First commit, done on M6 from the PLAN.MD

web/js/save/storage.js

@@ -0,0 +1,107 @@
+// Browser storage for the autosave, the manual slots and the settings.
+// Every access is wrapped: if localStorage is missing or throws (private window, blocked
+// site data, full quota) the game keeps working and uses memory for the rest of the session.
+
+export const SLOT_COUNT = 3;
+export const KEYS = {
+  auto: "cg.autosave",
+  slot: (n) => `cg.slot.${n}`,
+  settings: "cg.settings",
+};
+
+function browserStorage() {
+  try {
+    const probe = "cg.probe";
+    globalThis.localStorage.setItem(probe, "1");
+    globalThis.localStorage.removeItem(probe);
+    return globalThis.localStorage;
+  } catch {
+    return null;
+  }
+}
+
+// backend: anything with getItem/setItem/removeItem, for tests. Default: localStorage.
+export function createStorage(backend = browserStorage()) {
+  const memory = new Map();
+  const store = { persistent: backend !== null };
+
+  store.get = (key) => {
+    try {
+      if (backend) return backend.getItem(key);
+    } catch {
+      store.persistent = false;
+    }
+    return memory.get(key) ?? null;
+  };
+
+  // Returns false when the write could not be made durable.
+  store.set = (key, value) => {
+    try {
+      if (backend) {
+        backend.setItem(key, value);
+        return true;
+      }
+    } catch {
+      store.persistent = false;
+    }
+    memory.set(key, value);
+    return false;
+  };
+
+  store.remove = (key) => {
+    memory.delete(key);
+    try {
+      backend?.removeItem(key);
+    } catch {
+      store.persistent = false;
+    }
+  };
+
+  return store;
+}
+
+// ---- Saved games: { meta, state } under one key ----
+
+export function writeSave(store, key, state) {
+  const meta = {
+    savedAt: Date.now(),
+    day: state.day,
+    countryName: state.countryName,
+    pronouns: state.pronouns,
+    scenarioId: state.scenarioId,
+    over: state.over?.type ?? null,
+  };
+  return store.set(key, JSON.stringify({ meta, state }));
+}
+
+// Returns { meta, state } or null when the slot is empty or unreadable.
+export function readSave(store, key) {
+  const raw = store.get(key);
+  if (!raw) return null;
+  try {
+    const parsed = JSON.parse(raw);
+    return parsed?.state && parsed?.meta ? parsed : null;
+  } catch {
+    return null;
+  }
+}
+
+// ---- Settings ----
+
+const DEFAULT_SETTINGS = { lang: null, slow: false };
+
+export function loadSettings(store) {
+  try {
+    const s = JSON.parse(store.get(KEYS.settings) ?? "{}");
+    return {
+      lang: s.lang === "en" || s.lang === "fr" ? s.lang : DEFAULT_SETTINGS.lang,
+      slow: s.slow === true,
+    };
+  } catch {
+    return { ...DEFAULT_SETTINGS };
+  }
+}
+
+export function saveSettings(store, settings) {
+  return store.set(KEYS.settings, JSON.stringify(settings));
+}