest.current = { offer, openDay, today, router };
+  });
+
+  useEffect(() => {
+    const reader = createShortcutReader();
+    const onKeyDown = (event: KeyboardEvent) => {
+      if (event.defaultPrevented) return;
+      const action = reader.read(
+        {
+          key: event.key,
+          altKey: event.altKey,
+          ctrlKey: event.ctrlKey,
+          metaKey: event.metaKey,
+          altGraph: event.getModifierState?.("AltGraph") ?? false,
+          repeat: event.repeat,
+          isComposing: event.isComposing,
+          target: event.target,
+        },
+        shortcutScope(document),
+        event.timeStamp,
+      );
+      if (action === null || action === "pending") return;
+      const state = latest.current;
+      switch (action.type) {
+        case "go": {
+          const href = resolveGoTo(action.key, state.offer);
+          if (href === null) return;
+          event.preventDefault();
+          state.router.push(href);
+          return;
+        }
+        case "capture":
+          if (!state.offer.canCapture) return;
+          event.preventDefault();
+          setCaptureOpen(true);
+          return;
+        case "help":
+          event.preventDefault();
+          setShortcutsHelpOpen(true);
+          return;
+        case "day": {
+          const date = state.openDay;
+          if (date === null) return;
+          event.preventDefault();
+          // No day after today: the layer refuses it, so the step does too.
+          if (action.delta > 0 && date >= state.today) return;
+          stepDay(date, action.delta);
+          return;
+        }
+      }
+    };
+    document.addEventListener("keydown", onKeyDown);
+    return () => {
+      document.removeEventListener("keydown", onKeyDown);
+      // Leaving the shell (signing out) leaves the list closed.
+      setShortcutsHelpOpen(false);
+    };
+  }, []);
+
+  return (
+    <>
+      <KeyboardShortcutsDialog
+        open={open}
+        onOpenChange={setShortcutsHelpOpen}
+        offer={offer}
+        canCapture={offer.canCapture}
+      />
+      {offer.canCapture ? (
+        <CapturePicker open={captureOpen} onOpenChange={setCaptureOpen} />
+      ) : null}
+    </>
+  );
+}

src/components/layout/keyboard-shortcuts-dialog.tsx

@@ -0,0 +1,158 @@
+"use client";
+
+import { Fragment } from "react";
+
+import { NAV_DESTINATIONS } from "@/components/layout/nav-model";
+import { ResponsiveSheet } from "@/components/ui/responsive-sheet";
+import { useTranslations } from "@/lib/i18n/context";
+import {
+  GO_TO_SHORTCUTS,
+  resolveGoTo,
+  type ShortcutOffer,
+} from "@/lib/keyboard/global-shortcuts";
+
+/**
+ * The list of keyboard shortcuts, opened with `?` or from the account menu.
+ *
+ * It lists what works for this session: a destination whose module is off,
+ * or a Coach without an AI provider, is not offered by `g` and is not listed
+ * either. Key names are literal keys, not translated words.
+ */
+export interface KeyboardShortcutsDialogProps {
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  offer: ShortcutOffer;
+  /** Whether `n` has anything to open (a read-only record has not). */
+  canCapture: boolean;
+}
+
+interface Row {
+  id: string;
+  label: string;
+  /** Keys pressed one after the other. */
+  sequence: ReadonlyArray<string>;
+}
+
+function Kbd({ children }: { children: string }) {
+  // Foreground, not muted: a key name has to be readable at a glance, and
+  // the muted token sits under the contrast floor on the muted wash.
