diff --git a/.github/workflows/windows-msi-gui-test.yml b/.github/workflows/windows-msi-gui-test.yml
new file mode 100644
index 0000000000..5ca5328c1a
--- /dev/null
+++ b/.github/workflows/windows-msi-gui-test.yml
@@ -0,0 +1,93 @@
+name: windows-msi-gui-test
+run-name: "Windows GUI: ${{ inputs.scenario }} ${{ inputs.label }}"
+
+on:
+  workflow_dispatch:
+    inputs:
+      scenario:
+        description: "Scenario to run (all: every scenario except the known issue update-desktop; everything: all of them)"
+        required: true
+        default: all
+        type: choice
+        options: [all, everything, uninstall-desktop, update-desktop, update-same-build, default-folder, profile-folder, appdata-folder]
+      label:
+        description: "Free text shown in the run name"
+        required: false
+        default: ""
+        type: string
+      new_msi_run_id:
+        description: "Id of a workflow run that uploaded the MSI under test as an artifact (empty: use new_msi_url)"
+        required: false
+        default: ""
+        type: string
+      new_msi_artifact:
+        description: "Name of the MSI artifact in that run"
+        required: false
+        default: "simplex-desktop-windows-x86_64-msi"
+        type: string
+      new_msi_url:
+        description: "URL of the new MSI when new_msi_run_id is empty"
+        required: false
+        default: "https://github.com/simplex-chat/simplex-chat/releases/download/v7.0.3/simplex-desktop-windows-x86_64.msi"
+        type: string
+      old_msi_url:
+        description: "URL of the old MSI (installed before updating)"
+        required: false
+        default: "https://github.com/simplex-chat/simplex-chat/releases/download/v7.0.2/simplex-desktop-windows-x86_64.msi"
+        type: string
+      patch_with_ref:
+        description: "Branch whose scripts/desktop/disable-msi-install-dir-wipe-windows.ps1 is applied to the new MSI (empty: no patch)"
+        required: false
+        default: ""
+        type: string
+
+permissions:
+  contents: read
+  actions: read
+
+jobs:
+  windows-msi-gui-test:
+    runs-on: windows-latest
+    timeout-minutes: 60
+    steps:
+      - name: Checkout test scripts
+        uses: actions/checkout@v4
+        with:
+          sparse-checkout: apps/multiplatform/scripts/windows-msi
+
+      - name: Checkout MSI patch script
+        if: inputs.patch_with_ref != ''
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ inputs.patch_with_ref }}
+          path: patchsrc
+          sparse-checkout: scripts/desktop
+
+      - name: Download new MSI from build run
+        if: inputs.new_msi_run_id != ''
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.new_msi_artifact }}
+          run-id: ${{ inputs.new_msi_run_id }}
+          github-token: ${{ github.token }}
+          path: C:\msitest\artifact
+
+      - name: Run scenarios
+        shell: pwsh
+        env:
+          SCENARIO: ${{ inputs.scenario }}
+          NEW_MSI_URL: ${{ inputs.new_msi_url }}
+          NEW_MSI_DIR: ${{ inputs.new_msi_run_id != '' && 'C:\msitest\artifact' || '' }}
+          OLD_MSI_URL: ${{ inputs.old_msi_url }}
+          PATCH_SCRIPT: ${{ inputs.patch_with_ref != '' && 'patchsrc\scripts\desktop\disable-msi-install-dir-wipe-windows.ps1' || '' }}
+        run: |
+          New-Item -ItemType Directory -Force C:\msitest | Out-Null
+          & apps/multiplatform/scripts/windows-msi/msi-scenarios.ps1 -Scenario $env:SCENARIO -NewMsiUrl $env:NEW_MSI_URL -NewMsiDir $env:NEW_MSI_DIR -OldMsiUrl $env:OLD_MSI_URL -PatchScript $env:PATCH_SCRIPT
+
+      - name: Upload evidence
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: windows-gui-evidence
+          path: C:\msitest\evidence
+          retention-days: 30
diff --git a/apps/multiplatform/scripts/windows-msi/README.md b/apps/multiplatform/scripts/windows-msi/README.md
new file mode 100644
index 0000000000..1373f3a312
--- /dev/null
+++ b/apps/multiplatform/scripts/windows-msi/README.md
@@ -0,0 +1,62 @@
+# Windows installer GUI tests
+
+These tests install, update, start and uninstall the desktop app through the real MSI installer
+UI on a GitHub-hosted Windows runner. `msi-scenarios.ps1` drives the installer dialogs and
+Explorer through UI Automation (`wingui.psm1`), takes screenshots, keeps the installer logs, and
+asserts what is on disk after each step. There is no local Windows harness: the tests run only
+in the `windows-msi-gui-test` workflow, which is started manually.
