docs(render): ARCHITECTURE RESET — indoor render is a 3-gate patchwork; handoff + unified-PView target

A week on the indoor render (Phase U.4 → U.4c → 2026-05-31) fixed the flap but
produced NO shippable progress: walls/ceiling don't seal, outdoor terrain is
visible from inside (#78), the enclosure reads grey/transparent. Root cause is
ARCHITECTURAL, not a bug.

Evidence this session (direct, via the new [shell] probe + screenshots) RULED OUT
every subsystem except the gating architecture: the interior cell shells render
fine (geometry/texture/opaque/depth all correct, zh=0 tr=0); the visibility
traversal computes correct sets + non-empty portal clips; cull mode is fine; the
camera/eye thread was a detour. The residual is that OUTDOOR geometry is not gated
to portal openings when indoors, and acdream enforces visibility THREE inconsistent
ways (TerrainClipMode / per-cell shell clip / entity ParentCellId filter with an
outdoor-stab bypass) instead of retail's ONE PView gate.

This commit is the reset handoff + documentation, not a code fix:
- docs/research/2026-05-31-render-architecture-reset-handoff.md — canonical: honest
  state, evidence ledger (ruled-out / do-not-repeat), the mapped 3-gate patchwork,
  the retail PView target (one traversal → one gate for ALL geometry), the reset
  mission, and a copy-paste pickup prompt.
- docs/architecture/acdream-architecture.md — new "Render Pipeline" SSOT section
  (current divergence + unified-PView target + the one rule: compute visibility
  once, enforce it once). (Doc has pre-existing corruption below this section —
  flagged for separate cleanup.)
- Apparatus: ACDREAM_PROBE_SHELL → [shell] (EnvCellRenderer per-cell prepared/drawn
  geometry + flags) added to RenderingDiagnostics + EnvCellRenderer. Throwaway.
- docs/superpowers/specs/2026-05-31-camera-collision-indoor-engagement-design.md —
  spec for e099b4c (camera collision; now parked as orthogonal to the seam).

Next session: STOP point-fixing; do the architecture reset to a single PView gate.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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# Render Architecture Reset — assessment + handoff (2026-05-31)
> **Read this first, in full, before touching any render code.** This is a deliberate
> reset after a week of point-fixing the indoor render with **no shippable progress**.
> The next session's job is NOT another symptom fix — it is to bring acdream's render
> pipeline up to a **single, coherent, retail-faithful design (PView)** and close the
> indoor seams *by construction*.
## 1. The honest state
A full week (Phase U.4 → U.4c → this session) has gone into the indoor render. Net
result: the **doorway "flap" is fixed** (real, kept), but the indoor world is **still
broken** — walls/ceiling don't visually seal, you see outdoor terrain from inside the
cellar ("the world from below"), and the enclosure reads as a grey/transparent void.
The reason there's been no progress is **architectural, not a bug**: the render pipeline
is a **patchwork of three inconsistent visibility gates** bolted onto a half-finished
port of retail's PView. Seams are *structural* — fixing one place (the flap, the camera,
the shells) pops a seam in another. We have been chasing symptoms across different
subsystems (visibility → camera collision → shell rendering) instead of fixing the
architecture. That stops now.
**Mandate from the user (2026-05-31):** *"produce me a solid engine that produces a
retail-faithful experience… look over what we have done, check our design and if it
matches a solid engine design, and solve all our issues."* This handoff is the
assessment; the next session executes the reset.
## 2. Evidence ledger — what is RULED OUT and CONFIRMED (do not re-litigate)
This week was not all waste: it eliminated, **with direct evidence**, every subsystem
*except* the gating architecture. Do not re-investigate these.
**CONFIRMED (direct evidence):**
- **The interior cell shells RENDER correctly.** `[shell]` probe (ACDREAM_PROBE_SHELL):
every visible cell (`0xA9B40170-0175`) is prepared and drawn — `gfx=1`, `idx` 24270,
`tr=0` (not translucent), `zh=0` (textures present), opaque pass, depth-on. So the
shells are NOT the problem (geometry, textures, cull, depth all fine).
