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>
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