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, 85 insertions, 3 deletions

diff --git a/internal/store/sqlite.go b/internal/store/sqlite.go
index 24a24d7..158febc 100644
--- a/internal/store/sqlite.go
+++ b/internal/store/sqlite.go
@@ -19,9 +19,10 @@ import (
 
 // Cache key constants
 const (
-	CacheKeyTodoistTasks   = "todoist_tasks"
-	CacheKeyTrelloBoards   = "trello_boards"
-	CacheKeyPlanToEatMeals = "plantoeat_meals"
+	CacheKeyTodoistTasks      = "todoist_tasks"
+	CacheKeyTrelloBoards      = "trello_boards"
+	CacheKeyPlanToEatMeals    = "plantoeat_meals"
+	CacheKeyGoogleCalendar    = "google_calendar"
 )
 
 type Store struct {
@@ -800,6 +801,87 @@ func (s *Store) GetCardsByDateRange(start, end time.Time) ([]models.Card, error)
 	return cards, rows.Err()
 }
 
+// Calendar event operations
+
+// SaveCalendarEvents replaces all cached calendar events
+func (s *Store) SaveCalendarEvents(events []models.CalendarEvent) error {
+	tx, err := s.db.Begin()
+	if err != nil {
+		return err
+	}
+	defer func() { _ = tx.Rollback() }()
+
+	_, err = tx.Exec(`DELETE FROM calendar_events`)
+	if err != nil {
+		return err
+	}
+
+	stmt, err := tx.Prepare(`
+		INSERT INTO calendar_events (id, summary, description, start_time, end_time, html_link)
+		VALUES (?, ?, ?, ?, ?, ?)
+	`)
+	if err != nil {
+		return err
+	}
+	defer func() { _ = stmt.Close() }()
+
+	for _, e := range events {
+		_, err = stmt.Exec(e.ID, e.Summary, e.Description, e.Start, e.End, e.HTMLLink)
+		if err != nil {
+			return err
+		}
+	}
+
+	return tx.Commit()
+}
+
+// GetCalendarEvents retrieves all cached calendar events
+func (s *Store) GetCalendarEvents() ([]models.CalendarEvent, error) {
+	rows, err := s.db.Query(`
+		SELECT id, summary, description, start_time, end_time, html_link
+		FROM calendar_events
+		ORDER BY start_time ASC
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	var events []models.CalendarEvent
+	for rows.Next() {
+		var e models.CalendarEvent
+		if err := rows.Scan(&e.ID, &e.Summary, &e.Description, &e.Start, &e.End, &e.HTMLLink); err != nil {
+			return nil, err
+		}
+		events = append(events, e)
+	}
+	return events, rows.Err()
+}
+
+// GetCalendarEventsByDateRange retrieves cached calendar events within a date range
+func (s *Store) GetCalendarEventsByDateRange(start, end time.Time) ([]models.CalendarEvent, error) {
+	rows, err := s.db.Query(`
+		SELECT id, summary, description, start_time, end_time, html_link
+		FROM calendar_events
+		WHERE start_time >= ? AND start_time <= ?
+		ORDER BY start_time ASC
+	`, start, end)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+
+	var events []models.CalendarEvent
+	for rows.Next() {
+		var e models.CalendarEvent
+		if err := rows.Scan(&e.ID, &e.Summary, &e.Description, &e.Start, &e.End, &e.HTMLLink); err != nil {
+			return nil, err
+		}
+		events = append(events, e)
+	}
+	return events, rows.Err()
+}
+
 // Agent operations
 
 // CreateAgentSession creates a new pending agent session