- **The visibility traversal computes correct results.** `[flap]` probe: portals
traverse (`TRV`), project, and clip to **non-empty** screen regions (`clip=4/5`),
`vis=3` cells, `terrain=Skip`/`outPolys=0` correct for a windowless cellar.
- **The residual is OUTDOOR geometry not being gated to portal openings when indoors**
(issue #78): screenshots show outdoor terrain + scenery rendered and visible from
*inside* the cellar (from below), and the interior not sealing. The cell mesh renders
but does not occlude / the outside is not clipped to the window.
**RULED OUT (with evidence) — do NOT chase again:**
- The camera / eye position as the root (eye-displacement was reduced by `e099b4c` but
the residuals persisted unchanged — the camera thread was a **detour**).
- Cull mode (cell shells already render double-sided, `EnvCellRenderer.cs:1168`).
- Cell-shell geometry missing / textures missing (`[shell]` proves both present).
- The portal side-test / PortalSide (`b5f2bf2`, byte-identical no-op).
- PVS / stab_list grounding (H1, `639f20f` plumbed, not the fix).
- Camera zoom as the cause (errors persist at minimum zoom).
## 3. The current render architecture (mapped) — the patchwork
Per-frame, inside `GameWindow.OnRender` (~`:7290-7471`):
```
CellVisibility.ComputeVisibility(visRootPos = PLAYER pos) → visible-cell SET + VisibleCellIds + CameraCell
PortalVisibilityBuilder.Build(clipRoot, visRootPos=PLAYER, envCellViewProj=EYE) ← a partial port of retail ConstructView
│ → PortalVisibilityFrame { OutsideView, per-cell CellViews, OrderedVisibleCells }
│ (side-test + ordering use the PLAYER; projection uses the EYE — a split)
ClipFrameAssembler.Assemble(...) → TerrainClipMode {Skip|Scissor|Planes} + CellIdToSlot (per-cell clip regions) + OutdoorVisible
├── TerrainModernRenderer.Draw gated by TerrainClipMode (GATE #1)
├── EnvCellRenderer.Render(shells) gated by envCellShellFilter + per-cell clip slot (GATE #2)
└── WbDrawDispatcher.Draw(entities) gated by ParentCellId ∈ visibleCellIds … BUT outdoor stabs have ParentCellId==null and ALWAYS PASS (GATE #3)
```
**Why this is structurally fragile (the root of all the seams):**
1. **Three separate gates** (terrain / shells / entities) must independently agree to
produce a seamless interior. They don't. Retail has **one** gate (PView).
2. **Outdoor geometry is not gated to portal openings.** Terrain has its own
Skip/Scissor/Planes path (and the Scissor fallback *over-includes*), and outdoor
stabs/scenery (`ParentCellId==null`) **bypass the gate entirely** → you see the
outdoor world from inside (#78). Retail draws the landscape **only** through exit
portals, clipped to the opening.
3. **No single source of truth.** "What is visible and where on screen" is reassembled
from three consumers of one builder, instead of being the builder's authoritative,
uniformly-enforced output.
4. **Player-rooted set vs eye-projected clip split** adds a second axis of fragility
(the flap, the residual degeneracies) — secondary, but real.
This is the crux: **we compute visibility once but enforce it three different,
inconsistent ways.**
## 4. The retail-faithful target — PView: one traversal, one gate
Retail (decomp `docs/research/named-retail/acclient_2013_pseudo_c.txt`) renders the
world through **PView**, a single portal-clipped traversal:
- Root at the **viewer's cell** (`CellManager::ChangePosition` tracks `curr_cell`).
- `PView::ConstructView` (`:433750`) walks the portal graph; `InitCell` (`:432896`)
computes each cell's **screen-space clip region** (the portal opening it's seen
through, recursively intersected with the parent's region); cells go on
`cell_draw_list` closest-first.
- **Exit portals** add the **outside** (landscape) to the view, **clipped to the
exit-portal opening**.
- `PView::DrawCells` (`:432715`) renders each cell **clipped to its region**, and the
landscape **only where an exit portal reveals it**.
- The viewer (eye) is **collided** (`SmartBox::update_viewer` `:92761`) so the
projection stays well-conditioned.
- `CEnvCell::find_visible_child_cell` (`:311397`) + `seen_outside` gate the
landscape-keep.