+
+## Running
+
+Start the workflow from the Actions tab or with `gh`:
+
+```sh
+gh workflow run windows-msi-gui-test.yml -R <owner>/simplex-chat --ref <branch with the workflow> \
+  -f scenario=all -f label="what this run checks" \
+  -f new_msi_run_id=<run id of a workflow that uploaded the MSI as an artifact>
+```
+
+| Input | Meaning |
+|---|---|
+| `scenario` | One scenario, `all` (every scenario except known issues) or `everything`. |
+| `label` | Free text shown in the run name. |
+| `new_msi_run_id`, `new_msi_artifact` | Run id and artifact name of the MSI under test. |
+| `new_msi_url` | URL of the MSI under test, used when `new_msi_run_id` is empty (default: the v7.0.3 release). |
+| `old_msi_url` | MSI installed before the update in `update-desktop` (default: the v7.0.2 release). |
+| `patch_with_ref` | Branch whose `scripts/desktop/disable-msi-install-dir-wipe-windows.ps1` is applied to the MSI under test before the scenarios. Checks an MSI change in about 10 minutes without a Windows build. |
+
+The run uploads the artifact `windows-gui-evidence`:
+
+- `checks.txt`: one line per check, `name = actual (expected X) PASS|FAIL`, plus informational lines;
+- `captions.tsv` and numbered PNG screenshots (1024x768);
+- `logs/`: verbose `msiexec` logs (UTF-16) for every install and uninstall.
+
+The job fails if any check fails or a dialog does not appear in time. A missing dialog is
+recorded as an `Unexpected state` screenshot.
+
+`gh run view --log` can return an empty log; read it with
+`gh api repos/<owner>/simplex-chat/actions/jobs/<job id>/logs`.
+
+## Scenarios
+
+| Scenario | Steps | Expected |
+|---|---|---|
+| `uninstall-desktop` | Put user files on the Desktop, install into `Desktop\` (the installer warns that the folder exists), uninstall | User files and Desktop remain; `SimpleX.exe`, `app`, `runtime` are removed |
+| `update-same-build` | Install into `Desktop\`, update through the installer UI to a copy of the same MSI with a higher version | User files remain; old files removed; the updated app starts |
+| `default-folder` | Install into `C:\Program Files\SimpleX\`, start the app, uninstall | The app starts; the folder is removed |
+| `profile-folder` | Install into the user profile folder, start the app, add user files there, uninstall | User files and every file in `%AppData%\SimpleX` remain |
+| `appdata-folder` | The same with `%AppData%\` as the install folder | As above |
+| `update-desktop` (known issue) | Install the old MSI into `Desktop\`, update to the MSI under test | User files remain. Fails while the old MSI deletes its install folder on removal |
+
+The update scenarios update the way the in-app updater does: `msiexec /i` with the full UI and
+the default folder. The higher-version copy for `update-same-build` is made by the script: it
+changes the product version, product code, package code, `Upgrade` rows and the versioned
+registry key of the MSI under test.
+
+## Notes
+
+- Before a fix, `profile-folder` and `appdata-folder` delete files of the runner's user profile;
+  they run last.
+- The runner user is an administrator, so the installer does not show a UAC prompt.
+- Windows Installer keeps the MSI open after a COM call until the COM objects are released;
+  `Close-MsiHandles` forces that before the file is opened again.
diff --git a/apps/multiplatform/scripts/windows-msi/msi-scenarios.ps1 b/apps/multiplatform/scripts/windows-msi/msi-scenarios.ps1
