diff --git a/docs/ISSUES.md b/docs/ISSUES.md
index 6e656fb9..9a9dee1b 100644
--- a/docs/ISSUES.md
+++ b/docs/ISSUES.md
@@ -211,6 +211,50 @@ question costs far more to answer.
 sign/portal visible; a soak instrument counts published-vs-live entities per
 transit and holds at zero drift.
 
+### Discriminator result (2026-07-28, V11 step 0) — NEGATIVE ON BOTH ARMS
+
+The discriminator this issue demanded before V11 was built and run:
+`tools/run-portal-churn-soak.ps1`, 30 cycles x 3 portal-bearing stops
+(Holtburg town / Facility Hub interior / Aerlinthe island, all taken from the
+existing connected routes, every teleloc carrying the identity quaternion so the
+heading repeats), **90 transits per arm**, once on `gl` and once on `vulkan`
+from the same binary at `122fe8a7`. Both arms: 91 checkpoints, **zero** error
+lines, graceful exit, desktop witness `RENDERED`.
+
+The pixel half is a *within-arm* comparison — the Holtburg capture at cycle 1
+against cycles 10, 20 and 30 from the same process at a pinned viewpoint with
+MSAA off and all four determinism levers forced. An object that stopped being
+drawn would appear as a contiguous blob in the difference map.
+
+| Arm | c01 vs c10 | c01 vs c20 | c01 vs c30 |
+|---|---|---|---|
+| gl | 12,366 px | 14,492 px | 17,082 px |
+| vulkan | 12,774 px | 15,234 px | 16,183 px |
+
+**The two arms are the same to within noise, and the difference maps show
+nothing missing.** Every building, the portal cone, the statue, the distant
+treeline, the scenery and the NPC render identically at cycle 30 and cycle 1 on
+both backends. What differs is: the player avatar's animation phase, the
+portal's own scrolling texture, one corpse, the stamina readout — plus, on GL
+only, a scatter of single-pixel alpha fringes across the ground that Vulkan does
+not produce. Publication counters corroborate: `worldEntities` is **10,382 at
+every one of the 30 cycles on both arms**, `ownedCompositeTextures` is 471,
+`trackedGpuTextures` is 437 (GL) / 372 (VK) — all three constant from warmup to
+the last transit, with zero drift.
+
+**Verdict: the "Vulkan-arm-only lifecycle bug" hypothesis is refuted for this
+workload, so V11 is not blocked by this issue.** But neither arm *reproduced*
+the symptom, so this does not identify the pre-existing bug either — it rules
+out the one outcome that would have made deleting GL wrong.
+
+**This issue stays OPEN.** The next attempt must differ from this route the way
+the user's session did: real portal *use* (walk into a portal, F751 wormhole,
+materialization) rather than `/teleloc`, and Coldeve's town portal network
+rather than these three stops. `/teleloc` and a walked portal do not take the
+same path into the transit state machine, and that difference is now the leading
+suspect. Artifacts: `artifacts/v11-churn/` (per-checkpoint CSVs, memory sample
+CSVs, difference maps, `churn-soak.json`).
+
 ---
 
 ## #257 — Working set balloons to ~1.5 GB over a live portal-churn session
@@ -240,6 +284,52 @@ are the model to hold this to.
 **Acceptance:** a repeated-portal soak (≥30 transits) holds working set flat
 after warmup, with per-category GPU accounting drift at zero.
 
+### Discriminator result (2026-07-28, V11 step 0) — NEGATIVE ON BOTH ARMS
+
+Same run as #256's: `tools/run-portal-churn-soak.ps1`, 30 cycles x 3 stops =
+**90 transits per arm**, `gl` then `vulkan` from one binary at `122fe8a7`, with
+the OS sampling working set and private bytes every 2 s (547 / 548 samples per
+arm) and each checkpoint joined to its nearest sample by timestamp.
+
+Holtburg, every fifth cycle:
+
+| Cycle | GL WS | GL priv | GL GPU | VK WS | VK priv | VK GPU |
+|---|---|---|---|---|---|---|
+| 1 | 1878.1 | 1949.6 | 321.5 | 1893.3 | 1848.7 | 58.6 |
+| 5 | 1728.6 | 1783.3 | 332.3 | 1905.7 | 1843.7 | 58.6 |
+| 10 | 1902.7 | 1963.6 | 332.3 | 1928.5 | 1867.6 | 58.6 |
+| 15 | 1911.7 | 1972.9 | 332.3 | 1933.8 | 1870.6 | 58.6 |
+| 20 | 1976.1 | 2042.5 | 332.3 | 1757.8 | 1693.7 | 58.6 |
+| 25 | 1874.3 | 1940.7 | 332.3 | 1875.4 | 1812.0 | 58.6 |
+| 30 | 1920.4 | 1994.5 | 332.3 | 1774.5 | 1709.1 | 58.6 |
+
+(MiB. The GL/VK GPU-byte levels are not comparable to each other — the two
+backends' `GpuMemoryTracker` coverage differs — but each is comparable to
+itself, and **each is exactly constant**: GL pins at 332.3 MiB from cycle 2
+onward and never moves again; Vulkan sits at 58.6 MiB for all 30 cycles.)
