wip(assembler): M2 round 4 -- WorldAssemblerHybridV2: exact contacts, tagged tiles 1.18-1.27x MC

The round-3 'field contact error' measured hit-to-anchor distance; V2 contacts are 0 cm and on the zero
isosurface. Tagged-tile cost 5.7-6.7x -> 1.175-1.270x MC; organic 0.998x. Bound, shelf-thickness and route
audits rerun with negative controls; W1/W8/W16 stable; V1 and MarchingCubesV1 unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MmSoF64BbRFmk9C3p1VsBJ

Tools/TestVoxelForgeCoreWorldHost.ps1

@@ -2,7 +2,7 @@
 param(
     [ValidateRange(60, 900)][int]$TimeoutSeconds = 900,
     [string]$WorldAssemblyManifestPath = '',
-    [ValidateSet('MarchingCubesV1', 'WorldAssemblerHybridV1')][string]$CoreMesherRecipe = 'MarchingCubesV1',
+    [ValidateSet('MarchingCubesV1', 'WorldAssemblerHybridV1', 'WorldAssemblerHybridV2')][string]$CoreMesherRecipe = 'MarchingCubesV1',
     [switch]$EnableHybridFixturePlacement,
     [switch]$HybridCliffOnly,
     [switch]$HybridFixturesOnly
@@ -87,17 +87,17 @@ $ManifestData = Get-Content -LiteralPath $StagedWorldAssembly -Raw | ConvertFrom
 if ($ManifestData.content_hash -ne '8933693d9560ba9f') {
     throw "BuildHost world assembly input is not the reviewed round-4 manifest: $($ManifestData.content_hash)"
 }
-if ($EnableHybridFixturePlacement -and $CoreMesherRecipe -ne 'WorldAssemblerHybridV1') {
-    throw 'Hybrid fixture placement requires -CoreMesherRecipe WorldAssemblerHybridV1.'
+if ($EnableHybridFixturePlacement -and $CoreMesherRecipe -eq 'MarchingCubesV1') {
+    throw 'Hybrid fixture placement requires a WorldAssemblerHybrid recipe.'
 }
-if ($HybridCliffOnly -and $CoreMesherRecipe -ne 'WorldAssemblerHybridV1') {
-    throw '-HybridCliffOnly requires -CoreMesherRecipe WorldAssemblerHybridV1.'
+if ($HybridCliffOnly -and $CoreMesherRecipe -eq 'MarchingCubesV1') {
+    throw '-HybridCliffOnly requires a WorldAssemblerHybrid recipe.'
 }
 if ($HybridCliffOnly -and $EnableHybridFixturePlacement) {
     throw '-HybridCliffOnly uses the reviewed native cliff manifest and cannot add the surface fixtures.'
 }
-if ($HybridFixturesOnly -and $CoreMesherRecipe -ne 'WorldAssemblerHybridV1') {
-    throw '-HybridFixturesOnly requires -CoreMesherRecipe WorldAssemblerHybridV1.'
+if ($HybridFixturesOnly -and $CoreMesherRecipe -eq 'MarchingCubesV1') {
+    throw '-HybridFixturesOnly requires a WorldAssemblerHybrid recipe.'
 }
 if ($HybridFixturesOnly -and ($HybridCliffOnly -or $EnableHybridFixturePlacement)) {
     throw '-HybridFixturesOnly cannot be combined with the other focused hybrid modes.'
@@ -126,7 +126,11 @@ function Get-NewCrashFolders {
     return @($Found.ToArray())
 }
 
