Fix: Untitled documents can't format with requireConfig enabled

src/ModuleResolverNode.ts

@@ -218,6 +218,29 @@ export class ModuleResolver implements ModuleResolverInterface {
     return;
   }
 
+  /**
+   * Determines if a document is an untitled (unsaved) document.
+   * Untitled documents have a scheme other than "file" (e.g., "untitled").
+   */
+  private isUntitledDocument(doc: TextDocument): boolean {
+    return doc.uri.scheme !== "file";
+  }
+
+  /**
+   * Gets the appropriate base path for config file searches.
+   * For untitled documents, uses the workspace folder path.
+   * For regular files, uses the file path itself.
+   */
+  private getConfigSearchPath(doc: TextDocument): string {
+    if (this.isUntitledDocument(doc)) {
+      const workspaceFolder = workspace.getWorkspaceFolder(doc.uri);
+      if (workspaceFolder) {
+        return workspaceFolder.uri.fsPath;
+      }
+    }
+    return doc.fileName;
+  }
+
   public async getResolvedConfig(
     doc: TextDocument,
     vscodeConfig: PrettierVSCodeConfig,
@@ -227,7 +250,11 @@ export class ModuleResolver implements ModuleResolverInterface {
       (await this.getPrettierInstance(fileName)) ??
       (await getBundledPrettier());
 
-    return this.resolveConfig(prettier, fileName, vscodeConfig);
+    // For untitled documents (unsaved files), use workspace folder as base for config search
+    // This allows untitled documents to use workspace prettier configs when requireConfig is enabled
+    const configSearchPath = this.getConfigSearchPath(doc);
+
+    return this.resolveConfig(prettier, configSearchPath, vscodeConfig);
   }
 
   public async clearModuleCache(filePath: string): Promise<void> {

src/test/suite/untitled.test.ts

@@ -0,0 +1,70 @@
+import * as assert from "assert";
+import * as vscode from "vscode";
+import { ensureExtensionActivated } from "./testUtils.js";
+
+/**
+ * Tests for untitled documents (unsaved files)
+ */
+describe("Test untitled documents", () => {
+  before(async () => {
+    await ensureExtensionActivated();
+  });
+
+  it("formats untitled JavaScript document", async () => {
+    // Create an untitled document with ugly JavaScript
+    const uglyCode = 'const   x    =    1   ;   console.log(  x  )  ;';
+    const doc = await vscode.workspace.openTextDocument({
+      language: "javascript",
+      content: uglyCode,
+    });
+
+    const editor = await vscode.window.showTextDocument(doc);
+
+    // Format the document
+    await vscode.commands.executeCommand("editor.action.formatDocument");
+
+    // The document should be formatted
+    const formattedText = editor.document.getText();
+
+    assert.notEqual(
+      formattedText,
+      uglyCode,
+      "Untitled document should have been formatted",
+    );
+
+    // Should not have excessive spacing
+    assert.ok(
+      !formattedText.includes("   "),
+      "Formatted code should not have excessive spacing",
+    );
+  });
+
+  it("formats untitled TypeScript document", async () => {
+    // Create an untitled document with ugly TypeScript
+    const uglyCode = 'function   test (  a :  number  ) :  number {  return   a  *  2  ;  }';
+    const doc = await vscode.workspace.openTextDocument({
+      language: "typescript",
+      content: uglyCode,
+    });
+
+    const editor = await vscode.window.showTextDocument(doc);
+
+    // Format the document
+    await vscode.commands.executeCommand("editor.action.formatDocument");
+
+    // The document should be formatted
+    const formattedText = editor.document.getText();
+
+    assert.notEqual(
+      formattedText,
+      uglyCode,
+      "Untitled TypeScript document should have been formatted",
+    );
+
+    // Should not have excessive spacing
+    assert.ok(
+      !formattedText.includes("   "),
+      "Formatted code should not have excessive spacing",
+    );
+  });
+});

test-fixtures/require-config/.prettierrc

@@ -0,0 +1,4 @@
+{
+  "semi": false,
+  "singleQuote": true
+}

test-fixtures/require-config/.vscode/settings.json

@@ -0,0 +1,4 @@
+{
+  "prettier.requireConfig": true,
+  "files.eol": "\n"
+}

test-fixtures/require-config/package.json

@@ -0,0 +1,3 @@
+{
+  "name": "require-config-test"
+}

test-fixtures/test.code-workspace

@@ -65,6 +65,9 @@
     },
     {
       "path": "monorepo-subfolder"
+    },
+    {
+      "path": "require-config"
     }
   ],
   "settings": {