+
+Whole-run statistics over every OS sample:
+
+| Arm | min | mean | max | peak private | warm 1st-half mean | warm 2nd-half mean | drift |
+|---|---|---|---|---|---|---|---|
+| gl | 1713 | **1864** | 2210 | 2282 | 1927 | 1880 | **-48.0** |
+| vulkan | 1734 | **1863** | 2173 | 2112 | 1894 | 1867 | **-27.0** |
+
+**Neither arm grows.** The warm-half drift is *negative* on both, the two means
+agree to 1 MiB, and handle counts are flat (GL +1, VK -4 over 30 cycles).
+
+**Verdict: not reproduced, on either backend, so V11 is not blocked.** The
+~1.9 GB band is a *level*, not a leak: this route holds three very different
+landblocks' content live, which is a different residency profile from V8's
+stationary 877 MiB (VK) / 944 MiB (GL) vehicles. The 1.5 GB the user saw is
+inside this band, so the reported number may simply be what a multi-region
+session costs — but that is a hypothesis this run cannot confirm, because it
+did not reproduce unbounded growth to explain.
+
+**This issue stays OPEN**, coupled to #256 and blocked on the same follow-up:
+re-run with walked portal transits rather than `/teleloc`. Artifacts:
+`artifacts/v11-churn/`.
+
 ---
 
 ## #253 — Attribute/skill icons: not centered in their cells, and fully opaque
diff --git a/tools/run-portal-churn-soak.ps1 b/tools/run-portal-churn-soak.ps1
new file mode 100644
index 00000000..d74027a9
--- /dev/null
+++ b/tools/run-portal-churn-soak.ps1
@@ -0,0 +1,611 @@
+<#
+.SYNOPSIS
+    Campaign V slice V11 step 0: the #256/#257 discriminator, run on both backends.
+
+.DESCRIPTION
+    Issues #256 (server-spawned signs and portals go invisible after repeated
+    portal runs, while staying interactive) and #257 (working set grows to
+    ~1.5 GB over the same session) were both observed on the Vulkan backend in
+    one long live session. Both filings demand the SAME discriminator, and both
+    demand it BEFORE V11 deletes the OpenGL backend:
+
+        run the same repeated-churn route on GL and on Vulkan.
+
+        growth / drift on BOTH arms  -> a pre-existing publication or resource
+                                        lifetime bug that the campaign merely
+                                        witnessed;
+        growth / drift on VULKAN ONLY -> the new arm's resource lifecycle, and
+                                        deleting its predecessor would destroy
+                                        the only reference implementation that
+                                        can answer the question.
+
+    After V11 the GL arm does not exist and this question costs far more to
+    answer, which is why this script runs first and why its verdict can stop the
+    slice.
+
+    WHAT IT MEASURES, per stop, per cycle:
+
+      * working set and private bytes, sampled from the OS every -SampleSeconds
+        and joined to each checkpoint by timestamp. This is #257's quantity: the
+        client's own snapshot has no view of its own working set.
+      * the published-versus-live entity pair from the checkpoint JSON --
+        liveEntities / materializedLiveEntities against worldEntities and
+        meshRenderData. #256's symptom is "alive in the object table, gone from
+        the presentation", so a drift between those two halves at the SAME stop
+        across cycles is the instrument.
+      * the GPU accounting the checkpoint already carries: trackedGpuBytes,
+        residencyGpuBytes, their difference, tracked buffer and texture counts,
+        owned composite textures and their owners. GpuMemoryTracker's categories
+        reach the checkpoint as those counts.
+      * managed bytes, committed bytes, LOH size, and the streaming/retirement
+        backlogs, so a growth finding can be attributed to a heap rather than
+        left as "the process is bigger".
+
+    HOW THE ROUTE IS BUILT. -Cycles repetitions of three stops taken from the
+    two existing connected routes: Holtburg town (the dense outdoor stop the
+    differential route calls its smoke stop, and the one that has a portal in
+    frame), the Facility Hub interior EnvCell, and the Aerlinthe island. Every
+    teleloc carries the identity quaternion so the heading at a stop is the same
+    on every visit, which is what makes cycle 1 and cycle N comparable at all.
+    Each stop writes a checkpoint; Holtburg additionally captures a screenshot on
+    the cycles named by -ShotCycles.
+
+    THE PIXEL HALF. Within one arm, the Holtburg capture from cycle 1 and the
+    capture from the last shot cycle are compared against each other. Same
+    process, same position, same heading, same pinned clock: an object that has
+    stopped being drawn shows up as a contiguous mid-frame difference. This is
+    the closest automated instrument to what the user actually saw. The four
+    determinism levers the differential gate forces are forced here for the same
+    reason -- an unpinned sun or cloud sheet would swamp the signal.
+
+    NOT A PIXEL GATE. This script never compares the two backends to each other;
+    that is run-backend-differential-gate.ps1's job and its thresholds are the
+    campaign's. Here each arm is compared only with itself, and the verdict is
+    about growth and drift.
+
+.PARAMETER Out
+    Directory for both arms' logs, checkpoints, captures, samples and the verdict.
