fix(visits): open an upcoming appointment where it lives

Visits are the second tab of `/checkups`, and the bare path opens the
first one, the preventive-care list, which never shows an appointment.
Every surface that listed an upcoming appointment linked it there: the
dashboard's next-appointment line, the Today rail item, the Today
overview fact and the appointment's push notification. A tap on the
appointment landed on the list it is not on.

Each now opens the visit itself (`/checkups?visit=<id>`), or the visits
tab (`/checkups?view=visits`) for a line naming several appointments.
The checkups page reads `view` to pick a tab. The rail item stops
borrowing the check-up item's action: it carries its own label
("View appointment") and intent `visit.view`. The appointment push names
its visit through the producer's `metadata.url` override; a check-up's
push keeps the checkups list.

The same mis-route sat on three links that lead to visits without
being upcoming: a condition's visit rows, the address book's back link
and the onboarding and timeline prompts to add a visit.

`visit-link-guard.test.ts` keeps the visit paths in the builder and
counts every bare `/checkups` per file, each with the reason it names
the checkups list.

src/app/checkups/__tests__/page-client-view.test.tsx

@@ -0,0 +1,75 @@
+/**
+ * Which tab a link to `/checkups` opens.
+ *
+ * Visits are the page's second tab. `?visit=<id>` opens one, `?view=visits`
+ * the list, and the bare path keeps opening the checkups, which is what the
+ * nav entry and the checkup surfaces mean by it.
+ */
+import { describe, expect, it, vi } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+
+let search = new URLSearchParams();
+
+vi.mock("next/navigation", () => ({
+  useRouter: () => ({ push: vi.fn(), replace: vi.fn() }),
+  usePathname: () => "/checkups",
+  useSearchParams: () => search,
+}));
+vi.mock("@tanstack/react-query", async (importOriginal) => ({
+  ...(await importOriginal<typeof import("@tanstack/react-query")>()),
+  useQueryClient: () => ({}),
+}));
+vi.mock("@/hooks/use-auth", () => ({
+  useAuth: () => ({ isAuthenticated: true, isLoading: false }),
+}));
+vi.mock("@/hooks/use-mounted", () => ({ useMounted: () => true }));
+vi.mock("@/hooks/use-pull-to-refresh", () => ({
+  usePullToRefresh: () => ({}),
+}));
+vi.mock("@/components/ui/pull-to-refresh-indicator", () => ({
+  PullToRefreshIndicator: () => null,
+}));
+vi.mock("@/components/measurement-reminders/vorsorge-section", () => ({
+  VorsorgeSection: () => <div data-section="vorsorge" />,
+}));
+vi.mock("@/components/encounters/visits-section", () => ({
+  VisitsSection: () => <div data-section="visits" />,
+}));
+vi.mock("@/components/encounters/procedures-section", () => ({
+  ProceduresSection: () => <div data-section="procedures" />,
+}));
+vi.mock("@/components/body-sites/body-sites-section", () => ({
+  BodySitesSection: () => <div data-section="body-sites" />,
+}));
+
+import { I18nProvider } from "@/lib/i18n/context";
+import CheckupsPageClient from "../page-client";
+
+function openTab(query: string): string | null {
+  search = new URLSearchParams(query);
+  const html = renderToStaticMarkup(
+    <I18nProvider initialLocale="en">
+      <CheckupsPageClient />
+    </I18nProvider>,
+  );
+  return html.match(/data-section="([^"]+)"/)?.[1] ?? null;
+}
+
+describe("/checkups — the tab a link opens", () => {
+  it("opens the checkups on the bare path", () => {
+    expect(openTab("")).toBe("vorsorge");
+  });
+
+  it("opens the visits for a link to one visit", () => {
+    expect(openTab("visit=v1")).toBe("visits");
+  });
+
+  it("opens the tab `view` names", () => {
+    expect(openTab("view=visits")).toBe("visits");
+    expect(openTab("view=procedures")).toBe("procedures");
+  });
+
+  it("ignores a `view` it does not know", () => {
+    expect(openTab("view=elsewhere")).toBe("vorsorge");
+  });
+});

src/app/checkups/page-client.tsx

@@ -15,6 +15,7 @@ import { VisitsSection } from "@/components/encounters/visits-section";
 import { ProceduresSection } from "@/components/encounters/procedures-section";
 import { BodySitesSection } from "@/components/body-sites/body-sites-section";
 import type { BodySiteSide } from "@/hooks/use-body-sites";
+import { parseCheckupsView } from "@/lib/encounters/visit-links";
 import { useTranslations } from "@/lib/i18n/context";
 import { invalidateKeys, queryKeys } from "@/lib/query-keys";
 
@@ -66,17 +67,29 @@ export default function CheckupsPageClient() {
     linkedSideParam === "BOTH"
       ? linkedSideParam
       : null;
-  const [view, setView] = useState(
-    linkedVisit ? "visits" : linkedSite ? "body-sites" : "vorsorge",
+  // A link to one tab (`?view=visits`, from a line naming several
+  // appointments). Built by `src/lib/encounters/visit-links.ts`, never by hand.
+  const linkedView = parseCheckupsView(searchParams?.get("view"));
+  const [view, setView] = useState<string>(
+    linkedVisit
+      ? "visits"
+      : linkedSite
+        ? "body-sites"
+        : (linkedView ?? "vorsorge"),
   );
   // A link to a visit can arrive while the page is already open (the search
   // opens one from wherever the person is): it moves to the visits tab then
-  // too, rather than only on the first render.
+  // too, rather than only on the first render. A link to a tab does the same.
   const [observedVisit, setObservedVisit] = useState(linkedVisit);
   if (linkedVisit !== observedVisit) {
     setObservedVisit(linkedVisit);
     if (linkedVisit) setView("visits");
   }
+  const [observedView, setObservedView] = useState(linkedView);
+  if (linkedView !== observedView) {
+    setObservedView(linkedView);
+    if (linkedView && !linkedVisit) setView(linkedView);
+  }
 
   const refresh = useCallback(
     () =>