Implement last used calendar tracking with localStorage and database sync

- Add database migration for last_used_calendar field in user preferences
- Update backend models and handlers to support last_used_calendar persistence
- Modify frontend preferences service with update_last_used_calendar() method
- Implement automatic saving of selected calendar on event creation
- Add localStorage fallback for offline usage and immediate UI response
- Update create event modal to default to last used calendar for new events
- Clean up unused imports from event form components

🤖 Generated with [Claude Code](https://claude.ai/code)

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

frontend/src/app.rs

@@ -413,6 +413,21 @@ pub fn App() -> Html {
         let auth_token = auth_token.clone();
         Callback::from(move |event_data: EventCreationData| {
             web_sys::console::log_1(&format!("Creating event: {:?}", event_data).into());
+            
+            // Save the selected calendar as the last used calendar
+            if let Some(ref calendar_path) = event_data.selected_calendar {
+                let _ = LocalStorage::set("last_used_calendar", calendar_path);
+                
+                // Also sync to backend asynchronously
+                let calendar_path_for_sync = calendar_path.clone();
+                wasm_bindgen_futures::spawn_local(async move {
+                    let preferences_service = crate::services::preferences::PreferencesService::new();
+                    if let Err(e) = preferences_service.update_last_used_calendar(&calendar_path_for_sync).await {
+                        web_sys::console::warn_1(&format!("Failed to sync last used calendar to backend: {}", e).into());
+                    }
+                });
+            }
+            
             create_event_modal_open.set(false);
 
             if let Some(_token) = (*auth_token).clone() {

frontend/src/components/create_event_modal.rs

@@ -2,6 +2,7 @@ use crate::components::event_form::*;
 use crate::components::EditAction;
 use crate::models::ical::VEvent;
 use crate::services::calendar_service::CalendarInfo;
+use gloo_storage::{LocalStorage, Storage};
 use yew::prelude::*;
 
 #[derive(Properties, PartialEq)]
@@ -57,7 +58,25 @@ pub fn create_event_modal(props: &CreateEventModalProps) -> Html {
 
                 // Set default calendar
                 if data.selected_calendar.is_none() && !available_calendars.is_empty() {
-                    data.selected_calendar = Some(available_calendars[0].path.clone());
+                    // For new events, try to use the last used calendar
+                    if event_to_edit.is_none() {
+                        // Try to get last used calendar from localStorage
+                        if let Ok(last_used_calendar) = LocalStorage::get::<String>("last_used_calendar") {
+                            // Check if the last used calendar is still available
+                            if available_calendars.iter().any(|cal| cal.path == last_used_calendar) {
+                                data.selected_calendar = Some(last_used_calendar);
+                            } else {
+                                // Fall back to first available calendar
+                                data.selected_calendar = Some(available_calendars[0].path.clone());
+                            }
+                        } else {
+                            // No last used calendar, use first available
+                            data.selected_calendar = Some(available_calendars[0].path.clone());
+                        }
+                    } else {
+                        // For editing existing events, keep the current calendar as default
+                        data.selected_calendar = Some(available_calendars[0].path.clone());
+                    }
                 }
 
                 // Set edit scope if provided

frontend/src/components/event_form/advanced.rs

@@ -1,7 +1,7 @@
 use super::types::*;
 // Types are already imported from super::types::*
 use wasm_bindgen::JsCast;
-use web_sys::{HtmlInputElement, HtmlSelectElement};
+use web_sys::HtmlSelectElement;
 use yew::prelude::*;
 
 #[function_component(AdvancedTab)]

frontend/src/components/event_form/types.rs

@@ -1,7 +1,5 @@
-use crate::models::ical::VEvent;
 use crate::services::calendar_service::CalendarInfo;
-use chrono::{Datelike, Local, NaiveDate, NaiveTime, TimeZone, Utc};
-use serde::{Deserialize, Serialize};
+use chrono::{Local, NaiveDate, NaiveTime};
 use yew::prelude::*;
 
 #[derive(Clone, PartialEq, Debug)]

frontend/src/components/mod.rs

@@ -24,10 +24,6 @@ pub use create_calendar_modal::CreateCalendarModal;
 pub use create_event_modal::CreateEventModal;
 // Re-export event form types for backwards compatibility
 pub use event_form::EventCreationData;
-pub use event_form::{
-    EventClass as EventFormClass, EventCreationData as EventFormData, EventStatus as EventFormStatus, 
-    RecurrenceType as EventFormRecurrenceType, ReminderType as EventFormReminderType,
-};
 pub use event_context_menu::{DeleteAction, EditAction, EventContextMenu};
 pub use event_modal::EventModal;
 pub use login::Login;

frontend/src/services/preferences.rs

@@ -12,6 +12,7 @@ pub struct UserPreferences {
     pub calendar_view_mode: Option<String>,
     pub calendar_theme: Option<String>,
     pub calendar_colors: Option<String>,
+    pub last_used_calendar: Option<String>,
 }
 
 #[derive(Debug, Serialize)]
@@ -22,6 +23,7 @@ pub struct UpdatePreferencesRequest {
     pub calendar_view_mode: Option<String>,
     pub calendar_theme: Option<String>,
     pub calendar_colors: Option<String>,
+    pub last_used_calendar: Option<String>,
 }
 
 #[allow(dead_code)]
@@ -61,6 +63,7 @@ impl PreferencesService {
             calendar_view_mode: None,
             calendar_theme: None,
             calendar_colors: None,
+            last_used_calendar: None,
         });
         
         // Update the specific field
@@ -95,6 +98,7 @@ impl PreferencesService {
             calendar_view_mode: preferences.calendar_view_mode.clone(),
             calendar_theme: preferences.calendar_theme.clone(),
             calendar_colors: preferences.calendar_colors.clone(),
+            last_used_calendar: preferences.last_used_calendar.clone(),
         };
         
         self.sync_preferences(&session_token, &request).await
@@ -156,6 +160,7 @@ impl PreferencesService {
             calendar_view_mode: LocalStorage::get::<String>("calendar_view_mode").ok(),
             calendar_theme: LocalStorage::get::<String>("calendar_theme").ok(),
             calendar_colors: LocalStorage::get::<String>("calendar_colors").ok(),
+            last_used_calendar: LocalStorage::get::<String>("last_used_calendar").ok(),
         };
         
         // Only migrate if we have some preferences to migrate
@@ -164,6 +169,7 @@ impl PreferencesService {
             || request.calendar_view_mode.is_some()
             || request.calendar_theme.is_some()
             || request.calendar_colors.is_some()
+            || request.last_used_calendar.is_some()
         {
             self.sync_preferences(&session_token, &request).await?;
             
@@ -177,4 +183,24 @@ impl PreferencesService {
         
         Ok(())
     }
+
+    /// Update the last used calendar and sync with backend
+    pub async fn update_last_used_calendar(&self, calendar_path: &str) -> Result<(), String> {
+        // Get session token
+        let session_token = LocalStorage::get::<String>("session_token")
+            .map_err(|_| "No session token found".to_string())?;
+        
+        // Create minimal update request with only the last used calendar
+        let request = UpdatePreferencesRequest {
+            calendar_selected_date: None,
+            calendar_time_increment: None,
+            calendar_view_mode: None,
+            calendar_theme: None,
+            calendar_colors: None,
+            last_used_calendar: Some(calendar_path.to_string()),
+        };
+        
+        // Sync to backend
+        self.sync_preferences(&session_token, &request).await
+    }
 }