+
+.PARAMETER Cycles
+    Repetitions of the three-stop loop. Default 30 -- #257's acceptance criterion
+    is "a repeated-portal soak (>= 30 transits) holds working set flat after
+    warmup", and three stops per cycle makes 90 transits at the default.
+
+.PARAMETER Backends
+    Which arms to run, in order. Default gl then vulkan, so the arm under
+    suspicion runs second and cannot be blamed for warming the machine.
+
+.PARAMETER ShotCycles
+    Cycles on which Holtburg is captured. Default 1, 10, 20 and the last cycle.
+
+.PARAMETER SettleMilliseconds
+    Stationary window between arrival and the checkpoint. Default 6000.
+
+.EXAMPLE
+    tools/run-portal-churn-soak.ps1 -Out artifacts/v11-churn
+    tools/run-portal-churn-soak.ps1 -Out artifacts/v11-churn-short -Cycles 4 -SkipBuild
+#>
+[CmdletBinding()]
+param(
+    [Parameter(Mandatory = $true)][string]$Out,
+    [int]$Cycles = 30,
+    [string[]]$Backends = @('gl', 'vulkan'),
+    [int[]]$ShotCycles,
+    [int]$SettleMilliseconds = 6000,
+    [int]$ShotSettleMilliseconds = 12000,
+    [int]$SampleSeconds = 2,
+    [int]$DayGroup = 0,
+    [double]$WorldDayFraction = 0.5,
+    [double]$SkyPhaseSeconds = 0,
+    [int]$MaskTopPixels = 280,
+    [int]$Tolerance = 2,
+    [double]$MaxDifferentFraction = 0.001,
+    [int]$MinRenderedBytes = 500000,
+    # A soak whose subject is unbounded growth must not be allowed to take the
+    # machine down with it. Crossing this stops the arm early and keeps every
+    # sample and checkpoint taken so far -- which is the finding, not a failure.
+    [int]$AbortWorkingSetMiB = 10000,
+    [int]$CooldownSeconds = 20,
+    [int]$RouteTimeoutSeconds = 2400,
+    [switch]$SkipBuild
+)
+
+$ErrorActionPreference = 'Stop'
+Set-StrictMode -Version Latest
+$repo = Split-Path -Parent $PSScriptRoot
+$exe = Join-Path $repo 'src\AcDream.App\bin\Release\net10.0\AcDream.App.exe'
+$cli = Join-Path $repo 'src\AcDream.Cli\bin\Release\net10.0\AcDream.Cli.dll'
+
+function Write-Step($message) { Write-Host "[churn] $message" }
+
+if (-not $ShotCycles) {
+    $ShotCycles = @(1, 10, 20, $Cycles) | Where-Object { $_ -le $Cycles } | Sort-Object -Unique
+}
+
+# --- Preconditions ------------------------------------------------------------
+if (Get-Process -Name AcDream.App -ErrorAction SilentlyContinue) {
+    throw 'AcDream.App is already running. This soak uses the shared test account and must not steal its session.'
+}
+if (@(Get-NetUDPEndpoint -LocalPort 9000 -ErrorAction SilentlyContinue).Count -eq 0) {
+    throw 'local ACE is not listening on UDP port 9000.'
+}
+if (-not $SkipBuild) {
+    Write-Step 'building Release'
+    & dotnet build (Join-Path $repo 'AcDream.slnx') -c Release --nologo -v q | Out-Null
+    if ($LASTEXITCODE -ne 0) { throw "Release build failed with exit code $LASTEXITCODE." }
+}
+if (-not (Test-Path $exe)) { throw "Client not found at $exe." }
+if (-not (Test-Path $cli)) { throw "AcDream.Cli not found at $cli." }
+
+if (Test-Path $Out) { Remove-Item -Recurse -Force $Out }
+New-Item -ItemType Directory -Force -Path $Out | Out-Null
+
+# --- The route ----------------------------------------------------------------
+# Three stops per cycle, all three taken from routes that already exist. The
+# identity quaternion on every teleloc is what pins the heading across visits.
+$stops = @(
+    [pscustomobject]@{ Key = 'holtburg';  Teleloc = '0xA9B40019 84.0 7.1 94.005 1 0 0 0' }
+    [pscustomobject]@{ Key = 'hub';       Teleloc = '0x8A020164 70.35 -40.66 -5.9 1 0 0 0' }
+    [pscustomobject]@{ Key = 'aerlinthe'; Teleloc = '0x09040008 11.4 188.6 87.705 1 0 0 0' }
+)
+
+$lines = [System.Collections.Generic.List[string]]::new()
+$lines.Add('# GENERATED by tools/run-portal-churn-soak.ps1 -- the V11 step-0 discriminator.')
+$lines.Add("# $Cycles cycles x $($stops.Count) stops. Do not hand-edit; regenerate.")
