v1.9.0

[1.9.0] — 2026-07-24

The tower-tip MAP reads the top floor (ADR-019 Amendment 3): tip_mass 0.5 → 0.25.
Behavior change to tower_point/summarize_tower outputs, shipped MINOR per the C-44/C-45
precedent (estimator amendment with ADR evidence); CONFORMANCE_FLOOR stays 1.0.0.

Changed

• tip_mass default 0.5 → 0.25 (the top-quartile floor). The tower-tip MAP is now the
  median of the top floor of the published tower, matching the design intent the name
  always promised. Evidence (research/map_hdi/tip_mass_study.py, 1000-replicate battery +
  duplicate-capture frontier + the real-cell C-44 gate): the 0.5 shorth carried a structural
  rightward bias that does not shrink with sample count; 0.25 roughly halves it, beats the
  shorth on RMSE at pooled S, reads zero-inflated cells exactly, and passes the real-cell
  zero-stack gate with margin (masses ≤ 0.15 resurrect the C-44 signal loss; 0.20 has zero
  margin). Consumer note: published MAPs shift toward the mode on skewed cells — the intended
  C-32 direction.

Added

• MAP-containment law in assert_summarizer_contract: every floor holding more than half
  the tip floor's draws (asymptotically mass > tip_mass/2 = 12.5%) provably contains the
  tip — wider floors by nesting, narrower qualifying floors by the sub-window trim argument.
  All published bands (50/90/95/99) qualify; the unguaranteed region shrinks versus the old
  default (was: everything below 0.5).
• research/map_hdi/tip_mass_study.py — the committed evidence trail for the amendment.
• research/figures/ — permanent, seeded generators for the PRN06 tower figures (overlay +
  detail, upright-tower rendering), with reports/plots/ as the gitignored output home.