fix(auth): a Google connect names its tab's account too, and a refused tab says why

- /auth/google/connect is a navigation and carries no headers: the tab names the account it
  was built for in `expect`, checked by the same comparison as the request header
  (built_for_another_account); a mismatch lands on /?account=changed
- the link marker names the OAuth state of its own flow: an older flow coming back no longer
  spends the marker of the connect still open (which then returned as a plain sign-in)
- a 401 account_changed reloads the tab with a one-time flag, and the reloaded tab says it
  now shows the account signed in
- a refused switch to a suspended or not-yet-approved account says so in the signed-in
  app's words, naming the address a request was recorded for
- the prefs merge locks FOR NO KEY UPDATE, so a transaction that only added a row referring
  to the account does not hold the save up; a test pins the lock
- giving up a lost page closes a channel page open over it
- e2e README names the chromium-only specs

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

@@ -370,6 +370,20 @@ describe("NavigationProvider · a page the account cannot open", () => {
     await settle();
     expect(result.current.page).toBe("feed");
   });
+
+  it("closes a channel page open over the lost page, on screen and in the entry", async () => {
+    window.history.replaceState({ sfPage: "users" }, "", "/?page=users");
+    const { result } = render();
+    act(() => result.current.openChannel("UC1", "One"));
+    expect(window.location.search).toContain("chan=UC1");
+    act(() => {
+      qc.setQueryData(qk.me(), member);
+    });
+    await settle();
+    expect(result.current.channelView).toBeNull();
+    expect(window.location.search).toBe("");
+    expect(window.history.state?._chan).toBeUndefined();
+  });
 });
 
 describe("NavigationProvider · leaving a sub-view whose entry is the oldest of this document", () => {

frontend/src/components/NavigationProvider.tsx

@@ -67,16 +67,6 @@ export function NavigationProvider({ children }: { children: ReactNode }) {
   // and the address bar (stamped from it below) agree.
   const me = useMe();
   const page = reachablePage(chosenPage, me);
-  // A page this account can no longer open (a role taken away, a module switched off mid-session)
-  // is given up, not kept behind the feed: kept, the address bar would go on naming it, a click on
-  // Feed would be a no-op (setPage's same-page guard sees the feed already on screen), and a later
-  // grant would switch the page by itself. Adjusted during render; the history entry and the
-  // remembered page follow in the effect below.
-  const [givenUp, setGivenUp] = useState(0);
-  if (page !== chosenPage) {
-    setPageState(page);
-    setGivenUp((n) => n + 1);
-  }
   // Ephemeral: not persisted and not in the URL, so a reload returns to the normal feed (a search
   // spends quota, so we never auto-replay it) — UNLESS it was zero-quota scrape-sourced, which rides
   // in history.state and is free to re-fetch. The popstate handler derives it from history.state so
@@ -92,6 +82,18 @@ export function NavigationProvider({ children }: { children: ReactNode }) {
   const [channelView, setChannelView] = useState<ChannelView | null>(() =>
     channelViewFrom(window.history.state, window.location.search),
   );
+  // A page this account can no longer open (a role taken away, a module switched off mid-session)
+  // is given up, not kept behind the feed: kept, the address bar would go on naming it, a click on
+  // Feed would be a no-op (setPage's same-page guard sees the feed already on screen), and a later
+  // grant would switch the page by itself. A channel page open over it closes with it, as on any
+  // page switch. Adjusted during render; the history entry and the remembered page follow in the
+  // effect below.
+  const [givenUp, setGivenUp] = useState(0);
+  if (page !== chosenPage) {
+    setPageState(page);
+    setChannelView(null);
+    setGivenUp((n) => n + 1);
+  }
 
   // Latest-value refs so the STABLE action callbacks can read the latest state without depending on
   // it — a dep would recreate them on every navigation and re-render every actions consumer (e.g.
@@ -211,12 +213,14 @@ export function NavigationProvider({ children }: { children: ReactNode }) {
   }, [signedIn, page, objectTitle, i18n.language, t]);
 
   // The page given up above is the feed, and the current entry says so (replaced, not pushed: no
-  // step was taken). Its own keys go with it, as on any page switch.
+  // step was taken). Its own keys go with it, and the channel page closed with it, as on any page
+  // switch — left in the entry, a reload would reopen what the screen no longer shows.
   useEffect(() => {
     if (!givenUp) return;
     setAccountRaw(PAGE_KEY, "feed");
+    const { _chan: _closedChan, _chanName: _closedName, ...rest } = window.history.state ?? {};
     window.history.replaceState(
-      { ...window.history.state, sfPage: "feed" },
+      { ...rest, sfPage: "feed" },
       "",
       urlWithParams(pageRootParams("feed")),
     );