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>
P2 / M1.5 "blocked at the last step" cellar-lip wedge. This session built a faithful
deterministic reproduction and peeled the cause through six evidence-disproven framings
to one bounded question. NO fix landed — the last layers were each disproven by evidence,
and guessing at the load-bearing collision code is the saga's failure mode.
Apparatus:
- CellarLipWedgeTests.cs + Fixtures/cellar-lip/ (3 real cell dumps + wedge-records.jsonl =
29 captured ACDREAM_CAPTURE_RESOLVE wedge calls). Replays the exact calls + body-before
through the lip-cell engine: all 29 reproduce at 0% advance in <200 ms. Tests are
documents-the-bug / diagnostics (GREEN while the wedge exists).
- TEMP probes ([path5-wall]/[fw-enter]/[find-walkable] in BSPQuery; [neg-poly]/[stepsphereup]/
[stepdown-decide]/CheckOtherCells cn/sn/negHit in TransitionTypes), gated on
ACDREAM_PROBE_INDOOR_BSP, marked STRIP. TransitionTypes neg-poly shortcut has a reverted-fix
comment (slide attempt didn't clear the wedge).
- tools/cdb/retail-*-trace.cdb (retail cdb traces).
Findings (handoff: docs/research/2026-06-04-p2-cellar-lip-flatfloor-cp-handoff.md, see the
"NEXT-SESSION KICKOFF" at top):
- Flat-floor contact plane is retail-faithful (v1 trace, full-file correlation). NOT the bug.
- PosHitsSphere cull sign is retail-faithful (cdb -z verified; the Binary Ninja `test ah,N; jp`
parity-jump reads inverted — caught + reverted a wrong fix from that mis-read).
- Sphere radius correct (0.48 player / 0.30 camera probe).
- Retail connector cell 0xA9B40175 never blocks (CEnvCell::find_collisions trace: 0 Collided/Slid).
- PINNED: during the step-up's step-down, BSPQuery.FindWalkableInternal is never called for cell
0171, so the cottage floor (poly 0x0023, Z=94) is never tested as walkable -> no contact plane
-> step-up fails -> StepUpSlide=Collided -> wedge.
Next: trace FindEnvCollisions -> FindCollisions path dispatch for 0171 during StepDown=true (why
StepSphereDown/find_walkable is skipped), port retail, validate via CellarLipWedgeTests, regress
DoorBugTrajectoryReplayTests + visual gate.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