+$lines.Add('')
+$lines.Add('wait world-ready 90000')
+$lines.Add('wait world-visible 30000')
+$lines.Add('sleep 15000')
+$lines.Add('checkpoint c00_login')
+$lines.Add('')
+
+$transit = 0
+foreach ($cycle in 1..$Cycles) {
+    $tag = '{0:d2}' -f $cycle
+    $shot = $ShotCycles -contains $cycle
+    foreach ($stop in $stops) {
+        $transit++
+        $settle = if ($shot -and $stop.Key -eq 'holtburg') { $ShotSettleMilliseconds } else { $SettleMilliseconds }
+        $lines.Add("command /teleloc $($stop.Teleloc)")
+        $lines.Add("wait materialized $transit 90000")
+        $lines.Add('wait world-visible 30000')
+        $lines.Add("sleep $settle")
+        $lines.Add("checkpoint c${tag}_$($stop.Key)")
+        if ($shot -and $stop.Key -eq 'holtburg') {
+            $lines.Add("screenshot holtburg_c$tag 15000")
+        }
+    }
+    $lines.Add('')
+}
+$lines.Add('sleep 5000')
+
+$routePath = Join-Path $Out 'route.txt'
+Set-Content -Encoding utf8 -LiteralPath $routePath -Value $lines
+Write-Step "route: $Cycles cycles, $transit transits, $($lines.Count) lines -> $routePath"
+
+Add-Type -AssemblyName System.Drawing
+Add-Type @'
+using System;
+using System.Runtime.InteropServices;
+public static class ChurnSoakSurface {
+    [DllImport("user32.dll")] public static extern bool SetForegroundWindow(IntPtr hWnd);
+    [DllImport("user32.dll")] public static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
+    [DllImport("user32.dll")] public static extern bool GetClientRect(IntPtr hWnd, out RECT r);
+    [DllImport("user32.dll")] public static extern bool ClientToScreen(IntPtr hWnd, ref POINT p);
+    [StructLayout(LayoutKind.Sequential)] public struct RECT { public int L, T, R, B; }
+    [StructLayout(LayoutKind.Sequential)] public struct POINT { public int X, Y; }
+}
+'@
+
+# A number cannot tell an absent object from a walking NPC. The map and the row
+# histogram can: a vanished sign is a contiguous blob in one band, a creature is
+# a thin moving silhouette, and phase noise is scattered.
+Add-Type -ReferencedAssemblies System.Drawing @'
+using System;
+using System.Drawing;
+using System.Drawing.Imaging;
+using System.Runtime.InteropServices;
+public static class ChurnDiffMap {
+    public static int[] Write(string expected, string actual, string outPath, int tolerance, int maskTop) {
+        int[] bands = new int[18];
+        using (Bitmap a = new Bitmap(expected))
+        using (Bitmap b = new Bitmap(actual))
+        using (Bitmap map = new Bitmap(a.Width, a.Height, PixelFormat.Format32bppArgb)) {
+            Rectangle rect = new Rectangle(0, 0, a.Width, a.Height);
+            BitmapData da = a.LockBits(rect, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
+            BitmapData db = b.LockBits(rect, ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
+            BitmapData dm = map.LockBits(rect, ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);
+            int count = a.Width * a.Height;
+            int[] pa = new int[count], pb = new int[count], pm = new int[count];
+            Marshal.Copy(da.Scan0, pa, 0, count);
+            Marshal.Copy(db.Scan0, pb, 0, count);
+            for (int y = 0; y < a.Height; y++) {
+                for (int x = 0; x < a.Width; x++) {
+                    int i = y * a.Width + x;
+                    int ca = pa[i], cb = pb[i];
+                    int d = Math.Max(Math.Abs(((ca >> 16) & 255) - ((cb >> 16) & 255)),
+                            Math.Max(Math.Abs(((ca >> 8) & 255) - ((cb >> 8) & 255)),
+                                     Math.Abs((ca & 255) - (cb & 255))));
+                    if (y >= maskTop && d > tolerance) {
+                        pm[i] = unchecked((int)0xFFFF00FF);
+                        bands[Math.Min(17, y / 40)]++;
+                    } else {
+                        int grey = (int)((((cb >> 16) & 255) * 0.3 + ((cb >> 8) & 255) * 0.59 + (cb & 255) * 0.11) / 4);
+                        pm[i] = unchecked((int)0xFF000000) | (grey << 16) | (grey << 8) | grey;
+                    }
+                }
+            }
+            Marshal.Copy(pm, 0, dm.Scan0, count);
+            a.UnlockBits(da); b.UnlockBits(db); map.UnlockBits(dm);
+            map.Save(outPath, ImageFormat.Png);
+        }
+        return bands;
+    }
+}
+'@
+
+function Invoke-Arm([string]$Backend) {
+    $dir = Join-Path $Out $Backend
+    New-Item -ItemType Directory -Force -Path $dir | Out-Null
+    $log = Join-Path $dir 'client.log'
+    $grab = Join-Path $dir 'desktop-grab.png'
+    $timeline = Join-Path $dir 'world-lifecycle.checkpoints.jsonl'
+
+    $env:ACDREAM_DAT_DIR = Join-Path $env:USERPROFILE "Documents\Asheron's Call"
+    $env:ACDREAM_LIVE = '1'
+    $env:ACDREAM_TEST_HOST = '127.0.0.1'
+    $env:ACDREAM_TEST_PORT = '9000'
+    $env:ACDREAM_TEST_USER = 'testaccount'
+    $env:ACDREAM_TEST_PASS = 'testpassword'
+    $env:ACDREAM_RETAIL_UI = '1'
+    $env:ACDREAM_DEVTOOLS = '0'
+    $env:ACDREAM_UI_PROBE_DUMP = '0'
+    $env:ACDREAM_FRAME_PROF = '1'
+    # The four determinism levers, forced. Without them a cycle-1-versus-cycle-N
+    # capture measures the sun and the cloud sheet instead of the world.
