E5 needs to watch whether per-recipient delay variance manufactures the
depth->=2 forks the countable rule cannot reach, and no recorded metric measured
that. p_ref conflates "unreachable by construction" with "eligible but never
picked up" -- the distinction that turned out to be the whole answer to item 5 --
and deep_ref_share is 0 by construction under the countable model, since the
proposer's candidate filter drops deep-fork blocks before any reference to one
is proposed. deep_orphan_share is the fraction of in-window orphans sitting
below the first block of their fork, computed from the depth array fork_stats
already builds.
Also fixes a splat-unpack in test_selfish_engine that silently re-bound to the
wrong quantities when fork_stats grew this field (it read deep_orphan_share as
p_ref_honest). fork_stats has now gained a field twice; both call sites unpack
by position explicitly.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>