feat: background resuming for calendar syncing

src/plugins/built-in/timetable/calendarSyncUi.ts

@@ -3,7 +3,6 @@ import { settingsState } from "@/seqta/utils/listeners/SettingsState";
 import { extractSolidColor } from "@/seqta/ui/colors/parseCssColor";
 import { ensureFontLoaded } from "@/seqta/ui/fonts/Manager";
 import { getFontPreset } from "@/seqta/ui/fonts/presets";
-import { registerCalendarContentHandlers } from "@/seqta/utils/googleCalendar/calendarSyncListener";
 import type { GoogleCalendarSyncProgress } from "@/seqta/utils/googleCalendar/types";
 import hostStyles from "./calendarSyncHost.css?inline";
 
@@ -152,7 +151,6 @@ export async function mountGoogleCalendarButton(): Promise<void> {
   if (!toolbar) return;
 
   ensureHostStyles();
-  registerCalendarContentHandlers();
 
   const controls = document.createElement("div");
   controls.className = CONTROLS_CLASS;

src/plugins/built-in/timetable/index.ts

@@ -5,6 +5,7 @@ import { convertTo12HourFormat } from "@/seqta/utils/convertTo12HourFormat";
 import { waitForElm } from "@/seqta/utils/waitForElm";
 import { verboseLog } from "@/utils/verboseLog";
 import { mountGoogleCalendarButton, unmountGoogleCalendarButton } from "./calendarSyncUi";
+import { registerCalendarContentHandlers } from "@/seqta/utils/googleCalendar/calendarSyncListener";
 
 const timetablePlugin: Plugin<{}, {}> = {
   id: "timetable",
@@ -15,6 +16,8 @@ const timetablePlugin: Plugin<{}, {}> = {
   disableToggle: true,
 
   run: async (api) => {
+    registerCalendarContentHandlers();
+
     const { unregister } = api.seqta.onMount(".timetablepage", handleTimetable);
 
     return () => {

src/seqta/utils/calendarSync/settings.ts

@@ -10,6 +10,8 @@ import {
 } from "@/seqta/utils/calendarSync/providerStorage";
 
 export const BSPLUS_CALENDAR_SYNC_SETTINGS_KEY = "bsplus_calendar_sync_settings";
+/** Device-local interrupted sync marker — never cloud-synced. */
+export const BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY = "bsplus_calendar_sync_in_progress";
 export const CALENDAR_WEEKLY_ALARM = "bsplus_calendar_weekly";
 export const WEEKLY_SYNC_INTERVAL_MS = 7 * 24 * 60 * 60 * 1000;
 
@@ -98,3 +100,34 @@ export async function markWeeklySyncComplete(): Promise<void> {
 export async function markWeeklySyncPending(): Promise<void> {
   await writeSharedCalendarSyncSettings({ pendingWeeklySync: true });
 }
+
+type PendingCalendarSync = {
+  provider: "google" | "outlook";
+  mode: "full" | "incremental";
+  origin: string;
+  startedAt: number;
+};
+
+/** Returns a pending sync worth resuming, or clears and returns null. */
+export async function readResumableCalendarSync(): Promise<PendingCalendarSync | null> {
+  const got = await browser.storage.local.get(BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY);
+  const raw = got[BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY];
+  if (!raw || typeof raw !== "object" || Array.isArray(raw)) return null;
+
+  const pending = raw as PendingCalendarSync;
+  const validProvider = pending.provider === "google" || pending.provider === "outlook";
+  const validMode = pending.mode === "full" || pending.mode === "incremental";
+  const fresh = Date.now() - pending.startedAt < 24 * 60 * 60 * 1000;
+
+  if (
+    !validProvider ||
+    !validMode ||
+    pending.origin !== location.origin ||
+    !fresh
+  ) {
+    await browser.storage.local.remove(BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY);
+    return null;
+  }
+
+  return pending;
+}

src/seqta/utils/calendarSync/syncRunner.ts

@@ -9,7 +9,15 @@ import {
 } from "@/seqta/utils/calendarSync/syncEngine";
 import { reportSyncProgress } from "@/seqta/utils/calendarSync/lessonSyncShared";
 import type { OutlookCalendarStatus } from "@/seqta/utils/calendarSync/providerStorage";
-import { getSyncWeeksAhead } from "@/seqta/utils/calendarSync/settings";
+import {
+  readGoogleCalendarState,
+  readOutlookCalendarState,
+} from "@/seqta/utils/calendarSync/providerStorage";
+import {
+  BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY,
+  getSyncWeeksAhead,
+  readResumableCalendarSync,
+} from "@/seqta/utils/calendarSync/settings";
 import type {
   GoogleCalendarStatus,
   GoogleCalendarSyncProgress,
@@ -98,6 +106,16 @@ export async function runCalendarSync(
   const mode = params.mode ?? "full";
   const weeksAhead = await getSyncWeeksAhead();
 
+  await browser.storage.local.set({
+    [BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY]: {
+      provider: config.provider,
+      mode,
+      origin: location.origin,
+      startedAt: Date.now(),
+    },
+  });
+
+  try {
     reportSyncProgress(params.onProgress, {
       phase: "preparing",
       current: 0,
@@ -110,12 +128,34 @@ export async function runCalendarSync(
         ? await fetchTimetableLessons(trailingWeekRange(weeksAhead))
         : await fetchTimetableForSync(weeksAhead);
 
