Midified the package for windows (not a monolitic bin). And added the option to remove older versions in the setup.

package/innosetup/build.ps1

@@ -1,16 +1,36 @@
-# Build the Testium installer from testium.iss (needs Inno Setup 6 / ISCC.exe).
+# Build the Windows installer: PyInstaller one-folder build (fast start) + Inno Setup.
 # Install ISCC without admin: winget install --id JRSoftware.InnoSetup -e
 
 $ErrorActionPreference = 'Stop'
 $scriptDir = Split-Path -Parent $MyInvocation.MyCommand.Path
+$repoRoot = Resolve-Path (Join-Path $scriptDir '..\..')
+$pyiDir = Join-Path $repoRoot 'package\pyinstaller'
 
-# The PyInstaller exe must exist first.
-$exe = Join-Path $scriptDir '..\pyinstaller\dist\testium.exe'
-if (-not (Test-Path $exe)) {
-    throw "PyInstaller build not found: $exe`nRun package\pyinstaller\build first."
+# Locate PyInstaller: PATH first, then the known project venvs.
+$pyi = (Get-Command pyinstaller.exe -ErrorAction SilentlyContinue).Source
+if (-not $pyi) {
+    foreach ($p in @(
+        (Join-Path $repoRoot 'test\tmp\testium_venv\Scripts\pyinstaller.exe'),
+        (Join-Path $repoRoot 'test\tmp\.venv\Scripts\pyinstaller.exe'))) {
+        if (Test-Path $p) { $pyi = $p; break }
+    }
+}
+if (-not $pyi) { throw "pyinstaller.exe not found (PATH or project venv)." }
+
+# One-folder PyInstaller build => dist\testium\testium.exe + dist\testium\_internal\.
+Write-Host "Building one-folder exe with: $pyi"
+Remove-Item -Recurse -Force (Join-Path $pyiDir 'build'), (Join-Path $pyiDir 'dist') -ErrorAction SilentlyContinue
+Push-Location $pyiDir
+try {
+    $env:TESTIUM_ONEDIR = '1'
+    & $pyi 'testium.spec'
+    if ($LASTEXITCODE -ne 0) { throw "pyinstaller failed with exit code $LASTEXITCODE" }
+} finally {
+    Remove-Item Env:\TESTIUM_ONEDIR -ErrorAction SilentlyContinue
+    Pop-Location
 }
 
-# Locate ISCC.exe: PATH, then the usual install dirs.
+# Locate ISCC: PATH, then the usual install dirs.
 $iscc = (Get-Command ISCC.exe -ErrorAction SilentlyContinue).Source
 if (-not $iscc) {
     foreach ($p in @(

package/innosetup/testium.iss

@@ -49,9 +49,12 @@ Name: "english"; MessagesFile: "compiler:Default.isl"
 Name: "desktopicon"; Description: "{cm:CreateDesktopIcon}"; GroupDescription: "{cm:AdditionalIcons}"; Flags: unchecked
 ; PATH off by default: the exe is windowed (console=False), so CLI shows no output.
 Name: "addtopath"; Description: "Ajouter Testium au PATH (usage en ligne de commande)"; Flags: unchecked
+; Shown only if another version is already installed; unchecked => keep it.
+Name: "removeold"; Description: "Désinstaller les autres versions de Testium déjà installées"; Check: OtherVersionsExist; Flags: unchecked
 
 [Files]
-Source: "..\pyinstaller\dist\{#MyAppExeName}"; DestDir: "{app}"; Flags: ignoreversion
+; One-folder build: the exe plus its _internal\ tree (fast startup, no re-extract).
+Source: "..\pyinstaller\dist\testium\*"; DestDir: "{app}"; Flags: recursesubdirs ignoreversion
 ; Ship the .ico so shortcuts/uninstall reference it directly, not the embedded one.
 Source: "..\testium.ico"; DestDir: "{app}"; Flags: ignoreversion
 