new file mode 100644
index 0000000000..4930533770
--- /dev/null
+++ b/apps/multiplatform/scripts/windows-msi/msi-scenarios.ps1
@@ -0,0 +1,347 @@
+param(
+  [string]$Scenario = 'all',
+  [string]$NewMsiUrl = '',
+  [string]$NewMsiDir = '',
+  [string]$OldMsiUrl = '',
+  [string]$PatchScript = '',
+  [string]$Work = 'C:\msitest'
+)
+
+$ErrorActionPreference = 'Stop'
+$ProgressPreference = 'SilentlyContinue'
+Import-Module (Join-Path $PSScriptRoot 'wingui.psm1')
+
+$Evidence = Join-Path $Work 'evidence'
+$Logs = Join-Path $Evidence 'logs'
+Initialize-Evidence $Evidence
+New-Item -ItemType Directory -Force $Logs | Out-Null
+
+$Desktop = [Environment]::GetFolderPath('Desktop')
+if (-not $Desktop -or -not $Desktop.EndsWith('\Desktop')) { throw "Unexpected Desktop path '$Desktop'" }
+$UserProfile = $env:USERPROFILE
+if (-not $UserProfile -or -not (Test-Path (Join-Path $UserProfile 'AppData\Roaming'))) { throw "Unexpected user profile '$UserProfile'" }
+$DataDir = Join-Path $env:APPDATA 'SimpleX'
+$ProgramFilesDir = Join-Path $env:ProgramFiles 'SimpleX'
+$Setup = 'SimpleX Setup'
+$UserFiles = @('My notes.txt', 'Tax return 2025.txt', 'Holiday photos\beach.txt')
+$SeededNames = @('My notes.txt', 'Tax return 2025.txt', 'Holiday photos')
+$InstalledNames = @('SimpleX.exe', 'app', 'runtime')
+$FolderUserFiles = @('My profile notes.txt', '.my-settings\settings.txt')
+$FolderUserNames = @('My profile notes.txt', '.my-settings')
+$script:Failures = @()
+
+function Write-Check([string]$Name, $Value) {
+  Write-Host "CHECK $Name = $Value"
+  Add-Content (Join-Path $Evidence 'checks.txt') "$Name = $Value"
+}
+
+function Assert-Check([string]$Name, $Actual, $Expected) {
+  $verdict = if ("$Actual" -eq "$Expected") { 'PASS' } else { 'FAIL' }
+  if ($verdict -eq 'FAIL') { $script:Failures += $Name }
+  Write-Check $Name "$Actual (expected $Expected) $verdict"
+}
+
+function Invoke-Com($Object, [string]$Method, [object[]]$Arguments) {
+  $Object.GetType().InvokeMember($Method, [Reflection.BindingFlags]::InvokeMethod, $null, $Object, $Arguments)
+}
+
+function Get-ComProperty($Object, [string]$Name, [object[]]$Arguments) {
+  $Object.GetType().InvokeMember($Name, [Reflection.BindingFlags]::GetProperty, $null, $Object, $Arguments)
+}
+
+function Open-MsiDatabase([string]$Msi, [int]$Mode) {
+  Invoke-Com (New-Object -ComObject WindowsInstaller.Installer) 'OpenDatabase' @($Msi, $Mode)
+}
+
+function Invoke-MsiSql($Database, [string]$Sql) {
+  $view = Invoke-Com $Database 'OpenView' @($Sql)
+  Invoke-Com $view 'Execute' @() | Out-Null
+  $values = @()
+  if ($Sql.StartsWith('SELECT')) {
+    while ($record = Invoke-Com $view 'Fetch' @()) {
+      $values += Get-ComProperty $record 'StringData' @(1)
+    }
+  }
+  Invoke-Com $view 'Close' @() | Out-Null
+  [System.Runtime.InteropServices.Marshal]::ReleaseComObject($view) | Out-Null
+  $values
+}
+
+function Read-MsiColumn([string]$Msi, [string]$Sql) {
+  $db = Open-MsiDatabase $Msi 0
+  $values = Invoke-MsiSql $db $Sql
+  Close-MsiHandles
+  $values
+}
+
+function Close-MsiHandles {
+  [GC]::Collect()
+  [GC]::WaitForPendingFinalizers()
+}
+
+function New-LaterVersionMsi([string]$Msi, [string]$Path) {
+  Copy-Item $Msi $Path
+  Set-ItemProperty $Path -Name IsReadOnly -Value $false
+  $db = Open-MsiDatabase $Path 1
+  $version = Invoke-MsiSql $db 'SELECT `Value` FROM `Property` WHERE `Property`=''ProductVersion'''
+  $parts = $version.Split('.')