+  return (
+    <kbd className="border-border bg-muted text-foreground inline-flex min-w-6 items-center justify-center rounded border px-1.5 py-0.5 font-mono text-xs">
+      {children}
+    </kbd>
+  );
+}
+
+export function KeyboardShortcutsDialog({
+  open,
+  onOpenChange,
+  offer,
+  canCapture,
+}: KeyboardShortcutsDialogProps) {
+  const { t } = useTranslations();
+
+  const navigation: Row[] = GO_TO_SHORTCUTS.flatMap((shortcut) => {
+    if (resolveGoTo(shortcut.key, offer) === null) return [];
+    const tKey =
+      shortcut.destination === "settings"
+        ? "nav.settings"
+        : NAV_DESTINATIONS.find((d) => d.href === shortcut.destination)?.tKey;
+    if (!tKey) return [];
+    return [
+      {
+        id: `go-${shortcut.key}`,
+        label: t(tKey),
+        sequence: ["g", shortcut.key],
+      },
+    ];
+  });
+
+  const actions: Row[] = [
+    ...(canCapture
+      ? [
+          {
+            id: "capture",
+            label: t("nav.capture.title"),
+            sequence: ["n"],
+          },
+        ]
+      : []),
+    { id: "help", label: t("shortcuts.help"), sequence: ["?"] },
+    { id: "close", label: t("shortcuts.close"), sequence: ["Esc"] },
+  ];
+
+  const day: Row[] = [
+    { id: "day-previous", label: t("shortcuts.previousDay"), sequence: ["["] },
+    { id: "day-next", label: t("shortcuts.nextDay"), sequence: ["]"] },
+  ];
+
+  const groups = [
+    {
+      id: "navigation",
+      title: t("shortcuts.groups.navigation"),
+      rows: navigation,
+    },
+    { id: "actions", title: t("shortcuts.groups.actions"), rows: actions },
+    {
+      id: "day",
+      title: t("shortcuts.groups.day"),
+      hint: t("shortcuts.dayHint"),
+      rows: day,
+    },
+  ].filter((group) => group.rows.length > 0);
+
+  return (
+    <ResponsiveSheet
+      open={open}
+      onOpenChange={onOpenChange}
+      title={t("shortcuts.title")}
+      description={t("shortcuts.description")}
+    >
+      <div data-slot="keyboard-shortcuts" className="flex flex-col gap-6">
+        {groups.map((group) => (
+          <section
+            key={group.id}
+            data-group={group.id}
+            aria-labelledby={`shortcuts-group-${group.id}`}
+            className="flex flex-col gap-2"
+          >
+            <div className="flex flex-col gap-1">
+              <h3
+                id={`shortcuts-group-${group.id}`}
+                className="text-muted-foreground text-xs font-medium tracking-wide uppercase"
+              >
+                {group.title}
+              </h3>
+              {"hint" in group && group.hint ? (
+                <p className="text-muted-foreground text-xs">{group.hint}</p>
+              ) : null}
+            </div>
+            <dl className="flex flex-col gap-2">
+              {group.rows.map((row) => (
+                <div
+                  key={row.id}
+                  data-shortcut={row.id}
+                  className="flex items-center justify-between gap-3"
+                >
+                  <dt className="min-w-0 flex-1 text-sm">{row.label}</dt>
+                  <dd className="flex shrink-0 items-center gap-1.5">
+                    {row.sequence.map((key, index) => (
+                      <Fragment key={`${row.id}-${index}`}>
+                        {index > 0 ? (
+                          <span className="text-muted-foreground text-xs">
+                            {t("shortcuts.then")}
+                          </span>
+                        ) : null}
+                        <Kbd>{key}</Kbd>
+                      </Fragment>
+                    ))}
+                  </dd>
+                </div>
+              ))}
+            </dl>
+          </section>
+        ))}
+      </div>
+    </ResponsiveSheet>
+  );
+}

src/components/layout/sidebar-nav.tsx

@@ -3,6 +3,7 @@
 import { useEffect, useMemo, useRef, useState } from "react";
 import {
   Bell,
+  Keyboard,
   LogOut,
   Monitor,
   Moon,
@@ -17,6 +18,7 @@ import Link from "next/link";
 import { usePathname } from "next/navigation";
 import { useQueryClient } from "@tanstack/react-query";
 import { AccountSwitcherMenuItems } from "@/components/layout/account-switcher-menu";
+import { openShortcutsHelp } from "@/components/layout/global-shortcuts";
 import { medicationsPrefetchIntentProps } from "@/lib/queries/prefetch-medications";
 import {
   isNavDestinationActive,
@@ -46,6 +48,7 @@ import {
   DropdownMenuContent,
   DropdownMenuItem,
   DropdownMenuSeparator,
+  DropdownMenuShortcut,
   DropdownMenuSub,
   DropdownMenuSubContent,
   DropdownMenuSubTrigger,
@@ -200,6 +203,19 @@ function SidebarUserSection({ collapsed }: { collapsed: boolean }) {
           </Link>
         </DropdownMenuItem>
       )}
+      {/* v1.42 — the keyboard shortcuts, findable without knowing that `?`
+          lists them. Desktop only, like this menu: the phone's account menu
+          has no keyboard to describe. */}
+      <DropdownMenuItem
+        data-slot="open-keyboard-shortcuts"
+        aria-keyshortcuts="?"
