docs: abandon two-pipe render approach; scope Phase U (unified retail-faithful pipeline)

Decision (2026-05-30, with user): the WB-inherited two-pipe (inside/outside) render
split is the root cause of the indoor seam bugs (flap, missing/transparent walls,
terrain bleed) and cannot be seamless. Abandon A8/A8.F (#103); build ONE unified
pipeline driven by retail's PView portal visibility — seamless by construction. The
2026-05-30 camera-collision + physics viewer-cap work is kept (retail-faithful, but a
detour from the seam fix). New Phase U scoped; #103 superseded; CLAUDE.md / roadmap /
milestones updated; full decision + scope + next-session pickup prompt in
docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

CLAUDE.md

@@ -725,6 +725,22 @@ Visual side-by-side passed: Holtburg town, inn interior, dungeon all
 render identically to pre-O. Spec:
 [`docs/superpowers/specs/2026-05-21-phase-o-dat-path-unification-design.md`](docs/superpowers/specs/2026-05-21-phase-o-dat-path-unification-design.md).
 
+**2026-05-30 — RENDER PIPELINE PIVOT (read this first).** The two-pipe
+(inside / outside) render approach is **ABANDONED**. acdream inherited a
+WorldBuilder-style split — a normal outdoor draw plus a separate flat
+`RenderInsideOut` stencil pass toggled on `cameraInsideBuilding` — and that
+split is the root cause of every indoor seam bug (the flap, missing/transparent
+walls, terrain bleeding into interiors). Retail has no such split; it renders
+through one portal-visibility traversal (`PView`) and is seamless by
+construction. We are building **Phase U — a single unified retail-faithful
+render pipeline**. This supersedes the A8/A8.F two-pipe arc (issue #103). The
+camera-collision work (retail `SmartBox::update_viewer` spring arm) + a
+physics viewer-cap fix **SHIPPED this session and are kept** (they're real and
+retail-faithful, just not the seam fix). Full decision + scope + next-session
+pickup prompt:
+[`docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md`](docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md).
+The M1.5 narrative below is history retained for context.
+
 **Currently working toward: M1.5 — Indoor world feels right** (resumed
 from 2026-05-20 baseline after Phase O ship). **A6.P1 + A6.P2 + A6.P3
 slice 1 SHIPPED 2026-05-21.** **A6.P3 slice 2 v2 SHIPPED 2026-05-22**

docs/ISSUES.md

@@ -46,7 +46,12 @@ Copy this block when adding a new issue:
 
 ## #103 — Phase A8.F portal-frame indoor rendering broken at runtime (visual-gate failure)
 
-**Status:** OPEN
+**Status:** SUPERSEDED 2026-05-30 by **Phase U (Unified Render Pipeline)**. The
+two-pipe (inside/outside) approach this bug lives in is being abandoned wholesale —
+the broken `RenderInsideOut` two-pipe path is deleted as Task 1 of Phase U and
+replaced by a single unified retail `PView` portal-visibility pipeline. #103 will
+not be fixed in place. See
+[docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md](research/2026-05-30-unified-render-pipeline-decision-and-handoff.md).
 **Severity:** MEDIUM (opt-in branch only — default game unaffected)
 **Filed:** 2026-05-29
 **Component:** render (indoor visibility)

docs/plans/2026-04-11-roadmap.md

@@ -113,12 +113,47 @@ with no code changes lost — M1.5 doesn't touch WB-extracted territory.
 
 ### Milestone M1.5 — "Indoor world feels right" (ACTIVE — Phase O shipped; resuming from 2026-05-20 baseline)
 
-The current top of the work order. Two phases (A6 + A7) inside one
+The current top of the work order. M2 ("kill a drudge") is deferred until M1.5
-milestone. M2 ("kill a drudge") is deferred until M1.5 lands —
+lands — drudges live in dungeons and the M2 demo target requires solid indoor
-drudges live in dungeons and the M2 demo target requires solid indoor
 navigation. Full milestone block in
 [`docs/plans/2026-05-12-milestones.md`](2026-05-12-milestones.md).
 
