expired stays a terminal exit from valid (state machine unchanged),
but supersede() now also accepts it as a source status when the
caller supplies a validity window, linking a new successor approval
to the expired original instead of requiring a caller to mint an
unlinked replacement from scratch. Without a fresh window, an expired
source still conflicts exactly as before.
The original's status becomes superseded (not left as a bare dead-end
expired) and superseded_by points at the successor, so the link is
documented rather than hidden -- informed-decision's overview already
renders this automatically, no changes needed there.
Prompted by the operator missing infd-20260927-b01's approval window
during today's key-cape login outage (APPROVAL-WP-0003).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 169987@bnt-lap001
Assistant-Session: 322ef1ef-9048-4021-8570-b6d6f6347999