measure(step1): cook is 1.5-2.3 ms, RMC's route is 8-11 s; CMC cannot take a field floor; cap 16 uploads

Rebuild plan step 1 (RESEARCH-SPEED-2026-09.md), all behind default-off switches.
A. Direct cook on a dedicated thread, 27-tile support cohort: core cook p50 1.50 ms, p95 2.28 ms;
   a 3,949-tri tile 1.67 ms extract+cook. PASSES the 10 ms gate. Through RMC's route the same
   support bodies became ready 8.46 s p50 / 10.80 s p95 after their meshes existed: FAILS 150 ms.
   Exact-target capsule sweep confirmed (0.75 ms after body update).
B. 100 rapid underfoot digs on CMC with a field override: 883 false-support frames, 0 false-air,
   0 invented velocity. CMC's floor comes from collision-scene traces -> step 4 = field-aware Mover.
C. 341 prequeued tiles, render on: cap 4 = 238 applies/s, cap 8 = 476, cap 16 = 639 (drain p95
   2.22 ms vs 2 ms gate); first visible 1 frame after release; no RT/RHI backlog. Tune drain,
   no grouping needed yet.
D. Same 128^3 region, 64/64 tile hashes equal in export and game. The "263 ns/sample" was export
   WALL time with 15 workers sharing a lattice (~3.4 us CPU/sample); game tile time includes
   meshing and duplicated borders (+22%); contention cap 1 vs 14: 74 vs 112 ms per tile.
   Profiling is not the cause.

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

Tools/VoxelForgeTest.ps1

@@ -15,6 +15,9 @@ param(
     [int]$HorizonLevel = 5,
     [ValidateRange(1, 100000)]
     [int]$HorizonRenderDistanceChunks = 768,
+    [ValidateSet(32, 64, 128)]
+    [int]$ParityExportSize = 128,
+    [string]$ParityExportTile = '',
     [string]$SharedDDC
 )
 
@@ -673,7 +676,7 @@ function New-CommonArguments([string]$Kind, [string]$LogPath, $CvarMap, [bool]$E
 
