Marcin Pawlowski c202ad9c17
Add deep_orphan_share: the structural observable behind the first-fork cost
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>
2026-08-07 11:59:37 +02:00

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# Handoff E5 — the diagnostic: does per-recipient delay variance reproduce the standalone result?
#
# This is the only experiment in the handoff that could invalidate the REPORT rather than the spec
# section. The primary hypothesis for the original discrepancy is modelling, not measurement: the
# standalone simulation drew an INDEPENDENT propagation delay per (block, recipient), while this
# simulator's blend topology runs a cascade of relays and then floods network-wide from the LAST
# relay, so nodes receive a block at nearly the same time and their views stay synchronised.
# Independent per-recipient draws maximise view divergence, which is exactly what manufactures the
# depth->=2 forks the first-fork rule cannot recover.
#
# jitter_mean adds per-(block, node) arrival noise on top of the cascade, so sweeping it
# interpolates between the two models: 0 is the report's cascade, large values approach the
# standalone's independent-delay regime. The observable that decides it is deep_orphan_share --
# the fraction of in-window orphans sitting deeper than the first block of their fork, which is
# precisely the structural quantity behind claim C2.
#
# This is also the report's open item 15 (correlated/heterogeneous latency untested).
#
# EXACT ORACLE REQUIRED: the windowed fork choice and the arrival prune are only bit-exact at
# jitter_mean == 0 (a jittered arrival can cross the deterministic horizon), so both are off. That
# forces the full (N x n_blocks) matrix and makes each run ~17 s at k = 2160.
#
# Run TWICE — default (countable) and with --old. `--old` is NOT a candidate design: under the
# current spec a block carrying a deep-fork reference is REJECTED, so it is an unreachable upper
# bound on what any counting rule could recover, and the countable-vs-ceiling gap is the
# first-fork cost. Latency is in SLOTS (1 slot = 1 s).
n_nodes: [1000] # network size
stake_dist: [pareto] # heavy-tailed (realistic) stake distribution
topology: [blend] # Blend mixnet — the deployment transport
degree: [6] # peering degree of the d-regular graph
link_latency_mean: [0.5] # natural geographic transport (sub-slot)
link_latency_dist: [geo] # real-world geographic band mixture
blend_hops: [3] # the spec's Blend cascade length
blend_delay_max: [4.0] # E1: the spec's operating point (rho ~ 0.27)
max_uncles: [0, 1, 2, 4] # 0 = negative control; 4 = the spec's MAX_UNCLES
uncle_strategy: [oldest] # spec Uncle Selection
init_dest: [common] # per-node initial D_est from agreement
replicates: 12 # exact-oracle runs are ~17 s each; 12 x 40 cells
base: # per-run settings shared by every cell
k: 2160 # true security parameter
epochs: 20 # equilibrium within ~2 epochs; burn 50%
f: 0.03333333333333333 # slot activation coefficient (1/30)
genesis_d_factor: 0.5 # start near true stake (cheap epoch 0)
early_stop: true
windowed_fork_choice: false # exact oracle: required once jitter > 0
prune_arrival: false # ...and the prune needs the same horizon
jitter_mean: 0.0 # OVERRIDDEN per run by scripts/spec_jitter.py