The telemetry events PdfEx emits, and the single source of truth for their names. Attach handlers with :telemetry.attach/4 (or attach_many/4).

Every event is emitted via :telemetry.span/3, so each name below actually fires :start, :stop, and (on failure) :exception suffixed events with the standard span measurements (:monotonic_time, :duration).

• [:pdf_ex, :serialize] — wraps PdfEx.Serializer.serialize/2. Metadata: %{dirty: non_neg_integer(), mode: :incremental | :full}.
• [:pdf_ex, :session, :apply] — wraps each applied session write (both PdfEx.Session.apply_op/2 and submit_op/2). Metadata: %{document_id: term()}.