+  $later = "$($parts[0]).$($parts[1]).$([int]$parts[2] + 1)"
+  $upgradeCode = Invoke-MsiSql $db 'SELECT `Value` FROM `Property` WHERE `Property`=''UpgradeCode'''
+  Invoke-MsiSql $db "UPDATE ``Property`` SET ``Value``='$later' WHERE ``Property``='ProductVersion'" | Out-Null
+  Invoke-MsiSql $db "UPDATE ``Property`` SET ``Value``='{$([guid]::NewGuid().ToString().ToUpper())}' WHERE ``Property``='ProductCode'" | Out-Null
+  Invoke-MsiSql $db 'DELETE FROM `Upgrade`' | Out-Null
+  Invoke-MsiSql $db "INSERT INTO ``Upgrade`` (``UpgradeCode``, ``VersionMax``, ``Attributes``, ``ActionProperty``) VALUES ('$upgradeCode', '$later', 257, 'JP_UPGRADABLE_FOUND')" | Out-Null
+  Invoke-MsiSql $db "INSERT INTO ``Upgrade`` (``UpgradeCode``, ``VersionMin``, ``Attributes``, ``ActionProperty``) VALUES ('$upgradeCode', '$later', 1, 'JP_DOWNGRADABLE_FOUND')" | Out-Null
+  foreach ($table in 'Registry', 'RegLocator') {
+    foreach ($key in @(Invoke-MsiSql $db "SELECT ``Key`` FROM ``$table``")) {
+      if ($key.EndsWith("\$version")) {
+        $laterKey = $key.Substring(0, $key.Length - $version.Length) + $later
+        Invoke-MsiSql $db "UPDATE ``$table`` SET ``Key``='$laterKey' WHERE ``Key``='$key'" | Out-Null
+      }
+    }
+  }
+  $summary = Get-ComProperty $db 'SummaryInformation' @(20)
+  $summary.GetType().InvokeMember('Property', [Reflection.BindingFlags]::SetProperty, $null, $summary, @(9, "{$([guid]::NewGuid().ToString().ToUpper())}")) | Out-Null
+  Invoke-Com $summary 'Persist' @() | Out-Null
+  Invoke-Com $db 'Commit' @() | Out-Null
+  $summary = $null
+  $db = $null
+  Close-MsiHandles
+  $Path
+}
+
+function Get-Msi([string]$Url, [string]$Dir, [string]$Name) {
+  $path = Join-Path $Work "$Name.msi"
+  if ($Dir) {
+    $file = Get-ChildItem $Dir -Recurse -Filter *.msi | Select-Object -First 1
+    if (-not $file) { throw "No .msi in $Dir" }
+    Copy-Item $file.FullName $path
+  } else {
+    Invoke-WebRequest $Url -OutFile $path
+  }
+  $path
+}
+
+function Describe-Msi([string]$Msi, [string]$Name) {
+  $version = Read-MsiColumn $Msi 'SELECT `Value` FROM `Property` WHERE `Property`=''ProductVersion'''
+  $code = Read-MsiColumn $Msi 'SELECT `Value` FROM `Property` WHERE `Property`=''ProductCode'''
+  $rows = try { @(Read-MsiColumn $Msi 'SELECT `WixRemoveFolderEx` FROM `WixRemoveFolderEx`').Count } catch { 'table absent' }
+  Write-Check "$Name MSI version" $version
+  Write-Check "$Name MSI WixRemoveFolderEx rows" $rows
+  Write-Check "$Name MSI sha256" (Get-FileHash $Msi -Algorithm SHA256).Hash
+  $code
+}
+
+function Test-UserFiles([string]$Label) {
+  foreach ($file in $UserFiles) {
+    Assert-Check "$Label - Desktop\$file exists" (Test-Path (Join-Path $Desktop $file)) $true
+  }
+}
+
+function Reset-State {
+  Get-Process -Name SimpleX -ErrorAction SilentlyContinue | Stop-Process -Force
+  foreach ($code in $script:ProductCodes) {
+    Start-Process msiexec.exe -ArgumentList @('/x', $code, '/qn') -Wait
+  }
+  $installFolders = @($Desktop, $UserProfile, $env:APPDATA)
+  $paths = @($SeededNames | ForEach-Object { Join-Path $Desktop $_ })
+  foreach ($folder in $installFolders) {
+    $paths += @($InstalledNames + $FolderUserNames | ForEach-Object { Join-Path $folder $_ })
+  }
+  foreach ($path in $paths) {
+    if (Test-Path $path) { Remove-Item -Recurse -Force $path }
+  }
+  New-Item -ItemType Directory -Force $Desktop | Out-Null
+}
+
+function Add-FolderUserFiles([string]$Folder) {
+  Set-Content (Join-Path $Folder 'My profile notes.txt') 'A user file next to the install folder contents.'
+  New-Item -ItemType Directory -Force (Join-Path $Folder '.my-settings') | Out-Null
+  Set-Content (Join-Path $Folder '.my-settings\settings.txt') 'A user folder that sorts before AppData.'
+}
+
+function Add-UserFiles {
+  Set-Content (Join-Path $Desktop 'My notes.txt') 'Personal notes that must survive uninstalling SimpleX.'
+  Set-Content (Join-Path $Desktop 'Tax return 2025.txt') 'A document unrelated to SimpleX.'
+  New-Item -ItemType Directory -Force (Join-Path $Desktop 'Holiday photos') | Out-Null
+  Set-Content (Join-Path $Desktop 'Holiday photos\beach.txt') 'A file in a user folder.'
