Allow formatting untitled files when requireConfig is enabled

When `prettier.requireConfig` is enabled, untitled files couldn't be
formatted because the extension tried to find a config file starting
from the file's path, but untitled files don't have a real path.

This fix modifies `getResolvedConfig` to detect untitled documents
(scheme === "untitled") and use the first workspace folder's path
as the starting point for config file search instead.

Fixes #3885

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: ntotten

CHANGELOG.md

@@ -6,6 +6,8 @@ All notable changes to the "prettier-vscode" extension will be documented in thi
 
 ## [Unreleased]
 
+- Fixed formatting of untitled files when `requireConfig` is enabled. The extension now uses the workspace folder to search for Prettier config files when formatting untitled documents (#3885).
+
 ## [12.2.0]
 
 - Fixed `source.fixAll.prettier` code action running even when `editor.defaultFormatter` was set to a different extension (#3908). The code action now respects the user's formatter choice and only runs when Prettier is the default formatter or when `source.fixAll.prettier` is explicitly enabled.

src/ModuleResolverNode.ts

@@ -222,7 +222,21 @@ export class ModuleResolver implements ModuleResolverInterface {
     doc: TextDocument,
     vscodeConfig: PrettierVSCodeConfig,
   ): Promise<"error" | "disabled" | PrettierOptions | null> {
-    const fileName = doc.fileName;
+    let fileName = doc.fileName;
+
+    // For untitled documents, use the workspace folder path to search for config files.
+    // This allows untitled files to be formatted when requireConfig is enabled,
+    // as long as there's a Prettier config in the workspace.
+    if (doc.uri.scheme === "untitled") {
+      const workspaceFolder =
+        workspace.workspaceFolders && workspace.workspaceFolders.length > 0
+          ? workspace.workspaceFolders[0]
+          : undefined;
+      if (workspaceFolder) {
+        fileName = workspaceFolder.uri.fsPath;
+      }
+    }
+
     const prettier =
       (await this.getPrettierInstance(fileName)) ??
       (await getBundledPrettier());