The C-clip that retains the recoil springs on the guide rod broke, during use. (My fault, I tweaked it a bit, during the previous cleaning. )
The spring made its way between the slide and guide rod, and the washer behind the clip got bent. Everything got jammed with about 1.5 inches of spring sticking out the front of the pistol.
Very interesting! I hadn't heard of a P95 jamming when the clips break before, so this is a new failure mode to me.
I've had the clips break--I've even figured out how to make sturdier replacements from the right size springs. I've also shot P95s without the clips & washers--using the recoil springs loose on the guiderod.
One thing I typically try to do is to slightly bevel the hole in the slide so it's less likely to peel the clip off the guide rod.