+    $env:ACDREAM_MSAA_SAMPLES = '0'
+    $env:ACDREAM_DAY_GROUP = "$DayGroup"
+    $env:ACDREAM_WORLD_TIME =
+        $WorldDayFraction.ToString([System.Globalization.CultureInfo]::InvariantCulture)
+    $env:ACDREAM_SKY_PHASE_SECONDS =
+        $SkyPhaseSeconds.ToString([System.Globalization.CultureInfo]::InvariantCulture)
+    $env:ACDREAM_RENDER_BACKEND = $Backend
+    $env:ACDREAM_UI_PROBE_SCRIPT = $routePath
+    $env:ACDREAM_AUTOMATION_ARTIFACT_DIR = $dir
+
+    Write-Step "launching $Backend"
+    $proc = Start-Process -FilePath $exe -WorkingDirectory $repo `
+        -RedirectStandardOutput $log -RedirectStandardError "$log.err" -PassThru
+
+    $samples = [System.Collections.Generic.List[object]]::new()
+    $completed = $false
+    $aborted = $null
+    $deadline = (Get-Date).AddSeconds($RouteTimeoutSeconds)
+    $lastReport = Get-Date
+    while ((Get-Date) -lt $deadline) {
+        if (Select-String -Path $log -SimpleMatch '[UI-PROBE] UI probe script complete' `
+                -ErrorAction SilentlyContinue) { $completed = $true; break }
+        if ($proc.HasExited) { break }
+        try {
+            $proc.Refresh()
+            $samples.Add([pscustomobject][ordered]@{
+                UtcTicks = [DateTime]::UtcNow.Ticks
+                WorkingSetBytes = $proc.WorkingSet64
+                PrivateBytes = $proc.PrivateMemorySize64
+                HandleCount = $proc.HandleCount
+                ThreadCount = $proc.Threads.Count
+            })
+            if ($proc.WorkingSet64 / 1MB -gt $AbortWorkingSetMiB) {
+                $aborted = "working set crossed $AbortWorkingSetMiB MiB at sample $($samples.Count)"
+                Write-Step "$Backend : ABORTING -- $aborted"
+                break
+            }
+        }
+        catch { }
+        if (((Get-Date) - $lastReport).TotalSeconds -ge 60) {
+            $lastReport = Get-Date
+            $done = 0
+            if (Test-Path -LiteralPath $timeline) {
+                $done = @(Get-Content -LiteralPath $timeline -ErrorAction SilentlyContinue).Count
+            }
+            $ws = if ($samples.Count -gt 0) { [Math]::Round($samples[$samples.Count - 1].WorkingSetBytes / 1MB, 0) } else { 0 }
+            Write-Step "$Backend : $done checkpoints, working set ${ws} MiB"
+        }
+        Start-Sleep -Seconds $SampleSeconds
+    }
+
+    $grabBytes = 0
+    if (-not $proc.HasExited) {
+        try {
+            $proc.Refresh()
+            $h = $proc.MainWindowHandle
+            if ($h -ne [IntPtr]::Zero) {
+                [ChurnSoakSurface]::ShowWindow($h, 9) | Out-Null
+                [ChurnSoakSurface]::SetForegroundWindow($h) | Out-Null
+                Start-Sleep -Milliseconds 1200
+                $r = New-Object ChurnSoakSurface+RECT
+                [ChurnSoakSurface]::GetClientRect($h, [ref]$r) | Out-Null
+                $p = New-Object ChurnSoakSurface+POINT
+                [ChurnSoakSurface]::ClientToScreen($h, [ref]$p) | Out-Null
+                $w = $r.R - $r.L; $ht = $r.B - $r.T
+                if ($w -gt 0 -and $ht -gt 0) {
+                    $bmp = New-Object System.Drawing.Bitmap $w, $ht
+                    $g = [System.Drawing.Graphics]::FromImage($bmp)
+                    $g.CopyFromScreen($p.X, $p.Y, 0, 0, (New-Object System.Drawing.Size $w, $ht))
+                    $bmp.Save($grab, [System.Drawing.Imaging.ImageFormat]::Png)
+                    $g.Dispose(); $bmp.Dispose()
+                    $grabBytes = (Get-Item $grab).Length
+                }
+            }
+        }
+        catch { Write-Step "desktop grab failed on ${Backend}: $_" }
+    }
+
+    # The peak matters as much as the end value: #257 reported a number reached,
+    # not a number held. Take a final sample before the graceful close.