- **Outdoors**, PView is trivial (the LandCell + neighbours, no indoor clipping).
The defining property: **ONE visibility structure gates ALL geometry** — interior cell
shells, interior statics, and the outside (terrain + scenery) — all clipped to their
PView-derived regions. That is *why retail is seamless by construction.*
Reference port to crib (acdream owns it but **never invokes it**): WorldBuilder's
`RenderInsideOut` / `VisibilityManager`
(`references/WorldBuilder/Chorizite.OpenGLSDLBackend/Lib/VisibilityManager.cs`).
## 5. The solid design for acdream (the reset target)
We already have the hard part (the `PortalVisibilityBuilder` ConstructView port + the
`ClipFrame` clip-plane machinery + per-cell clip slots). The reset is a
**consolidation, not a rewrite**: make the PView output the **single gate for every
geometry type**.
1. **One gate.** Every draw — cell shells, interior statics, terrain, outdoor scenery —
is clipped to its PView region:
- Interior cell `C` → its per-cell clip region (already ≈done in `EnvCellRenderer`).
- Interior static in cell `C` → cell `C`'s region (route via the same per-instance
clip slot).
- **Outside** (terrain + outdoor scenery + `ParentCellId==null` stabs) → the
**`OutsideView` region** (union of exit-portal openings). **Empty `OutsideView`
(windowless interior) ⇒ draw NO outdoor geometry.** **No `ParentCellId==null`
bypass.**
- **Outdoor root** (camera/player in a LandCell, no indoor cell) ⇒ gate = everything
(today's normal path).
2. **Delete the ad-hoc gates.** Collapse GATE #1/#2/#3 into the single clip-to-region.
Remove the `ParentCellId==null` always-pass in `WbDrawDispatcher`. Remove the
terrain Scissor over-include fallback in favour of retail's exact portal clip.
3. **Resolve the set/clip split.** Decide one rooting story (the flap fix proved the
*set* must be player-rooted; the *clip/projection* is the eye's — confirm this is
retail-faithful under the unified gate, or collide the eye so they coincide).
4. **U.5 (eye outside, looking into a building)** is the same machinery with the root at
the eye's cell and the interior shown through the building's portals — design it in,
don't special-case it.
Result, by construction: #78 (outdoor gated to openings), transparent walls (interior
uniformly clipped), grey enclosure (no spurious ungated gaps), terrain-through-floor
(no outdoor outside the window) all resolve together — because there is one consistent
rule instead of three.
## 6. Next-session mission (the reset — in order)
1. **Audit** the current render data-flow against §3; confirm the three-gate divergence
in the live code.
2. **Verify the target against retail**: read PView in full
(`ConstructView`/`InitCell`/`ClipPortals`/`AddViewToPortals`/`DrawCells`/
`grab_visible_cells`/`find_visible_child_cell`) **and** WB `RenderInsideOut`. Do not
trust this doc's summary alone — confirm the one-gate model from the source.
3. **Design** the unified gate (`superpowers:brainstorming` → spec). This is
architectural; brainstorm it, don't free-solo.
4. **Implement** the single gate; delete the ad-hoc gates/bypasses.
5. **Verify** at the visual gate: flap stays fixed; walls/ceiling solid; no
terrain-through-floor; no grey; outdoor visible *only* through windows/doors, clipped.
**Operating rules for the reset:** evidence-first; no point-fixes; no new gate bolted on
to mask a seam (that is exactly what produced this mess). If a fix starts to look like a
fourth special-case gate, stop — it belongs in the one gate.
## 7. What the week produced (status of each artifact)
- **KEEP — `0ee328a` flap fix:** root indoor visibility at the player's cell. A correct,
retail-faithful PView piece (the set must be player-rooted). Keep.
- **ORTHOGONAL — `e099b4c` camera-collision viewer-gate-exemption:** retail-faithful but
**not** the seam fix (the camera thread was a detour). **Open decision:** keep (it's a
real, faithful improvement) or revert to keep the reset branch focused. Recommendation:
**park it** — keep the commit but treat camera collision as out-of-scope for the reset;
revisit only after the unified gate lands. Its sibling diagnosis (`3066460`) +
spec (`docs/superpowers/specs/2026-05-31-camera-collision-indoor-engagement-design.md`)
+ the `CameraCollisionIndoorTests` are accurate for what they cover but are about an
orthogonal subsystem.