 function New-CommandletArguments([string]$CommandletOut, [string]$Modes, [bool]$UseOwnerAssets,
                                  [bool]$GameRuntimeConfig, [int]$ExportSize = 128,
-                                 [int]$Slot = 1) {
+                                 [int]$Slot = 1, [string]$ExportTile = '') {
     $args = [System.Collections.Generic.List[string]]::new()
     [void]$args.Add('-seed=0')
     [void]$args.Add('-archetype=TunnelNetwork')
@@ -682,6 +685,14 @@ function New-CommandletArguments([string]$CommandletOut, [string]$Modes, [bool]$
     [void]$args.Add('-blockearlyout=0')
     [void]$args.Add('-densitygridreuse=1')
     [void]$args.Add("-exportsize=$ExportSize")
+    if (-not [string]::IsNullOrWhiteSpace($ExportTile)) {
+        if ($ExportTile -notmatch '^\s*(-?\d+)\s*,\s*(-?\d+)\s*,\s*(-?\d+)\s*$') {
+            throw "-ParityExportTile must be three comma-separated level-0 tile coordinates: $ExportTile"
+        }
+        [void]$args.Add("-exporttilex=$($Matches[1])")
+        [void]$args.Add("-exporttiley=$($Matches[2])")
+        [void]$args.Add("-exporttilez=$($Matches[3])")
+    }
     if ($GameRuntimeConfig) { [void]$args.Add('-gameconfig=1') }
     if ($UseOwnerAssets) {
         [void]$args.Add('-strateref=/Game/VoxelForge/DA_Strate3.DA_Strate3')
@@ -1108,11 +1119,17 @@ function Get-DigMotionMetrics([string]$LogPath) {
     if ($result.Success -and $result.Groups['v'].Value -eq 'PASS') { $metrics.status = 'passed' }
     foreach ($key in @('near_digs', 'near_frames', 'near_gate_frames', 'near_falling_frames',
                         'near_vertical_motion_frames', 'under_saw_falling', 'under_gate_frames',
-                        'under_fall_cm', 'under_max_downward_velocity_cm_s')) {
+                        'under_fall_cm', 'under_max_downward_velocity_cm_s', 'under_digs',
+                        'first_frame_checks', 'support_observed_frames',
+                        'false_support_frames', 'false_air_frames',
+                        'invented_downward_velocity_events', 'field_override')) {
         $match = [regex]::Match($line, ('{0}=(?<v>[^ ]+)' -f $key))
         if (-not $match.Success) { continue }
         if ($key -in @('near_digs', 'near_frames', 'near_gate_frames', 'near_falling_frames',
-                       'near_vertical_motion_frames', 'under_saw_falling', 'under_gate_frames')) {
+                       'near_vertical_motion_frames', 'under_saw_falling', 'under_gate_frames',
+                       'under_digs', 'first_frame_checks', 'false_support_frames',
+                       'support_observed_frames',
+                       'false_air_frames', 'invented_downward_velocity_events', 'field_override')) {
             $metrics[$key] = [int]$match.Groups['v'].Value
         } else {
             $metrics[$key] = [double]$match.Groups['v'].Value
@@ -1695,10 +1712,10 @@ try {
         }
         'parity' {
             $parityArgs = New-CommonArguments 'commandlet' (Join-Path $RunRoot 'Logs\parity-commandlet.log') (Merge-Cvars $baseCvars)
-            # Use the same 128-voxel / 64-tile bounded region as the canonical exporter. The game
-            # harness streams a larger clipmap around its center; comparison is restricted to these
-            # exact level-0 tiles, including non-empty geometry rather than only an air tile.
-            $parityArgs += New-CommandletArguments $commandletOut 'export' $true $true 128 0
+            # Export one selected region size. The game harness streams a clipmap around its center;
+            # comparison is restricted to these exact level-0 tiles, including non-empty geometry.
+            $parityArgs += New-CommandletArguments $commandletOut 'export' $true $true `
+                $ParityExportSize 0 $ParityExportTile
             $commandletLedger = Invoke-UnrealLaunch 'parity-commandlet' $parityArgs `
                 (Join-Path $RunRoot 'Logs\parity-commandlet.log') (Join-Path $RunRoot 'Logs\parity-commandlet.stdout.log') (Join-Path $RunRoot 'Logs\parity-commandlet.stderr.log')
             $CommandletMetrics = Get-CommandletMetrics $commandletOut 'owner assets; game_runtime_config=1'
@@ -1707,13 +1724,15 @@ try {
             $parityExport = Get-JsonValue $parityJson 'export'
             $region = Get-JsonValue $parityExport 'region_origin_voxels'
             if ($null -eq $region) { throw 'Parity commandlet did not report export.region_origin_voxels.' }
-            $paritySize = [int](Get-JsonValue $parityExport 'region_size_cells_per_axis' 128)
+            $paritySize = [int](Get-JsonValue $parityExport 'region_size_cells_per_axis' $ParityExportSize)
             $centerOffset = [int]($paritySize / 2)
             $centerX = [int]$region.x + $centerOffset
             $centerY = [int]$region.y + $centerOffset
             $centerZ = [int]$region.z + $centerOffset
             $gameDump = Join-Path $RunRoot 'game_tile_hashes.json'
-            $baseCvars['voxel.TestExitSeconds'] = 15
+            if ($null -eq $Cvars -or -not $Cvars.Contains('voxel.TestExitSeconds')) {
+                $baseCvars['voxel.TestExitSeconds'] = 15
+            }
             $baseCvars['voxel.StreamingTestCenterX'] = $centerX
             $baseCvars['voxel.StreamingTestCenterY'] = $centerY
             $baseCvars['voxel.StreamingTestCenterZ'] = $centerZ
@@ -1721,7 +1740,8 @@ try {
             $baseCvars['voxel.UseBlockEarlyOut'] = 0
             $baseCvars['voxel.OuterClassifierMode'] = 0
             $baseCvars['voxel.SealedSolidProof'] = 0
-            $gameArgs = New-CommonArguments 'game' (Join-Path $RunRoot 'Logs\parity-game.log') (Merge-Cvars $baseCvars)
+            $gameArgs = New-CommonArguments 'game' (Join-Path $RunRoot 'Logs\parity-game.log') `
+                (Merge-Cvars $baseCvars) $EnableRender.IsPresent
             $gameLedger = Invoke-UnrealLaunch 'parity-game' $gameArgs `
                 (Join-Path $RunRoot 'Logs\parity-game.log') (Join-Path $RunRoot 'Logs\parity-game.stdout.log') (Join-Path $RunRoot 'Logs\parity-game.stderr.log')
             $GameMetrics = Get-StreamingMetrics (Join-Path $RunRoot 'Logs\parity-game.log')