+}
+
+function Install-WithUi([string]$Msi, [string]$Folder, [string]$Tag, [string]$What) {
+  $log = Join-Path $Logs "$Tag-install.log"
+  $process = Start-Process msiexec.exe -ArgumentList @('/i', "`"$Msi`"", '/l*v', "`"$log`"") -PassThru
+  Invoke-Element (Wait-Button $Setup @('Next') 180)
+  Wait-Button $Setup @('Change...') | Out-Null
+  if ($Folder) {
+    Set-EditText $Setup $Folder | Out-Null
+    Start-Sleep -Milliseconds 500
+    Save-Screenshot "$What - $Folder typed as the install folder"
+  } else {
+    Save-Screenshot "$What - default install folder"
+  }
+  $next = Wait-Button $Setup @('Next')
+  $next.SetFocus()
+  Start-Sleep -Milliseconds 300
+  Invoke-Element $next
+  $button = Wait-Button $Setup @('Yes', 'Install')
+  if ($button.Current.Name -eq 'Yes') {
+    Save-Screenshot "$What - installer warns the folder already exists"
+    Invoke-Element $button
+    $button = Wait-Button $Setup @('Install')
+  }
+  Invoke-Element $button
+  $finish = Wait-Button $Setup @('Finish') 900
+  Save-Screenshot "$What - installer finished"
+  Invoke-Element $finish
+  $process.WaitForExit()
+  Assert-Check "$Tag install exit code" $process.ExitCode 0
+  $installDir = Select-String -Path $log -Pattern 'Property\(S\): INSTALLDIR = (.*)' | Select-Object -Last 1
+  Write-Check "$Tag INSTALLDIR" $(if ($installDir) { $installDir.Matches[0].Groups[1].Value } else { '<not in log>' })
+}
+
+function Uninstall-WithUi([string]$Msi, [string]$Tag, [string]$What) {
+  $log = Join-Path $Logs "$Tag-uninstall.log"
+  $process = Start-Process msiexec.exe -ArgumentList @('/x', "`"$Msi`"", '/l*v', "`"$log`"") -PassThru
+  $yes = Wait-Button 'Windows Installer' @('Yes') 180
+  Save-Screenshot "$What - uninstall confirmation"
+  Invoke-Element $yes
+  $process.WaitForExit()
+  Assert-Check "$Tag uninstall exit code" $process.ExitCode 0
+}
+
+function Start-App([string]$Exe, [string]$Caption) {
+  $app = Start-Process $Exe -PassThru
+  Start-Sleep -Seconds 45
+  Save-Screenshot $Caption
+  $running = -not $app.HasExited
+  Get-Process -Name SimpleX -ErrorAction SilentlyContinue | Stop-Process -Force
+  Start-Sleep -Seconds 3
+  $running
+}
+
+function Test-UninstallDesktop {
+  Reset-State
+  Add-UserFiles
+  Show-Folder $Desktop 'Desktop with the user''s own files, before installing SimpleX'
+  Install-WithUi $script:NewMsi "$Desktop\" 'uninstall-desktop' 'Install into Desktop'
+  Show-Folder $Desktop 'Desktop after installing SimpleX into it'
+  Assert-Check 'uninstall-desktop - SimpleX.exe installed in Desktop' (Test-Path (Join-Path $Desktop 'SimpleX.exe')) $true
+  Uninstall-WithUi $script:NewMsi 'uninstall-desktop' 'Uninstall from Desktop'
+  Show-Folder $Desktop 'Desktop after uninstalling SimpleX'
+  Test-UserFiles 'uninstall-desktop after uninstall'
+  foreach ($name in $InstalledNames) {
+    Assert-Check "uninstall-desktop after uninstall - Desktop\$name exists" (Test-Path (Join-Path $Desktop $name)) $false
+  }
+}
+
+function Test-Update([string]$Tag, [string]$FromMsi, [string]$ToMsi, [string]$FromWhat, [string]$ToWhat) {
+  if (-not $FromMsi -or -not $ToMsi) { throw "$Tag needs two MSIs" }
+  Reset-State
+  Add-UserFiles
+  Show-Folder $Desktop "Desktop with the user's own files, before installing $FromWhat"
+  Install-WithUi $FromMsi "$Desktop\" "$Tag-from" "Install $FromWhat into Desktop"
+  Show-Folder $Desktop "Desktop after installing $FromWhat into it"
+  Install-WithUi $ToMsi '' "$Tag-to" "Update to $ToWhat"
+  Show-Folder $Desktop "Desktop after updating to $ToWhat"
+  Test-UserFiles "$Tag after update"
+  foreach ($name in $InstalledNames) {
+    Assert-Check "$Tag after update - Desktop\$name exists" (Test-Path (Join-Path $Desktop $name)) $false
+  }
+  Assert-Check "$Tag - updated SimpleX.exe in Program Files" (Test-Path (Join-Path $ProgramFilesDir 'SimpleX.exe')) $true