+    try {
+        $proc.Refresh()
+        $samples.Add([pscustomobject][ordered]@{
+            UtcTicks = [DateTime]::UtcNow.Ticks
+            WorkingSetBytes = $proc.WorkingSet64
+            PrivateBytes = $proc.PrivateMemorySize64
+            HandleCount = $proc.HandleCount
+            ThreadCount = $proc.Threads.Count
+        })
+    }
+    catch { }
+
+    $graceful = $false
+    $exitCode = $null
+    $app = Get-Process -Name AcDream.App -ErrorAction SilentlyContinue
+    if ($app) {
+        $app.CloseMainWindow() | Out-Null
+        if ($app.WaitForExit(45000)) { $graceful = $true; $exitCode = $app.ExitCode }
+        else {
+            Write-Step "WM_CLOSE timed out on $Backend; forcing"
+            $app | Stop-Process -Force
+        }
+    }
+    elseif ($proc.HasExited) { $exitCode = $proc.ExitCode }
+
+    foreach ($name in @('ACDREAM_RENDER_BACKEND', 'ACDREAM_MSAA_SAMPLES',
+                        'ACDREAM_SKY_PHASE_SECONDS', 'ACDREAM_WORLD_TIME',
+                        'ACDREAM_DAY_GROUP')) {
+        Remove-Item "Env:\$name" -ErrorAction SilentlyContinue
+    }
+
+    $samples | Export-Csv -NoTypeInformation -Encoding utf8 -LiteralPath (Join-Path $dir 'memory-samples.csv')
+
+    $checkpoints = @()
+    if (Test-Path -LiteralPath $timeline) {
+        $checkpoints = @(Get-Content -LiteralPath $timeline |
+            Where-Object { $_.Trim().Length -gt 0 } |
+            ForEach-Object { $_ | ConvertFrom-Json })
+    }
+
+    $rows = [System.Collections.Generic.List[object]]::new()
+    foreach ($cp in $checkpoints) {
+        $ticks = ([DateTime]::Parse(
+            $cp.timestampUtc,
+            [System.Globalization.CultureInfo]::InvariantCulture,
+            [System.Globalization.DateTimeStyles]::AdjustToUniversal -bor
+            [System.Globalization.DateTimeStyles]::AssumeUniversal)).Ticks
+        $nearest = $null
+        $bestDelta = [long]::MaxValue
+        foreach ($s in $samples) {
+            $delta = [Math]::Abs($s.UtcTicks - $ticks)
+            if ($delta -lt $bestDelta) { $bestDelta = $delta; $nearest = $s }
+        }
+        $r = $cp.resources
+        $rows.Add([pscustomobject][ordered]@{
+            Sequence = $cp.sequence
+            Name = $cp.name
+            Cycle = if ($cp.name -match '^c(\d+)_') { [int]$Matches[1] } else { -1 }
+            Stop = if ($cp.name -match '^c\d+_(.+)$') { $Matches[1] } else { $cp.name }
+            WorkingSetMiB = if ($nearest) { [Math]::Round($nearest.WorkingSetBytes / 1MB, 1) } else { $null }
+            PrivateMiB = if ($nearest) { [Math]::Round($nearest.PrivateBytes / 1MB, 1) } else { $null }
+            Handles = if ($nearest) { $nearest.HandleCount } else { $null }
+            SampleSkewMs = if ($nearest) { [Math]::Round($bestDelta / 10000.0, 0) } else { $null }
+            LiveEntities = $r.liveEntities
+            Materialized = $r.materializedLiveEntities
+            WorldEntities = $r.worldEntities
+            LoadedLandblocks = $r.loadedLandblocks
+            VisibleLandblocks = $r.visibleLandblocks
+            MeshRenderData = $r.meshRenderData
+            MeshMiB = [Math]::Round($r.meshEstimatedBytes / 1MB, 1)
+            GpuMiB = [Math]::Round($r.trackedGpuBytes / 1MB, 1)
+            ResidencyGpuMiB = [Math]::Round($r.residencyGpuBytes / 1MB, 1)
+            GpuMinusResidencyMiB = [Math]::Round($r.gpuTrackerMinusResidencyBytes / 1MB, 1)
+            GpuBuffers = $r.trackedGpuBuffers
+            GpuTextures = $r.trackedGpuTextures
+            CompositeTextures = $r.ownedCompositeTextures
+            CompositeOwners = $r.compositeTextureOwners
+            ParticleTextures = $r.activeParticleTextures
+            ManagedMiB = [Math]::Round($r.managedBytes / 1MB, 1)
+            CommittedMiB = [Math]::Round($r.managedCommittedBytes / 1MB, 1)
+            LohMiB = [Math]::Round($r.lohSizeBytes / 1MB, 1)
+            PendingTeardowns = $r.pendingLiveTeardowns
+            PendingRetirements = $r.pendingLandblockRetirements
+            StagedMeshUploads = $r.stagedMeshUploads
+            Fps = [Math]::Round($r.fps, 1)
