phase(N.5): retirement amendment — InstancedMeshRenderer + StaticMeshRenderer + WbFoundationFlag deleted

Final cross-cutting review of N.5 found that Task 15's deletion of
mesh_instanced.vert/.frag left InstancedMeshRenderer orphaned —
ACDREAM_USE_WB_FOUNDATION=0 silently rendered terrain+sky only with
no entities. The SHIP commit's "[x] ACDREAM_USE_WB_FOUNDATION=0 still
works" claim was inaccurate.

Resolution: formal retirement of the legacy renderer path within N.5
instead of deferring to N.6.

Deleted:
- src/AcDream.App/Rendering/InstancedMeshRenderer.cs
- src/AcDream.App/Rendering/StaticMeshRenderer.cs
- src/AcDream.App/Rendering/Wb/WbFoundationFlag.cs

GameWindow simplified — capability detection is unconditional, missing
bindless throws NotSupportedException with a clear message at startup.
WbDrawDispatcher + mesh_modern shader load are mandatory after init.
No escape hatch.

GpuWorldState simplified — WbFoundationFlag.IsEnabled guards on
AddLandblock/RemoveLandblock removed; adapter calls are unconditional
when the adapter is non-null.

PendingSpawnIntegrationTests updated — WbFoundationFlag.ForTestsOnly_ForceEnable
static ctor removed (flag is gone; adapter calls are unconditional).

The ApplyLoadedTerrain physics-data loop was also simplified: the
EnsureUploaded sub-loop that fed InstancedMeshRenderer is gone;
_pendingCellMeshes is now explicitly cleared to prevent unbounded
accumulation (the worker thread still populates it, but WB handles
EnvCell geometry through its own pipeline).

Spec §2 Decision 5 + §10 Out-of-Scope updated. Plan ship-amendment
section added. Roadmap updated (N.5 ships with retirement; N.6 scope
narrowed to perf-only). CLAUDE.md "WB integration cribs" updated.
Perf baseline doc updated. WbDrawDispatcher class summary docstring
corrected to describe the as-shipped SSBO + multi-draw-indirect path.
ISSUES.md #51 updated (terrain not in N.5 scope; deferred to N.7).

Bindless support is now a hard requirement. Modern desktop GPUs
universally expose GL_ARB_bindless_texture + GL_ARB_shader_draw_parameters;
if a user hits the NotSupportedException, that's a real bug report
worth investigating, not a silent fallback.

Build: 0 errors, 0 warnings. Tests: 71/71 (Wb+MatrixComposition+TextureCacheBindless filter).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/superpowers/plans/2026-05-08-phase-n5-modern-rendering.md

@@ -2561,10 +2561,10 @@ SHIP commit at Task 19.
       `FullyQualifiedName~Wb|FullyQualifiedName~MatrixComposition`.
       Pre-existing 8 failures in physics/input/movement tests carry
       forward unchanged from before N.5.
-- [x] **`ACDREAM_USE_WB_FOUNDATION=0` still works** — Task 15 confirmed
-      InstancedMeshRenderer remains intact as the escape hatch; if
-      bindless is missing, `_meshShader` stays null + `_wbDrawDispatcher`
-      stays null, falling through to InstancedMeshRenderer naturally.
+- [N/A] **`ACDREAM_USE_WB_FOUNDATION=0` still works** — escape hatch
+      formally retired in N.5 ship amendment (see section below).
+      `InstancedMeshRenderer`, `StaticMeshRenderer`, and `WbFoundationFlag`
+      deleted. Missing bindless throws `NotSupportedException` at startup.
 
 ### Plan amendments captured during execution
 
@@ -2613,7 +2613,7 @@ adjustments captured beyond the plan:
 - **Persistent-mapped buffers** (Decision 7 deferral). Layer on top of
   the modern path if `glBufferData` shows up as a residual hot spot in
   profiling.
-- **Retire `InstancedMeshRenderer`** entirely — N.6 primary scope.
+- ~~**Retire `InstancedMeshRenderer`** entirely — N.6 primary scope.~~ **Done in N.5 ship amendment.**
 - **WB atlas adoption** for memory savings on shared content (trees,
   walls, etc).
 - **GPU-side culling** via compute pre-pass.
@@ -2655,3 +2655,52 @@ CLAUDE.md "WB integration cribs" updated with N.5 patterns (Task 16).
 **Deleted:**
 - `src/AcDream.App/Rendering/Shaders/mesh_instanced.vert`
 - `src/AcDream.App/Rendering/Shaders/mesh_instanced.frag`
+
+---
+
+## Ship amendment — 2026-05-08
+
+### Problem discovered in cross-cutting review
+
+Task 15's deletion of `mesh_instanced.vert/.frag` left `InstancedMeshRenderer`
+orphaned. The `_staticMesh` construction was gated on `_meshShader is not null`,
+and `_meshShader` was only assigned when bindless was present. So with
+`ACDREAM_USE_WB_FOUNDATION=0`, the flag path produced `_meshShader=null` →
+`_staticMesh=null` → terrain+sky only with no entity rendering. The SHIP
+commit's `[x] ACDREAM_USE_WB_FOUNDATION=0 still works` claim was inaccurate.
+
+### Resolution
+
+User authorized **Option B**: formal retirement of the legacy path in N.5
+instead of restoring it. Reasons: bindless + WB foundation has been default-on
+since N.4, escape hatch was never exercised in practice, N.6 was already
+planning to retire it — we did it now instead.
+
+**Files deleted:**
+- `src/AcDream.App/Rendering/InstancedMeshRenderer.cs`
+- `src/AcDream.App/Rendering/StaticMeshRenderer.cs`
+- `src/AcDream.App/Rendering/Wb/WbFoundationFlag.cs`
+
+**GameWindow simplified:**
+- `_staticMesh` field removed
+- Capability detection block is unconditional (no `WbFoundationFlag.IsEnabled` guard)
+- Missing bindless throws `NotSupportedException` at startup with a clear message
+- `_wbMeshAdapter`, `_wbEntitySpawnAdapter`, `_wbDrawDispatcher` all construct
+  unconditionally after the capability check
+- Draw path: `_wbDrawDispatcher!.Draw(...)` — no null-conditional, no else branch
+
+**GpuWorldState simplified:**
+- `WbFoundationFlag.IsEnabled` guards removed from `AddLandblock` /
+  `RemoveLandblock`; adapter calls are unconditional when adapter is non-null
+
+**Test file updated:**
+- `PendingSpawnIntegrationTests.cs`: removed `static WbFoundationFlag.ForTestsOnly_ForceEnable()` ctor
+  (no longer needed — `GpuWorldState` adapter calls are unconditional)
+
+**Spec §2 Decision 5 updated:** two-way flag → mandatory modern path.
+**Spec §10 Out-of-scope updated:** `InstancedMeshRenderer` deletion crossed off (done).
+**Roadmap updated:** N.5 entry notes retirement; N.6 scope narrowed.
+**Perf baseline doc updated:** acceptance gate row corrected to N/A.
+**CLAUDE.md updated:** WB integration cribs no longer reference WbFoundationFlag.
+
+Build: green (0 errors, 0 warnings). Tests: 71/71 in Wb+MatrixComposition+TextureCacheBindless filter.