+  Assert-Check "$Tag - updated app running after 45 s" (Start-App (Join-Path $ProgramFilesDir 'SimpleX.exe') "SimpleX started after updating to $ToWhat") $true
+}
+
+function Test-DefaultFolder {
+  Reset-State
+  Add-UserFiles
+  Install-WithUi $script:NewMsi '' 'default-folder' 'Install into the default folder'
+  Show-Folder $ProgramFilesDir 'Program Files SimpleX folder after installing'
+  Assert-Check 'default-folder - app running after 45 s' (Start-App (Join-Path $ProgramFilesDir 'SimpleX.exe') 'SimpleX started from the default install folder') $true
+  Uninstall-WithUi $script:NewMsi 'default-folder' 'Uninstall from the default folder'
+  Show-Folder $env:ProgramFiles 'Program Files after uninstalling SimpleX'
+  Assert-Check 'default-folder after uninstall - Program Files SimpleX folder exists' (Test-Path $ProgramFilesDir) $false
+  Test-UserFiles 'default-folder after uninstall'
+}
+
+function Test-DataFolder([string]$Tag, [string]$Folder, [string]$What) {
+  Reset-State
+  Install-WithUi $script:NewMsi "$Folder\" $Tag "Install into $What"
+  Assert-Check "$Tag - app running after 45 s" (Start-App (Join-Path $Folder 'SimpleX.exe') "SimpleX started from $What") $true
+  Add-FolderUserFiles $Folder
+  $dataFiles = @(Get-ChildItem -Recurse -File $DataDir | ForEach-Object { $_.FullName })
+  Write-Check "$Tag - SimpleX data files before uninstall" ($dataFiles -join ', ')
+  Assert-Check "$Tag - chat database exists before uninstall" (Test-Path (Join-Path $DataDir 'simplex_v1_chat.db')) $true
+  Show-Folder $Folder "$What with SimpleX and the user's files, before uninstalling"
+  Show-Folder $DataDir 'SimpleX data folder (database) before uninstalling'
+  Uninstall-WithUi $script:NewMsi $Tag "Uninstall from $What"
+  Show-Folder $Folder "$What after uninstalling SimpleX"
+  Show-Folder $DataDir 'SimpleX data folder (database) after uninstalling'
+  foreach ($file in $FolderUserFiles) {
+    Assert-Check "$Tag after uninstall - $file in $What exists" (Test-Path (Join-Path $Folder $file)) $true
+  }
+  foreach ($file in $dataFiles) {
+    Assert-Check "$Tag after uninstall - $file exists" (Test-Path $file) $true
+  }
+  foreach ($name in $InstalledNames) {
+    Assert-Check "$Tag after uninstall - $name in $What exists" (Test-Path (Join-Path $Folder $name)) $false
+  }
+}
+
+Write-Check 'session id' ([System.Diagnostics.Process]::GetCurrentProcess().SessionId)
+Write-Check 'explorer running' ([bool](Get-Process explorer -ErrorAction SilentlyContinue))
+Write-Check 'screen' ([System.Windows.Forms.SystemInformation]::VirtualScreen)
+Write-Check 'EnableLUA' (Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System').EnableLUA
+Write-Check 'Desktop' $Desktop
+Write-Check 'user profile' $UserProfile
+Save-Screenshot 'Runner screen at start'
+
+$script:NewMsi = Get-Msi $NewMsiUrl $NewMsiDir 'new'
+Write-Check 'direct COM call WindowsInstaller.Installer.OpenDatabase' $(try { $null = (New-Object -ComObject WindowsInstaller.Installer).OpenDatabase($script:NewMsi, 0); 'works' } catch { "fails: $($_.Exception.Message)" })
+Close-MsiHandles
+if ($PatchScript) {
+  & powershell.exe -NoProfile -ExecutionPolicy Bypass -File (Resolve-Path $PatchScript) $script:NewMsi
+  Assert-Check 'patch script exit code' $LASTEXITCODE 0
+  Write-Check 'patched new MSI - ClearOlderVersionsInstallDirWipe action' ((Read-MsiColumn $script:NewMsi 'SELECT `Target` FROM `CustomAction` WHERE `Action`=''ClearOlderVersionsInstallDirWipe''') -join ' | ')
+  Write-Check 'patched new MSI - RemoveExistingProducts sequence' (Read-MsiColumn $script:NewMsi 'SELECT `Sequence` FROM `InstallExecuteSequence` WHERE `Action`=''RemoveExistingProducts''')
+}
+$script:OldMsi = Get-Msi $OldMsiUrl '' 'old'
+$script:ProductCodes = @((Describe-Msi $script:NewMsi 'new'), (Describe-Msi $script:OldMsi 'old'))
+$script:LaterMsi = $null
+try {
+  $script:LaterMsi = New-LaterVersionMsi $script:NewMsi (Join-Path $Work 'later.msi')
