A structured diagnostic delivered through the renderer's diagnostic wire channel.

Wire shape: %{type: "diagnostic", session, level, diagnostic: %{kind, ...}}. The :diagnostic field is one of the typed variants defined under Plushie.Event.Diagnostic.*.

Fields

• :session - session ID the diagnostic is attributed to. An empty string for process-scoped diagnostics (font load failures, renderer startup or panic, writer-dead, anything that affects the whole renderer rather than a single session). Non-empty for session-scoped diagnostics (widget panics, view errors, tree validation warnings, anything produced inside a session's update or apply pipeline).
• :level - severity: :info, :warn, or :error.
• :diagnostic - typed diagnostic variant struct.

Pattern matching

def update(model, %DiagnosticMessage{diagnostic: %FontFamilyNotFound{family: f}}) do
  Logger.warning("font missing: #{f}")
  model
end

def update(model, %DiagnosticMessage{level: :error, diagnostic: diag}) do
  Logger.error("plushie renderer error: #{inspect(diag)}")
  model
end