posit-dev · bricestacey · May 27, 2026 · May 26, 2026 · May 27, 2026 · May 27, 2026
diff --git a/extensions/positron-r/src/packages.ts b/extensions/positron-r/src/packages.ts
@@ -76,13 +76,9 @@ export class RPackageManager {
 			const pkgVector = this._formatRVector(pkgSpecs);
 			code = `renv::install(${pkgVector}, lock = TRUE, prompt = FALSE)`;
 		} else {
-			// If we're installing pak, don't prompt to install pak
-			let method: string;
-			if (packages.some((pkg) => pkg.name === 'pak')) {
-				method = await this._getPakMethod();
-			} else {
-				method = await this._ensurePak();
-			}
+			// If we're installing pak itself, don't try to install pak as a side effect.
+			const installingPak = packages.some((pkg) => pkg.name === 'pak');
+			const method = await this._resolveMethod(!installingPak);
 
 			if (method === 'pak') {
 				// pak supports "pkg@version" syntax directly
@@ -125,7 +121,7 @@ export class RPackageManager {
 			const pkgVector = this._formatRVector(pkgSpecs);
 			code = `renv::install(${pkgVector}, lock = TRUE, prompt = FALSE)`;
 		} else {
-			const method = await this._ensurePak();
+			const method = await this._resolveMethod(true);
 
 			if (method === 'pak') {
 				// pak supports "pkg@version" syntax directly
@@ -159,7 +155,7 @@ export class RPackageManager {
 		if (isRenv) {
 			await this._execute(`renv::update(lock = TRUE, prompt = FALSE)`, token);
 		} else {
-			const method = await this._ensurePak();
+			const method = await this._resolveMethod(true);
 
 			if (method === 'pak') {
 				// Get outdated packages via RPC, then update with pak
@@ -203,7 +199,7 @@ export class RPackageManager {
 		if (isRenv) {
 			code = `renv::remove(${pkgVector})`;
 		} else {
-			const method = await this._getPakMethod();
+			const method = await this._resolveMethod(false);
 
 			if (method === 'pak') {
 				code = `pak::pkg_remove(${pkgVector})`;
@@ -242,7 +238,7 @@ export class RPackageManager {
 			throw new vscode.CancellationError();
 		}
 
-		const method = await this._getPakMethod();
+		const method = await this._resolveMethod(false);
 		const result = await this._callMethod<positron.LanguageRuntimePackage[] | null>(
 			'pkg_search', token, query, method
 		);
@@ -294,21 +290,24 @@ export class RPackageManager {
 	}
 
 	/**
-	 * Get the method string based on pak availability (without prompting).
+	 * Read the configured R packages installer preference.
+	 * 'auto' means: prefer pak, prompt to install it when missing, fall back to base on decline.
+	 * 'pak' means: prefer pak, install it without prompting when missing.
+	 * 'base' means: never use or install pak.
 	 */
-	private async _getPakMethod(): Promise<string> {
-		const hasPak = await this._detectPak();
-		return hasPak ? 'pak' : 'base';
+	private _getConfiguredInstaller(): 'auto' | 'pak' | 'base' {
+		const value = vscode.workspace.getConfiguration('packages.r').get<string>('installer');
+		return value === 'pak' || value === 'base' ? value : 'auto';
 	}
 
 	/**
-	 * Get the method string for package listing (renv > pak > base).
+	 * Get the method string for package listing (renv > resolved method).
 	 */
 	private async _getPackageMethod(): Promise<string> {
 		if (await this._detectRenv()) {
 			return 'renv';
 		}
-		return this._getPakMethod();
+		return this._resolveMethod(false);
 	}
 
 	/**
@@ -325,29 +324,42 @@ export class RPackageManager {
 	}
 
 	/**
-	 * Ensure pak is available, prompting to install if needed.
-	 * Returns 'pak' or 'base' depending on availability.
+	 * Resolve which installer to use, honoring the `packages.r.installer` setting.
+	 *
+	 * @param allowInstallPak When true (install/update operations), may install pak, either
+	 *                       by prompting the user (setting: 'auto') or silently (setting: 'pak').
+	 *                       When false (list/search/uninstall), only detects what is available.
 	 */
-	private async _ensurePak(): Promise<string> {
-		const hasPak = await this._detectPak();
-		if (hasPak) {
+	private async _resolveMethod(allowInstallPak: boolean): Promise<string> {
+		const setting = this._getConfiguredInstaller();
+		if (setting === 'base') {
+			return 'base';
+		}
+
+		if (await this._detectPak()) {
 			return 'pak';
 		}
 
-		if (this._pakDeclined) {
+		if (!allowInstallPak) {
 			return 'base';
 		}
 
-		const install = await this._promptInstallPak();
-		if (install) {
-			// Use base R to install pak
+		if (setting === 'pak') {
+			// User opted in to pak; install without prompting.
 			await this._execute('install.packages("pak")');
-			const nowHasPak = await this._detectPak();
-			return nowHasPak ? 'pak' : 'base';
-		} else {
-			this._pakDeclined = true;
+			return (await this._detectPak()) ? 'pak' : 'base';
+		}
+
+		// setting === 'auto': prompt once per session, remember declines.
+		if (this._pakDeclined) {
 			return 'base';
 		}
+		if (await this._promptInstallPak()) {
+			await this._execute('install.packages("pak")');
+			return (await this._detectPak()) ? 'pak' : 'base';
+		}
+		this._pakDeclined = true;
+		return 'base';
 	}
 
 	/**

diff --git a/src/vs/workbench/contrib/positronPackages/browser/positronPackages.contribution.ts b/src/vs/workbench/contrib/positronPackages/browser/positronPackages.contribution.ts
@@ -91,6 +91,19 @@ Registry.as<IConfigurationRegistry>(ConfigurationExtensions.Configuration).regis
 			scope: ConfigurationScope.APPLICATION,
 			description: nls.localize('positron.packages.enable', 'Show the Packages pane.'),
 			markdownDeprecationMessage: nls.localize('positron.packages.enable.deprecated', "Deprecated. Use `#packages.enabled#` instead."),
+		},
+		'packages.r.installer': {
+			type: 'string',
+			enum: ['auto', 'pak', 'base'],
+			enumDescriptions: [
+				nls.localize('positron.packages.r.installer.auto', "Use pak if installed; otherwise prompt and fall back to base R."),
+				nls.localize('positron.packages.r.installer.pak', "Always use pak. Silently install it if missing."),
+				nls.localize('positron.packages.r.installer.base', "Always use base R."),
+			],
+			default: 'auto',
+			scope: ConfigurationScope.RESOURCE,
+			markdownDescription: nls.localize('positron.packages.r.installer', "Which package installer to use for installing, updating, and removing R packages. Does not affect projects using renv, which always use renv."),
+			tags: ['preview'],
 		}
 	}
 });