fix(notifications): keep the history under a key of its own, so an older build never reads its new shape

A build from before the change renders history rows as text; an object there crashed its
Notifications page after a rollback. The old key is read once while the new one does not exist,
and never written.

frontend/src/lib/claimedStores.dom.test.ts

@@ -20,7 +20,7 @@ const entry = (id: number, message: string) => ({
 });
 const storedMessages = () =>
   (
-    JSON.parse(localStorage.getItem("siftlode.notifications") ?? "[]") as {
+    JSON.parse(localStorage.getItem("siftlode.notifHistory") ?? "[]") as {
       message: NotifText;
     }[]
   ).map((n) => sayNotif(n.message));
@@ -48,7 +48,7 @@ beforeEach(() => {
 describe("stores read at import, before the account is known", { timeout: CASE_BUDGET }, () => {
   it("keep the account's notification history and settings once it is claimed", async () => {
     localStorage.setItem("siftlode.owner", "5");
-    localStorage.setItem("siftlode.notifications", JSON.stringify([entry(7, "older")]));
+    localStorage.setItem("siftlode.notifHistory", JSON.stringify([entry(7, "older")]));
     localStorage.setItem("siftlode.notifSettings", JSON.stringify({ durationMs: 0 }));
     const notifications = await import("./notifications");
     const { claimLocalData } = await import("./storage");
@@ -76,7 +76,7 @@ describe("stores read at import, before the account is known", { timeout: CASE_B
 describe("a browser that held another account's state", { timeout: CASE_BUDGET }, () => {
   it("starts the new account's notices from an empty history", async () => {
     localStorage.setItem("siftlode.owner", "4");
-    localStorage.setItem("siftlode.notifications", JSON.stringify([entry(7, "four's")]));
+    localStorage.setItem("siftlode.notifHistory", JSON.stringify([entry(7, "four's")]));
     const notifications = await import("./notifications");
     const { claimLocalData } = await import("./storage");
 

frontend/src/lib/notifHistory.dom.test.ts

@@ -0,0 +1,72 @@
+// @vitest-environment jsdom
+//
+// The notice history changed shape (a notice keeps what to say, not the said text). A build from
+// before it reads the old key and renders its rows as text, so an object there crashed its
+// Notifications page after a rollback. The history now lives under a key of its own: the old one is
+// read once, while the new one does not exist yet, and never written.
+import { beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+import { msg, raw, sayNotif, type NotifText } from "./notifications";
+
+const OLD_KEY = "siftlode.notifications";
+
+// A row as the build before wrote it: its text already said.
+const oldRow = (id: number, message: string) => ({
+  id,
+  level: "info",
+  message,
+  ts: 1,
+  read: true,
+  dismissed: true,
+  transient: false,
+  repeat: 1,
+  requiresInteraction: false,
+});
+
+const saidHistory = (key: string) =>
+  (JSON.parse(localStorage.getItem(key) ?? "[]") as { message: NotifText }[]).map((n) =>
+    sayNotif(n.message),
+  );
+
+beforeAll(async () => {
+  await import("./notifications");
+  await import("./storage");
+}, 60_000);
+
+beforeEach(() => {
+  localStorage.clear();
+  sessionStorage.clear();
+  vi.resetModules(); // the store loads at import: each case needs a fresh one
+});
+
+describe("the notice history's own key", { timeout: 30_000 }, () => {
+  it("carries the old history forward and leaves the old key as the build before wrote it", async () => {
+    const old = JSON.stringify([oldRow(7, "older")]);
+    localStorage.setItem("siftlode.owner", "5");
+    localStorage.setItem(OLD_KEY, old);
+    const notifications = await import("./notifications");
+    const { claimLocalData, LS } = await import("./storage");
+
+    claimLocalData(5);
+    notifications.notify({ message: msg("common.copy.done") });
+
+    expect(LS.notifHistory).not.toBe(OLD_KEY);
+    expect(localStorage.getItem(OLD_KEY)).toBe(old);
+    expect(saidHistory(LS.notifHistory)).toEqual(["older", "Copied to the clipboard"]);
+  });
+
+  it("reads the old key only while the new one does not exist", async () => {
+    const { LS } = await import("./storage");
+    localStorage.setItem("siftlode.owner", "5");
+    localStorage.setItem(OLD_KEY, JSON.stringify([oldRow(7, "older")]));
+    localStorage.setItem(
+      LS.notifHistory,
+      JSON.stringify([{ ...oldRow(8, ""), message: raw("newer") }]),
+    );
+    const notifications = await import("./notifications");
+    const { claimLocalData } = await import("./storage");
+
+    claimLocalData(5);
+
+    expect(notifications.getNotifications().map((n) => sayNotif(n.message))).toEqual(["newer"]);
+  });
+});

frontend/src/lib/notifications.ts

@@ -222,7 +222,9 @@ let cachedUnread = 0;
 
 function load(): Notification[] {
   try {
-    const stored = readAccount<unknown>(HISTORY_KEY, []);
+    // The old key only until the new one exists: its rows carry forward, said text as `raw`.
+    const stored =
+      readAccount<unknown>(HISTORY_KEY, null) ?? readAccount<unknown>(LS.legacyNotifHistory, []);
     if (!Array.isArray(stored)) return [];
     // Restored entries are history only. Mark them dismissed so they don't
     // resurrect as active toasts on reload — their auto-dismiss timers aren't

frontend/src/lib/storage.ts

@@ -100,7 +100,12 @@ const KEYS = {
   // flag). A YT.Player instance is created per video and starts at full volume, so without this
   // every next video is loud again (same idea as plexPlayerPrefs).
   ytPlayerPrefs: { key: "siftlode.ytPlayerPrefs", kind: "device" },
-  notifHistory: { key: "siftlode.notifications", kind: "cache" },
+  // The notice history: what each notice says (lib/notifications NotifText), not the said text.
+  notifHistory: { key: "siftlode.notifHistory", kind: "cache" },
+  // DEPRECATED — the history as said text, which a build from before the change still reads (and
+  // renders as text: an object there crashed its Notifications page after a rollback). Read once while
+  // `notifHistory` does not exist yet, then inert. Do not write.
+  legacyNotifHistory: { key: "siftlode.notifications", kind: "cache" },
   notifSettings: { key: "siftlode.notifSettings", kind: "pref" },
   onboardingDismissed: { key: "siftlode.onboarding.dismissed", kind: "pref" },
   seenVersion: { key: "siftlode.seenVersion", kind: "pref" },