+**2026-05-30 — render-pipeline pivot.** Indoor *rendering* (the seamless in/out
+seam: the flap, missing/transparent walls, terrain bleed) is NO LONGER pursued via
+the WB-inherited two-pipe (inside/outside) split. That whole approach (Phase A8/A8.F,
+issue #103) is **abandoned**. Indoor rendering is now **Phase U** below. Phase A6
+(physics) and A7 (lighting) inside M1.5 are unaffected.
+
+#### Phase U — Unified retail-faithful render pipeline (NEW — supersedes A8/A8.F)
+
+**Decision (2026-05-30):** replace the two render paths (outdoor `Draw` +
+`RenderInsideOut` stencil, toggled on `cameraInsideBuilding`) with ONE pipeline driven
+by retail's portal-visibility view (`PView::ConstructView` / `ClipPortals` / `GetClip`;
+`CEnvCell::find_visible_child_cell`). The camera's cell is just the root of a recursive
+per-portal clip-region traversal; all visible cells (indoor + outdoor) draw in one pass.
+Seamless in/out **by construction** — no inside/outside branch. Modern code, retail
+behavior.
+
+- **Why:** the two-pipe split is a WB-editor inheritance, not a game-client design; you
+  cannot make two pipes hand off seamlessly at a doorway. Retail never splits. The A8.F
+  attempt to graft retail recursion onto the WB stencil failed its visual gate (#103).
+- **Keep:** WB mesh/dat pipeline (ObjectMeshManager/WbDrawDispatcher/terrain), the
+  2026-05-30 camera-collision + physics work. **Salvage (verify):** the A8.F CPU
+  clip-builder (PortalProjection/ScreenPolygonClip/ViewPolygon/PortalVisibilityBuilder —
+  unit-test-correct). **Task 1:** delete the dead two-pipe code (RenderInsideOutAcdream,
+  the cameraInsideBuilding branch, IndoorCellStencilPipeline, the ACDREAM_A8_INDOOR_BRANCH
+  kill-switch) — audit first; some A8 commits fixed real bugs (BuildingId stamping, pool
+  aliasing) that stay.
+- **Scope + next-session pickup:**
+  [`docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md`](../research/2026-05-30-unified-render-pipeline-decision-and-handoff.md).
+  Start with `superpowers:brainstorming`; visual verification at Holtburg
+  cottage/cellar/inn + a portal dungeon is the acceptance gate (unit tests did not
+  catch #103).
+- **Camera-collision (shipped 2026-05-30, kept):** retail `SmartBox::update_viewer`
+  swept-sphere spring arm (`CameraDiagnostics.CollideCamera`, `PhysicsCameraCollisionProbe`,
+  `RetailChaseCamera` integration) + viewer/sight bypass of the 30-step transition cap.
+  Specs: [`2026-05-29-a8f-camera-collision-design.md`](../superpowers/specs/2026-05-29-a8f-camera-collision-design.md).
+
 **Today's pre-M1.5 baseline** (2026-05-20 — committed in this
 session): A4 multi-cell BSP iteration (`691493e`), #89 sphere-overlap
 in CheckBuildingTransit (`7ac8f54`), #90 sphere-overlap stickiness in

docs/plans/2026-05-12-milestones.md

@@ -187,6 +187,17 @@ close range and the player sees "You pick up the X." in chat.
 
 ### M1.5 — "Indoor world feels right" — 🔵 ACTIVE (resumed 2026-05-21 after Phase O ship)
 
+**2026-05-30 — render-pipeline pivot.** The indoor *rendering* seam (seamless
+in/out: the flap, missing/transparent walls, terrain bleed) will be solved by a
+**single unified retail-faithful render pipeline (Phase U)**, replacing the
+abandoned two-pipe inside/outside split (A8/A8.F, issue #103). The two-pipe split
+is a WorldBuilder inheritance; retail uses one portal-visibility pass and is
+seamless by construction. Decision + scope:
+[`docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md`](../research/2026-05-30-unified-render-pipeline-decision-and-handoff.md).
+Camera-collision + a physics viewer-cap fix shipped 2026-05-30 and are kept (they
+were a detour from the real seam fix, but retail-faithful and worth keeping). A6
+(physics) and A7 (lighting) are unaffected.
+
 **Phase O — DatPath Unification — shipped 2026-05-21.** ONE thing
 touches the DATs. ~33 WB files (~7.7K LOC) extracted into
 `src/AcDream.{Core,App}/Rendering/Wb/`; project references to

docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md

@@ -0,0 +1,218 @@
+# Unified retail-faithful render pipeline — decision, scope, and handoff (2026-05-30)
+
+## TL;DR (the decision)
+
+We are **abandoning the two-pipe (inside / outside) rendering approach** and
+committing to a **single, unified, retail-faithful render pipeline** built around
+retail's portal-visibility view (`PView`). Modern code, retail behavior. This is a
+new roadmap phase — **Phase U (Unified Render Pipeline)** — and it is milestone-scale
+work, not a patch.
+
+**Why:** acdream inherited a *two-pipe* render structure from WorldBuilder (WB) — a
+normal outdoor draw plus a separate flat `RenderInsideOut` stencil pass toggled on
+`cameraInsideBuilding` (`GameWindow.cs` ~7345). That split is the root cause of every
+indoor/outdoor seam bug (the "flap", missing/transparent walls, terrain bleeding into
+interiors). **Retail has no such split.** Retail renders through one portal-visibility
+traversal: starting from whatever cell the camera is in, it walks recursively through
+portals (doors, windows, cell openings), builds a screen-space clip region per opening,
+and draws every visible cell — indoor *and* outdoor — in one pass. There is no
+"am I inside a building?" branch, so transitions are seamless **by construction**.
+
+The A8.F effort tried to graft retail's recursive clip *on top of* WB's two-pipe
+stencil (a CPU-built NDC mask bridging the two pipes). That hybrid is inherently
+fragile and failed its visual gate (**issue #103**). You cannot make two pipes hand
+off seamlessly at a doorway; retail avoids the entire bug class by never splitting.
+
+This was confirmed in collaboration with the user, who correctly identified that the
+whole direction was wrong: *"in retail there is totally seamless transitions between
+out and in… it's like we are on the wrong path here."* Correct.
+
+---
+
+## What this session actually shipped (the salvage)
+
+This session was originally a "camera collision" effort (a reframing of the #103
+failure onto the camera eye — itself a detour). The camera work is **real,
+retail-faithful, and kept**, but it is **not** the fix for seamless transitions:
+
+- **Swept-sphere camera collision** (retail `SmartBox::update_viewer`, `0x00453ce0`):
+  `CameraDiagnostics.CollideCamera` (default on), `ICameraCollisionProbe` +
+  `PhysicsCameraCollisionProbe` (reuses `PhysicsEngine.ResolveWithTransition`,
+  retail `viewer_sphere` 0.3 m, `init_object(player, 0x5c)` =
+  `IsViewer|PathClipped|FreeRotate|PerfectClip`), wired into `RetailChaseCamera`
+  (collide into a *separate* published eye — never the damped sought eye — to avoid
+  the wall-press oscillation), `GameWindow` wiring + a Camera-menu toggle.
+- **Physics fix (retail-faithful):** viewer/sight sweeps bypass acdream's 30-step
+  safety cap in `Transition.FindTransitionalPosition` (retail `find_transitional_position`
+  has no cap; `calc_num_steps` has a `state & 4` viewer branch). Gate: `&& !ObjectInfo.IsViewer`.
+- Commits `69c7f8d` → `aae5300` (plus the design spec/plan docs).
+
+**Camera-collision residual nits (minor, deferred — NOT blockers):**
+- Eye can clip ~0.3 m into a wall and reveal outside (near-clip plane 1 m vs collision
+  radius 0.3 m — tuning).
+- Residual non-retail-smooth feel at walls (the gross oscillation is fixed; tuning remains).
+
+These are polish; revisit after the pipeline lands (or never — they're cosmetic).
+
+---
+
+## Git state at handoff
+
+- Branch `claude/strange-albattani-3fc83c` was **239 commits ahead of `main`**
+  (both forked at Phase O, `2256006`, 2026-05-21). The branch carries ~9 days of good
+  work since Phase O: A6 physics, issues #98/#100/#101, A7 lighting, the A8/A8.F
+  rendering arc, and the camera work — all of it.
+- Per user decision (2026-05-30): **the whole branch was merged into `main`** so none
+  of that work is lost. The dormant, gated-off A8 two-pipe rendering rides along and is
+  **deleted as Task 1 of Phase U** (see below). The user pushes `main` to remotes.
+- The `#98`/`#101` physics WIP from a prior session is preserved in `git stash` on this