+        onSelect={() => openShortcutsHelp()}
+        className="cursor-pointer"
+      >
+        <Keyboard className="mr-2 h-4 w-4" />
+        {t("shortcuts.menuEntry")}
+        <DropdownMenuShortcut aria-hidden="true">?</DropdownMenuShortcut>
+      </DropdownMenuItem>
       {/* The about section lives at the end of the settings shell nav;
           the avatar menu stays focused on account-level actions. */}
       <DropdownMenuSub>

src/lib/keyboard/__tests__/global-shortcuts.test.ts

@@ -0,0 +1,285 @@
+import { describe, expect, it } from "vitest";
+
+import { visibleNavDestinations } from "@/components/layout/nav-model";
+import {
+  SEQUENCE_TIMEOUT_MS,
+  blockedByModifier,
+  createShortcutReader,
+  isEditableTarget,
+  resolveGoTo,
+  shortcutScope,
+  type ShortcutKeyEvent,
+} from "@/lib/keyboard/global-shortcuts";
+
+function key(
+  k: string,
+  over: Partial<ShortcutKeyEvent> = {},
+): ShortcutKeyEvent {
+  return {
+    key: k,
+    altKey: false,
+    ctrlKey: false,
+    metaKey: false,
+    target: null,
+    ...over,
+  };
+}
+
+/** An element whose `closest` answers for the selectors it matches. */
+function element(matches: (selector: string) => boolean) {
+  return {
+    closest: (selector: string) =>
+      selector.split(", ").some((s) => matches(s)) ? {} : null,
+  };
+}
+
+const input = element((s) => s === "input");
+const textarea = element((s) => s === "textarea");
+const select = element((s) => s === "select");
+const combobox = element((s) => s === '[role="combobox"]');
+const editable = { isContentEditable: true, closest: () => null };
+const button = element(() => false);
+
+describe("isEditableTarget", () => {
+  it("treats fields, comboboxes and contenteditable as the field's", () => {
+    for (const target of [input, textarea, select, combobox, editable]) {
+      expect(isEditableTarget(target)).toBe(true);
+    }
+  });
+
+  it("leaves buttons, the body and non-elements to the shortcuts", () => {
+    expect(isEditableTarget(button)).toBe(false);
+    expect(isEditableTarget(null)).toBe(false);
+    expect(isEditableTarget(undefined)).toBe(false);
+    expect(isEditableTarget({})).toBe(false);
+  });
+});
+
+describe("the reader ignores keys typed into a field", () => {
+  it.each([
+    ["input", input],
+    ["textarea", textarea],
+    ["select", select],
+    ["combobox", combobox],
+    ["contenteditable", editable],
+  ])("%s: no action for g d, n, ? or [", (_name, target) => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("g", { target }), "page", 0)).toBeNull();
+    expect(reader.read(key("d", { target }), "page", 10)).toBeNull();
+    expect(reader.read(key("n", { target }), "page", 20)).toBeNull();
+    expect(reader.read(key("?", { target }), "page", 30)).toBeNull();
+    expect(reader.read(key("[", { target }), "page", 40)).toBeNull();
+  });
+
+  it("a field between g and d breaks the sequence", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("g"), "page", 0)).toBe("pending");
+    expect(reader.read(key("d", { target: input }), "page", 10)).toBeNull();
+    expect(reader.read(key("d"), "page", 20)).toBeNull();
+  });
+});
+
+describe("modifiers", () => {
+  it("Cmd, Ctrl and Alt make a letter somebody else's", () => {
+    const reader = createShortcutReader();
+    for (const over of [
+      { metaKey: true },
+      { ctrlKey: true },
+      { altKey: true },
+    ]) {
+      expect(reader.read(key("n", over), "page", 0)).toBeNull();
+      expect(reader.read(key("g", over), "page", 0)).toBeNull();
+    }
+    expect(reader.read(key("?", { metaKey: true }), "page", 0)).toBeNull();
+    expect(reader.read(key("?", { ctrlKey: true }), "page", 0)).toBeNull();
+  });
+
+  it("a modified second key does not complete g", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("g"), "page", 0)).toBe("pending");
+    expect(reader.read(key("d", { metaKey: true }), "page", 10)).toBeNull();