- **APPARATUS (throwaway, gated, useful for the reset):**
- `ACDREAM_PROBE_FLAP``[flap]`/`[flap-cam]`/`[flap-sweep]` (visibility + eye + camera sweep).
- `ACDREAM_PROBE_SHELL``[shell]` (per-cell shell render: prepared? geometry? flags?).
Strip both once the reset lands.
- **Disproven hypotheses (do NOT repeat):** H1 (PVS grounding), H2 (PortalSide),
zoom-confound, back-face-cull, eye-displacement-as-root, shell-geometry/texture-missing.
## 8. Git / safety
- Branch `claude/thirsty-goldberg-51bb9b`, **UNPUSHED** (push pending with the user).
- Two `git stash` entries preserved (#98/#101 WIP) — **do NOT drop.**
- Throwaway capture logs `u4c-*.log` are untracked — ignore/delete, do not commit.
## 9. Pickup prompt (copy-paste for the next session)
```
RENDER ARCHITECTURE RESET — acdream indoor pipeline. Continue on branch
claude/thirsty-goldberg-51bb9b (do NOT branch/worktree; preserve the 2 git stashes).
READ FIRST, in full: docs/research/2026-05-31-render-architecture-reset-handoff.md, then
the "Render Pipeline" section of docs/architecture/acdream-architecture.md.
State both altitudes: Working toward M1.5 "indoor world feels right." After a week of
point-fixing with no shippable progress, this is an ARCHITECTURE RESET, not a symptom fix.
THE PROBLEM (root cause, evidence in the handoff): acdream's render pipeline is a
patchwork of THREE inconsistent visibility gates (terrain TerrainClipMode / shell
per-cell clip / entity ParentCellId filter with an outdoor-stab bypass) bolted onto a
half-finished PView port. Seams are structural. The interior cell shells RENDER FINE
(proven); the residual is that OUTDOOR geometry isn't gated to portal openings when
indoors (#78) and the three gates don't agree.
THE TARGET (retail PView, §4-5 of the handoff): ONE portal-visibility traversal whose
output is the SINGLE GATE for ALL geometry — interior shells, interior statics, AND the
outside (terrain + scenery) all clipped to their PView regions; outside drawn ONLY
through exit-portal openings; empty OutsideView ⇒ no outdoor; no ParentCellId==null
bypass; outdoor root ⇒ gate=everything. We already own the builder (PortalVisibilityBuilder
= ConstructView port) + ClipFrame; this is CONSOLIDATION, not a rewrite.
MISSION (in order): (1) audit the current 3-gate data-flow in GameWindow.OnRender
~:7290-7471; (2) VERIFY the one-gate model against retail PView (ConstructView :433750,
InitCell :432896, DrawCells :432715, find_visible_child_cell :311397) + WB RenderInsideOut
(references/WorldBuilder/.../VisibilityManager.cs) — confirm from source, not the handoff
summary; (3) brainstorm + spec the unified gate (superpowers:brainstorming); (4) implement
the single gate, delete the ad-hoc gates/bypasses; (5) visual-verify ALL indoor issues
resolve together.
DO NOT REPEAT (evidence-disproven, handoff §2): camera/eye as root, cull mode, shell
geometry/texture missing, H1 PVS grounding, H2 PortalSide, zoom-confound. DO NOT bolt on
a fourth gate to mask a seam. Evidence-first; no point-fixes; brainstorm the architecture
before coding; only stop for visual verification.
Apparatus ready: ACDREAM_PROBE_FLAP ([flap]/[flap-cam]/[flap-sweep]) + ACDREAM_PROBE_SHELL
([shell]). Open decision: keep or revert e099b4c (camera collision, orthogonal — parked).
Launch per CLAUDE.md "Running the client"; Holtburg cottage cellar/stairs is the test
scenario; visual verification at that threshold is the acceptance gate.
