fix(fusion_schedule): stop archiving valid events on @removed=changed

Microsoft Graph's delta API returns @removed={reason:'changed'} when an
event drifts outside the original delta-query window — the event still
exists upstream. The old code treated any truthy @removed the same as a
real delete and archived the local calendar.event. Combined with
_find_existing_event filtering by active=True, every subsequent sync
recreated a duplicate (then archived it on the next pass), accumulating
5x duplicates and emptying the user's calendar.

- _process_microsoft_event: only archive on isCancelled or
  @removed.reason='deleted'; skip on @removed.reason='changed'
- _process_microsoft_event link path: reactivate when MS Graph confirms
  a previously-archived event still exists
- _process_microsoft_event iCalUId path: same reactivation
- _find_existing_event: include archived records so wrongly-archived
  duplicates are reused instead of piling up
- callers reactivate the matched archived record

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

fusion_schedule/__manifest__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 {
     'name': 'Fusion Schedule',
-    'version': '19.0.2.0.0',
+    'version': '19.0.2.1.0',
     'category': 'Services/Appointment',
     'summary': 'Multi-calendar sync, portal booking, and shareable scheduling links',
     'description': """

fusion_schedule/models/fusion_calendar_account.py

@@ -399,12 +399,17 @@ class FusionCalendarAccount(models.Model):
         }
 
     def _find_existing_event(self, CalendarEvent, vals):
-        """Find an existing calendar event matching name+start+stop to avoid duplicates."""
+        """Find an existing calendar event matching name+start+stop to avoid duplicates.
+
+        Includes archived records so prior wrongly-archived duplicates get
+        reused (the caller is expected to reactivate them) instead of new
+        copies piling up on every sync iteration.
+        """
         start_val = vals.get('start') or vals.get('start_date')
         stop_val = vals.get('stop') or vals.get('stop_date')
         if not (start_val and stop_val and vals.get('name')):
             return None
-        domain = [('name', '=', vals['name']), ('active', '=', True)]
+        domain = [('name', '=', vals['name']), ('active', 'in', [True, False])]
         if vals.get('allday'):
             domain += [('start_date', '=', start_val), ('stop_date', '=', stop_val)]
         else:
@@ -485,6 +490,8 @@ class FusionCalendarAccount(models.Model):
 
         reuse_event = self._find_existing_event(CalendarEvent, vals)
         if reuse_event:
+            if not reuse_event.active:
+                reuse_event.with_context(**ctx).write({'active': True})
             self._upsert_event_link(EventLink, reuse_event.id, external_id, ical_uid)
             return 'updated'
 
@@ -677,11 +684,18 @@ class FusionCalendarAccount(models.Model):
             ('x_fc_external_id', '=', external_id),
         ], limit=1)
 
-        if event_data.get('@removed') or event_data.get('isCancelled'):
+        removed = event_data.get('@removed')
+        removed_reason = removed.get('reason') if isinstance(removed, dict) else None
+        if event_data.get('isCancelled') or removed_reason == 'deleted':
             if link and link.x_fc_event_id:
                 link.x_fc_event_id.with_context(**ctx).write({'active': False})
                 link.unlink()
             return 'deleted'
+        if removed:
+            # @removed with reason != 'deleted' (typically 'changed') means the
+            # event drifted outside the original delta query window — it still
+            # exists upstream. Leave the local copy alone so it stays visible.
+            return 'skipped'
 
         vals = self._microsoft_event_to_odoo_vals(event_data)
         if not vals:
@@ -690,8 +704,11 @@ class FusionCalendarAccount(models.Model):
         ical_uid = event_data.get('iCalUId', '')
 
         if link:
-            if link.x_fc_event_id and link.x_fc_event_id.active:
-                link.x_fc_event_id.with_context(**ctx).write(vals)
+            if link.x_fc_event_id:
+                update_vals = dict(vals)
+                if not link.x_fc_event_id.active:
+                    update_vals['active'] = True
+                link.x_fc_event_id.with_context(**ctx).write(update_vals)
                 link.write({'x_fc_last_synced': fields.Datetime.now()})
             return 'updated'
 
@@ -701,11 +718,15 @@ class FusionCalendarAccount(models.Model):
         ], limit=1) if ical_uid else None
 
         if existing_link and existing_link.x_fc_event_id:
+            if not existing_link.x_fc_event_id.active:
+                existing_link.x_fc_event_id.with_context(**ctx).write({'active': True})
             self._upsert_event_link(EventLink, existing_link.x_fc_event_id.id, external_id, ical_uid)
             return 'updated'
 
         reuse_event = self._find_existing_event(CalendarEvent, vals)
         if reuse_event:
+            if not reuse_event.active:
+                reuse_event.with_context(**ctx).write({'active': True})
             self._upsert_event_link(EventLink, reuse_event.id, external_id, ical_uid)
             return 'updated'