3 files changed, 149 insertions, 5 deletions

diff --git a/internal/api/server.go b/internal/api/server.go
index 8290738..59d59eb 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -384,7 +384,15 @@ func (s *Server) handleListWorkspaces(w http.ResponseWriter, r *http.Request) {
 }
 
 func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
-	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
+	lastUpdated, err := s.store.GetMaxUpdatedAt()
+	if err != nil {
+		s.logger.Error("failed to get max updated_at", "error", err)
+		lastUpdated = time.Time{}
+	}
+	writeJSON(w, http.StatusOK, map[string]interface{}{
+		"status":       "ok",
+		"last_updated": lastUpdated,
+	})
 }
 
 func (s *Server) handleCreateTask(w http.ResponseWriter, r *http.Request) {
@@ -477,6 +485,14 @@ func (s *Server) handleListTasks(w http.ResponseWriter, r *http.Request) {
 		}
 		filter.State = ts
 	}
+	if since := r.URL.Query().Get("since"); since != "" {
+		t, err := time.Parse(time.RFC3339, since)
+		if err != nil {
+			writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid since: " + since})
+			return
+		}
+		filter.Since = t
+	}
 	tasks, err := s.store.ListTasks(filter)
 	if err != nil {
 		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": err.Error()})
diff --git a/internal/storage/db.go b/internal/storage/db.go
index 69bcf68..a77b1b1 100644
--- a/internal/storage/db.go
+++ b/internal/storage/db.go
@@ -146,6 +146,10 @@ func (s *DB) ListTasks(filter TaskFilter) ([]*task.Task, error) {
 		query += " AND state = ?"
 		args = append(args, string(filter.State))
 	}
+	if !filter.Since.IsZero() {
+		query += " AND updated_at > ?"
+		args = append(args, filter.Since.UTC())
+	}
 	query += " ORDER BY created_at DESC"
 	if filter.Limit > 0 {
 		query += " LIMIT ?"
@@ -350,6 +354,33 @@ func (s *DB) UpdateTask(id string, u TaskUpdate) error {
 type TaskFilter struct {
 	State task.State
 	Limit int
+	Since time.Time
+}
+
+// GetMaxUpdatedAt returns the most recent updated_at timestamp across all tasks.
+func (s *DB) GetMaxUpdatedAt() (time.Time, error) {
+	var t sql.NullString
+	err := s.db.QueryRow(`SELECT MAX(updated_at) FROM tasks`).Scan(&t)
+	if err != nil {
+		return time.Time{}, err
+	}
+	if !t.Valid || t.String == "" {
+		return time.Time{}, nil
+	}
+	// Try parsing different formats SQLite might return
+	formats := []string{
+		"2006-01-02 15:04:05.999999999-07:00",
+		"2006-01-02T15:04:05Z07:00",
+		time.RFC3339,
+		"2006-01-02 15:04:05",
+	}
+	for _, f := range formats {
+		parsed, err := time.Parse(f, t.String)
+		if err == nil {
+			return parsed.UTC(), nil
+		}
+	}
+	return time.Time{}, fmt.Errorf("could not parse max updated_at: %q", t.String)
 }
 
 // Execution represents a single run of a task.
diff --git a/internal/storage/db_test.go b/internal/storage/db_test.go
index a16311d..752c5b1 100644
--- a/internal/storage/db_test.go
+++ b/internal/storage/db_test.go
@@ -148,11 +148,108 @@ func TestUpdateTaskState_InvalidTransition(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected error for invalid state transition PENDING → COMPLETED")
 	}
+	}
 