```

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# Camera-collision indoor engagement — the shared-root residual fix (2026-05-31)
**Phase:** M1.5 "indoor world feels right" — post-flap-fix residuals.
**Status:** design (pre-approved by user 2026-05-31; "most thorough + retail-faithful").
**Predecessors:** flap fix `0ee328a`; diagnosis `docs/research/2026-05-31-camera-collision-indoor-diagnosis.md`; camera-collision research `docs/research/2026-05-29-a8f-camera-collision-handoff.md`.
## Problem (one shared root, three faces)
After the U.4c flap fix (indoor visibility rooted at the **player's** cell; the 3rd-person
camera **eye** still drives the per-frame projection), three residuals remain — transparent
outer walls (#2), terrain-through-floor (#78), "stairs everything grey" (#3). Evidence
(`u4c-fix.log`, current code state): the eye is **outside the player's cell ~90% of frames**,
at full chase distance (~3.4 m) — i.e. **the shipped camera collision is not engaging in
interior cells.** When the eye is displaced, it projects the player-traversed portal openings
to garbage/off-screen NDC (74% of frames), collapsing `OutsideView` to empty → terrain `Skip`
(grey, #3) or tripping the giant-scissor fallback → over-include (bleed, #78/#2). The projection
**from the eye is correct** (the OutsideView is a screen-space clip and the screen is the eye's
view) — the fault is the eye being in the wrong place. So the root fix is **keeping the eye in
valid space**, which resolves all three faces at once.
## Why the shipped collision doesn't engage (code-verified)
`PhysicsCameraCollisionProbe.SweepEye` → `PhysicsEngine.ResolveWithTransition(... cellId =
playerCell, moverFlags = IsViewer|PathClipped|FreeRotate|PerfectClip ...)`. The camera eye
sweeps UP+BACK from the head-pivot (~2.6 m back, ~2.25 m up). In an acdream cottage the
enclosing geometry (walls/floor/roof) lives in a **landblock-baked exterior-shell GfxObj**
registered `cellScope=0` (outdoor/landblock-wide shadow list) — established by issue #98
(the cottage floor that capped the player's head sphere is GfxObj `0x01000A2B`, not cell BSP).
`ShadowObjectRegistry.GetNearbyObjects` has the **issue-#98 indoor gate** at
`ShadowObjectRegistry.cs:480`:
```csharp
if ((primaryCellId & 0xFFFFu) >= 0x0100u) // primary cell is indoor
return; // skip the outdoor radial sweep entirely
```
So while the viewer sphere's primary cell is the indoor cottage cell, the sweep is **gated
away from the exterior-shell GfxObj** — the only geometry that encloses the cottage in our
data model. The eye therefore finds nothing to stop it and flies to full distance.
## Retail behavior (decomp-verified — the faithfulness anchor)
`SmartBox::update_viewer` @ `acclient_2013_pseudo_c.txt:92761-92892`:
- roots the viewer `CTransition` at the **player/pivot cell** (`init_path(t, cell_1, pivot,
sought)`; `cell_1` = `AdjustPosition`'s pivot cell, fallback `player->cell`);
- `init_object(player, 0x5c)` = `IsViewer|PathClipped|FreeRotate|PerfectClip` (acdream matches);
- sweeps `viewer_sphere` (0.3 m) via `find_valid_position` and publishes the **stopped**
`sphere_path.curr_pos` + `curr_cell`; fallbacks `AdjustPosition` → snap-to-player.
So retail bounds the viewer by **whatever the swept transition hits inside the player's cell.**
Retail's interior EnvCells are **self-enclosing** (walls + ceiling in the cell's own geometry),
so the viewer is stopped by interior geometry, and retail's "structural separation" (`CObjCell::
find_cell_list` `:308751-308769` adds outdoor GfxObjs only to outdoor cells' shadow lists)
holds *because* the interior is self-contained.
**acdream's divergence:** our cottages are NOT self-enclosing — the enclosure is the landblock
shell GfxObj (per #98). So for our data model, the shell GfxObj **is** the enclosure the viewer
must collide. Letting the viewer reach it is the faithful analog of retail's
viewer-bounded-by-enclosure.
