fix(format): reformat with the Code Style indent, not the detected one

Without a per-language Tabs and Indents override, Reformat Code asked the
language server for the indent detected in the file. A file indented with 2
spaces (e.g. formatted elsewhere with Google style) then reformatted to 2
spaces and reported "already properly formatted", while a new file got 4.
Reformat now always asks for the Code Style indent (EditorConfig included);
detection only affects editing, and an indent chosen for the file in the
status bar still applies.

Fixes #2467

src/editor/core/cm/setup.ts

@@ -167,9 +167,8 @@ export function indentExtension(indent: EffectiveIndent, format: EffectiveIndent
 /**
  * Indentation explicit reformat requests use: the Code Style without the file's
  * detected indents (detection affects editing, reformatting uses the configured
- * style, as in IDEA). Set only when the language has an explicit Tabs and Indents
- * override — unset, formatting keeps the editor's indent, the status bar choice
- * included.
+ * style, as in IDEA), or the indent chosen for the file in the status bar.
+ * Unset (editors outside a document model), formatting keeps the editor's indent.
  */
 export const formatIndentFacet = Facet.define<EffectiveIndent | null>({
   combine: (values) => [values.find((v) => v !== null) ?? null],

src/editor/core/model/document.test.ts

@@ -91,6 +91,16 @@ describe("DocumentManager + slots", () => {
       expect(formatOptionsOf(slot.currentState())).toEqual({ tabSize: 1, insertSpaces: false });
   });
 
+  it("reformats with the Code Style indent also without a language override (#2467)", async () => {
+    const settings = { editor: { codeStyle: { languages: {}, detectIndents: true, editorconfig: false } } };
+    const { manager } = setup({ "/p/A.java": "class A {\n  int x;\n}\n" }, settings);
+    const model = await manager.acquire("/p/A.java");
+    const slot = new EditorSlot(model, "t1", host);
+    // Editing follows the 2-space indent detected in the file; Reformat Code uses Java's 4.
+    expect(slot.currentState().facet(indentUnit)).toBe("  ");
+    expect(formatOptionsOf(slot.currentState())).toEqual({ tabSize: 4, insertSpaces: true });
+  });
+
   it("detects the indents again after Reformat Code rewrote them", async () => {
     const settings = {
       editor: {

src/editor/core/model/document.ts

@@ -414,16 +414,14 @@ export class DocModel {
   }
 
   /**
-   * Indentation explicit reformat requests use (`formatIndentFacet`): with an
-   * explicit per-language Tabs and Indents override, the Code Style without the
-   * file's detected indents — the override must reach the formatter, or the
-   * language server keeps its own style. Without an override formatting keeps
-   * the editor's indent.
+   * Indentation explicit reformat requests use (`formatIndentFacet`): the Code Style
+   * (EditorConfig included) without the file's detected indents, as in IDEA, where
+   * detection only affects editing. Otherwise a file indented differently from the
+   * Code Style reformats to its own indent and other files to the Code Style's.
+   * An indent chosen for this file in the status bar still applies.
    */
   formatIndent() {
-    const lang = this.info ? prefsOf(this.settings()).codeStyle.languages[this.info.id] : undefined;
-    if (!lang || (lang.useTab === undefined && lang.tabSize === undefined && lang.indent === undefined)) return null;
-    return effectiveIndent(this.settings(), this.info, this.editorconfig, null);
+    return this.indentOverride ?? effectiveIndent(this.settings(), this.info, this.editorconfig, null);
   }
 
   /**