feat: native task management + Todoist migration

Adds doot-owned task storage (native_tasks table) so tasks can be
managed without Todoist. CompleteTask for 'doot' source just updates
the DB — no external API call, no token dependency.

Migration path:
  POST /settings/import-from-todoist  — copies Todoist cache → native_tasks
  Then remove TODOIST_TOKEN from .env to disable Todoist

Changes:
- migration 020: native_tasks table
- store: GetNativeTasks, GetNativeTasksByDateRange, GetUndatedNativeTasks,
  CreateNativeTask, CompleteNativeTask, UncompleteNativeTask,
  UpdateNativeTask, ImportFromTodoist
- timeline: native tasks appear as source="doot" (teal)
- handleAtomToggle: "doot" case — no external API needed
- HandleWidgetComplete: method on Handler, handles "doot" natively
- HandleUnifiedAdd: "doot" source creates in native_tasks
- widget: "doot" tasks are completable, teal color indicator

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

1 files changed, 135 insertions, 0 deletions

diff --git a/internal/store/native_tasks.go b/internal/store/native_tasks.go
new file mode 100644
index 0000000..3ec043b
--- /dev/null
+++ b/internal/store/native_tasks.go
@@ -0,0 +1,135 @@
+package store
+
+import (
+	"encoding/json"
+	"log"
+	"time"
+
+	"task-dashboard/internal/models"
+)
+
+// GetNativeTasks returns all non-completed native tasks.
+func (s *Store) GetNativeTasks() ([]models.Task, error) {
+	rows, err := s.db.Query(`
+		SELECT id, content, description, project_name, due_date, priority, completed, labels, created_at
+		FROM native_tasks
+		WHERE completed = 0
+		ORDER BY CASE WHEN due_date IS NULL THEN 1 ELSE 0 END, due_date ASC, priority DESC
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+	return scanNativeTasks(rows)
+}
+
+// GetNativeTasksByDateRange returns non-completed native tasks due within the given range.
+func (s *Store) GetNativeTasksByDateRange(start, end time.Time) ([]models.Task, error) {
+	rows, err := s.db.Query(`
+		SELECT id, content, description, project_name, due_date, priority, completed, labels, created_at
+		FROM native_tasks
+		WHERE completed = 0 AND due_date IS NOT NULL AND due_date >= ? AND due_date < ?
+		ORDER BY due_date ASC, priority DESC
+	`, start, end)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+	return scanNativeTasks(rows)
+}
+
+// GetUndatedNativeTasks returns non-completed native tasks with no due date.
+func (s *Store) GetUndatedNativeTasks() ([]models.Task, error) {
+	rows, err := s.db.Query(`
+		SELECT id, content, description, project_name, due_date, priority, completed, labels, created_at
+		FROM native_tasks
+		WHERE completed = 0 AND due_date IS NULL
+		ORDER BY priority DESC, created_at ASC
+	`)
+	if err != nil {
+		return nil, err
+	}
+	defer func() { _ = rows.Close() }()
+	return scanNativeTasks(rows)
+}
+
+// CreateNativeTask inserts a new native task.
+func (s *Store) CreateNativeTask(task models.Task) error {
+	labelsJSON, _ := json.Marshal(task.Labels)
+	_, err := s.db.Exec(`
+		INSERT INTO native_tasks (id, content, description, project_name, due_date, priority, labels, created_at, updated_at)
+		VALUES (?, ?, ?, ?, ?, ?, ?, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP)
+	`, task.ID, task.Content, task.Description, task.ProjectName, task.DueDate, task.Priority, string(labelsJSON))
+	return err
+}
+
+// UpdateNativeTask updates a native task's content and description.
+func (s *Store) UpdateNativeTask(id, content, description string) error {
+	_, err := s.db.Exec(`
+		UPDATE native_tasks SET content = ?, description = ?, updated_at = CURRENT_TIMESTAMP
+		WHERE id = ?
+	`, content, description, id)
+	return err
+}
+
+// CompleteNativeTask marks a task as completed.
+func (s *Store) CompleteNativeTask(id string) error {
+	_, err := s.db.Exec(`
+		UPDATE native_tasks SET completed = 1, updated_at = CURRENT_TIMESTAMP WHERE id = ?
+	`, id)
+	return err
+}
+
+// UncompleteNativeTask marks a task as not completed.
+func (s *Store) UncompleteNativeTask(id string) error {
+	_, err := s.db.Exec(`
+		UPDATE native_tasks SET completed = 0, updated_at = CURRENT_TIMESTAMP WHERE id = ?
+	`, id)
+	return err
+}
+
+// ImportFromTodoist copies all incomplete tasks from the Todoist cache into native_tasks.
+// Skips tasks already present (by ID). Returns the count of newly imported tasks.
+func (s *Store) ImportFromTodoist() (int, error) {
+	result, err := s.db.Exec(`
+		INSERT OR IGNORE INTO native_tasks
+			(id, content, description, project_name, due_date, priority, completed, labels, created_at, updated_at)
+		SELECT
+			id, content, COALESCE(description, ''), COALESCE(project_name, ''),
+			due_date, priority, 0, COALESCE(labels, '[]'), created_at, CURRENT_TIMESTAMP
+		FROM tasks
+		WHERE completed = 0
+	`)
+	if err != nil {
+		return 0, err
+	}
+	n, _ := result.RowsAffected()
+	log.Printf("ImportFromTodoist: imported %d tasks", n)
+	return int(n), nil
+}
+
+func scanNativeTasks(rows interface{ Next() bool; Scan(...interface{}) error; Err() error }) ([]models.Task, error) {
+	var tasks []models.Task
+	for rows.Next() {
+		var t models.Task
+		var labelsJSON string
+		var dueDateStr *string
+		if err := rows.Scan(&t.ID, &t.Content, &t.Description, &t.ProjectName, &dueDateStr, &t.Priority, &t.Completed, &labelsJSON, &t.CreatedAt); err != nil {
+			return nil, err
+		}
+		if dueDateStr != nil {
+			if parsed, err := time.Parse(time.RFC3339, *dueDateStr); err == nil {
+				t.DueDate = &parsed
+			} else if parsed, err := time.Parse("2006-01-02 15:04:05", *dueDateStr); err == nil {
+				t.DueDate = &parsed
+			} else if parsed, err := time.Parse("2006-01-02", *dueDateStr); err == nil {
+				t.DueDate = &parsed
+			}
+		}
+		if err := json.Unmarshal([]byte(labelsJSON), &t.Labels); err != nil {
+			t.Labels = nil
+		}
+		tasks = append(tasks, t)
+	}
+	return tasks, rows.Err()
+}