[rush] Can update-autoinstallers write common/autoinstallers/rush-plugins/.rush/temp/last-install.flag?

[LPegasus]

Summary

After executing rush update-autoinstaller, the .rush/temp/last-install.flag file was not written, causing subsequent related commands to perform the installation again.

Repro steps

• Change any dependencies version in autoinstallers/*/package.json
• Run rush update-autoinstaller --name xxx.
• Run rush install-autoinstaller --name xxx. Expect to skip installation.

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/rush globally installed version?	5.155.1
rushVersion from rush.json?	5.155.1
useWorkspaces from rush.json?	Yes
Operating system?	Mac
Would you consider contributing a PR?	Yes
Node.js version (node -v)?	22.20.0

[LPegasus]

Do I understand correctly that we just need to refer to the code logic in

rushstack/libraries/rush-lib/src/logic/Autoinstaller.ts

Lines 106 to 170 in 1627a83

	try {
	// Example: .../common/autoinstallers/my-task/.rush/temp
	const lastInstallFlagPath: string = path.join(
	autoinstallerFullPath,
	RushConstants.projectRushFolderName,
	'temp'
	);
	const packageJsonPath: string = path.join(autoinstallerFullPath, 'package.json');
	const packageJson: IPackageJson = JsonFile.load(packageJsonPath);
	const lastInstallFlag: LastInstallFlag = new LastInstallFlag(lastInstallFlagPath, {
	node: process.versions.node,
	packageManager: this._rushConfiguration.packageManager,
	packageManagerVersion: this._rushConfiguration.packageManagerToolVersion,
	packageJson: packageJson,
	rushJsonFolder: this._rushConfiguration.rushJsonFolder
	});
	// Example: ../common/autoinstallers/my-task/node_modules
	const nodeModulesFolder: string = `${autoinstallerFullPath}/${RushConstants.nodeModulesFolderName}`;
	const flagPath: string = `${nodeModulesFolder}/rush-autoinstaller.flag`;
	const isLastInstallFlagDirty: boolean =
	!(await lastInstallFlag.isValidAsync()) || !FileSystem.exists(flagPath);
	if (isLastInstallFlagDirty || lock.dirtyWhenAcquired) {
	if (FileSystem.exists(nodeModulesFolder)) {
	this._logIfConsoleOutputIsNotRestricted('Deleting old files from ' + nodeModulesFolder);
	FileSystem.ensureEmptyFolder(nodeModulesFolder);
	}
	// Copy: .../common/autoinstallers/my-task/.npmrc
	Utilities.syncNpmrc({
	sourceNpmrcFolder: this._rushConfiguration.commonRushConfigFolder,
	targetNpmrcFolder: autoinstallerFullPath,
	supportEnvVarFallbackSyntax: this._rushConfiguration.isPnpm
	});
	this._logIfConsoleOutputIsNotRestricted(
	`Installing dependencies under ${autoinstallerFullPath}...\n`
	);
	await Utilities.executeCommandAsync({
	command: this._rushConfiguration.packageManagerToolFilename,
	args: ['install', '--frozen-lockfile'],
	workingDirectory: autoinstallerFullPath,
	keepEnvironment: true
	});
	// Create file: ../common/autoinstallers/my-task/.rush/temp/last-install.flag
	await lastInstallFlag.createAsync();
	FileSystem.writeFile(
	flagPath,
	'If this file is deleted, Rush will assume that the node_modules folder has been cleaned and will reinstall it.'
	);
	this._logIfConsoleOutputIsNotRestricted('Auto install completed successfully\n');
	} else {
	this._logIfConsoleOutputIsNotRestricted('Autoinstaller folder is already up to date\n');
	}
	} finally {
	// Ensure the lockfile is released when we are finished.
	lock.release();
	}

and implement the same generation logic for the last-install.flag file in

rushstack/libraries/rush-lib/src/logic/Autoinstaller.ts

Line 173 in 1627a83

public async updateAsync(): Promise<void> {

?

[iclanton]

Looks like a simple oversight. @LPegasus, that seems like the right place.