+  branch (a subagent had `git stash apply`-ed it mid-session; it was re-stashed). Do not
+  lose it.
+
+---
+
+## Phase U — Unified Render Pipeline (scope / design sketch)
+
+> This is a scope sketch to start a proper brainstorm + spec from — **not** a finalized
+> design. The next session brainstorms it.
+
+### Goal
+
+One render path. The camera's current cell is the root of a per-frame portal-visibility
+traversal that yields *(visible cells, per-cell screen-space clip region)*; the renderer
+draws all visible geometry (indoor cells, outdoor cells, entities, terrain) in a single
+pass gated by that visibility. **No `cameraInsideBuilding` branch. No `RenderInsideOut`
+stencil pass. No outdoor-vs-indoor toggle.** Seamless in/out by construction.
+
+### Retail oracle (the thing to port)
+
+- `PView::ConstructView` (decomp ~`433750`), `PView::ClipPortals` (~`433572`),
+  `PView::GetClip` (~`432344`) — the recursive per-portal screen-space clip-region BFS.
+- `CEnvCell::find_visible_child_cell` (`acclient_2013_pseudo_c.txt:311397`,
+  `0x0052dc50`) — per-cell portal-visible-child resolution; call site `:280028`.
+- `RenderDeviceD3D::DrawBlock` (~`430027`) — the render loop the visibility chain feeds.
+- See the project memory note **indoor-portal-visibility-wb-vs-retail** for why WB
+  cannot express per-portal clipping and the oracle is retail `PView`.
+
+### What to KEEP (do not re-port)
+
+- The WB-derived **mesh/dat pipeline** is fine and stays: `ObjectMeshManager`,
+  `WbMeshAdapter`, `WbDrawDispatcher`, terrain (`TerrainModernRenderer`,
+  `LandblockMesh`), `DatCollection`, texture decode. Phase U is about **visibility +
+  draw orchestration**, not mesh extraction.
+- The **camera collision** and **physics** work from this session.
+- Cell data: `CellVisibility` (`FindCameraCell`, `PointInCell`, portal data),
+  `PhysicsDataCache` cell structures.
+
+### What is likely SALVAGEABLE from the failed A8.F (verify, don't assume)
+
+The A8.F CPU clip-builder pieces are **unit-test-correct** (the integration is what
+failed). They may feed a unified draw directly:
+- `PortalProjection` (GL near-plane clip), `ScreenPolygonClip` (2D convex intersection),
+  `ViewPolygon`/`CellView` (clip-region model), `PortalVisibilityBuilder` (recursive
+  portal-clip BFS producing per-cell `OutsideView`).
+The failure was the *two-pipe stencil graft* around them (the CPU NDC mask gating a
+*separate* outdoor pipe), not the clip math. A unified pipeline can likely reuse the
+builder to produce per-cell clip frames and gate **one** pass.
+
+### What to DELETE (Task 1 — clear the deck)
+
+The dead two-pipe rendering, so the unified path is built clean, not bolted on:
+- `RenderInsideOutAcdream` and the `cameraInsideBuilding` branch in `GameWindow.cs`
+  (~`7345`+), the `IndoorCellStencilPipeline` / `MarkAndPunchNdc` stencil graft, the
+  Job-A/B decouple, the `ACDREAM_A8_INDOOR_BRANCH` kill-switch, the
+  `EnvCellRenderer` WB `RenderInsideOut` port (`f9a644a` lineage).
+- Keep `EnvCellRenderManager`'s *mesh* path if the unified draw needs it; delete only
+  the inside-out *visibility/stencil* machinery.
+- Audit before deleting: some A8 commits also fixed real bugs (e.g. `BuildingId`
+  stamping, pool aliasing `9559726`) — keep those.
+
+### Approach sketch (for the brainstorm to refine)
+
+1. **Visibility pass** (CPU, GL-free, testable): from the camera cell, recursive portal
+   BFS → ordered set of visible cells, each with a screen-space clip polygon (intersection
+   of the portal openings along its chain). This is retail `PView::ConstructView`.
+   Likely reuses the salvaged A8.F `PortalVisibilityBuilder` family.
+2. **Draw pass** (single, unified): for each visible cell (front-to-back), draw its
+   geometry + entities clipped to its clip region (scissor or stencil-per-cell, retail
+   uses a clip rect/region). Outdoor cells are just cells in this set — no special path.
+   Terrain is drawn per visible outdoor cell, gated the same way.
+3. **No branch:** the camera being indoors vs outdoors changes only *which cell is the
+   root*, not the algorithm.
