The Holtburg town-network portal platform (stab 0xC0A9B465, Setup
0x020019E3, CylSphere r=2.597m h=0.256m) blocked the player with an
endless rim slide instead of retail's step-up-onto-top — gating the
whole #137 dungeon repro. Surfaced when #149 started registering
BSP-less stab CylSpheres: the collision SHAPE became right while the
RESPONSE was still the hand-rolled AP-6 approximation (step-up gate +
radial wall-slide only).
Root cause: no cylinder-TOP support anywhere. DoStepUp's internal
step-down probe needs retail's step_sphere_down (0x0053a9b0) to land on
the flat top — a cylinder has no polygons for the walkable search — so
every step-up onto a wide cylinder failed into StepUpSlide and the
player orbited the rim (probe-confirmed: [cyl-test] result=Slid with
horizontal rim normals, launch-137-repro.log).
Port the full family verbatim: dispatcher intersects_sphere 0x0053b440
(placement/ethereal detection, step-down cap landing, walkable probe,
grounded step_sphere_up 0x0053b310, PathClipped collide_with_point
0x0053acb0, airborne land_on_cylinder 0x0053b3d0, Collide-flag
exact-TOI cap rest) + collides_with_sphere 0x0053a880 +
normal_of_collision 0x0053ab50 + slide_sphere 0x0053b2a0. Pseudocode +
settled BN x87 ambiguities (via ACE cross-ref) + two ACE bugs found and
NOT copied (head-slide foot-disp; see doc §8):
docs/research/2026-07-05-ccylsphere-collision-family-pseudocode.md
Ethereal cylinders now flow through retail's Layer-2 override
(pc:276961) instead of the early-OK consume — same net #150 behavior,
plus retail placement-blocked-by-cylinder semantics. SlideSphere gains
a sphereNum param (retail slides the head sphere by its own
displacement, 0x0053b843).
Register: AP-6 retired; AP-83 added (PerfectClip TOI tail decoded per
ACE, dead code until missiles). Tests: CylSphereFamilyTests (grounded
step-up onto the exact platform shape, tall-cylinder block, airborne
top landing, ethereal guard); the #42 self-shadow control assertion
updated to the retail observable (denied movement — the old ~1m radial
self-push was the approximation's artifact, not retail). Suites: Core
2533 / App 713 / UI 425 / Net 385 green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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