Add calendar cache layer, incremental sync tests, completion assertions

- Google Calendar events now cached via CacheFetcher pattern with
  stale-cache fallback on API errors (new migration 015, store methods,
  fetchCalendarEvents handler, BuildTimeline reads from store)
- Todoist incremental sync path covered by 5 new tests
- Task completion tests assert response body, headers, and template data

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

1 files changed, 21 insertions, 23 deletions

diff --git a/internal/handlers/timeline_logic.go b/internal/handlers/timeline_logic.go
index 7a85393..4334f6d 100644
--- a/internal/handlers/timeline_logic.go
+++ b/internal/handlers/timeline_logic.go
@@ -14,7 +14,7 @@ import (
 )
 
 // BuildTimeline aggregates and normalizes data into a timeline structure
-func BuildTimeline(ctx context.Context, s *store.Store, calendarClient api.GoogleCalendarAPI, tasksClient api.GoogleTasksAPI, start, end time.Time) ([]models.TimelineItem, error) {
+func BuildTimeline(ctx context.Context, s *store.Store, tasksClient api.GoogleTasksAPI, start, end time.Time) ([]models.TimelineItem, error) {
 	var items []models.TimelineItem
 	now := config.Now()
 
@@ -128,29 +128,27 @@ func BuildTimeline(ctx context.Context, s *store.Store, calendarClient api.Googl
 		items = append(items, item)
 	}
 
-	// 4. Fetch Events
-	if calendarClient != nil {
-		events, err := calendarClient.GetEventsByDateRange(ctx, start, end)
-		if err != nil {
-			log.Printf("Warning: failed to fetch calendar events: %v", err)
-		} else {
-			for _, event := range events {
-				endTime := event.End
-				item := models.TimelineItem{
-					ID:           event.ID,
-					Type:         models.TimelineItemTypeEvent,
-					Title:        event.Summary,
-					Time:         event.Start,
-					EndTime:      &endTime,
-					Description:  event.Description,
-					URL:          event.HTMLLink,
-					OriginalItem: event,
-					IsCompleted:  false,
-					Source:       "calendar",
-				}
-				item.ComputeDaySection(now)
-				items = append(items, item)
+	// 4. Fetch Events from store cache (populated by fetchCalendarEvents)
+	events, err := s.GetCalendarEventsByDateRange(start, end)
+	if err != nil {
+		log.Printf("Warning: failed to read cached calendar events: %v", err)
+	} else {
+		for _, event := range events {
+			endTime := event.End
+			item := models.TimelineItem{
+				ID:           event.ID,
+				Type:         models.TimelineItemTypeEvent,
+				Title:        event.Summary,
+				Time:         event.Start,
+				EndTime:      &endTime,
+				Description:  event.Description,
+				URL:          event.HTMLLink,
+				OriginalItem: event,
+				IsCompleted:  false,
+				Source:       "calendar",
 			}
+			item.ComputeDaySection(now)
+			items = append(items, item)
 		}
 	}