## The fix (Option A — viewer-exempt the #98 gate)
Thread the mover flags (or a derived `isViewer` bool) from the `FindObjCollisions` call site
(`ObjectInfo.State` is already on the `Transition`) down through to
`ShadowObjectRegistry.GetNearbyObjects`, and change the gate to:
```csharp
// Issue #98 gate is correct ONLY for the player foot/head capsule (it stops the cottage-floor
// GfxObj from capping the head sphere from the cellar below). The camera viewer (IsViewer, a
// single 0.3 m sphere, no capsule, no contact-plane) must reach the landblock-baked building
// shell that forms the cottage enclosure — retail's update_viewer bounds the viewer by the
// cell enclosure (acclient_2013_pseudo_c.txt:92761); in acdream's data model that enclosure is
// the shell GfxObj. find_obj_collisions has no indoor gate (acclient_2013_pseudo_c.txt:308918).
if ((primaryCellId & 0xFFFFu) >= 0x0100u && !isViewer)
return;
```
`GetNearbyObjects` gains an `isViewer` parameter (default `false` → existing callers keep the
gate). Only `PhysicsCameraCollisionProbe.SweepEye` passes `IsViewer`, so only the camera sweep
changes behavior.
### Why not the alternatives
- **Re-scope the cottage shell registration to the indoor cell** (`cellScope` = cottage cell):
requires per-GfxObj→cell adjacency we don't have and isn't how retail models it; would also
re-expose the player to the #98 head-cap. Rejected.
- **Make interior cells self-enclosing (faithful hydration of ceiling/walls into cell BSP):**
the genuinely-retail-faithful end state, but a large, #98-adjacent, high-risk refactor of
cottage hydration. **Documented out-of-scope follow-on** (file as a residual after the visual
gate). Option A is the low-risk bridge that matches retail's *observable* behavior for our
data model.
- **Retail fallback chain (`AdjustPosition` → snap-to-player):** faithful completeness, but not
load-bearing for this residual (our sweep succeeds and returns a position; it doesn't *fail*).
Out-of-scope follow-on.
## Tests (TDD)
1. **GREEN the RED test** `CameraCollisionIndoorTests.SweepEye_IndoorCellExteriorGfxObjWall_
NotReachedFromIndoorContext_CurrentlyFails`: after the fix, the viewer sweep stops at the
shell wall → `pulledIn ≥ 0.5` (rename to drop `_CurrentlyFails`).
2. **#98 regression guard (new):** an `IsViewer` sweep in the cellar toward the cottage-floor
GfxObj behaves correctly (the viewer single-sphere is not a head-capsule, so the #98 cap does
not apply); assert the player's gate behavior is untouched (an `IsPlayer` sweep at the same
site still hits the gate / keeps the #98 fix). Use the cottage GfxObj fixture
(`RegisterCottageGfxObj`, `0x01000A2B`).
3. Full `dotnet build` + `dotnet test` green; with-fix failure set ⊆ baseline (the pre-existing
static-leak flakiness is independent).
## Acceptance
- Build + tests green; RED→GREEN; #98 guard passes.
- **Visual gate (the one user step):** walk `+Acdream` into a Holtburg cottage / cellar / stairs
and a window room with `ACDREAM_PROBE_FLAP=1`. Expect: the eye stops at walls/ceiling (no
transparent outer walls, no grey, no terrain-through-floor); `[flap-sweep]` shows `pulledIn > 0`
+ `eyeInRoot=Y` for indoor cells; `[flap-cam]` shows `terrain=Planes` through windows (not
`Skip`/`Scissor`-fallback). The visual gate is the **arbiter on real geometry** — if the eye
still flies free in the main-floor residual cells (0174/0175), the residual is a different
cause (interior-BSP completeness) and we iterate with the live `[flap-sweep]` data.
## Out of scope (documented residuals)
- **U.5** outside-camera → building-interior peering, and the legitimate eye-through-an-open-
doorway exit (both deferred in the Phase U spec).
- **Interior-cell self-enclosure hydration** (the deeper retail divergence; faithful end state).
- **Viewer fallback chain** (`AdjustPosition` → snap-to-player) for the find-valid-position-fails
path.
- The throwaway `[flap]`/`[flap-cam]`/`[flap-sweep]` apparatus is kept for the visual gate and
stripped once the indoor residuals close.