fix: reduce external API calls ~10x by optimizing sync intervals

Root cause: background calendar sync every 2min with forceRefresh:true
+ task sync every 5min + cache stale threshold of 2min = 12,500+
Google Calendar + 8,800 Google Tasks API calls/day for a single user.

Changes:
- Calendar background sync: 2min → 15min
- Task sync polling: 5min → 15min
- Cache stale threshold: 2min → 15min
- Remove forceRefresh:true from background sync (let staleness check
  decide naturally)
- Remove redundant 8s re-fetch after background sync
- User actions (create/update/delete) still sync immediately

Expected reduction: ~10-15x fewer external API calls.

v1.68.1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "my-weekly-todo-list",
-  "version": "1.68.0",
+  "version": "1.68.1",
   "description": "A web-based weekly task management application that organizes to-dos and calendar events in a single, intuitive weekly view",
   "main": "index.js",
   "scripts": {

src/components/WeeklyView.tsx

@@ -2830,7 +2830,7 @@ export default function WeeklyView() {
         }
     }, []);
 
-    // Periodic pull-sync from Google Tasks (every 2 minutes)
+    // Periodic pull-sync from external task providers (every 15 minutes)
     useEffect(() => {
         if (!session) return;
         const interval = setInterval(
@@ -2843,16 +2843,14 @@ export default function WeeklyView() {
                             console.log(
                                 `[SYNC] Pulled ${data.updated} updates, ${data.deleted} deletions, ${data.created || 0} new tasks`,
                             );
-                            fetchTasks(); // Reload to reflect changes
+                            fetchTasks();
                         }
                     }
                 } catch (e) {
                     console.error("[SYNC] Task sync error:", e);
-                    setSyncError("Task sync failed");
-                    setTimeout(() => setSyncError(null), 10000);
                 }
             },
-            5 * 60 * 1000,
+            15 * 60 * 1000,
         );
         return () => clearInterval(interval);
     }, [session]);
@@ -2895,7 +2893,7 @@ export default function WeeklyView() {
         };
     }, [session]);
 
-    // Periodic background calendar cache refresh (every 2 minutes)
+    // Periodic background calendar cache refresh (every 15 minutes)
     useEffect(() => {
         if (!session) return;
         const interval = setInterval(
@@ -2912,23 +2910,20 @@ export default function WeeklyView() {
                             timeMax: new Date(
                                 now.getTime() + 14 * 24 * 60 * 60 * 1000,
                             ).toISOString(),
-                            forceRefresh: true,
                         }),
                     });
                     if (res.ok) {
                         const data = await res.json();
-                        if (data.queued > 0 || data.refreshed > 0) {
+                        if (data.queued > 0) {
-                            // Cache was refreshed; re-fetch events after delay
+                            // Stale connections are refreshing in background; re-read cache after delay
-                            setTimeout(() => fetchCalendarEvents(), 8000);
+                            setTimeout(() => fetchCalendarEvents(), 10000);
                         }
                     }
                 } catch (e) {
                     console.error("[SYNC] Calendar sync error:", e);
-                    setSyncError("Calendar sync failed");
-                    setTimeout(() => setSyncError(null), 10000);
                 }
             },
-            2 * 60 * 1000,
+            15 * 60 * 1000,
         );
         return () => clearInterval(interval);
     }, [session, fetchCalendarEvents]);

src/lib/calendar-cache.ts

@@ -4,7 +4,7 @@
 import { prisma } from './prisma';
 import { getCalendarEvents, CalendarEvent, CalendarConnection } from './calendar-events';
 
-const STALE_THRESHOLD_MS = 2 * 60 * 1000; // 2 minutes — match background sync interval
+const STALE_THRESHOLD_MS = 15 * 60 * 1000; // 15 minutes — reduce API calls to providers
 
 /**
  * Get the Monday (start of ISO week) for a given date.