…tatistics work as C1b

Post-merge hygiene, written on merge rather than as later cleanup (the delay is
the anti-pattern the arc's own recovery note documents). Arc entries for #881,
#882 and #883, plus the matching LATEST_STATE entry.

The #883 entry records the ruling in its canonical wording: #879 is the complete
and independent production phase-progression path; KanbanActor has no assigned
architectural responsibility and its presence designates it as the future home
of nothing. It also records the separation that must not blur -- MulAdvance and
drive_mul_advance are legacy actor-message WRAPPERS, not the canonical MUL
reasoning engine; gate_decision_i4 is independent, consumed directly by the #879
path, and not deprecated; the NARS recipes and awareness rung ladder are
separate and untouched. The spawn inventory is recorded as deletion-impact
evidence and a removal work-list only, with no architectural legitimacy.

Restores the statistics scope that was deliberately removed from #883, now as
its own deliverable rather than mixed into a legacy-surface correction:

- C1 result: jc is in-tree; reliability.rs ships pearson / spearman /
  cronbach_alpha / icc (Icc2_1, Icc3_1), plus jirak.rs for the C4 noise floors.
  phi = pearson on two binary variables and KR-20 = alpha on dichotomous items,
  so those two renames are reporting work, not new math. kappa is absent from jc
  entirely -- the real gap, and it blocks D3's fusion falsifier.
- C1b: kappa + McDonald's omega + effect size (Effektstärke), ADDITIVE ONLY.
  pearson/spearman/cronbach_alpha/icc stay untouched; any diff editing an
  existing jc statistic is an automatic reject, independent of merit.
- C2 corrected: kappa is a SEPARATE estimator, not a renamed ICC. ICC stays ICC
  for the non-binary escalation only.

No code, no runtime behaviour, no actor content.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3RyLEbuNSHxxB3NTTrGki

…w-h9osnl

board: post-merge entries for #881/#882/#883 + re-scope the removed statistics work as C1b

#884 was itself the post-merge hygiene PR for #881/#882/#883 — and it merged
without its own arc entry, reproducing one level up exactly the gap it was
written to close. Writing the hygiene PR does not discharge the rule for the
hygiene PR. Entry added, with that noted in it.

Records what #884 locked:

- The C1 audit finding: phi = pearson-on-binaries and KR-20 =
  alpha-on-dichotomous are the SAME computations already in jc (named wrapper +
  caveat only, arithmetic not re-implemented); kappa is absent and is NOT a
  renamed ICC — the real gap, and the one that blocks D3's fusion falsifier.
- Effect size means the r-family: R, R-squared, eta-squared, phi. Cohen's d
  explicitly out, calculated separately if ever wanted. The t-test is the
  significance companion to eta-squared, not a d-family route.
- ADDITIVE ONLY with one carve-out: existing jc statistics keep their
  arithmetic, signature and semantics; the sole permitted edit to an existing
  file is widening reliability.rs's private helpers to pub(crate) for reuse —
  visibility only.
- The transport-vs-engine separation carried from #883, and that the spawn
  inventory carries no architectural legitimacy.

Board prose only. D-KIA-C1b remains Queued.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3RyLEbuNSHxxB3NTTrGki

#881/#882/#883 merged with no arc entries. #884 closed that gap and merged
without its own. #885 closed THAT gap and merged. An entry for #885 would need
an entry, and so on without end: each step was the rule correctly applied, but
the composition does not terminate.

The recursion was invisible for three links because the rule is stated per-PR
and every single application is locally correct — which is exactly what hides a
divergent chain. Two earlier sessions each wrote the honest local lesson
("writing the hygiene PR does not discharge the rule for the hygiene PR")
without noticing that the lesson, applied uniformly, never bottoms out.

Amendment: a PR whose ENTIRE content is board hygiene for prior PRs — no type,
plan, deliverable, epiphany or code — does not itself generate an arc entry; it
is discharged by the entry it wrote. The test is content, not intent: does the
PR change anything a future session needs the "why" for? Mixed PRs still get
their entry (#884 landed hygiene AND the D-KIA-C1b re-scope; the entry exists
for the re-scope half).

This is a stopping rule, not a loosening. Merging three PRs with no entries at
all remains a violation and the retroactive-hygiene anti-pattern is unchanged;
only the degenerate tail is excluded. Consequence: #885 gets no arc entry,
deliberately, and its absence is not a gap.

Transferable shape recorded: a per-item obligation whose discharge is itself an
item of that kind needs an explicit base case, or it is a recursion with no
bottom. The cheap check is to apply a rule twice to its own output and see
whether the third application says anything new.

Board/doc prose only.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01K3RyLEbuNSHxxB3NTTrGki