feat(tasks): add HTTP endpoints for task detail, update, and recurrence

GET /api/widget/task, POST /api/widget/task/update,
POST /api/widget/task/recurrence, POST /api/widget/task/next-date.
Doot-only; the recurrence/next-date fields are null in the detail
response for a non-recurring task.

1 files changed, 197 insertions, 0 deletions

diff --git a/internal/handlers/widget_test.go b/internal/handlers/widget_test.go
index 2a6967e..35c21e2 100644
--- a/internal/handlers/widget_test.go
+++ b/internal/handlers/widget_test.go
@@ -816,3 +816,200 @@ func TestTimelineItemToWidgetItem_NonRecurring_EmptyRecurringEventID(t *testing.
 	}
 }
 
+func TestHandleWidgetTaskDetail_ReturnsFullDetail(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`
+		INSERT INTO native_tasks (id, content, description, due_date, recurrence_freq, recurrence_interval, recurrence_weekdays, recurrence_series_id)
+		VALUES ('rec-1', 'Water plants', 'Use the blue can', '2026-07-13', 'weekly', 1, '1,3,5', 'series-1')
+	`); err != nil {
+		t.Fatal(err)
+	}
+
+	req := httptest.NewRequest("GET", "/api/widget/task?id=rec-1&source=doot", nil)
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskDetail).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	var resp taskDetailResponse
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatalf("failed to decode response: %v", err)
+	}
+	if resp.Title != "Water plants" {
+		t.Errorf("Title = %q, want %q", resp.Title, "Water plants")
+	}
+	if resp.Description != "Use the blue can" {
+		t.Errorf("Description = %q, want %q", resp.Description, "Use the blue can")
+	}
+	if resp.Recurrence == nil {
+		t.Fatal("expected non-nil Recurrence")
+	}
+	if resp.Recurrence.Freq != "weekly" || len(resp.Recurrence.Weekdays) != 3 {
+		t.Errorf("Recurrence = %+v, want freq=weekly with 3 weekdays", resp.Recurrence)
+	}
+	if resp.NextDate == nil {
+		t.Fatal("expected computed NextDate for a recurring task")
+	}
+}
+
+func TestHandleWidgetTaskDetail_NonRecurring_NilRecurrenceAndNextDate(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`INSERT INTO native_tasks (id, content) VALUES ('plain-1', 'Buy milk')`); err != nil {
+		t.Fatal(err)
+	}
+
+	req := httptest.NewRequest("GET", "/api/widget/task?id=plain-1&source=doot", nil)
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskDetail).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d", w.Code)
+	}
+	var resp taskDetailResponse
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatalf("failed to decode response: %v", err)
+	}
+	if resp.Recurrence != nil {
+		t.Errorf("expected nil Recurrence for a non-recurring task, got %+v", resp.Recurrence)
+	}
+	if resp.NextDate != nil {
+		t.Errorf("expected nil NextDate for a non-recurring task, got %v", resp.NextDate)
+	}
+}
+
+func TestHandleWidgetTaskDetail_UnknownID_Returns404(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	req := httptest.NewRequest("GET", "/api/widget/task?id=does-not-exist&source=doot", nil)
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskDetail).ServeHTTP(w, req)
+
+	if w.Code != http.StatusNotFound {
+		t.Errorf("expected 404, got %d", w.Code)
+	}
+}
+
+func TestHandleWidgetTaskUpdate_UpdatesTitleAndDescription(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`INSERT INTO native_tasks (id, content) VALUES ('plain-1', 'Old title')`); err != nil {
+		t.Fatal(err)
+	}
+
+	body := `{"id":"plain-1","title":"New title","description":"New description"}`
+	req := httptest.NewRequest("POST", "/api/widget/task/update", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskUpdate).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	task, err := s.GetNativeTaskByID("plain-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if task.Content != "New title" || task.Description != "New description" {
+		t.Errorf("task = %+v, want title/description updated", task)
+	}
+}
+
+func TestHandleWidgetTaskRecurrence_SetsPattern(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`INSERT INTO native_tasks (id, content) VALUES ('plain-1', 'Water plants')`); err != nil {
+		t.Fatal(err)
+	}
+
+	body := `{"id":"plain-1","freq":"weekly","interval":2,"weekdays":[1,3]}`
+	req := httptest.NewRequest("POST", "/api/widget/task/recurrence", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskRecurrence).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	task, err := s.GetNativeTaskByID("plain-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if task.RecurrenceFreq != "weekly" || task.RecurrenceInterval != 2 || task.RecurrenceSeriesID == "" {
+		t.Errorf("task = %+v, want recurrence set with a generated series id", task)
+	}
+}
+
+func TestHandleWidgetTaskRecurrence_InvalidFreq_Returns400(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	body := `{"id":"plain-1","freq":"bogus","interval":1}`
+	req := httptest.NewRequest("POST", "/api/widget/task/recurrence", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskRecurrence).ServeHTTP(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for an invalid freq, got %d", w.Code)
+	}
+}
+
+func TestHandleWidgetTaskNextDate_SetsOverride(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`
+		INSERT INTO native_tasks (id, content, due_date, recurrence_freq, recurrence_series_id)
+		VALUES ('rec-1', 'Water plants', '2026-07-13', 'weekly', 'series-1')
+	`); err != nil {
+		t.Fatal(err)
+	}
+
+	body := `{"id":"rec-1","date":"2026-08-01"}`
+	req := httptest.NewRequest("POST", "/api/widget/task/next-date", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskNextDate).ServeHTTP(w, req)
+
+	if w.Code != http.StatusOK {
+		t.Fatalf("expected 200, got %d: %s", w.Code, w.Body.String())
+	}
+	task, err := s.GetNativeTaskByID("rec-1")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if task.NextOccurrenceOverride == nil || task.NextOccurrenceOverride.Format("2006-01-02") != "2026-08-01" {
+		t.Errorf("NextOccurrenceOverride = %v, want 2026-08-01", task.NextOccurrenceOverride)
+	}
+}
+
+func TestHandleWidgetTaskNextDate_NonRecurringTask_Returns400(t *testing.T) {
+	s, cleanup := setupTestDB(t)
+	defer cleanup()
+	h := &Handler{store: s}
+
+	if _, err := s.DB().Exec(`INSERT INTO native_tasks (id, content) VALUES ('plain-1', 'Buy milk')`); err != nil {
+		t.Fatal(err)
+	}
+
+	body := `{"id":"plain-1","date":"2026-08-01"}`
+	req := httptest.NewRequest("POST", "/api/widget/task/next-date", strings.NewReader(body))
+	w := httptest.NewRecorder()
+	http.HandlerFunc(h.HandleWidgetTaskNextDate).ServeHTTP(w, req)
+
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("expected 400 for a non-recurring task, got %d", w.Code)
+	}
+}
+