+  $script:ProductCodes += Describe-Msi $script:LaterMsi 'later'
+} catch {
+  Write-Check 'later MSI error' $_.Exception.Message
+}
+
+$scenarios = [ordered]@{
+  'uninstall-desktop' = { Test-UninstallDesktop }
+  'update-desktop' = { Test-Update 'update-desktop' $script:OldMsi $script:NewMsi 'the old version' 'the new version' }
+  'update-same-build' = { Test-Update 'update-same-build' $script:NewMsi $script:LaterMsi 'the new version' 'a later version of the same build' }
+  'default-folder' = { Test-DefaultFolder }
+  'profile-folder' = { Test-DataFolder 'profile-folder' $UserProfile 'the user profile folder' }
+  'appdata-folder' = { Test-DataFolder 'appdata-folder' $env:APPDATA 'the AppData Roaming folder' }
+}
+$knownIssues = @('update-desktop')
+$selected = switch ($Scenario) {
+  'all' { @($scenarios.Keys | Where-Object { $_ -notin $knownIssues }) }
+  'everything' { @($scenarios.Keys) }
+  default { @($Scenario) }
+}
+$errors = @()
+foreach ($name in $selected) {
+  Write-Host "=== SCENARIO $name"
+  try {
+    & $scenarios[$name]
+  } catch {
+    Write-Host "SCENARIO $name ERROR: $($_.Exception.Message)"
+    Write-Check "$name error" $_.Exception.Message
+    $errors += $name
+    Get-Process -Name msiexec -ErrorAction SilentlyContinue | Stop-Process -Force -ErrorAction SilentlyContinue
+  }
+}
+Reset-State
+Write-Host "FAILED CHECKS: $($script:Failures.Count)"
+$script:Failures | ForEach-Object { Write-Host "  FAIL $_" }
+if ($errors) { throw "Scenarios with unexpected state: $($errors -join ', ')" }
+if ($script:Failures) { throw "$($script:Failures.Count) checks failed" }
diff --git a/apps/multiplatform/scripts/windows-msi/wingui.psm1 b/apps/multiplatform/scripts/windows-msi/wingui.psm1
new file mode 100644
index 0000000000..3e13bc6e2d
--- /dev/null
+++ b/apps/multiplatform/scripts/windows-msi/wingui.psm1
@@ -0,0 +1,135 @@
+Add-Type -AssemblyName UIAutomationClient, UIAutomationTypes, System.Windows.Forms, System.Drawing
+
+$script:EvidenceDir = $null
+$script:ShotIndex = 0
+
+function Initialize-Evidence([string]$Dir) {
+  New-Item -ItemType Directory -Force $Dir | Out-Null
+  $script:EvidenceDir = $Dir
+  $script:ShotIndex = 0
+  Set-Content (Join-Path $Dir 'captions.tsv') "file`tcaption"
+}
+
+function Save-Screenshot([string]$Caption) {
+  $script:ShotIndex++
+  $slug = ($Caption -replace '[^A-Za-z0-9]+', '-').Trim('-').ToLower()
+  $name = '{0:D2}-{1}.png' -f $script:ShotIndex, $slug
+  try {
+    $bounds = [System.Windows.Forms.SystemInformation]::VirtualScreen
+    $bmp = New-Object System.Drawing.Bitmap $bounds.Width, $bounds.Height
+    $g = [System.Drawing.Graphics]::FromImage($bmp)
+    $g.CopyFromScreen($bounds.Left, $bounds.Top, 0, 0, $bmp.Size)
+    $bmp.Save((Join-Path $script:EvidenceDir $name), [System.Drawing.Imaging.ImageFormat]::Png)
+    $g.Dispose()
+    $bmp.Dispose()
+    Add-Content (Join-Path $script:EvidenceDir 'captions.tsv') "$name`t$Caption"
+    Write-Host "SHOT $name : $Caption"
+  } catch {
+    Write-Host "SHOT FAILED $name : $Caption : $($_.Exception.Message)"
+  }
+}
+
+function Get-TopWindow([string]$Title) {
+  $cond = New-Object System.Windows.Automation.PropertyCondition([System.Windows.Automation.AutomationElement]::NameProperty, $Title)
+  [System.Windows.Automation.AutomationElement]::RootElement.FindFirst([System.Windows.Automation.TreeScope]::Children, $cond)
+}
+
+function Find-InWindow([string]$Title, [string]$Name, $ControlType) {
+  $window = Get-TopWindow $Title
+  if (-not $window) { return $null }
+  $cond = New-Object System.Windows.Automation.AndCondition(
+    (New-Object System.Windows.Automation.PropertyCondition([System.Windows.Automation.AutomationElement]::NameProperty, $Name)),
+    (New-Object System.Windows.Automation.PropertyCondition([System.Windows.Automation.AutomationElement]::ControlTypeProperty, $ControlType)))