-$HybridMesherFlag = if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV1') { 1 } else { 0 }
+$HybridMesherFlag = switch ($CoreMesherRecipe) {
+    'WorldAssemblerHybridV1' { 1; break }
+    'WorldAssemblerHybridV2' { 2; break }
+    default { 0 }
+}
 $HybridFixturePlacementFlag = if ($EnableHybridFixturePlacement) { 1 } else { 0 }
 $HybridCliffOnlyFlag = if ($HybridCliffOnly) { 1 } else { 0 }
 $HybridFixturesOnlyFlag = if ($HybridFixturesOnly) { 1 } else { 0 }
@@ -238,6 +242,18 @@ if ($HybridFixturesOnly) {
         $Text -notmatch '\[WorldAssemblerHybridPluginBorder\] lod0_lod1_doorway=1 cases=125 over_50cm_cases=0') {
         throw "BuildHost fixture log is missing passing border probes. See $FinalLog."
     }
+    if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV2') {
+        foreach ($Fixture in @('corner90', 'doorway', 'riser1m', 'cliff_ledge', 'organic_cave_chamber')) {
+            $FixtureMarker = '\[WorldAssemblerHybridPluginFixtureV2\] name=' +
+                [regex]::Escape($Fixture) + ' lod=0 .*exact_repeat=1'
+            if ($Text -notmatch $FixtureMarker) {
+                throw "BuildHost V2 fixture log is missing '$Fixture'. See $FinalLog."
+            }
+        }
+        if ($Text -notmatch '\[WorldAssemblerHybridPluginBorderV2\] same_lod=PASS independent=1 mc_identity=1') {
+            throw "BuildHost fixture log is missing the V2 border identity proof. See $FinalLog."
+        }
+    }
     $NewCrashes = @(Get-NewCrashFolders)
     if ($NewCrashes.Count -gt 0) {
         throw "New UECC crash folders appeared during plugin fixture checks: $($NewCrashes -join '; ')"
@@ -287,13 +303,20 @@ $RecipeMarker = '\[VoxelForgeCoreWorldTest\] world_initialized=1 recipe=' +
 if ($Text -notmatch $RecipeMarker) {
     throw "BuildHost actor log does not confirm the requested $CoreMesherRecipe runtime selection. See $FinalLog."
 }
-if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV1') {
+if ($CoreMesherRecipe -in @('WorldAssemblerHybridV1', 'WorldAssemblerHybridV2')) {
     foreach ($Fixture in @('corner90', 'doorway', 'riser1m', 'cliff_ledge', 'organic_cave_chamber')) {
         $FixtureMarker = '\[WorldAssemblerHybridPluginFixture\] name=' +
             [regex]::Escape($Fixture) + ' lod=0 .*exact_repeat=1'
         if ($Text -notmatch $FixtureMarker) {
             throw "BuildHost log is missing the production mesher fixture '$Fixture'. See $FinalLog."
         }
+        if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV2') {
+            $V2FixtureMarker = '\[WorldAssemblerHybridPluginFixtureV2\] name=' +
+                [regex]::Escape($Fixture) + ' lod=0 .*exact_repeat=1'
+            if ($Text -notmatch $V2FixtureMarker) {
+                throw "BuildHost actor log is missing the V2 production mesher fixture '$Fixture'. See $FinalLog."
+            }
+        }
     }
     if ($Text -notmatch '\[WorldAssemblerHybridPluginBorder\] same_lod=PASS independent=1') {
         throw "BuildHost log is missing the independent same-LOD border proof. See $FinalLog."
@@ -305,6 +328,10 @@ if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV1') {
 if ($EnableHybridFixturePlacement -and $Text -notmatch '\[VoxelForgeHybridCollisionContact\] pass=1 probes=5') {
     throw "BuildHost log is missing the cooked hybrid fixture trace contacts. See $FinalLog."
 }
+if ($CoreMesherRecipe -eq 'WorldAssemblerHybridV2' -and $EnableHybridFixturePlacement -and
+    $Text -notmatch '\[VoxelForgeHybridCollisionContact\] fixture=corner_top .*expected_point_error_cm=[0-9.]+') {
+    throw "BuildHost log is missing the V2 flat-face contact precision proof. See $FinalLog."
+}
 if ($Text -notmatch '\[VoxelForgeCoreWorldTest\] native_biome_field=1 .*sampled_biomes=[2-9]') {
     throw "BuildHost Core actor log does not prove native SurfaceWorld biome assignment. See $FinalLog."
 }