Verify Windows registration cleanup after uninstall

builds/installer.nsh

@@ -329,3 +329,41 @@ FunctionEnd
 
   ; Data choices were applied and verified before application removal.
 !macroend
+
+; Shell plugins may change the shell context. Never rely on that context for
+; the final registration cleanup of this per-user installation. Keep a live
+; installation registered, and do not remove another installation's entry.
+!macro POSNIC_VERIFY_REMOVAL
+  IfFileExists "$INSTDIR\${APP_EXECUTABLE_FILENAME}" posnic_removal_failed
+  ReadRegStr $0 HKCU "${INSTALL_REGISTRY_KEY}" "InstallLocation"
+  ${If} $0 != ""
+  ${AndIf} $0 != $INSTDIR
+    Goto posnic_removal_failed
+  ${EndIf}
+  ReadRegStr $0 HKCU "Software\Microsoft\Windows\CurrentVersion\Run" "${PRODUCT_NAME}"
+  ${If} $0 == "$INSTDIR\${APP_EXECUTABLE_FILENAME}"
+    DeleteRegValue HKCU "Software\Microsoft\Windows\CurrentVersion\Run" "${PRODUCT_NAME}"
+  ${EndIf}
+  DeleteRegKey HKCU "${UNINSTALL_REGISTRY_KEY}"
+  DeleteRegKey HKCU "${INSTALL_REGISTRY_KEY}"
+  ClearErrors
+  EnumRegValue $0 HKCU "${UNINSTALL_REGISTRY_KEY}" 0
+  IfErrors 0 posnic_removal_failed
+  ClearErrors
+  EnumRegValue $0 HKCU "${INSTALL_REGISTRY_KEY}" 0
+  IfErrors posnic_removal_verified posnic_removal_failed
+  posnic_removal_failed:
+    SetErrorLevel 1
+    Abort "Removal is incomplete. Close the application and run the installer to repair it, then retry removal."
+  posnic_removal_verified:
+    DetailPrint "Application removal and Windows registration verified."
+!macroend
+
+; Runs after electron-builder's file, shortcut and registration cleanup. A
+; failure must not reach the successful finish page.
+!macro customUnInstallSection
+  Section "un.Verify removal"
+    !insertmacro check64BitAndSetRegView
+    !insertmacro POSNIC_VERIFY_REMOVAL
+  SectionEnd
+!macroend

tests/uninstall-registration-windows.test.js

@@ -0,0 +1,68 @@
+'use strict';
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const os = require('node:os');
+const path = require('node:path');
+const { spawnSync } = require('node:child_process');
+
+const compiler = process.env.NSIS_MAKENSIS || path.join(process.env.LOCALAPPDATA || '', 'electron-builder/Cache/nsis/nsis-3.0.4.1/Bin/makensis.exe');
+const available = process.platform === 'win32' && fs.existsSync(compiler);
+const source = fs.readFileSync(path.join(__dirname, '../builds/installer.nsh'), 'utf8');
+const macro = source.match(/!macro POSNIC_VERIFY_REMOVAL\r?\n[\s\S]*?!macroend/)[0];
+
+// Execute the production cleanup macro against disposable registry keys only.
+// This harness never installs or uninstalls a real application.
+test('Windows registration finalizer handles stale, absent, live and unrelated installations', { skip: !available }, t => {
+  for (const scenario of ['stale', 'absent', 'live', 'other']) {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'posnic-registration-test-'));
+    const key = 'HKCU\\Software\\PosnicRemovalTests\\' + path.basename(dir);
+    const runKey = 'HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\Run';
+    const nsisKey = key.replace(/^HKCU\\/, '');
+    const run = (file, args) => spawnSync(file, args, { encoding: 'utf8', windowsHide: true });
+    t.after(() => {
+      assert.ok(key.startsWith('HKCU\\Software\\PosnicRemovalTests\\posnic-registration-test-'));
+      run('reg.exe', ['delete', key, '/f', '/reg:64']);
+      run('reg.exe', ['delete', runKey, '/v', path.basename(dir), '/f', '/reg:64']);
+      assert.equal(path.dirname(dir), os.tmpdir());
+      assert.ok(path.basename(dir).startsWith('posnic-registration-test-'));
+      fs.rmSync(dir, { recursive: true, force: true });
+    });
+    const exe = path.join(dir, 'check.exe');
+    const nsi = path.join(dir, 'check.nsi');
+    fs.writeFileSync(nsi, `Unicode true
+!include LogicLib.nsh
+Name "Registration cleanup test"
+OutFile "${exe}"
+RequestExecutionLevel user
+SilentInstall silent
+!define APP_EXECUTABLE_FILENAME "fixture.exe"
+!define PRODUCT_NAME "${path.basename(dir)}"
+!define INSTALL_REGISTRY_KEY "${nsisKey}\\Install"
+!define UNINSTALL_REGISTRY_KEY "${nsisKey}\\Uninstall"
+${macro}
+Section
+  SetRegView 64
+  StrCpy $INSTDIR "${dir}"
+  WriteRegStr HKCU "Software\\Microsoft\\Windows\\CurrentVersion\\Run" "\${PRODUCT_NAME}" "$INSTDIR\\fixture.exe"
+  ${scenario !== 'absent' ? `WriteRegStr HKCU "\${INSTALL_REGISTRY_KEY}" InstallLocation "${scenario === 'other' ? dir + '-other' : dir}"
+  WriteRegStr HKCU "\${UNINSTALL_REGISTRY_KEY}" DisplayName "Fixture"` : ''}
+  ${scenario === 'live' ? 'FileOpen $0 "$INSTDIR\\fixture.exe" w\n  FileClose $0' : ''}
+  ; Simulate a shell plugin leaving a different context behind.
+  SetShellVarContext all
+  !insertmacro POSNIC_VERIFY_REMOVAL
+SectionEnd
+`);
+    const compiled = run(compiler, ['/V2', nsi]);
+    assert.equal(compiled.status, 0, compiled.stdout + compiled.stderr);
+    const result = run(exe, []);
+    const shouldKeep = scenario === 'live' || scenario === 'other';
+    assert.equal(result.status, shouldKeep ? 1 : 0, scenario + ': ' + result.stderr);
+    for (const child of ['Install', 'Uninstall']) {
+      const query = run('reg.exe', ['query', key + '\\' + child, '/reg:64']);
+      assert.equal(query.status === 0, shouldKeep, scenario + ': ' + child);
+    }
+    const startup = run('reg.exe', ['query', runKey, '/v', path.basename(dir), '/reg:64']);
+    assert.equal(startup.status === 0, shouldKeep, scenario + ': startup');
+  }
+});