@@ -67,6 +70,54 @@ Filename: "{app}\{#MyAppExeName}"; Description: "{cm:LaunchProgram,{#MyAppName}}
 [Code]
 const
   EnvKey = 'Environment';
+  UninstallRoot = 'Software\Microsoft\Windows\CurrentVersion\Uninstall';
+  AppGuid = '{B7E6F1C2-9A4D-4E3B-8F71-7C2D5A6E0B14}';
+
+// Inno's uninstall subkey for *this* version: "{AppId}_is1".
+function CurrentUninstallSubkey(): string;
+begin
+  Result := AppGuid + '_{#MyAppVersion}_is1';
+end;
+
+// Uninstall subkeys of every installed Testium version except this one.
+function OtherTestiumSubkeys(): TArrayOfString;
+var
+  names: TArrayOfString;
+  i: Integer;
+  prefix, cur: string;
+begin
+  SetArrayLength(Result, 0);
+  prefix := Uppercase(AppGuid + '_');
+  cur := Uppercase(CurrentUninstallSubkey());
+  if RegGetSubkeyNames(HKEY_CURRENT_USER, UninstallRoot, names) then
+    for i := 0 to GetArrayLength(names) - 1 do
+      if (Pos(prefix, Uppercase(names[i])) = 1) and (Uppercase(names[i]) <> cur) then
+      begin
+        SetArrayLength(Result, GetArrayLength(Result) + 1);
+        Result[GetArrayLength(Result) - 1] := names[i];
+      end;
+end;
+
+// Drives the "removeold" task: only offered when another version exists.
+function OtherVersionsExist(): Boolean;
+begin
+  Result := GetArrayLength(OtherTestiumSubkeys()) > 0;
+end;
+
+// Silently run each other version's uninstaller.
+procedure RemoveOtherVersions();
+var
+  subs: TArrayOfString;
+  i, rc: Integer;
+  cmd: string;
+begin
+  subs := OtherTestiumSubkeys();
+  for i := 0 to GetArrayLength(subs) - 1 do
+    if RegQueryStringValue(HKEY_CURRENT_USER, UninstallRoot + '\' + subs[i],
+         'UninstallString', cmd) and (cmd <> '') then
+      Exec(RemoveQuotes(cmd), '/VERYSILENT /SUPPRESSMSGBOXES /NORESTART',
+           '', SW_HIDE, ewWaitUntilTerminated, rc);
+end;
 
 // True if Param is not already a full segment of the per-user PATH.
 function NeedsAddPath(Param: string): Boolean;
@@ -97,6 +148,8 @@ begin
       Path := Path + ExpandConstant('{app}');
       RegWriteStringValue(HKEY_CURRENT_USER, EnvKey, 'Path', Path);
     end;
+    if WizardIsTaskSelected('removeold') then
+      RemoveOtherVersions();
   end;
 end;
 

package/pyinstaller/testium.spec

@@ -79,26 +79,60 @@ a = Analysis(
 )
 pyz = PYZ(a.pure)
 
-exe = EXE(
-    pyz,
-    a.scripts,
-    a.binaries,
-    a.datas,
-    [],
-    name='testium',
-    debug=False,
-    bootloader_ignore_signals=False,
-    strip=False,
-    # UPX is CPU+IO heavy for a marginal size gain — build_all --ram sets
-    # TESTIUM_NO_UPX=1 to skip it (much faster on slow/flash storage).
-    upx=not os.environ.get("TESTIUM_NO_UPX"),
-    upx_exclude=[],
-    runtime_tmpdir=None,
-    console=False,
-    disable_windowed_traceback=False,
-    argv_emulation=False,
-    target_arch=None,
-    codesign_identity=None,
-    entitlements_file=None,
-    ico='../testium.ico'
-)
+# TESTIUM_ONEDIR=1 => one-folder build (fast startup), used by the Windows
+# installer; default one-file keeps the Linux build_all portable binary.
+ONEDIR = bool(os.environ.get("TESTIUM_ONEDIR"))
+# UPX skipped via TESTIUM_NO_UPX (build_all --ram) — slow for a marginal gain.
+_upx = not os.environ.get("TESTIUM_NO_UPX")
+
+if ONEDIR:
+    exe = EXE(
+        pyz,
+        a.scripts,
+        [],
+        exclude_binaries=True,
+        name='testium',
+        debug=False,
+        bootloader_ignore_signals=False,
+        strip=False,
+        upx=_upx,
+        upx_exclude=[],
+        console=False,
+        disable_windowed_traceback=False,
+        argv_emulation=False,
+        target_arch=None,
+        codesign_identity=None,
+        entitlements_file=None,
+        ico='../testium.ico'
+    )
+    coll = COLLECT(
+        exe,
+        a.binaries,
+        a.datas,
+        strip=False,
+        upx=_upx,
+        upx_exclude=[],
+        name='testium',
+    )
+else:
+    exe = EXE(
+        pyz,
+        a.scripts,
+        a.binaries,
+        a.datas,
+        [],
+        name='testium',
+        debug=False,
+        bootloader_ignore_signals=False,
+        strip=False,
+        upx=_upx,
+        upx_exclude=[],
+        runtime_tmpdir=None,
+        console=False,
+        disable_windowed_traceback=False,
+        argv_emulation=False,
+        target_arch=None,
+        codesign_identity=None,
+        entitlements_file=None,
+        ico='../testium.ico'
+    )