fix: KnowledgeView infinite scroll root + calendar event refresh

- KnowledgeView: IntersectionObserver was watching the viewport instead
  of the card-grid scroll container, causing infinite scroll to stop
  loading after only ~29 items. Pass card-grid element as `root`.
- CalendarView: listen for 'fable:calendar-changed' custom event and
  call refetchEvents() so tool-created events appear without navigation.
- ChatPanel: dispatch 'fable:calendar-changed' when create_event,
  update_event, or delete_event tool calls succeed.
- tools.py: normalize naive datetimes to UTC before storing events so
  timezone comparisons in list_events queries are always consistent.

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

frontend/src/components/ChatPanel.vue

@@ -76,6 +76,19 @@ function scrollToBottom() {
 watch(() => store.streamingContent, () => scrollToBottom())
 watch(() => store.currentConversation?.messages.length, () => scrollToBottom())
 
+// Notify CalendarView when an event is created/updated/deleted via tool
+const _calendarToolNames = new Set(['create_event', 'update_event', 'delete_event'])
+const _seenCalendarToolIdx = new Set<number>()
+watch(() => store.streamingToolCalls, (calls) => {
+  calls.forEach((tc, i) => {
+    if (!_seenCalendarToolIdx.has(i) && _calendarToolNames.has(tc.function) && tc.status === 'success') {
+      _seenCalendarToolIdx.add(i)
+      document.dispatchEvent(new CustomEvent('fable:calendar-changed'))
+    }
+  })
+}, { deep: true })
+watch(() => store.streaming, (s) => { if (!s) _seenCalendarToolIdx.clear() })
+
 // ── RAG scope chip (full, non-briefing, non-workspace) ────────────────────────
 const projects = ref<{ id: number; title: string }[]>([])
 const scopeDropdownOpen = ref(false)

frontend/src/views/CalendarView.vue

@@ -115,8 +115,18 @@ function onDocClick(e: MouseEvent) {
   }
 }
 
-onMounted(() => document.addEventListener("mousedown", onDocClick));
-onUnmounted(() => document.removeEventListener("mousedown", onDocClick));
+function onCalendarChanged() {
+  calendarRef.value?.getApi().refetchEvents();
+}
+
+onMounted(() => {
+  document.addEventListener("mousedown", onDocClick);
+  document.addEventListener("fable:calendar-changed", onCalendarChanged);
+});
+onUnmounted(() => {
+  document.removeEventListener("mousedown", onDocClick);
+  document.removeEventListener("fable:calendar-changed", onCalendarChanged);
+});
 
 // ── Calendar callbacks ─────────────────────────────────────────────────────
 async function loadEvents(

frontend/src/views/KnowledgeView.vue

@@ -333,11 +333,12 @@ function formatDate(iso: string): string {
 // ─── Infinite scroll ──────────────────────────────────────────────────────────
 
 const sentinelEl = ref<HTMLElement | null>(null);
+const cardGridEl = ref<HTMLElement | null>(null);
 let scrollObserver: IntersectionObserver | null = null;
 
 function setupScrollObserver() {
   if (scrollObserver) scrollObserver.disconnect();
-  if (!sentinelEl.value) return;
+  if (!sentinelEl.value || !cardGridEl.value) return;
   scrollObserver = new IntersectionObserver(
     (entries) => {
       if (entries[0].isIntersecting && !loading.value && items.value.length < total.value) {
@@ -345,7 +346,7 @@ function setupScrollObserver() {
         fetchItems();
       }
     },
-    { rootMargin: "200px" }
+    { root: cardGridEl.value, rootMargin: "200px" }
   );
   scrollObserver.observe(sentinelEl.value);
 }
@@ -368,7 +369,7 @@ onUnmounted(() => {
 });
 
 watchEffect(() => {
-  if (sentinelEl.value) setupScrollObserver();
+  if (sentinelEl.value && cardGridEl.value) setupScrollObserver();
 });
 </script>
 
@@ -471,7 +472,7 @@ watchEffect(() => {
         </div>
 
         <!-- Card grid -->
-        <div v-else class="card-grid">
+        <div v-else ref="cardGridEl" class="card-grid">
           <div
             v-for="item in items"
             :key="item.id"

src/fabledassistant/services/tools.py

@@ -3,7 +3,7 @@
 import asyncio
 import logging
 import re
-from datetime import date, datetime
+from datetime import date, datetime, timezone
 from difflib import SequenceMatcher
 
 from fabledassistant.services.caldav import (
@@ -1409,6 +1409,8 @@ async def execute_tool(
                 start_str = f"{start_str}T00:00:00"
             try:
                 start_dt = datetime.fromisoformat(start_str)
+                if start_dt.tzinfo is None:
+                    start_dt = start_dt.replace(tzinfo=timezone.utc)
             except (ValueError, TypeError):
                 return {"success": False, "error": f"Invalid start datetime: {start_str!r}"}
             end_dt = None
@@ -1417,6 +1419,8 @@ async def execute_tool(
                     end_str = f"{end_str}T00:00:00"
                 try:
                     end_dt = datetime.fromisoformat(end_str)
+                    if end_dt.tzinfo is None:
+                        end_dt = end_dt.replace(tzinfo=timezone.utc)
                 except (ValueError, TypeError):
                     return {"success": False, "error": f"Invalid end datetime: {end_str!r}"}
             project_id = None