diff --git a/deploy/Install-NodePilot.ps1 b/deploy/Install-NodePilot.ps1
index f7be3f4..062881f 100644
--- a/deploy/Install-NodePilot.ps1
+++ b/deploy/Install-NodePilot.ps1
@@ -1202,6 +1202,35 @@ Assert-SafeInstallRoot -Path $InstallPath
 if (Test-Path $InstallPath) {
     # Empty install path but do NOT touch DataPath.
     Get-ChildItem $InstallPath -Force -ErrorAction SilentlyContinue | Remove-Item -Recurse -Force
+
+    # The GUI setup keeps its uninstaller in this directory, so emptying it invalidates whatever
+    # Add/Remove Programs entry pointed at that uninstaller. Both the setup and this script are
+    # documented ways to install the same product and an operator may well mix them - and an entry
+    # whose uninstaller no longer exists is one Windows can neither run nor clear, so it sits there
+    # until somebody edits the registry.
+    #
+    # Sparing the uninstaller instead is not an option: Assert-NodePilotExtractedFiles a few steps
+    # below requires this directory to hold exactly the signed artifact and nothing else, which is
+    # what stops a binary being swapped before the service executes it.
+    #
+    # Deliberately narrow - an entry is removed only when its uninstaller lived in the directory
+    # just emptied AND is really gone. One that still works belongs to somebody else.
+    $deadEntryPrefix = $InstallPath.TrimEnd('\') + '\'
+    foreach ($uninstallRoot in @(
+            'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall',
+            'HKLM:\SOFTWARE\WOW6432Node\Microsoft\Windows\CurrentVersion\Uninstall')) {
+        foreach ($entry in @(Get-ChildItem -LiteralPath $uninstallRoot -ErrorAction SilentlyContinue)) {
+            $uninstallString = [string]$entry.GetValue('UninstallString')
+            if ([string]::IsNullOrWhiteSpace($uninstallString)) { continue }
+            # Strip the quoting an uninstaller path normally carries, plus any trailing switches.
+            $uninstallTarget = ($uninstallString -replace '^\s*"([^"]+)".*$', '$1').Trim()
+            if (-not $uninstallTarget.StartsWith($deadEntryPrefix, [StringComparison]::OrdinalIgnoreCase)) { continue }
+            if (Test-Path -LiteralPath $uninstallTarget) { continue }
+            $deadEntryName = [string]$entry.GetValue('DisplayName')
+            Remove-Item -LiteralPath $entry.PSPath -Recurse -Force -ErrorAction SilentlyContinue
+            Write-Info "  Removed the stale uninstall entry '$deadEntryName' - its uninstaller was in $InstallPath."
+        }
+    }
 } else {
     New-Item -ItemType Directory -Path $InstallPath -Force | Out-Null
 }
diff --git a/deploy/Test-DeploymentTemplates.ps1 b/deploy/Test-DeploymentTemplates.ps1
index bb12097..55fdc9c 100644
--- a/deploy/Test-DeploymentTemplates.ps1
+++ b/deploy/Test-DeploymentTemplates.ps1
@@ -307,6 +307,20 @@ Assert-TextMatches -Name 'installer renders the trusted-proxy placeholder' `
     -Text $installer -Pattern "Replace\('\{\{KNOWN_PROXIES_JSON\}\}'"
 Assert-TextMatches -Name 'installer validates trusted proxy addresses' `
     -Text $installer -Pattern 'IPAddress\]::TryParse\(\$proxyIp'
+# Emptying the install directory kills the GUI setup's uninstaller, which lives in it. Sparing that
+# file is not an option - Assert-NodePilotExtractedFiles requires the directory to hold exactly the
+# signed artifact - so the Add/Remove Programs entry it leaves behind is removed instead, or Windows
+# keeps an entry it can neither run nor clear.
