diff --git a/.claude/settings.local.json b/.claude/settings.local.json
index 5472cb5..9921e42 100644
--- a/.claude/settings.local.json
+++ b/.claude/settings.local.json
@@ -7,7 +7,10 @@
       "WebFetch(domain:caniuse.com)",
       "WebFetch(domain:blog.rasc.ch)",
       "WebFetch(domain:developer.chrome.com)",
-      "Bash(npx tsc:*)"
+      "Bash(npx tsc:*)",
+      "WebFetch(domain:github.com)",
+      "Bash(npm install:*)",
+      "WebFetch(domain:raw.githubusercontent.com)"
     ],
     "deny": [],
     "ask": []
diff --git a/package-lock.json b/package-lock.json
index 1389069..9de71a8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -12,7 +12,8 @@
         "@rollup/rollup-win32-x64-msvc": "^4.52.2",
         "dayjs": "^1.11.19",
         "fuse.js": "^7.1.0",
-        "json-diff-ts": "^4.8.2"
+        "json-diff-ts": "^4.8.2",
+        "ts-linq-light": "^1.0.0"
       },
       "devDependencies": {
         "@fullhuman/postcss-purgecss": "^7.0.2",
@@ -4958,6 +4959,31 @@
         "node": ">=20"
       }
     },
+    "node_modules/ts-linq-light": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/ts-linq-light/-/ts-linq-light-1.0.0.tgz",
+      "integrity": "sha512-8GGyHkHlKuKFTbT/Xz/0y72OTKl1hVRMJ0MqXAaWaergCExKw3bd5M6DR3NSOA7UL0gkTMhWsql9kFYyAjkIdQ==",
+      "license": "MIT",
+      "engines": {
+        "node": ">=18.0.0"
+      },
+      "optionalDependencies": {
+        "@rollup/rollup-win32-x64-msvc": "^4.53.3"
+      }
+    },
+    "node_modules/ts-linq-light/node_modules/@rollup/rollup-win32-x64-msvc": {
+      "version": "4.53.3",
+      "resolved": "https://registry.npmjs.org/@rollup/rollup-win32-x64-msvc/-/rollup-win32-x64-msvc-4.53.3.tgz",
+      "integrity": "sha512-UhTd8u31dXadv0MopwGgNOBpUVROFKWVQgAg5N1ESyCz8AuBcMqm4AuTjrwgQKGDfoFuz02EuMRHQIw/frmYKQ==",
+      "cpu": [
+        "x64"
+      ],
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "win32"
+      ]
+    },
     "node_modules/tslib": {
       "version": "2.8.1",
       "resolved": "https://registry.npmjs.org/tslib/-/tslib-2.8.1.tgz",
diff --git a/package.json b/package.json
index d2aadc1..2b53162 100644
--- a/package.json
+++ b/package.json
@@ -43,6 +43,7 @@
     "@rollup/rollup-win32-x64-msvc": "^4.52.2",
     "dayjs": "^1.11.19",
     "fuse.js": "^7.1.0",
-    "json-diff-ts": "^4.8.2"
+    "json-diff-ts": "^4.8.2",
+    "ts-linq-light": "^1.0.0"
   }
 }
diff --git a/src/v2/core/CalendarOrchestrator.ts b/src/v2/core/CalendarOrchestrator.ts
index a69b934..78964a7 100644
--- a/src/v2/core/CalendarOrchestrator.ts
+++ b/src/v2/core/CalendarOrchestrator.ts
@@ -1,3 +1,4 @@
+import { from } from 'ts-linq-light';
 import { ViewConfig, GroupingConfig } from './ViewConfig';
 import { RenderContext } from './RenderContext';
 import { IGroupingRenderer } from './IGroupingRenderer';
@@ -25,11 +26,11 @@ export class CalendarOrchestrator {
   ) {}
 
   private getRenderer(type: string): IGroupingRenderer | undefined {
-    return this.renderers.find(r => r.type === type);
+    return from(this.renderers).firstOrDefault(r => r.type === type);
   }
 
   private getStore(type: string): IGroupingStore | undefined {
-    return this.stores.find(s => s.type === type);
+    return from(this.stores).firstOrDefault(s => s.type === type);
   }
 
   async render(viewConfig: ViewConfig, container: HTMLElement): Promise<void> {
@@ -45,7 +46,7 @@ export class CalendarOrchestrator {
 
     container.style.setProperty('--grid-columns', String(totalColumns));
 
-    const types = viewConfig.groupings.map(g => g.type);
+    const types = from(viewConfig.groupings).select(g => g.type).toArray();
     headerContainer.dataset.levels = types.join(' ');
 
     headerContainer.innerHTML = '';
@@ -58,12 +59,8 @@ export class CalendarOrchestrator {
     await this.eventRenderer.render(container, visibleDates);
   }
 
-  /**
-   * Extract visible dates from view config
-   */
   private extractVisibleDates(viewConfig: ViewConfig): string[] {
-    const dateGrouping = viewConfig.groupings.find(g => g.type === 'date');
-    return dateGrouping?.values || [];
+    return from(viewConfig.groupings).firstOrDefault(g => g.type === 'date')?.values || [];
   }
 
   private fetchAllData(groupings: GroupingConfig[]): Map<string, GroupingData> {
@@ -72,7 +69,7 @@ export class CalendarOrchestrator {
     for (const g of groupings) {
       if (g.type === 'date') {
         result.set(g.type, {
-          items: g.values.map(v => ({ id: v, data: { id: v } })),
+          items: from(g.values).select(v => ({ id: v, data: { id: v } })).toArray(),
           byParent: null
         });
         continue;
@@ -81,10 +78,17 @@ export class CalendarOrchestrator {
       const store = this.getStore(g.type);
       if (!store) continue;
       const rawItems = store.getByIds(g.values);
-      const items = rawItems.map((item: any) => ({ id: item.id, data: item }));
-      const byParent = g.parentKey
-        ? this.groupBy(items, item => (item.data as any)[g.parentKey!])
-        : null;
+      const items = from(rawItems).select((item: any) => ({ id: item.id, data: item })).toArray();
+      let byParent: Map<string, { id: string; data: unknown }[]> | null = null;
+      if (g.parentKey) {
+        byParent = new Map();
+        const grouped = from(items)
+          .where(item => (item.data as any)[g.parentKey!] != null)
+          .groupBy(item => (item.data as any)[g.parentKey!] as string);
+        for (const group of grouped) {
+          byParent.set(group.key, group.toArray());
+        }
+      }
 
       result.set(g.type, { items, byParent });
     }
@@ -108,24 +112,13 @@ export class CalendarOrchestrator {
       ? gData.byParent.get(parentId) ?? []
       : gData.items;
 
-    return items.map(item => ({
+    return from(items).select(item => ({
       type: g.type,
       id: item.id,
       data: item.data,
       parentId,
       children: this.buildHierarchy(groupings, data, level + 1, item.id)
-    }));
-  }
-
-  private groupBy<T>(items: T[], keyFn: (item: T) => string): Map<string, T[]> {
-    const map = new Map<string, T[]>();
-    for (const item of items) {
-      const key = keyFn(item);
-      if (key == null) continue;
-      if (!map.has(key)) map.set(key, []);
-      map.get(key)!.push(item);
-    }
-    return map;
+    })).toArray();
   }
 
   private countLeaves(nodes: HierarchyNode[]): number {