MAJOR from the 2026-04-22 review (audio.rs:236-257): filenames were
derived from SystemTime::now().as_secs(), so two recordings started
within the same second resolved to the same path — possible overwrite
or merge.
Extracts the filename generation into a private helper and appends
the sub-second nanosecond component. Format is now
`kon-<secs>-<nanos_in_sec>.wav`, e.g. `kon-1776828000-123456789.wav`,
which stays human-readable, sortable by timestamp, and effectively
uncollidable under any realistic live-capture pattern.
Two tests cover the regression:
- recording_filenames_are_unique_across_rapid_calls: 64 tight-loop
calls must produce at least 32 unique names.
- recording_filename_has_expected_shape: prefix/suffix plus the
zero-padded 9-digit nanos component.
Jake
6e9ed99b3a