+Assert-TextMatches -Name 'a ZIP install clears the uninstall entry it just invalidated' `
+    -Text $installer `
+    -Pattern '(?s)CurrentVersion\\Uninstall[\s\S]{0,1400}Remove-Item -LiteralPath \$entry\.PSPath'
+# Both halves matter: an entry pointing somewhere else, or one whose uninstaller still exists, is
+# somebody else's. Without either test this silently becomes "delete every uninstall entry".
+Assert-TextMatches -Name 'and only one whose uninstaller lived in the emptied directory' `
+    -Text $installer -Pattern '\$uninstallTarget\.StartsWith\(\$deadEntryPrefix'
+Assert-TextMatches -Name 'and only one whose uninstaller is really gone' `
+    -Text $installer -Pattern '(?s)if \(Test-Path -LiteralPath \$uninstallTarget\) \{ continue \}'
+
 Assert-TextMatches -Name 'installer keeps the Postgres secret in the service-scoped environment' `
     -Text $installer -Pattern 'ConnectionStrings__Postgres=\$postgresServiceConnStr'
 Assert-TextMatches -Name 'installer protects the service registry key before writing the Postgres secret' `
@@ -506,6 +520,17 @@ $successCode = ($successPath -split "`n" | Where-Object { $_.TrimStart() -notmat
 Assert-TextDoesNotMatch -Name 'a successful update must not stop the service again' `
     -Text $successCode -Pattern 'Stop-ServiceAndVerify'
 
+# Only the installer used to write the marker, so its Version kept naming the last INSTALL and a
+# script-driven update was invisible in it - including on the setup wizard's own mode page, which
+# reads exactly this value to tell the operator what is already installed.
+Assert-TextMatches -Name 'a successful update refreshes the installation marker' `
+    -Text $successCode `
+    -Pattern "(?s)SOFTWARE\\NodePilot\\Server[\s\S]{0,700}New-ItemProperty[^\r\n]*-Name 'Version'"
+# The marker is one machine-wide key, so on a host with a second instance it may well describe a
+# different installation. Stamping this update's version onto that one is worse than leaving it stale.
+Assert-TextMatches -Name 'and only when the marker describes this installation' `
+    -Text $successCode -Pattern '\$markerInstallPath\.TrimEnd\([^)]*\) -eq \$InstallPath\.TrimEnd\('
+
 # The rollback path is the one place the prior state still governs.
 $rollbackPath = $updateScript.Substring($catchStart)
 Assert-TextMatches -Name 'a failed update still restores the pre-update state' `
@@ -1072,6 +1097,16 @@ Assert-TextDoesNotMatch -Name 'the uninstall must not pass the wizard default as
 Assert-TextDoesNotMatch -Name 'the uninstall must not pass {app} as the install path' `
     -Text $serverIssCode -Pattern '-InstallPath[\s\S]{0,24}ExpandConstant'
 
+# Apps & Features must name the directory NodePilot is in, not the one the uninstaller landed in.
+# With /ANSWERFILE the directory page never runs, so {app} keeps DefaultDirName while the adapter
+# installs to the answer file's installPath - and Inno fills InstallLocation with {app}.
+Assert-TextMatches -Name 'the ARP entry is corrected to the real install path' `
+    -Text $serverIssCode `
+    -Pattern '(?s)ssPostInstall[\s\S]{0,900}RegWriteStringValue\(HKLM64,[\s\S]{0,200}InstallLocation'
+Assert-TextMatches -Name 'and it takes that path from the installer marker' `
+    -Text $serverIssCode `
+    -Pattern '(?s)ssPostInstall[\s\S]{0,600}RegQueryStringValue\(HKLM64,[^)]*InstallPath'
+
 # /ANSWERFILE skips the mode page, so IsUpdateSelected() reads ModePage's hard default of 0
 # ('update') and AnswerMode contradicts a file that says "mode": "install". Gating the silent
 # provisioning run on AnswerMode alone therefore dropped every provisioning key - database, login,
diff --git a/deploy/Update-NodePilot.ps1 b/deploy/Update-NodePilot.ps1
index 9855dfe..8774f61 100644
--- a/deploy/Update-NodePilot.ps1
+++ b/deploy/Update-NodePilot.ps1
@@ -328,6 +328,35 @@ public class TrustAllCertsUpdate : ICertificatePolicy {
         catch {
             Write-Host "[update] Update succeeded, but old backup pruning failed: $($_.Exception.Message)" -ForegroundColor Yellow
         }
+
+        # Only Install-NodePilot.ps1 used to write this, so the marker kept the version of the last
+        # INSTALL and every script-driven update was invisible in it. That value is what the setup
+        # wizard puts on its mode page ("NodePilot <version> is already installed in <path>") and
+        # the obvious thing for an inventory to read - measured in the lab: binaries updated from
+        # 1.2.6-rc1 to the 1.2.5 artifact, marker still claiming 1.2.6-rc1.
