Module layer 

The audit layer.

Rollup requires state accumulated across events within a span, which a FormatEvent implementation cannot hold — so this is a full Layer that keeps per-span state in span extensions:

• on_new_span — capture the envelope fields, install an empty Rollup
• on_record — pick up outcome / duration_ms recorded at finish
• on_event — print exceptions now, fold allows into the parent span
• on_close — render and flush the rollup line

Structs

AuditLayer

StderrWriter

The production sink: stderr, line-buffered, failures ignored.

Enums

Detail

How much the operator wants to see.

Constants

DEFAULT_ROLLUP_CAP

Default cap on distinct rollup groups per tool call. Chosen to comfortably cover a well-behaved component; past it, new groups collapse into a count.

Traits

AuditWriter

Where rendered lines go. Abstracted so tests can capture them.