Root cause of the "blocked at the last cellar step" wedge (the primary,
ramp-climb family — 20/29 captured records). The prior session's pinned
"find_walkable is never called during the step-down" was a probe artifact:
a fresh [fc-dispatch]/[step-sphere-down] trace proves Path-3 StepSphereDown
IS reached for both the carried cell and the iterated other-cell.
The real divergence is in Transition.CheckOtherCells. Retail's
check_other_cells (acclient_2013_pseudo_c.txt:272735 → (*cell+0x88)(this))
re-collides the OTHER cells against the LIVE sphere_path.global_sphere — the
position AFTER the primary insert_into_cell ran. The primary collide can MOVE
the sphere: a Path-5 full-hit dispatches step_sphere_up, and a successful
step-up climbs the foot onto the cottage floor yet still returns OK. acdream
instead reused a footCenter snapshot captured BEFORE the primary collide, so
once the lip-riser step-up climbed the foot onto the floor, check_other_cells
still queried 0171 at the pre-climb (sunk ~0.25 m below the floor) position →
the foot spuriously near-missed the very floor it had climbed onto →
neg_step_up → a doomed second step_up vs the floor normal (0,0,1) whose
step_up_slide unwound the climb → validate_transition reverted → 0% advance.
Fix: re-read footCenter = sp.GlobalSphere[0].Origin at the top of
RunCheckOtherCellsAndAdvance (one line). Pre-fix 0/29 wedge records advanced;
post-fix 20/29 climb onto Z≈94.
No regression: full Core suite 1321 pass / 4 fail (the documented baseline:
Apparatus_Grounded_50cmOffCenter, 2× DoorBugTrajectoryReplay LiveCompare_*,
BSPStepUpTests.D4) / 1 skip. The 2 door LiveCompare divergences are
byte-identical with/without the fix (the door's step_up FAILS → sphere
restored → position unchanged → footCenter == live).
Tests: CellarLipWedgeTests.Fix_StaleFootCenter_RampRecordClimbsCottageFloor +
Fix_StaleFootCenter_MajorityOfWedgeRecordsAdvance (new, GREEN).
DocumentsResidualWedge_LiveFloorCp_SlidingNormalKillsPlusY documents the
remaining 9/29 (0,-1,0)-sliding-normal +Y-kill family (slide territory,
deferred to the visual gate).
Apparatus retained (gated on ACDREAM_PROBE_INDOOR_BSP): [fc-dispatch] in
BSPQuery.FindCollisions + [step-sphere-down] in BSPQuery.StepSphereDown +
CellarLipWedgeTests.Diagnostic_TraceRecordByIndex — strip once the residual
is resolved.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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