docs(render): S3 chunk 4 contract draft — the deletions

Retail CPU-clips only portal polygons, punch fans and exit seals
(polyClipFinish); ordinary meshes, shells, terrain, particles and the
weather are never view-clipped. Inventory at edb32783: keep the seal and
punch clips (with equivalence pins), delete the per-slice weather loop,
the sky-post-scene particle clip slot, the dead cell-shell clip routing,
the slot-list shape of the part classifier, and the seven
ProbeCathedral* discriminators with their launch-option rows.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/research/2026-09-01-overhaul/s3-walk-ownership-map.md

@@ -487,3 +487,78 @@ owner's G2 screenshot spot) plus the two cathedral poses, pixel-diffed
 against the chunk-2 run: the ONLY expected delta is the punch region at
 Holtburg (fragments gone); dense-outdoor p50/p99 recorded before/after with
 the existing frame-time diagnostics (no new counters).
+
+## 10. Chunk 4 contract — deletions (lead draft, 2026-09-03; re-locate every owner at chunk time, after chunks 2 and 3 land)
+
+### 10.1 What retail clips, and what it does not (verified)
+
+- Retail polygon-clips exactly three things on the CPU with
+  `ACRender::polyClipFinish`: portal polygons when building child views
+  (`PView::GetClip` @0x005a4320 → `polyClipFinish`), the punch fans
+  (`DrawPortalPolyInternal` @0x0059bc90 clips the fan against the installed
+  view — `building_view` @0x0059f3bf during the building pass), and the
+  exit seals (the same function under `CEnvCell::setup_view` per live view,
+  @0x005a4983–0x005a49b7). Ordinary meshes, cell shells, terrain, particles
+  and the weather are NEVER view-clipped: `DrawMeshInternal` @0x0059f360
+  submits the whole mesh after the sphere test, `DrawEnvCell` @0x0059f170
+  draws the whole shell, `LScape::draw` draws whole blocks, and
+  `GameSky::Draw(sky, 1)` @0x00506396 runs ONCE after the blocks with only
+  the `is_player_outside` gate (§9 R5).
+
+### 10.2 acdream inventory (at `edb32783`; names, not lines)
+
+KEEP (translated clips with a retail CPU counterpart — each gets a
+CPU/GPU equivalence pin if it lacks one):
+- exit seals: `RetailPViewRenderer.DrawWalkExitPortalMasks` →
+  `DrawExitPortalMask(cell, InteriorFloodViewClipPlanesAt(...))` per (flood
+  cell, live view) — retail's `setup_view` + `polyClipFinish` per view;
+- punch fans: `DrawPunchFan(worldPolygon, activeViewIndex)` clipped by the
+  pinned view's slice planes — retail's `building_view` clip;
+- the walk's `CaptureViews`/`AppendClipSlot` slot table ONLY as far as the
+  two consumers above need it.
+
+DELETE (no retail counterpart):
+- the whole-stage terrain event and `DrawTerrainSlice` leaf — already
+  replaced by chunk 3 (§9 R4); chunk 4 verifies nothing re-grew;
+- the per-outside-view-slice weather/late landscape loop
+  (`RetailPViewRenderer` "GameSky's weather pass still runs through each
+  active landscape view": `SetTerrainClip` + `ClearClipRouting` +
+  `DrawLandscapeSliceLate` per slice with `BeginDoorwayScissor` +
+  `BindTerrainClip`) — retail draws the weather ONCE, unclipped; one
+  weather draw after the last land cell (chunk 3 places it; chunk 4 deletes
+  the loop, the scissor, and the terrain-clip binding if no consumer
+  remains);
+- the sky-post-scene particle submission's per-slice `clipSlot:
+  slice.Slot` — retail inserts emitters into one unclipped alpha list;
+- `RetailPViewPassExecutor.SetCellShellClipRouting` (no caller in src or
+  tests) and every `SetClipRouting`/`ClearClipRouting`/
+  `UseIndoorMembershipOnlyRouting` call that becomes a no-op once no shell
+  or entity clip routing exists — the "first view clips the shell" residue;
+- `WbDrawDispatcher.WalkClassify.ResolvePartClipSlots`'s slot LIST return
+  shape: it already answers "whole mesh" (`RetailWholeMeshSlot`) whenever
+  any view admits the sphere; reduce it to the Boolean retail asks
+  (`SphereVisibleInLookInTurn`) and delete `VisibleClipSlotsInLookInTurn`
+  if the seals/punches do not use it (they read planes, not slots — verify);
+- the `ProbeCathedralSkip*` discriminators (`ProbeCathedralSkipFloatingStairSeals`,
+  `…StairBuildingPunch`, `…FloatingStairCellShells`, `…SouthLookInCellShells`,
+  `…LookInShellCellId`, `…SouthBuildingShell`, `ProbeCathedralShellOrderEnabled`)
+  with their `docs/launch-options.md` rows and `RenderingDiagnostics`
+  members — the investigation they served is closed by the retail axiom
+  (the cathedral leak is retail behavior); the S5 inventory already lists
+  them, chunk 4 takes them because it touches every one of their call
+  sites anyway.
+
+### 10.3 Gate
+
+- no duplicate draw of a stamped part across a pan/zoom replay (the
+  existing replay pins); membership/draw counts change only at a retail view
+  boundary;
+- the three-pose self-gate + Holtburg + the two cathedral poses pixel-diffed
+  against the chunk-3 run: expected delta ZERO except where a deleted
+  per-slice scissor previously under-painted the weather at an exit-view
+  edge (record the region if it appears; it is the deletion's intended
+  effect, not a regression);
+- `LaunchOptionsDocumentationTests` green with the seven probe rows and
+  their read sites removed together (the test enforces both directions);
+- the register: no row is added (every deletion removes an acdream-only
+  rule); any KEEP item still lacking a CPU/GPU equivalence pin gets one.