+    expect(reader.read(key("d"), "page", 20)).toBeNull();
+  });
+
+  it("Shift alone, pressed to type ?, neither acts nor breaks a sequence", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("Shift"), "page", 0)).toBeNull();
+    expect(reader.read(key("?"), "page", 5)).toEqual({ type: "help" });
+    expect(reader.read(key("g"), "page", 10)).toBe("pending");
+    expect(reader.read(key("Shift"), "page", 20)).toBeNull();
+    expect(reader.read(key("D"), "page", 30)).toEqual({ type: "go", key: "d" });
+  });
+
+  it("[ typed with Option (German Mac) or AltGr (German PC) still steps the day", () => {
+    expect(blockedByModifier(key("[", { altKey: true }))).toBe(false);
+    expect(
+      blockedByModifier(
+        key("]", { altKey: true, ctrlKey: true, altGraph: true }),
+      ),
+    ).toBe(false);
+    // Ctrl+Alt without AltGr is a command, not a layout key.
+    expect(blockedByModifier(key("[", { altKey: true, ctrlKey: true }))).toBe(
+      true,
+    );
+    expect(blockedByModifier(key("[", { metaKey: true }))).toBe(true);
+    // An Alt+arrow is the day layer's own step and stays its own.
+    expect(blockedByModifier(key("ArrowLeft", { altKey: true }))).toBe(true);
+  });
+});
+
+describe("sequence timing", () => {
+  it("g then a destination within the window goes there", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("g"), "page", 1000)).toBe("pending");
+    expect(reader.read(key("t"), "page", 1000 + SEQUENCE_TIMEOUT_MS)).toEqual({
+      type: "go",
+      key: "t",
+    });
+  });
+
+  it("a second key after the window does nothing", () => {
+    const reader = createShortcutReader();
+    reader.read(key("g"), "page", 0);
+    expect(reader.read(key("t"), "page", SEQUENCE_TIMEOUT_MS + 1)).toBeNull();
+  });
+
+  it("a destination key without g does nothing", () => {
+    const reader = createShortcutReader();
+    for (const k of ["d", "t", "c", "m", "l", "i", "s"]) {
+      expect(reader.read(key(k), "page", 0)).toBeNull();
+    }
+  });
+
+  it("an unknown second key cancels; it does not fall through to n", () => {
+    const reader = createShortcutReader();
+    reader.read(key("g"), "page", 0);
+    expect(reader.read(key("n"), "page", 10)).toBeNull();
+    expect(reader.read(key("d"), "page", 20)).toBeNull();
+  });
+
+  it("g g restarts the window", () => {
+    const reader = createShortcutReader();
+    reader.read(key("g"), "page", 0);
+    expect(reader.read(key("g"), "page", 900)).toBe("pending");
+    expect(reader.read(key("s"), "page", 1800)).toEqual({
+      type: "go",
+      key: "s",
+    });
+  });
+
+  it("a held key does not repeat the action", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("n", { repeat: true }), "page", 0)).toBeNull();
+  });
+
+  it("reset forgets a pending g", () => {
+    const reader = createShortcutReader();
+    reader.read(key("g"), "page", 0);
+    reader.reset();
+    expect(reader.read(key("d"), "page", 10)).toBeNull();
+  });
+});
+
+describe("scope", () => {
+  it("an open dialog, menu or popover takes every key", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("n"), "off", 0)).toBeNull();
+    expect(reader.read(key("?"), "off", 0)).toBeNull();
+    expect(reader.read(key("["), "off", 0)).toBeNull();
+    reader.read(key("g"), "page", 0);
+    expect(reader.read(key("d"), "off", 10)).toBeNull();
+  });
+
+  it("over the day sheet only [ and ] act", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("["), "day-sheet", 0)).toEqual({
+      type: "day",
+      delta: -1,
+    });
+    expect(reader.read(key("]"), "day-sheet", 0)).toEqual({
+      type: "day",
+      delta: 1,
+    });
+    expect(reader.read(key("n"), "day-sheet", 0)).toBeNull();
+    expect(reader.read(key("g"), "day-sheet", 0)).toBeNull();
+  });
+
+  it("Escape is never ours", () => {
+    const reader = createShortcutReader();