+        })
+    }
+    $rows | Export-Csv -NoTypeInformation -Encoding utf8 -LiteralPath (Join-Path $dir 'per-checkpoint.csv')
+
+    $witness = if ($grabBytes -ge $MinRenderedBytes) { 'RENDERED' }
+               elseif ($grabBytes -gt 0) { 'BLANK' }
+               else { 'NO-CAPTURE' }
+
+    $errors = @(Select-String -Path $log -Pattern 'Unhandled exception|AccessViolation|OutOfMemoryException|event=invariant-failure|device removed|screenshot-failed' `
+        -ErrorAction SilentlyContinue | Select-Object -First 10 | ForEach-Object { $_.Line })
+
+    return [pscustomobject][ordered]@{
+        Backend = $Backend
+        RouteCompleted = $completed
+        Aborted = $aborted
+        Graceful = $graceful
+        ExitCode = $exitCode
+        Witness = $witness
+        GrabBytes = $grabBytes
+        Checkpoints = $rows.Count
+        Rows = $rows
+        Samples = $samples.Count
+        PeakWorkingSetMiB = if ($samples.Count -gt 0) { [Math]::Round((($samples | Measure-Object WorkingSetBytes -Maximum).Maximum) / 1MB, 1) } else { $null }
+        PeakPrivateMiB = if ($samples.Count -gt 0) { [Math]::Round((($samples | Measure-Object PrivateBytes -Maximum).Maximum) / 1MB, 1) } else { $null }
+        FinalWorkingSetMiB = if ($samples.Count -gt 0) { [Math]::Round($samples[$samples.Count - 1].WorkingSetBytes / 1MB, 1) } else { $null }
+        ErrorLines = $errors
+        Dir = $dir
+        ScreenshotDir = Join-Path $dir 'screenshots'
+        Log = $log
+    }
+}
+
+$arms = @()
+foreach ($backend in $Backends) {
+    if ($arms.Count -gt 0) {
+        Write-Step "cooldown ${CooldownSeconds}s so ACE clears the graceful logout"
+        Start-Sleep -Seconds $CooldownSeconds
+    }
+    $arms += Invoke-Arm $backend
+}
+
+# --- Within-arm capture comparison -------------------------------------------
+# The #256 half. First Holtburg capture against the last, inside one arm.
+$maskPath = $null
+$comparisons = @()
+foreach ($arm in $arms) {
+    $shots = @(Get-ChildItem $arm.ScreenshotDir -Filter 'holtburg_c*.png' -ErrorAction SilentlyContinue |
+        Sort-Object Name)
+    if ($shots.Count -lt 2) {
+        $comparisons += [pscustomobject][ordered]@{
+            Backend = $arm.Backend; Pair = 'n/a'; Verdict = 'UNPAIRED'
+            DifferentPixels = $null; Fraction = $null; MaxChannelDelta = $null
+        }
+        continue
+    }
+    if ($MaskTopPixels -gt 0 -and -not $maskPath) {
+        $probe = [System.Drawing.Bitmap]::FromFile($shots[0].FullName)
+        $mw = $probe.Width; $mh = $probe.Height
+        $probe.Dispose()
+        $mask = New-Object System.Drawing.Bitmap($mw, $mh, [System.Drawing.Imaging.PixelFormat]::Format32bppArgb)
+        $graphics = [System.Drawing.Graphics]::FromImage($mask)
+        $graphics.Clear([System.Drawing.Color]::FromArgb(0, 0, 0, 0))
+        $opaque = New-Object System.Drawing.SolidBrush ([System.Drawing.Color]::FromArgb(255, 255, 0, 255))
+        $graphics.FillRectangle($opaque, 0, 0, $mw, [Math]::Min($MaskTopPixels, $mh))
+        $graphics.Dispose(); $opaque.Dispose()
+        $maskPath = Join-Path $Out 'mask.png'
+        $mask.Save($maskPath, [System.Drawing.Imaging.ImageFormat]::Png)
+        $mask.Dispose()
+    }
+    $first = $shots[0]
+    foreach ($later in $shots[1..($shots.Count - 1)]) {
+        $report = Join-Path $Out "compare-$($arm.Backend)-$($first.BaseName)-vs-$($later.BaseName).json"
+        if ($maskPath) {
+            & dotnet $cli compare-screenshots $first.FullName $later.FullName $report $Tolerance $MaxDifferentFraction $maskPath | Out-Null
+        }
+        else {
+            & dotnet $cli compare-screenshots $first.FullName $later.FullName $report $Tolerance $MaxDifferentFraction | Out-Null
+        }
+        $verdict = Get-Content $report -Raw | ConvertFrom-Json
+        # A number cannot tell an absent object from a walking NPC. The map and
+        # the row histogram can: a vanished sign is a contiguous blob in one
+        # band, a creature is a thin moving silhouette, and phase noise is
+        # scattered. Both are written beside the report.