+        #
+        # Version only: path, service name, provider and port are not changed by an update and are
+        # already correct. Guarded on InstallPath because the marker is a single machine-wide key -
+        # on a host running more than one instance it describes whichever was installed last, and
+        # stamping this update's version onto another instance's marker is worse than leaving it
+        # stale. A failure here is a warning: it costs discoverability, not a working installation.
+        try {
+            $markerPath = 'HKLM:\SOFTWARE\NodePilot\Server'
+            $marker = Get-ItemProperty -LiteralPath $markerPath -ErrorAction Stop
+            $markerInstallPath = [string]$marker.InstallPath
+            if ($markerInstallPath -and
+                $markerInstallPath.TrimEnd('\') -eq $InstallPath.TrimEnd('\')) {
+                New-ItemProperty -LiteralPath $markerPath -Name 'Version' `
+                    -Value ([string]$verifiedArtifact.Version) -PropertyType String -Force | Out-Null
+                Write-Info "Installation marker updated to version $($verifiedArtifact.Version)."
+            }
+            else {
+                Write-Info 'Installation marker describes another installation; left untouched.'
+            }
+        } catch {
+            Write-Warn "Could not update the installation marker: $($_.Exception.Message)"
+        }
+
         Write-Ok 'Update complete.'
     }
     catch {
diff --git a/deploy/server/NodePilotServer.iss b/deploy/server/NodePilotServer.iss
index 222f895..cb8be1e 100644
--- a/deploy/server/NodePilotServer.iss
+++ b/deploy/server/NodePilotServer.iss
@@ -1833,6 +1833,30 @@ begin
   UninstallPurgeData := Response = IDNO;
 end;
 
+procedure CurStepChanged(CurStep: TSetupStep);
+var
+  InstalledInstallPath: String;
+begin
+  if CurStep = ssPostInstall then
+  begin
+    // Apps & Features shows InstallLocation, and Inno fills it with {app} - which is where the
+    // uninstaller ended up, not where NodePilot was installed. /ANSWERFILE skips the directory
+    // page, so {app} keeps DefaultDirName while the adapter installs to the answer file's
+    // installPath; the entry then points an operator at a directory holding the uninstaller and
+    // nothing else. Corrected from the marker the installer has just written, which is the same
+    // source the uninstaller reads.
+    //
+    // Best-effort on purpose. An exception in ssPostInstall does NOT change the exit code (see the
+    // note in [Files]), so nothing load-bearing may live here - a failed write leaves Inno's own
+    // value in place, which is exactly today's behaviour.
+    if RegQueryStringValue(HKLM64, 'SOFTWARE\NodePilot\Server', 'InstallPath', InstalledInstallPath) and
+       (InstalledInstallPath <> '') then
+      RegWriteStringValue(HKLM64,
+        'SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{03EAD540-1472-4A1B-9F06-9CB3D358E202}_is1',
+        'InstallLocation', AddBackslash(InstalledInstallPath));
+  end;
+end;
+
 procedure CurUninstallStepChanged(CurUninstallStep: TUninstallStep);
 var
   ResultCode: Integer;