-  return syncLessonsToCalendar(
+    return await syncLessonsToCalendar(
       config.lessonSyncProvider,
       { origin: location.origin, lessons, mode, weeksAhead },
       () => getCalendarAccessToken(config.provider),
       { onProgress: params.onProgress },
     );
+  } finally {
+    await browser.storage.local.remove(BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY);
+  }
+}
+
+export async function resumeInterruptedCalendarSync(
+  params: RunCalendarSyncParams = {},
+): Promise<GoogleCalendarSyncResult | null> {
+  const pending = await readResumableCalendarSync();
+  if (!pending) return null;
+
+  const state =
+    pending.provider === "google"
+      ? await readGoogleCalendarState()
+      : await readOutlookCalendarState();
+  if (!state.refreshToken && !state.accessToken) {
+    await browser.storage.local.remove(BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY);
+    return null;
+  }
+
+  const config = pending.provider === "google" ? GOOGLE_SYNC_RUNNER : OUTLOOK_SYNC_RUNNER;
+  return runCalendarSync(config, { ...params, mode: pending.mode });
 }
 
 export const runGoogleCalendarSync = (params?: RunCalendarSyncParams) =>

src/seqta/utils/cloudSettingsSync.legacy.test.ts

@@ -4,6 +4,7 @@ import {
   normalizeThemeIdForSync,
   resolveThemeIdForPostSyncDownload,
 } from "./cloudSettingsSync";
+import { BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY } from "@/seqta/utils/calendarSync/settings";
 
 describe("migrateLegacyToPluginSettings", () => {
   it("maps animatedbk without overwriting existing plugin fields", () => {
@@ -30,6 +31,7 @@ describe("isKeyIncludedInCloudUploadPayload", () => {
   it("excludes auth and device cache prefixes", () => {
     expect(isKeyIncludedInCloudUploadPayload("bsplus_token")).toBe(false);
     expect(isKeyIncludedInCloudUploadPayload("bsplus_install_id")).toBe(false);
+    expect(isKeyIncludedInCloudUploadPayload(BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY)).toBe(false);
     expect(isKeyIncludedInCloudUploadPayload("plugin.global-search.storage.index")).toBe(
       false,
     );

src/seqta/utils/cloudSettingsSync.ts

@@ -1,5 +1,6 @@
 import browser from "webextension-polyfill";
 import isEqual from "@/seqta/utils/isEqual";
+import { BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY } from "@/seqta/utils/calendarSync/settings";
 
 /** Matches the contract in docs/CLOUD_SETTINGS_SYNC_SERVER.md */
 export const CLOUD_SETTINGS_SYNC_SCHEMA_VERSION = 1;
@@ -42,6 +43,7 @@ export const KEYS_OMITTED_FROM_CLOUD_UPLOAD = [
   "bsplus_install_id",
   /** Pending feedback ids awaiting a reply notification — device-local. */
   "bsplus_pending_feedback_ids",
+  BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY,
 ] as const;
 
 /**
@@ -64,6 +66,7 @@ const CLIENT_ONLY_CLOUD_KEYS_EXACT = [
   BSPLUS_CLOUD_LAST_UPLOADED_SNAPSHOT_KEY,
   "bsplus_lastCloudPoll",
   BSPLUS_PENDING_THEME_ENSURE_AFTER_CLOUD_KEY,
+  BSPLUS_CALENDAR_SYNC_IN_PROGRESS_KEY,
 ] as const;
 
 /** After restoring from cloud, keep local session so the user stays signed in. */

src/seqta/utils/googleCalendar/calendarSyncListener.ts

@@ -4,7 +4,11 @@ import {
   shouldRunWeeklySync,
 } from "@/seqta/utils/calendarSync/settings";
 import { formatLessonSyncResultMessage } from "@/seqta/utils/calendarSync/lessonSyncShared";
-import { runGoogleCalendarSync, runOutlookCalendarSync } from "@/seqta/utils/calendarSync/syncRunner";
+import {
+  resumeInterruptedCalendarSync,
+  runGoogleCalendarSync,
+  runOutlookCalendarSync,
+} from "@/seqta/utils/calendarSync/syncRunner";
 import {
   readGoogleCalendarState,
   readOutlookCalendarState,
@@ -12,6 +16,7 @@ import {
 import type { GoogleCalendarSyncResult } from "@/seqta/utils/googleCalendar/types";
 
 let listenerRegistered = false;
+let resumeChecked = false;
 
 const WEEKLY_PROVIDERS = [
   { label: "Google Calendar", read: readGoogleCalendarState, run: runGoogleCalendarSync },
@@ -44,6 +49,10 @@ async function runWeeklySyncForConnectedProviders(): Promise<
 }
 
 export function registerCalendarContentHandlers(): void {
+  if (!resumeChecked) {
+    resumeChecked = true;
+    void resumeInterruptedCalendarSync();
+  }
   if (listenerRegistered) return;
   listenerRegistered = true;