# What sits under the port's hot residual tiles on the main menu? 2026-08-31.
#
# sylpheed-port mapped the menu's edge residual at 64 px tiles and handed over
# COORDINATES WITHOUT NAMES -- the element inventory is this side's. Their result:
# hot tiles cluster at x 384..704, y 64..256, hottest (512,128) at 3.66x the median
# tile, and NO tile in the hot region has moved (every |dx|,|dy| < 0.1 px against a
# control reading a true 1 px at +0.949).
#
# ⚠️ COORDINATE FRAME. Their tiles are in the frame they compare in; the disc is
# design space, and the two differ by the capture offset
# (capture_y = 64.82 + 0.9919 * design_y). So both readings were tested rather than
# one assumed -- and the answer does not depend on it: three elements are hot under
# BOTH.
#
# ✅ ELEMENTS WHOSE REST POSITION FALLS IN THE HOT BAND (GP_TITLE entry 5):
#
#   ptframe1.t32   (440, 108)  pivot (124,140)   HOT under both readings
#   ptbtn01.rat    (542, 162)  pivot ( 42, 22)   HOT under both -- the NEW GAME button
#   pteff12.t32    (467, 180)  pivot (174,180)   HOT under both -- an effect element
#   ptbtn02.rat    (542, 242)  pivot ( 58, 22)   hot in DESIGN space only
#
# 📌 THE HOT REGION IS NOT ONE ELEMENT. It is where a FRAME, a BUTTON and an
# EFFECT overlap -- three elements of different kinds stacked in the same band.
# That is consistent with their null result: they went looking for two families of
# tile (edge-only versus hot-everywhere) and found one continuous population, so
# the region has no character of its own.
#
# ⚠️ WHAT THIS DOES NOT SAY. It names what is THERE, not what is wrong. Their map
# already excludes local displacement in these tiles, so this is not a misplaced
# element; the inventory is offered as the next reader's starting point, not as a
# diagnosis. The residual's cause remains open.
#
# 📌 AND A CONTROL LIMIT OF THEIRS THAT CHANGES HOW ANY SLOPE READS: a known +2 px
# displacement localises perfectly but reads back +0.839, because the slope is a
# linearisation (residual ~ dx * gradient) that saturates once dx approaches the
# width of an edge. So their +1 px control gives localisation AND magnitude, the
# +2 px control gives localisation and SIGN only, and **any slope they report is a
# FLOOR on the displacement, never a ceiling**.
