Add user-facing notifications for fatal errors with configuration option

package.json

@@ -225,6 +225,12 @@
           "markdownDescription": "%ext.config.enableDebugLogs%",
           "scope": "resource"
         },
+        "prettier.enableErrorNotifications": {
+          "type": "boolean",
+          "default": true,
+          "markdownDescription": "%ext.config.enableErrorNotifications%",
+          "scope": "resource"
+        },
         "prettier.printWidth": {
           "type": "integer",
           "default": 80,

package.nls.json

@@ -39,6 +39,7 @@
   "ext.config.embeddedLanguageFormatting": "Control whether Prettier formats quoted code embedded in the file.",
   "ext.config.enable": "Controls whether Prettier is enabled or not. Reload required.",
   "ext.config.enableDebugLogs": "Enable debug logs for troubleshooting.",
+  "ext.config.enableErrorNotifications": "Show error notifications when Prettier encounters fatal errors (e.g., module loading failures, invalid configuration files). When disabled, errors will only be logged to the output channel.",
   "ext.config.experimentalTernaries": "Try prettier's [new ternary formatting](https://github.com/prettier/prettier/pull/13183) before it becomes the default behavior.",
   "ext.config.objectWrap": "Controls how object literals are wrapped.\nValid options:\n- `preserve` - Preserve the original wrapping of object literals.\n- `collapse` - Collapse object literals to fit on one line when possible.",
   "ext.config.experimentalOperatorPosition": "Controls where to break lines around binary operators.\nValid options:\n- `end` - Break lines after operators.\n- `start` - Break lines before operators.",

src/ModuleResolverNode.ts

@@ -10,6 +10,7 @@ import {
 } from "./utils/global-node-paths.js";
 import { findUp, pathExists, FIND_UP_STOP } from "./utils/find-up.js";
 import { LoggingService } from "./LoggingService.js";
+import { NotificationService } from "./NotificationService.js";
 import {
   FAILED_TO_LOAD_MODULE_MESSAGE,
   INVALID_PRETTIER_CONFIG,
@@ -85,7 +86,10 @@ async function globalPathGet(
 export class ModuleResolver implements ModuleResolverInterface {
   private path2Module = new Map<string, PrettierInstance>();
 
-  constructor(private loggingService: LoggingService) {}
+  constructor(
+    private loggingService: LoggingService,
+    private notificationService: NotificationService,
+  ) {}
 
   public async getGlobalPrettierInstance(): Promise<PrettierNodeModule> {
     return getBundledPrettier();
@@ -152,6 +156,8 @@ export class ModuleResolver implements ModuleResolverInterface {
         `${FAILED_TO_LOAD_MODULE_MESSAGE}: ${modulePath}`,
         error,
       );
+      // Show user-facing notification
+      void this.notificationService.showPrettierLoadFailedError(fileName);
       return undefined;
     }
 
@@ -176,6 +182,8 @@ export class ModuleResolver implements ModuleResolverInterface {
     }
 
     this.loggingService.logError(INVALID_PRETTIER_PATH_MESSAGE);
+    // Show user-facing notification for invalid prettier path
+    void this.notificationService.showInvalidPrettierPathError();
     return undefined;
   }
 
@@ -399,6 +407,8 @@ export class ModuleResolver implements ModuleResolverInterface {
         `Failed to resolve config file for ${fileName}`,
         error,
       );
+      // Show user-facing notification for config resolution error
+      void this.notificationService.showConfigResolutionError();
       return "error";
     }
 
@@ -437,6 +447,8 @@ export class ModuleResolver implements ModuleResolverInterface {
       );
     } catch (error) {
       this.loggingService.logError(INVALID_PRETTIER_CONFIG, error);
+      // Show user-facing notification for invalid config
+      void this.notificationService.showInvalidConfigError();
       return "error";
     }
 

src/ModuleResolverWeb.ts

@@ -9,6 +9,7 @@ import {
 } from "./types.js";
 import { TextDocument } from "vscode";
 import { LoggingService } from "./LoggingService.js";
+import { NotificationService } from "./NotificationService.js";
 import { getWorkspaceRelativePath } from "./utils/workspace.js";
 import type { ResolveConfigOptions, Options, Plugin } from "prettier";
 
@@ -48,7 +49,12 @@ const plugins: Plugin[] = [
 ];
 
 export class ModuleResolver implements ModuleResolverInterface {
-  constructor(private loggingService: LoggingService) {}
+  constructor(
+    private loggingService: LoggingService,
+    // NotificationService is not used in web mode (always uses bundled prettier)
+    // but is required for interface consistency
+    _notificationService: NotificationService,
+  ) {}
 
