Documents telemetry emitted around public Letterpress operations.

Discovery, analysis, compilation, formatting, translation, and rendering emit :start followed by either :stop or :exception. Metadata never includes template source, rendered output, values, variable names, or caller identifiers.

Events

All event names have the form [:letterpress, operation, phase].

• :start measures :system_time and includes :profile and :operation
• :stop measures :duration and :input_size, and adds a low-cardinality :result classification
• :exception measures :duration and :input_size, and adds :kind plus a redacted :reason_class

Durations use native time units. Convert them with System.convert_time_unit/3 in handlers or metric definitions.

Attaching a handler

:telemetry.attach(
  "my-app-letterpress-render",
  [:letterpress, :render, :stop],
  fn _event, measurements, metadata, _config ->
    MyApp.Metrics.record_render(measurements.duration, metadata.result)
  end,
  nil
)