From 6fed38381c4bc0c5ebab2dc869f3578aed8d59ce Mon Sep 17 00:00:00 2001
From: mARTin <mail@martin-bierschenk.de>
Date: Mon, 30 Mar 2026 16:02:56 +0200
Subject: [PATCH] perf: limit recurring task projection + O(1) calendar event
 dedup
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- tasks/route.ts: add per-unit instance cap for virtual task projection
  (daily: 60, weekly: 26, monthly: 12, yearly: 3) to prevent unbounded
  generation from high-frequency recurring tasks
- WeeklyView: extract calendarEditabilityMap as a separate useMemo keyed
  on connections; replace O(n²) nested find() loop with O(1) Map.get()
  lookup in the calendarEvents deduplication useMemo

v1.79.0
---
 package.json                  |  2 +-
 src/app/api/tasks/route.ts    | 16 ++++++++++++--
 src/components/WeeklyView.tsx | 39 +++++++++++++++++++----------------
 3 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/package.json b/package.json
index 3f555e9..eacc0ea 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "my-weekly-todo-list",
-  "version": "1.78.0",
+  "version": "1.79.0",
   "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": {
diff --git a/src/app/api/tasks/route.ts b/src/app/api/tasks/route.ts
index a6205f6..640a866 100644
--- a/src/app/api/tasks/route.ts
+++ b/src/app/api/tasks/route.ts
@@ -11,6 +11,15 @@ const generateVirtualId = (originalId: string, dateStr: string) => {
   return `virtual-${originalId}-${dateStr}`;
 };
 
+// Max virtual instances generated per recurring series, keyed by recurrence unit.
+// Caps pathological cases (e.g. a daily task with 90-day horizon = 90 instances).
+const MAX_INSTANCES_PER_SERIES: Record<string, number> = {
+  days: 60,
+  weeks: 26,
+  months: 12,
+  years: 3,
+};
+
 // Helper to project future tasks
 const projectFutureTasks = (tasks: Task[], horizonDays = 90) => {
   const projectedTasks: any[] = [];
@@ -53,6 +62,7 @@ const projectFutureTasks = (tasks: Task[], horizonDays = 90) => {
     const currentDate = new Date(baseDate);
     const interval = latestTask.recurrenceInterval || 1;
     const unit = latestTask.recurrenceUnit || 'weeks'; // 'days', 'weeks', 'months', 'years'
+    const maxInstances = MAX_INSTANCES_PER_SERIES[unit] ?? 26;
 
     // Parse recurrenceDays for weekly multi-day recurrence
     let recDays: number[] | null = null;
@@ -60,9 +70,10 @@ const projectFutureTasks = (tasks: Task[], horizonDays = 90) => {
       try { recDays = JSON.parse(latestTask.recurrenceDays); } catch { recDays = null; }
     }
 
-    // Safety break
+    let instanceCount = 0;
+    // Safety break: stop at horizon OR per-unit instance cap, whichever comes first
     let iterations = 0;
-    while (currentDate < horizonDate && iterations < 500) {
+    while (currentDate < horizonDate && iterations < 500 && instanceCount < maxInstances) {
       iterations++;
 
       // Advance date
@@ -123,6 +134,7 @@ const projectFutureTasks = (tasks: Task[], horizonDays = 90) => {
         isVirtual: true, // Flag for frontend if needed (not in Prisma type, but JS object accepts it)
         originalTaskId: latestTask.id // Reference
       });
+      instanceCount++;
     }
   });
 
diff --git a/src/components/WeeklyView.tsx b/src/components/WeeklyView.tsx
index cd1bf01..0bef9ee 100644
--- a/src/components/WeeklyView.tsx
+++ b/src/components/WeeklyView.tsx
@@ -1674,6 +1674,22 @@ export default function WeeklyView() {
     // When a recurring event is created, the master is cached. Then the sync
     // returns expanded instances with different IDs but the same recurringEventId.
     // We keep instances and discard masters that overlap with them.
+
+    // Build calendarId → editable map once per connections change (O(connections × calendars))
+    const calendarEditabilityMap = useMemo(() => {
+        const map = new Map<string, boolean>();
+        for (const conn of connections) {
+            if (conn.calendars && Array.isArray(conn.calendars)) {
+                for (const cal of conn.calendars as any[]) {
+                    if (cal.id && !map.has(cal.id)) {
+                        map.set(cal.id, !!cal.editable);
+                    }
+                }
+            }
+        }
+        return map;
+    }, [connections]);
+
     const calendarEvents = useMemo(() => {
         const seen = new Set<string>();
         const seenSlot = new Set<string>();
@@ -1694,24 +1710,11 @@ export default function WeeklyView() {
             if (seenSlot.has(slotKey)) return false;
             seenSlot.add(slotKey);
             return true;
-        }).map((event) => {
-            let isEditable = false;
-            if (event.calendarId) {
-                for (const conn of connections) {
-                    if (conn.calendars && Array.isArray(conn.calendars)) {
-                        const cal = conn.calendars.find(
-                            (c: any) => c.id === event.calendarId,
-                        );
-                        if (cal && cal.editable) {
-                            isEditable = true;
-                            break;
-                        }
-                    }
-                }
-            }
-            return { ...event, editable: isEditable };
-        });
-    }, [rawCalendarEvents, connections]);
+        }).map((event) => ({
+            ...event,
+            editable: event.calendarId ? (calendarEditabilityMap.get(event.calendarId) ?? false) : false,
+        }));
+    }, [rawCalendarEvents, calendarEditabilityMap]);
     const [currentWeekStart, setCurrentWeekStart] = useState(() => {
         const d = new Date();
         d.setHours(0, 0, 0, 0);