Campaign P Slice P2 step 2-3
(docs/research/2026-07-30-response-layer-edge-family-pseudocode.md §4, §6
Step 3). Per the research doc's own port order, TS-4's Path-6 steep-poly
shortcut may only be removed after a fixture reproduces the original
"stuck in falling animation on a steep roof" symptom cleanly with the
shortcut disabled. No surviving live-session fixture exists from the
2026-04-30 L.4 commit (b1af56e); this adds a dat-free multi-frame capture
(Ts4SteepRoofWedgeCaptureTests) using BSPStepUpFixtures.SlopedUnwalkable's
63.4 degree slope, replayed at 30 Hz with gravity integrated between
PhysicsEngine.ResolveWithTransition calls -- the same idiom as
Issue185OutdoorStairsSeamReplayTests.
Against today's baseline (shortcut active) the capture is green, as
expected (the shortcut's explicit AddOffsetToCheckPos keeps the body
moving every tick by construction).
Scratch-removed the shortcut (both BSPQuery.cs sphere0/sphere1 branches,
not committed -- reverted after capture) and re-ran the same test: the
body falls and lands cleanly on the steep polygon at tick 17 (InContact,
OnWalkable=false, via retail's own permissive CTransition::check_walkable
LandingZ gate, pc:273202), then freezes at that exact position for the
rest of the run -- the exact historical wedge shape, tripping the test's
own >0.5s-frozen threshold at tick 33.
Root-cause diagnosis via ACDREAM_DUMP_EDGE_SLIDE=1: the freeze is upstream
of EdgeSlideAfterStepDownFailed/CliffSlide entirely (none of that
dispatch's diagnostics fire). TransitionalInsert's Phase 2 object-collision
check returns Adjusted on every retry attempt because Path 6's retail-
faithful SetCollide returns ADJUSTED_TS without repositioning the sphere
(unlike the interim shortcut, which explicitly pushes the sphere off the
face) -- the same steep polygon re-triggers Path 6 on the immediate retry,
forever, and Phase 3 (the sp.Collide handling that contains DoCheckWalkable,
the Placement re-test, and the TS-1 CliffSlide chain) is gated on Phase 1
AND Phase 2 both returning OK, so it is structurally unreachable from this
state. TS-1's completeness is moot here -- the code path that would call
into it never runs.
Per the mission's explicit escape valve: STOP here, keep the shortcut, and
report -- do not improvise a third variant. Full diagnosis, the exact
capture, and the concrete next research question (does retail's own
transitional_insert loop check sphere_path.collide on every iteration
regardless of Phase 2's own return value, or only when Phase 2 returns OK?)
are recorded in the research doc's §7 item 6 and the doc's headline; the
campaign plan's P2 section gets a matching status note.
Physics test suite: 1841 passed, 1 skipped (D4, pre-existing/unrelated), 0
failed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
65de6921ce