+    expect(reader.read(key("Escape"), "page", 0)).toBeNull();
+  });
+
+  it("reads the scope from the open surfaces", () => {
+    const none = { querySelectorAll: () => [] };
+    expect(shortcutScope(none)).toBe("page");
+    const daySheet = {
+      querySelectorAll: () => [
+        {
+          closest: (s: string) => (s === '[data-slot="day-panel"]' ? {} : null),
+        },
+      ],
+    };
+    expect(shortcutScope(daySheet)).toBe("day-sheet");
+    const other = { querySelectorAll: () => [{ closest: () => null }] };
+    expect(shortcutScope(other)).toBe("off");
+    const both = {
+      querySelectorAll: () => [
+        {
+          closest: (s: string) => (s === '[data-slot="day-panel"]' ? {} : null),
+        },
+        { closest: () => null },
+      ],
+    };
+    expect(shortcutScope(both)).toBe("off");
+  });
+});
+
+describe("module gating", () => {
+  function offer(modules: Record<string, boolean> | undefined) {
+    return {
+      navHrefs: visibleNavDestinations(modules).map((d) => d.href),
+      settingsHref: "/settings/account",
+    };
+  }
+
+  it("g t goes nowhere while the timeline module is off", () => {
+    expect(resolveGoTo("t", offer({ timeline: false }))).toBeNull();
+    expect(resolveGoTo("t", offer({ timeline: true }))).toBe("/timeline");
+  });
+
+  it("g m and g l follow the medications and labs modules", () => {
+    expect(resolveGoTo("m", offer({ medications: false }))).toBeNull();
+    expect(resolveGoTo("l", offer({ labs: false }))).toBeNull();
+    expect(resolveGoTo("m", offer({ medications: true }))).toBe("/medications");
+    expect(resolveGoTo("l", offer({ labs: true }))).toBe("/labs");
+  });
+
+  it("g c follows the coach entry, which carries the AI capability", () => {
+    // `useNavModules` folds the capability into `coach`.
+    expect(resolveGoTo("c", offer({ coach: false }))).toBeNull();
+    expect(resolveGoTo("c", offer({ coach: true }))).toBe("/coach");
+  });
+
+  it("g d and g i belong to no module", () => {
+    const off = offer({ timeline: false, labs: false, medications: false });
+    expect(resolveGoTo("d", off)).toBe("/");
+    expect(resolveGoTo("i", off)).toBe("/insights");
+  });
+
+  it("inside a shared record the doors sharing does not cover stay shut", () => {
+    const shared = {
+      navHrefs: visibleNavDestinations({}, true, true).map((d) => d.href),
+      settingsHref: null,
+    };
+    expect(resolveGoTo("i", shared)).toBeNull();
+    expect(resolveGoTo("c", shared)).toBeNull();
+    expect(resolveGoTo("s", shared)).toBeNull();
+    expect(resolveGoTo("d", shared)).toBe("/");
+  });
+
+  it("g s lands where the Settings entry lands", () => {
+    expect(
+      resolveGoTo("s", { navHrefs: [], settingsHref: "/settings/profile" }),
+    ).toBe("/settings/profile");
+  });
+});

src/lib/keyboard/global-shortcuts.ts

@@ -0,0 +1,239 @@
+/**
+ * The app-wide keyboard shortcuts, as pure logic.
+ *
+ * The listener in `src/components/layout/global-shortcuts.tsx` hands every
+ * keydown to `createShortcutReader().read()` together with the scope the page
+ * is in, and gets back an action, a "wait for the second key", or nothing.
+ * Everything that decides whether a key is ours lives here, so it can be
+ * pinned without a DOM:
+ *
+ *   - a key typed into a field is the field's (`isEditableTarget`);
+ *   - a key held with Cmd, Ctrl or Alt belongs to the browser, the operating
+ *     system or a screen reader (`blockedByModifier`), with one exception: a
+ *     punctuation key the layout itself needs Alt or AltGr to type (`[` is
+ *     Option+5 on a German Mac, AltGr+8 on a German PC) still counts, because
+ *     for that person there is no other way to press it;
+ *   - while a dialog, sheet, menu or popover is open the keys are its own,
+ *     except over the day sheet, where `[` and `]` step the day it shows.
