docs: file #136 — red-cone dungeon decoration renders red (frozen-phase render divergence)

Investigated the user-reported divergence (a solid-red cone in the 0x0007 dungeon
that retail doesn't draw). Narrowed by elimination:
- geometry, not VFX (survives particles-off)
- object 0x70007055 / Setup 0x020019F0, physState=0x1C — NOT NoDraw/Hidden
- its distinguishing texture 0x06006D65 (DXT1 256x128) DECODES tan/opaque offline,
  identical to a neighbour decoration (0x020019EE / tex 0x06006D63) that renders fine
- not a per-instance tint (hook dropped)
=> the red is introduced at runtime in the WB bindless texture-array upload/sampling
path (a #105-class "samples undefined until flushed" / layer-handle misassignment),
possibly lighting. Both WB-render-migration and sky/lighting are FROZEN phases, so the
fix awaits explicit sign-off. Full diagnosis + reusable diagnostic approach in the issue.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/ISSUES.md

@@ -46,6 +46,63 @@ Copy this block when adding a new issue:
 
 ---
 
+## #136 — "Red cone" decoration renders solid red in the 0x0007 dungeon (retail shows nothing)
+
+**Status:** OPEN — root-cause narrowed; fix touches a FROZEN phase (awaiting decision)
+**Severity:** LOW (cosmetic; one decoration in one dungeon)
+**Filed:** 2026-06-14
+**Component:** rendering — WB bindless texture-array pipeline (FROZEN) / possibly lighting (FROZEN)
+
+**Description:** In the `0x0007` Town Network dungeon, a static decoration renders as a
+solid bright-RED cone (apex toward the floor) ~3 m up, ~6.8 m from the login spawn. The
+user's side-by-side retail client shows NOTHING there — acdream draws geometry retail
+doesn't. Became visible only after the #135 login-into-dungeon fix placed the player at the
+exact saved spawn next to it (the object always existed; it wasn't reachable/rendered
+before).
+
+**Root cause / status (investigated 2026-06-14):** narrowed by elimination, NOT yet fixed.
+- It is GEOMETRY, not a VFX: survives with particle rendering fully disabled.
+- The object: server static landblock object `guid=0x70007055` (ACE `0x7`+lb`0x0007`+idx
+  `0x55`), Setup `0x020019F0`, `physState=0x1C` (Ethereal) — **NoDraw (0x20) and Hidden
+  (0x4000) are NOT set**, so it's not acdream ignoring retail's NODRAW_PS gate
+  (`acclient.h:2822`; `CPhysicsObj::set_nodraw` 0x0050fca0).
+- Setup `0x020019F0` = 1 part (GfxObj `0x0100447F`, 23 polys), 2 surfaces; it is
+  near-IDENTICAL to neighbour decoration `0x020019EE` (renders FINE) — they share surface
+  `0x0800122B` and differ only in one surface: cone `0x0800162B` → tex `0x06006D65`,
+  neighbour `0x08001629` → tex `0x06006D63`.
+- Both distinguishing textures are `PFID_DXT1 256x128`, and BOTH **decode to the same
+  tan/beige, fully-opaque** image offline (`SurfaceDecoder`: cone avgRGB (210,179,126),
+  neighbour (214,181,127), 0% alpha). So the source texture is NOT red and NOT transparent
+  — acdream's decode is correct.
+- It is NOT a per-instance tint/highlight (that hook was dropped; `EnvCellRenderer`).
+- => The red is introduced at RUNTIME, downstream of decode: most likely the WB bindless
+  `sampler2DArray` UPLOAD/SAMPLING path (a layer that samples UNDEFINED storage until a
+  flush runs — the #105 white-walls mechanism class, `ManagedGLTextureArray` PendingUpdate),
+  or a layer/handle misassignment for this specific texture. Lighting not fully excluded.
+
+**Why deferred:** the fix lands in the **WB rendering migration** (and possibly **sky/
+lighting**) — both FROZEN phases (CLAUDE.md). A genuine defect, but touching a frozen
+subsystem needs explicit user sign-off; flagged for that decision. Also: the acdream dev
+window can't be granted to computer-use (not a Start-menu app) and acdream has no
+screenshot-to-disk feature, so autonomous visual verification needs a frame-dump feature
+added first.
+
+**Files:** `src/AcDream.App/Rendering/Wb/ManagedGLTextureArray.cs` (array upload/flush),
+`src/AcDream.App/Rendering/Wb/TextureCache.cs` (id→array/layer), `mesh_modern.frag:87`
+(bindless `sampler2DArray(vTextureHandle)`), the cone = `0x70007055`/Setup `0x020019F0`/tex
+`0x06006D65` in cell `0x00070145`.
+
+**Diagnostic approach (reusable):** a throwaway `RedConeSetupProbeTests` dumped the
+Setup→part→surface→SurfaceTexture→texture chain + decoded alpha/avg-color from the dat; the
+`[static-spawn]` + nearby-entity probes in `OnLiveEntitySpawnedLocked`/`OnUpdate` ID'd the
+guid/flags. A draw-time probe of the cone's resolved bindless handle/layer/PendingUpdateCount
+would confirm the exact mechanism.
+
+**Acceptance:** the `0x70007055` decoration renders with its tan texture (matching its
+neighbour) OR is correctly suppressed to match retail (which shows nothing there).
+
+---
+
 ## #135 — ~30 s low-FPS ramp at login (≈10 fps → high) before streaming settles
 
 **Status:** FIX LANDED — pending visual gate (login into the 0x0007 dungeon → FPS steady in ~1–2 s, no neighbour load/unload churn)