Adds two files under tests/:
BSPStepUpFixtures.cs — synthetic PhysicsBSPNode trees for four canonical
collision shapes: low step (25 cm), too-tall wall (5 m), flat roof (3 m),
and steep slope (60deg). Pre-builds ResolvedPolygon dicts with correct
polygon_hits_sphere_precise winding (CCW relative to outward normal).
BSPStepUpTests.cs — 11 conformance tests:
A1-A6: baselines that pass before and after implementation (no-hit, geometry
fixture sanity checks).
B1-B3: Phase L.2.1 targets, currently RED (Path 5 wall-slides).
C1-C3: Phase L.2.2 targets, currently RED (Path 6 wall-slides).
Retail refs in test docstrings:
BSPTREE::find_collisions Path 5 acclient_2013_pseudo_c.txt:323849 /
ACE BSPTree.cs:192-196.
CTransition::step_up acclient_2013_pseudo_c.txt:273099-273133 /
ACE Transition.cs:746-777.
SPHEREPATH::set_collide acclient_2013_pseudo_c.txt:321594-321607 /
ACE SpherePath.cs:279-286.
CTransition::transitional_insert Collide branch
acclient_2013_pseudo_c.txt:273193-273239 / ACE Transition.cs:891-930.
Also adds PhysicsDataCache.RegisterGfxObjForTest() for test-only GfxObjPhysics
injection without real DAT content.
Test delta: 811 -> 823 (+12). 6 passing (A1-A6 + B2), 5 intentionally failing.
Pre-flight: object-translation plane D is in object-local space. Bug is dormant
for outdoor movement where terrain sets the world-space ContactPlane. Tagged TODO.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>