Basic pluto test with west has auto=ondemand and xfrm stack.

It shows two packets are dropped while negotiating.
tcpdump shows they don't leak in the clear

note this shows an unexpected:

src 192.0.1.254 dst 192.0.2.254
        proto esp spi 0xSPISPI reqid REQID mode transport
        replay-window 0
        sel src 192.0.1.254/32 dst 192.0.2.254/32 proto icmp type 8 code 0 dev eth1

which was the trigger packet. Unknown if we are supposed to delete this?
