Path 5 (Contact mover hits BSP polygon) calls DoStepUp → DoStepDown →
TransitionalInsert(5) → FindObjCollisions → which can hit the same wall
again → Path 5 fires AGAIN → recursive DoStepUp.
Bounded by the inner numAttempts=5 budget, but with significant per-step
churn — every recursion clears and re-establishes the contact plane,
finishing in an inconsistent state when the ranges decay. Also produced
gratuitous slowdown against tall walls.
Retail (acclient_2013_pseudo_c.txt:272954) gates step_sphere_up on
`if (sp.step_up == 0 && sp.step_down == 0)`. acdream's port was
missing this guard. Mid-recursion we now fall back to the wall-slide
response that already exists for the no-engine path.
Files:
- BSPQuery.cs Path 5 (foot sphere): added `&& !path.StepUp && !path.StepDown`
- BSPQuery.cs Path 5 (head sphere): same guard
Live-test bug: walking into building walls intermittently locked the
player in falling animation, hard to recover. After the guard, the
single-shot wall-slide produces clean blocking + horizontal slide.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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