-	// State must not have changed.
-	got, _ := db.GetTask("task-invalid")
-	if got.State != task.StatePending {
-		t.Errorf("state must remain PENDING, got %v", got.State)
+	func TestGetMaxUpdatedAt(t *testing.T) {
+	db := testDB(t)
+
+	// Initial: should be zero time (SQLite might return a placeholder)
+	t0, err := db.GetMaxUpdatedAt()
+	if err != nil {
+		t.Fatalf("GetMaxUpdatedAt (empty): %v", err)
+	}
+	if !t0.IsZero() && t0.Year() != 1 {
+		t.Errorf("expected zero time for empty table, got %v", t0)
+	}
+
+	now := time.Now().UTC().Truncate(time.Second)
+	tk := &task.Task{
+		ID:        "max-1",
+		Name:      "Max Updated",
+		Agent:    task.AgentConfig{Type: "claude", Instructions: "test"},
+		Priority:  task.PriorityNormal,
+		Retry:     task.RetryConfig{MaxAttempts: 1, Backoff: "linear"},
+		Tags:      []string{},
+		State:     task.StatePending,
+		CreatedAt: now,
+		UpdatedAt: now,
+	}
+
+	if err := db.CreateTask(tk); err != nil {
+		t.Fatalf("CreateTask: %v", err)
+	}
+
+	t1, err := db.GetMaxUpdatedAt()
+	if err != nil {
+		t.Fatalf("GetMaxUpdatedAt (1 task): %v", err)
+	}
+	if !t1.Equal(now) {
+		t.Errorf("expected %v, got %v", now, t1)
+	}
+
+	if err := db.UpdateTaskState("max-1", task.StateQueued); err != nil {
+		t.Fatalf("UpdateTaskState: %v", err)
+	}
+	// Note: UpdateTaskState in db.go uses time.Now().UTC() for updated_at.
+	// We can't easily control it in the test without changing db.go to accept a time.
+	// So we just check that it's after or equal now.
+	t2, err := db.GetMaxUpdatedAt()
+	if err != nil {
+		t.Fatalf("GetMaxUpdatedAt (updated): %v", err)
+	}
+	if !t2.After(now) && !t2.Equal(now) {
+		t.Errorf("expected max updated_at to be >= %v, got %v", now, t2)
+	}
+	}
+
+	func TestListTasksSince(t *testing.T) {
+	db := testDB(t)
+	t1 := time.Date(2026, 3, 15, 10, 0, 0, 0, time.UTC)
+	t2 := time.Date(2026, 3, 15, 11, 0, 0, 0, time.UTC)
+	t3 := time.Date(2026, 3, 15, 12, 0, 0, 0, time.UTC)
+
+	tasks := []*task.Task{
+		{ID: "since-1", Name: "T1", CreatedAt: t1, UpdatedAt: t1, Agent: task.AgentConfig{Instructions: "t1"}},
+		{ID: "since-2", Name: "T2", CreatedAt: t2, UpdatedAt: t2, Agent: task.AgentConfig{Instructions: "t2"}},
+		{ID: "since-3", Name: "T3", CreatedAt: t3, UpdatedAt: t3, Agent: task.AgentConfig{Instructions: "t3"}},
+	}
+	for _, tk := range tasks {
+		if err := db.CreateTask(tk); err != nil {
+			t.Fatalf("CreateTask: %v", err)
+		}
+	}
+
+	// Fetch all
+	all, err := db.ListTasks(TaskFilter{})
+	if err != nil || len(all) != 3 {
+		t.Fatalf("ListTasks(all): err=%v, len=%d", err, len(all))
+	}
+
+	// Fetch since T1
+	sinceT1, err := db.ListTasks(TaskFilter{Since: t1})
+	if err != nil {
+		t.Fatalf("ListTasks(since T1): %v", err)
+	}
+	if len(sinceT1) != 2 {
+		t.Errorf("expected 2 tasks (T2, T3), got %d", len(sinceT1))
+	}
+
+	// Fetch since T2
+	sinceT2, err := db.ListTasks(TaskFilter{Since: t2})
+	if err != nil {
+		t.Fatalf("ListTasks(since T2): %v", err)
+	}
+	if len(sinceT2) != 1 {
+		t.Errorf("expected 1 task (T3), got %d", len(sinceT2))
+	}
+
+	// Fetch since T3
+	sinceT3, err := db.ListTasks(TaskFilter{Since: t3})
+	if err != nil {
+		t.Fatalf("ListTasks(since T3): %v", err)
+	}
+	if len(sinceT3) != 0 {
+		t.Errorf("expected 0 tasks, got %d", len(sinceT3))
 	}
 }