research(vm2): retail runs SINGLE-PASS detail texturing - the #226 port targets the fallback

Live cdb read on the PDB-paired retail client (owner's AMD GPU):
  m_caps.bCanDoSinglePassDetailing = 1, trysinglepass = 1,
  MaxSimultaneousTextures = 8, bTexOpDotProduct3 = 1,
  LandscapeDetailTextures = 0, EnvironmentDetailTextures = 1,
  landscape/object detail surfaces null, building/environment non-null,
  tiling 4 everywhere.

So retail's detail combine on modern hardware is the texture-stage path in
D3DPolyRender::SetSurface (stage0 alpha PREMODULATE, stage1 colour
BLENDCURRENTALPHA): lerp(base*diffuse, detail.rgb, detail.a*diffuse.a) -
a mild DARKENING (~-10% mid-tones with 0x06006D58), not the
DSTCOLOR+INVSRCALPHA brightening that Campaign AR ported and that the
2026-08-21 findings doc + AR review both analysed. Those described the
fallback for adapters without D3DTEXOPCAPS_PREMODULATE; the reviewer's
guess that consumer drivers rarely advertised it was wrong.

VM1 now carries the re-port (SRCALPHA+INVSRCALPHA, detail.rgb /
detail.a*diffuseAlpha, neutral at a==0) together with the fade removal.
No distance fade exists on either path. Scripts are read-only attaches
with no breakpoints.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tools/cdb/vm2-trysinglepass.cdb

@@ -0,0 +1,11 @@
+.logopen C:\Users\erikn\source\repos\acdream\.claude\worktrees\peaceful-blackburn-5333f0\artifacts\vm2\vm2-trysinglepass.log
+.sympath C:\Users\erikn\source\repos\acdream\refs
+.reload /f acclient.exe
+.echo === trysinglepass candidates (decomp: 00820e40 / 00835c04 / 00835c10, all init 1) ===
+dd 00820e40 L1
+dd 00835c04 L1
+dd 00835c10 L1
+.echo === RenderPrefs ===
+dt acclient!Render::m_RenderPrefs
+.logclose
+qd