+  $window.FindFirst([System.Windows.Automation.TreeScope]::Descendants, $cond)
+}
+
+function Wait-Window([string]$Title, [int]$TimeoutSec = 60) {
+  $deadline = (Get-Date).AddSeconds($TimeoutSec)
+  while ((Get-Date) -lt $deadline) {
+    $window = Get-TopWindow $Title
+    if ($window) { return $window }
+    Start-Sleep -Milliseconds 300
+  }
+  Save-Screenshot "Unexpected state: no window $Title"
+  throw "UNEXPECTED STATE: window '$Title' not found within $TimeoutSec s"
+}
+
+function Wait-Button([string]$Title, [string[]]$Names, [int]$TimeoutSec = 60) {
+  $deadline = (Get-Date).AddSeconds($TimeoutSec)
+  while ((Get-Date) -lt $deadline) {
+    foreach ($name in $Names) {
+      $button = Find-InWindow $Title $name ([System.Windows.Automation.ControlType]::Button)
+      if ($button -and $button.Current.IsEnabled) { return $button }
+    }
+    Start-Sleep -Milliseconds 300
+  }
+  Save-Screenshot "Unexpected state: no button $($Names -join ' or ') in $Title"
+  throw "UNEXPECTED STATE: button '$($Names -join "' or '")' not found in '$Title' within $TimeoutSec s"
+}
+
+function Invoke-Element($Element) {
+  $Element.GetCurrentPattern([System.Windows.Automation.InvokePattern]::Pattern).Invoke()
+}
+
+function Set-EditText([string]$Title, [string]$Text, [int]$TimeoutSec = 60) {
+  $deadline = (Get-Date).AddSeconds($TimeoutSec)
+  $edit = $null
+  while (-not $edit -and (Get-Date) -lt $deadline) {
+    $window = Get-TopWindow $Title
+    if ($window) {
+      $cond = New-Object System.Windows.Automation.PropertyCondition([System.Windows.Automation.AutomationElement]::ControlTypeProperty, [System.Windows.Automation.ControlType]::Edit)
+      $edit = $window.FindFirst([System.Windows.Automation.TreeScope]::Descendants, $cond)
+    }
+    if (-not $edit) { Start-Sleep -Milliseconds 300 }
+  }
+  if (-not $edit) {
+    Save-Screenshot "Unexpected state: no edit box in $Title"
+    throw "UNEXPECTED STATE: no edit box in '$Title' within $TimeoutSec s"
+  }
+  $edit.SetFocus()
+  try {
+    $edit.GetCurrentPattern([System.Windows.Automation.ValuePattern]::Pattern).SetValue($Text)
+  } catch {
+    Write-Host "ValuePattern failed ($($_.Exception.Message)), typing instead"
+    [System.Windows.Forms.SendKeys]::SendWait('^a')
+    [System.Windows.Forms.SendKeys]::SendWait($Text)
+  }
+  $edit
+}
+
+function Close-ExplorerWindows {
+  foreach ($window in @((New-Object -ComObject Shell.Application).Windows())) {
+    try { $window.Quit() } catch {}
+  }
+  Start-Sleep -Seconds 1
+}
+
+function Show-Folder([string]$Path, [string]$Caption) {
+  $listing = if (Test-Path $Path) { (Get-ChildItem -Force $Path | ForEach-Object { $_.Name }) -join ', ' } else { '<folder does not exist>' }
+  Write-Host "LISTING $Path : $listing"
+  Close-ExplorerWindows
+  if (-not (Test-Path $Path)) {
+    $Caption = "$Caption (the folder itself no longer exists, its parent is shown)"
+    $Path = Split-Path $Path -Parent
+  }
+  $leaf = Split-Path $Path -Leaf
+  Start-Process explorer.exe -ArgumentList "`"$Path`""
+  $window = $null
+  $deadline = (Get-Date).AddSeconds(20)
+  while (-not $window -and (Get-Date) -lt $deadline) {
+    $window = Get-TopWindow $leaf
+    if (-not $window) { Start-Sleep -Milliseconds 300 }
+  }
+  if ($window) {
+    try {
+      $window.GetCurrentPattern([System.Windows.Automation.WindowPattern]::Pattern).SetWindowVisualState([System.Windows.Automation.WindowVisualState]::Maximized)
+    } catch {}
+    Start-Sleep -Seconds 2
+  }
+  Save-Screenshot $Caption
+  Close-ExplorerWindows
+  $unavailable = Find-InWindow 'Location is not available' 'OK' ([System.Windows.Automation.ControlType]::Button)
+  if ($unavailable) { Invoke-Element $unavailable }
+}
+
+Export-ModuleMember -Function Initialize-Evidence, Save-Screenshot, Get-TopWindow, Find-InWindow, Wait-Window, Wait-Button, Invoke-Element, Set-EditText, Close-ExplorerWindows, Show-Folder