+ *
+ * `g` starts a two-key sequence; the second key has to follow within
+ * `SEQUENCE_TIMEOUT_MS`. Escape is never handled here: every surface closes
+ * itself on it, as before.
+ */
+
+/** How long `g` waits for its second key. */
+export const SEQUENCE_TIMEOUT_MS = 1000;
+
+/**
+ * `g` + key: where it goes. The destination is a nav href, or `settings`,
+ * which lands wherever the Settings entry of the account menu lands (it
+ * differs inside a shared record). Listed in navigation order, which is the
+ * order the help dialog shows them in.
+ */
+export const GO_TO_SHORTCUTS = [
+  { key: "d", destination: "/" },
+  { key: "m", destination: "/medications" },
+  { key: "l", destination: "/labs" },
+  { key: "t", destination: "/timeline" },
+  { key: "i", destination: "/insights" },
+  { key: "c", destination: "/coach" },
+  { key: "s", destination: "settings" },
+] as const;
+
+export type GoToKey = (typeof GO_TO_SHORTCUTS)[number]["key"];
+
+export type ShortcutAction =
+  | { type: "go"; key: GoToKey }
+  | { type: "capture" }
+  | { type: "help" }
+  | { type: "day"; delta: -1 | 1 };
+
+/**
+ * Where the keyboard is:
+ *  - `page`: nothing modal is open, every shortcut applies;
+ *  - `day-sheet`: the day sheet is the only modal surface, `[` / `]` apply;
+ *  - `off`: another dialog, sheet, menu or popover has the keys.
+ */
+export type ShortcutScope = "page" | "day-sheet" | "off";
+
+/** What the reader needs from a `KeyboardEvent`. */
+export interface ShortcutKeyEvent {
+  key: string;
+  altKey: boolean;
+  ctrlKey: boolean;
+  metaKey: boolean;
+  /** `event.getModifierState("AltGraph")`. */
+  altGraph?: boolean;
+  repeat?: boolean;
+  isComposing?: boolean;
+  target?: unknown;
+}
+
+/** Keys a layout may need Alt or AltGr for, and that still count then. */
+const LAYOUT_CHARACTERS: ReadonlySet<string> = new Set(["[", "]", "?"]);
+
+/** Pressing one of these alone never starts, ends or breaks a shortcut. */
+const MODIFIER_KEYS: ReadonlySet<string> = new Set([
+  "Shift",
+  "Control",
+  "Alt",
+  "AltGraph",
+  "Meta",
+  "CapsLock",
+  "Fn",
+  "OS",
+]);
+
+/** Something a person types into, by element or by role. */
+const EDITABLE_SELECTOR = [
+  "input",
+  "textarea",
+  "select",
+  '[contenteditable]:not([contenteditable="false"])',
+  '[role="combobox"]',
+  '[role="textbox"]',
+  '[role="searchbox"]',
+  '[role="spinbutton"]',
+].join(", ");
+
+/** Open surfaces that own the keyboard while they are up. */
+export const MODAL_SURFACE_SELECTOR = [
+  '[role="dialog"][data-state="open"]',
+  '[role="alertdialog"][data-state="open"]',
+  '[aria-modal="true"]',
+  '[role="menu"][data-state="open"]',
+  '[role="listbox"][data-state="open"]',
+].join(", ");
+
+/** The day layer's frame, docked or as a sheet (`day-layer.tsx`). */
+const DAY_PANEL_SELECTOR = '[data-slot="day-panel"]';
+
+/** True when the key went to a field, which keeps every key it gets. */
+export function isEditableTarget(target: unknown): boolean {
+  if (target === null || typeof target !== "object") return false;
+  const el = target as {
+    isContentEditable?: boolean;
+    closest?: (selector: string) => unknown;
+  };
+  if (el.isContentEditable === true) return true;
+  if (typeof el.closest !== "function") return false;
+  return el.closest(EDITABLE_SELECTOR) != null;
+}
+
+/**
+ * True when a modifier makes the key somebody else's: Cmd and Ctrl always
+ * (browser and screen-reader commands), Alt unless the layout needs it to
+ * type one of our punctuation keys. Shift is free: it is how `?` is typed.