+
+### Key risks / lessons (do not repeat)
+
+- **Do not graft retail recursion onto WB's flat two-pipe stencil** — that's what
+  #103 was. Build the unified pass; don't bridge two pipes.
+- **Unit tests on synthetic visibility data did not catch #103 — only the visual gate
+  did.** Visual verification at the cottage/cellar/inn/dungeon is the real acceptance.
+  Build a runtime visibility probe early (`ACDREAM_PROBE_VIS`) and validate against live
+  frames, not just synthetic fixtures.
+- **A CPU-built mask gating ALL outdoor geometry is fragile.** The unified pass should
+  gate per-cell at draw time (scissor/stencil per visible cell), close to how retail
+  clips, rather than one global mask.
+- **The camera is not the fix.** That reframing cost this session; the fix is the
+  visibility architecture.
+
+### Success criteria (visual)
+
+- Walk Holtburg cottage → cellar → out the door: no flap, walls solid, no terrain
+  bleed, seamless threshold crossing from any camera angle/zoom.
+- Holtburg Inn: no outdoor stabs/terrain visible through the floor/walls (closes #78).
+- Dungeon via Town Network portal: `visibleCells` stays sane (~4–15), no other-dungeon
+  geometry (closes/relates #95).
+- No regression to outdoor rendering (the default game today).
+
+---
+
+## Next-session pickup prompt
+
+```
+We are building Phase U — a single unified retail-faithful render pipeline (retail
+PView portal-visibility), abandoning the WB-inherited two-pipe (inside/outside) split
+that caused the indoor seam bugs (the flap, missing/transparent walls, terrain bleed).
+The decision + full scope is in
+docs/research/2026-05-30-unified-render-pipeline-decision-and-handoff.md — READ IT FIRST,
+then the project memory note "indoor-portal-visibility-wb-vs-retail" and the #103
+failure handoff (docs/research/2026-05-29-a8f-visual-gate-failure-handoff.md).
+
+State both altitudes:
+  Currently working toward: M1.5 — Indoor world feels right.
+  Current phase: U (Unified Render Pipeline). This supersedes the abandoned A8/A8.F
+  two-pipe approach (#103).
+
+Start with superpowers:brainstorming to design the unified pipeline (do NOT jump to
+code). The scope sketch in the handoff doc is the input. Key decisions to settle in the
+brainstorm: (a) reuse the salvaged A8.F clip-builder (PortalProjection/ScreenPolygonClip/
+ViewPolygon/PortalVisibilityBuilder — unit-test-correct) vs fresh port; (b) per-cell
+clip mechanism (scissor rect vs stencil-per-cell) matching retail's GetClip; (c) how
+terrain + outdoor entities become "just cells" in the visible set.
+
+Task 1 of implementation is to DELETE the dead two-pipe code (RenderInsideOutAcdream,
+the cameraInsideBuilding branch, IndoorCellStencilPipeline/MarkAndPunchNdc, the
+ACDREAM_A8_INDOOR_BRANCH kill-switch) to clear the deck — but audit first; some A8
+commits fixed real bugs (BuildingId stamping, pool aliasing) that must be kept.
+
+Retail anchors: PView::ConstructView ~433750, ClipPortals ~433572, GetClip ~432344,
+CEnvCell::find_visible_child_cell :311397, RenderDeviceD3D::DrawBlock ~430027.
+
+Keep: the WB mesh/dat pipeline (ObjectMeshManager/WbDrawDispatcher/terrain), the camera
+collision + physics from the 2026-05-30 session. Visual verification at Holtburg
+cottage/cellar/inn + a portal dungeon is the acceptance gate — unit tests did not catch
+#103.
+
+Preserve the git stash on the branch (#98/#101 physics WIP).
+```
+
+---
+
+## Reference index
+
+- Decision context / why WB can't do it: project memory **indoor-portal-visibility-wb-vs-retail**.
+- #103 failure detail: `docs/research/2026-05-29-a8f-visual-gate-failure-handoff.md`.
+- Camera-collision work this session: `docs/superpowers/specs/2026-05-29-a8f-camera-collision-design.md`,
+  `docs/superpowers/plans/2026-05-29-a8f-camera-collision.md`.
+- A8.F portal-frame port (the failed two-pipe graft):
+  `docs/superpowers/specs/2026-05-29-phase-a8f-portal-frame-visibility-design.md`.
+- Retail decomp: `docs/research/named-retail/acclient_2013_pseudo_c.txt`.
+- WB visibility reference: `references/WorldBuilder/Chorizite.OpenGLSDLBackend/Lib/VisibilityManager.cs`.