acdream/docs/research/2026-07-06-137-closeout-render-pair-pickup.md

Pickup prompt — post-#137-corridor session: the #176/#177 render pair (paste into a fresh session)

Read claude-memory/project_render_pipeline_digest.md FIRST (Option A — one DrawInside(viewer_cell); binding DO-NOT-RETRY table), then ISSUES #176 and #177, then this file. The physics digest (claude-memory/project_physics_collision_digest.md) carries the full 2026-07-06 collision saga if background is needed — do NOT reopen it.

Where we are (2026-07-06 end of session)

The #137 Facility Hub corridor collision arc is DONE, user-gated ("not collision anymore. Good." / "Looks good"). Branch claude/vigorous-joliot-f0c3ad (worktree), 10 commits ahead of e73e45da, NOT merged to main. All suites green (Core 2562 / App 713 / UI 425 / Net 385).

Commit	Fix
a11df5b8	BSPQuery Contact-branch stub slide responses leaked sliding normals (the absorbing wedge). Retail's BSP layer never writes collision_info.sliding_normal — only validate_transition 0x0050ac21; body persistence success-only (SetPositionInternal 0x005154c2).
e8651b38	slide_sphere opposing-normals branch returned OK; retail returns COLLIDED_TS (0x0053762c). The "phantom wall" normal was SYNTHETIC (negated movement). PortalSide-poly theory refuted.
d4869154	CheckOtherCells queried remaining cells at a stale pre-climb center (P2 lesson one loop deeper) — the seam shake. Per-iteration footCenter = sp.GlobalSphere[0].Origin refresh.
aa96d7ad	The collision capsule topped out at 1.2 m (callers passed sphereHeight: 1.2f; head sphere center 0.72). Dat Setup 0x02000001: spheres (0,0,0.475)+(0,0,1.350) r=0.48, top 1.83 = Height 1.835. Callers now pass 1.835. Register TS-46. The window climb.

#137 stays OPEN for the DOORS half only (block/pass per open state). The #175 door-pose fix (2026-07-05) still needs its user gate — ask for it whenever the user is next at the hub double door (closed blocks AT the visual panels from both sides, no embed, no phantom wall).

NEXT ARC: #176 + #177 (render, both filed 2026-07-06 from the gate session)

• #176 — purple flashing on dungeon floors at cell seams, camera-angle dependent. Survives all physics fixes → render-side. Magenta/purple = the placeholder-texture class (feedback_ui_resolve_zero_magenta).
• #177 — stairs between levels pop in/out. Invisible from the corridor looking into the stair room, appear on entering, vanish on the last step running down. The #119 visibility class, dungeon edition. Anchor cells: the transit 0x8A020182 → 0x8A020183 drops z −6 → −9 on stairs (launch-137-gate2.log).

The load-bearing topology fact both issues share (discovered this session): Facility Hub corridor FLOORS are portal polygons — PortalSide floor-portals to under-rooms (e.g. 0x8A02016E visual polys 1/3/5 → 0x011E, horizontal at z=−6, spanning the whole floor; 0x011E is a hall at z=−12). Level connections run through these floor-portals. "Purple at the seams" is purple exactly where portal surfaces meet, and the stairs' rooms hang off the same portal graph — suspect the render portal-flood/portal-surface handling of HORIZONTAL portals.

⚠️ The id-space trap (cost this saga a wrong mechanism): CellPortal.PolygonId indexes the VISUAL polygon table (CellStruct.Polygons), NOT PhysicsPolygons. Same ids in both tables are UNRELATED polygons.

Tooling built this session (reuse, don't rebuild)

• Issue137CorridorSeamInspectionTests — dat-inspection theories (add InlineData cells as needed): portal spans (CorridorCell_PortalPolygonWorldSpans), full-vertex poly dumps (WindowShaft_FullPolyDump), physics-BSP leaf membership, hit-normal candidate sweep (use |align| — winding flips), HumanSetup_CollisionSpheres_DatTruth.
• Issue137CorridorSeamReplayTests — dat-backed PhysicsEngine corridor harness (BuildCorridorEngine: hydrate THREE portal rings or ring-3 cells are invisible to the flood — why clean-room replays kept passing). In-test probe capture pattern: Console.SetOut(StringWriter) + PhysicsDiagnostics.Probe*Enabled = true → line-diff offline vs live.
• Live probe logs (worktree root, PowerShell Tee = UTF-16, tr -d '\000' before grep): launch-137-seam-probes.log (790 MB, step-level), launch-137-gate2.log, launch-137-gate3.log, resolve-137-seam-capture.jsonl (body snapshots, untracked).

Physics DO-NOT-RETRY highlights from today (full table in the digest)

• No SetSlidingNormal in the BSP/sphere layer; opposing branch returns Collided; failed transitions never write body sliding state.
• The absorbed exactly-anti-parallel frame against a persisted sliding normal is RETAIL behavior — fix normal PROVENANCE, not the abort.
• No height-budget check in the step-down accept — retail's climb cap is adjust_sphere_to_plane's walk_interp −0.5 overshoot bound (0x00538210)
  • the placement insert rejecting the HEAD in solids.
• Probe-field misreads: [neg-poly]/[neg-poly-dispatch] print stepUp= = NegStepUp (dispatch class), NOT sp.StepUp. [walkable-nearest] is a logger, not the decision-maker.
• Remaining registered leaks (rows exist, fix later): TS-45 (SphereCollision's SetSlidingNormal tail), TS-4 (Path-6 steep-tangent), TS-46 (scalar sphere approximation; remotes use human dims).

Launch protocol (unchanged)

Build green first; PowerShell launch with the env block from CLAUDE.md (+ ACDREAM_PROBE_RESOLVE=1 ACDREAM_PROBE_CELL=1 for gates), background + Tee to launch-*.log. The user manages client lifecycle. Graceful close → ACE session clears in ~5 s; hard kill → ~3 min. The test character may be saved in odd places after collision testing (last session it was inside the window alcove and ACE bounced it to Holtburg — the user portals back).