+ */
+export function blockedByModifier(event: ShortcutKeyEvent): boolean {
+  if (event.metaKey) return true;
+  const altGraph = event.altGraph === true;
+  // AltGr reports as Ctrl+Alt on Windows; it is a layout key, not a command.
+  if (event.ctrlKey && !altGraph) return true;
+  if ((event.altKey || altGraph) && !LAYOUT_CHARACTERS.has(event.key)) {
+    return true;
+  }
+  return false;
+}
+
+/** The scope the page is in, read from the open surfaces. */
+export function shortcutScope(root: {
+  querySelectorAll: (selector: string) => ArrayLike<unknown>;
+}): ShortcutScope {
+  const open = Array.from(root.querySelectorAll(MODAL_SURFACE_SELECTOR));
+  if (open.length === 0) return "page";
+  const onlyDay = open.every((el) => {
+    const node = el as { closest?: (selector: string) => unknown };
+    return (
+      typeof node.closest === "function" &&
+      node.closest(DAY_PANEL_SELECTOR) != null
+    );
+  });
+  return onlyDay ? "day-sheet" : "off";
+}
+
+function normalise(key: string): string {
+  return key.length === 1 ? key.toLowerCase() : key;
+}
+
+function isGoToKey(key: string): key is GoToKey {
+  return GO_TO_SHORTCUTS.some((shortcut) => shortcut.key === key);
+}
+
+/**
+ * A reader with the one piece of state a sequence needs: when `g` was
+ * pressed. `read` returns the action a key completes, `"pending"` after `g`,
+ * or `null` for a key that is not ours (which also drops a pending `g`).
+ */
+export function createShortcutReader(timeoutMs = SEQUENCE_TIMEOUT_MS) {
+  let pendingSince: number | null = null;
+
+  function read(
+    event: ShortcutKeyEvent,
+    scope: ShortcutScope,
+    now: number,
+  ): ShortcutAction | "pending" | null {
+    if (event.isComposing) return null;
+    if (MODIFIER_KEYS.has(event.key)) return null;
+    if (event.repeat) return null;
+
+    const pending = pendingSince;
+    pendingSince = null;
+
+    if (scope === "off") return null;
+    if (isEditableTarget(event.target)) return null;
+    if (blockedByModifier(event)) return null;
+
+    const key = normalise(event.key);
+
+    if (key === "[" || key === "]") {
+      return { type: "day", delta: key === "[" ? -1 : 1 };
+    }
+    if (scope !== "page") return null;
+
+    if (pending !== null && now - pending <= timeoutMs) {
+      // The second key of a sequence: a destination, or nothing at all, so
+      // a mistyped `g n` does not open the add menu.
+      if (isGoToKey(key)) return { type: "go", key };
+      if (key !== "g") return null;
+    }
+    if (key === "g") {
+      pendingSince = now;
+      return "pending";
+    }
+    if (key === "n") return { type: "capture" };
+    if (key === "?") return { type: "help" };
+    return null;
+  }
+
+  return {
+    read,
+    /** Forget a pending `g`. */
+    reset() {
+      pendingSince = null;
+    },
+  };
+}
+
+/** What this session may open, as the navigation offers it. */
+export interface ShortcutOffer {
+  /** The hrefs of the visible nav destinations. */
+  navHrefs: ReadonlyArray<string>;
+  /** Where the Settings entry lands, or null when there is none. */
+  settingsHref: string | null;
+}
+
+/**
+ * The href `g` + `key` opens, or null when the destination is not offered: a
+ * switched-off module, a Coach without an AI provider, a page a shared record
+ * does not cover. Read from the same lists the navigation renders, so a
+ * shortcut never opens a door the sidebar does not show.
+ */
+export function resolveGoTo(key: GoToKey, offer: ShortcutOffer): string | null {
+  const shortcut = GO_TO_SHORTCUTS.find((s) => s.key === key);
+  if (!shortcut) return null;
+  if (shortcut.destination === "settings") return offer.settingsHref;
+  return offer.navHrefs.includes(shortcut.destination)
+    ? shortcut.destination
+    : null;
+}