   public async getPrettierInstance(
     _fileName: string,

src/NotificationService.ts

@@ -0,0 +1,183 @@
+import * as fs from "fs";
+import * as path from "path";
+import { commands, Uri, window, workspace } from "vscode";
+import { pathExists } from "./utils/find-up.js";
+
+/**
+ * Service for showing user-facing notifications for fatal errors
+ */
+export class NotificationService {
+  // Track which errors we've already shown to avoid spam
+  private shownErrors = new Set<string>();
+
+  /**
+   * Check if error notifications are enabled in settings
+   */
+  private isNotificationEnabled(): boolean {
+    const config = workspace.getConfiguration("prettier");
+    return config.get<boolean>("enableErrorNotifications", true);
+  }
+
+  /**
+   * Check if prettier is listed in package.json dependencies
+   */
+  private async isPrettierInPackageJson(
+    fileName: string,
+  ): Promise<boolean | undefined> {
+    try {
+      const workspaceFolder = workspace.getWorkspaceFolder(Uri.file(fileName));
+      if (!workspaceFolder) {
+        return undefined;
+      }
+
+      const packageJsonPath = path.join(
+        workspaceFolder.uri.fsPath,
+        "package.json",
+      );
+
+      if (!(await pathExists(packageJsonPath))) {
+        return undefined;
+      }
+
+      const content = await fs.promises.readFile(packageJsonPath, "utf8");
+      const packageJson = JSON.parse(content);
+
+      return !!(
+        packageJson.dependencies?.prettier ||
+        packageJson.devDependencies?.prettier ||
+        packageJson.peerDependencies?.prettier
+      );
+    } catch {
+      return undefined;
+    }
+  }
+
+  /**
+   * Helper to show an error message with optional action buttons
+   */
+  private async showErrorWithActions(
+    message: string,
+    ...actions: string[]
+  ): Promise<string | undefined> {
+    return window.showErrorMessage(message, ...actions);
+  }
+
+  /**
+   * Show error notification when prettier module cannot be loaded
+   */
+  public async showPrettierLoadFailedError(fileName: string): Promise<void> {
+    if (!this.isNotificationEnabled()) {
+      return;
+    }
+
+    const errorKey = `load-failed:${fileName}`;
+    if (this.shownErrors.has(errorKey)) {
+      return;
+    }
+    this.shownErrors.add(errorKey);
+
+    const isInPackageJson = await this.isPrettierInPackageJson(fileName);
+
+    const message = isInPackageJson
+      ? "Prettier: Failed to load module. Prettier is listed in package.json but could not be loaded. Please run npm install (or yarn/pnpm install)."
+      : "Prettier: Failed to load module. See output for more details.";
+
+    const selection = await this.showErrorWithActions(
+      message,
+      "View Output",
+      "Dismiss",
+    );
+
+    if (selection === "View Output") {
+      void commands.executeCommand("prettier.openOutput");
+    }
+  }
+
+  /**
+   * Show error notification for invalid prettier path configuration
+   */
+  public async showInvalidPrettierPathError(): Promise<void> {
+    if (!this.isNotificationEnabled()) {
+      return;
+    }
+
+    const errorKey = "invalid-prettier-path";
+    if (this.shownErrors.has(errorKey)) {
+      return;
+    }
+    this.shownErrors.add(errorKey);
+
+    const selection = await this.showErrorWithActions(
+      "Prettier: The 'prettierPath' setting does not reference a valid Prettier installation. Please check your settings.",
+      "Open Settings",
+      "View Output",
+      "Dismiss",
+    );
+
+    if (selection === "Open Settings") {
+      void commands.executeCommand(
+        "workbench.action.openSettings",
+        "prettier.prettierPath",
+      );
+    } else if (selection === "View Output") {
+      void commands.executeCommand("prettier.openOutput");
+    }
+  }
+
+  /**
+   * Show error notification for invalid prettier configuration file
+   */
+  public async showInvalidConfigError(): Promise<void> {
+    if (!this.isNotificationEnabled()) {
+      return;
+    }
+
+    const errorKey = "invalid-config";
+    if (this.shownErrors.has(errorKey)) {
+      return;
+    }
+    this.shownErrors.add(errorKey);
+
+    const selection = await this.showErrorWithActions(
+      "Prettier: Invalid configuration file detected. Please check your Prettier config files (.prettierrc, prettier.config.js, etc.).",
+      "View Output",
+      "Dismiss",
+    );
+
+    if (selection === "View Output") {
+      void commands.executeCommand("prettier.openOutput");
+    }
+  }
+
+  /**
+   * Show error notification for config resolution failures
+   */
+  public async showConfigResolutionError(): Promise<void> {
+    if (!this.isNotificationEnabled()) {
+      return;
+    }
+
+    const errorKey = "config-resolution";
+    if (this.shownErrors.has(errorKey)) {
+      return;
+    }
+    this.shownErrors.add(errorKey);
+
+    const selection = await this.showErrorWithActions(
+      "Prettier: Failed to resolve configuration file. See output for details.",
+      "View Output",
+      "Dismiss",
+    );
+
+    if (selection === "View Output") {
+      void commands.executeCommand("prettier.openOutput");
+    }
+  }
+
+  /**
+   * Reset notification tracking (useful for testing or when configuration changes)
+   */
+  public reset(): void {
+    this.shownErrors.clear();
+  }
+}

src/extension.ts

@@ -1,6 +1,7 @@
 import { commands, ExtensionContext, workspace } from "vscode";
 import { createConfigFile } from "./commands.js";
 import { LoggingService } from "./LoggingService.js";
+import { NotificationService } from "./NotificationService.js";
 import { ModuleResolver } from "./ModuleResolverNode.js";
 import PrettierEditService from "./PrettierEditService.js";
 import { StatusBar } from "./StatusBar.js";
@@ -14,6 +15,7 @@ const extensionVersion = process.env.EXTENSION_VERSION || "0.0.0";
 
 export async function activate(context: ExtensionContext) {
   const loggingService = new LoggingService();
+  const notificationService = new NotificationService();
 
   loggingService.logInfo(`Extension Name: ${extensionName}.`);
   loggingService.logInfo(`Extension Version: ${extensionVersion}.`);
@@ -36,7 +38,10 @@ export async function activate(context: ExtensionContext) {
     return;
   }
 
-  const moduleResolver = new ModuleResolver(loggingService);
+  const moduleResolver = new ModuleResolver(
+    loggingService,
+    notificationService,
+  );
 
   // Get the global prettier instance promise - needed for TemplateService
   // and editService registration

src/types.ts

@@ -129,6 +129,10 @@ export interface IExtensionConfig {
    * If true, enabled debug logs
    */
   enableDebugLogs: boolean;
+  /**
+   * If true, show error notifications for fatal errors
+   */
+  enableErrorNotifications: boolean;
 }
 /**
  * Configuration for prettier-vscode