+        $mapPath = Join-Path $Out "diff-$($arm.Backend)-$($first.BaseName)-vs-$($later.BaseName).png"
+        $bands = New-Object 'int[]' 18
+        try { $bands = [ChurnDiffMap]::Write($first.FullName, $later.FullName, $mapPath, $Tolerance, $MaskTopPixels) }
+        catch { Write-Step "diff map failed for $($later.BaseName): $_" }
+        $comparisons += [pscustomobject][ordered]@{
+            Backend = $arm.Backend
+            Pair = "$($first.BaseName) vs $($later.BaseName)"
+            Verdict = if ($verdict.passed) { 'MATCH' } else { 'DIVERGED' }
+            DifferentPixels = $verdict.differentPixels
+            Fraction = $verdict.differentPixelFraction
+            MaxChannelDelta = $verdict.maximumChannelDelta
+            RowBands40px = ($bands -join ',')
+            DiffMap = $mapPath
+        }
+    }
+}
+
+# --- Verdict ------------------------------------------------------------------
+function Get-StopTrend($rows, [string]$Stop, [string]$Column) {
+    $series = @($rows | Where-Object { $_.Stop -eq $Stop -and $_.Cycle -ge 1 } | Sort-Object Cycle)
+    if ($series.Count -lt 2) { return $null }
+    $warm = if ($series.Count -ge 6) { $series[2..($series.Count - 1)] } else { $series }
+    $firstValue = [double]$warm[0].$Column
+    $lastValue = [double]$warm[-1].$Column
+    $spanCycles = [double]($warm[-1].Cycle - $warm[0].Cycle)
+    return [pscustomobject][ordered]@{
+        Stop = $Stop
+        Column = $Column
+        FirstCycle = $warm[0].Cycle
+        LastCycle = $warm[-1].Cycle
+        First = $firstValue
+        Last = $lastValue
+        Delta = [Math]::Round($lastValue - $firstValue, 1)
+        PerCycle = if ($spanCycles -gt 0) { [Math]::Round(($lastValue - $firstValue) / $spanCycles, 2) } else { $null }
+    }
+}
+
+$trends = @()
+foreach ($arm in $arms) {
+    foreach ($stop in @('holtburg', 'hub', 'aerlinthe')) {
+        foreach ($column in @('WorkingSetMiB', 'PrivateMiB', 'GpuMiB', 'ManagedMiB',
+                              'Materialized', 'WorldEntities', 'MeshRenderData',
+                              'CompositeTextures', 'GpuTextures', 'Handles')) {
+            $t = Get-StopTrend $arm.Rows $stop $column
+            if ($t) {
+                $trends += [pscustomobject][ordered]@{
+                    Backend = $arm.Backend; Stop = $t.Stop; Column = $t.Column
+                    FirstCycle = $t.FirstCycle; LastCycle = $t.LastCycle
+                    First = $t.First; Last = $t.Last; Delta = $t.Delta; PerCycle = $t.PerCycle
+                }
+            }
+        }
+    }
+}
+
+Write-Host ''
+foreach ($arm in $arms) {
+    if ($arm.Aborted) { Write-Host "!!! $($arm.Backend) aborted: $($arm.Aborted)" -ForegroundColor Yellow }
+    Write-Host "=== $($arm.Backend) : completed=$($arm.RouteCompleted) graceful=$($arm.Graceful) exit=$($arm.ExitCode) witness=$($arm.Witness) checkpoints=$($arm.Checkpoints) peakWS=$($arm.PeakWorkingSetMiB) MiB finalWS=$($arm.FinalWorkingSetMiB) MiB"
+    $arm.Rows | Where-Object { $_.Stop -eq 'holtburg' } |
+        Select-Object Cycle, WorkingSetMiB, PrivateMiB, GpuMiB, ManagedMiB, LiveEntities, Materialized, WorldEntities, MeshRenderData, CompositeTextures, GpuTextures, Handles |
+        Format-Table -AutoSize | Out-String | Write-Host
+}
+Write-Host '=== within-arm capture comparison (the #256 half) ==='
+$comparisons | Format-Table -AutoSize | Out-String | Write-Host
+Write-Host '=== warm trends (cycle 3 -> last) ==='
+$trends | Where-Object { $_.Stop -eq 'holtburg' } | Format-Table -AutoSize | Out-String | Write-Host
+
+$report = [pscustomobject][ordered]@{
+    Commit = (& git -C $repo rev-parse HEAD).Trim()
+    GeneratedUtc = [DateTime]::UtcNow.ToString('o')
+    Cycles = $Cycles
+    Transits = $transit
+    Stops = @($stops | ForEach-Object { $_.Key })
+    ShotCycles = @($ShotCycles)
+    Route = $routePath
+    DayGroup = $DayGroup
+    WorldDayFraction = $WorldDayFraction
+    SkyPhaseSeconds = $SkyPhaseSeconds
+    MsaaSamples = 0
+    MaskTopPixels = $MaskTopPixels
+    Arms = @($arms | ForEach-Object {
+        [pscustomobject][ordered]@{
+            Backend = $_.Backend; RouteCompleted = $_.RouteCompleted; Aborted = $_.Aborted
+            Graceful = $_.Graceful
+            ExitCode = $_.ExitCode; Witness = $_.Witness; GrabBytes = $_.GrabBytes
+            Checkpoints = $_.Checkpoints; Samples = $_.Samples
+            PeakWorkingSetMiB = $_.PeakWorkingSetMiB; PeakPrivateMiB = $_.PeakPrivateMiB
+            FinalWorkingSetMiB = $_.FinalWorkingSetMiB; ErrorLines = $_.ErrorLines
+            Rows = $_.Rows
+        }
+    })
+    Comparisons = @($comparisons)
+    Trends = @($trends)
+}
+$reportPath = Join-Path $Out 'churn-soak.json'
+$report | ConvertTo-Json -Depth 8 | Set-Content -LiteralPath $reportPath -Encoding utf8
+Write-Step "report: $reportPath"