refactor(oxfmt): allow missing lint config

apps/oxfmt/src-js/cli/js_config.ts

@@ -1,10 +1,16 @@
+import { basename as pathBasename } from "node:path";
 import { pathToFileURL } from "node:url";
 
+const VITE_CONFIG_NAME = "vite.config.ts";
+const VITE_OXFMT_CONFIG_FIELD = "fmt";
+
 /**
  * Load a JavaScript/TypeScript config file.
  *
  * Uses native Node.js `import()` to evaluate the config file.
- * The config file should have a default export containing the oxfmt configuration object.
+ * For:
+ *  - oxfmt.config.ts files, the entire default export is used as the config object.
+ *  - vite.config.ts files, the config is read from the `fmt` field of the default export. If the `fmt` field is missing, an empty object is used as the config.
  *
  * @param path - Absolute path to the JavaScript/TypeScript config file
  * @returns Config object
@@ -13,12 +19,26 @@ export async function loadJsConfig(path: string): Promise<object> {
   // Bypass Node.js module cache to allow reloading changed config files (used for LSP)
   const fileUrl = pathToFileURL(path);
   fileUrl.searchParams.set("cache", Date.now().toString());
-  const { default: config } = await import(fileUrl.href);
+  const { default: rawConfig } = await import(fileUrl.href);
+
+  let config = rawConfig;
 
   if (config === undefined) throw new Error(`Configuration file has no default export: ${path}`);
   if (typeof config !== "object" || config === null || Array.isArray(config)) {
     throw new Error(`Configuration file must have a default export that is an object: ${path}`);
   }
 
+  if (pathBasename(path) === VITE_CONFIG_NAME) {
+    config =
+      VITE_OXFMT_CONFIG_FIELD in config
+        ? (config as Record<string, unknown>)[VITE_OXFMT_CONFIG_FIELD]
+        : {};
+    if (typeof config !== "object" || config === null || Array.isArray(config)) {
+      throw new Error(
+        `The \`${VITE_OXFMT_CONFIG_FIELD}\` field in the default export must be an object: ${path}`,
+      );
+    }
+  }
+
   return config;
 }

apps/oxfmt/src/core/config.rs

@@ -32,8 +32,6 @@ const OXFMT_JS_CONFIG_NAME: &str = "oxfmt.config.ts";
 /// Vite+ config file name that may contain Oxfmt config under a `.fmt` field.
 /// Only `.ts` extension is supported, matching oxlint's behavior.
 const VITE_PLUS_CONFIG_NAME: &str = "vite.config.ts";
-#[cfg(feature = "napi")]
-const VITE_PLUS_OXFMT_CONFIG_FIELD: &str = "fmt";
 
 /// Returns an iterator of all supported config file names, in priority order.
 pub fn all_config_file_names() -> impl Iterator<Item = String> {
@@ -269,20 +267,6 @@ impl ConfigResolver {
                 )
             })?;
 
-            // Vite+ config files (e.g. `vite.config.ts`),
-            // under a `.fmt` field instead of the default export directly.
-            let is_vite_plus = path
-                .file_name()
-                .and_then(|f| f.to_str())
-                .is_some_and(|name| name == VITE_PLUS_CONFIG_NAME);
-            let raw_config = if is_vite_plus {
-                raw_config.get(VITE_PLUS_OXFMT_CONFIG_FIELD).cloned().ok_or_else(|| {
-                    format!("{}\nExpected a `{VITE_PLUS_OXFMT_CONFIG_FIELD}` field in the default export.", path.display())
-                })?
-            } else {
-                raw_config
-            };
-
             let config_dir = path.parent().map(Path::to_path_buf);
             let editorconfig = load_editorconfig(cwd, editorconfig_path)?;
 

apps/oxfmt/test/cli/vite_config/__snapshots__/vite_config.test.ts.snap

@@ -17,17 +17,18 @@ Finished in <variable>ms on 1 files using 1 threads.
 --------------------"
 `;
 
-exports[`vite_config > error: no fmt field in vite.config.ts 1`] = `
+exports[`vite_config > missing fmt field in vite.config.ts falls back to default config 1`] = `
 "--------------------
 arguments: --check test.ts
-working directory: vite_config/fixtures/error_no_fmt_field
-exit code: 1
+working directory: vite_config/fixtures/missing_fmt_field
+exit code: 0
 --- STDOUT ---------
+Checking formatting...
 
+All matched files use the correct format.
+Finished in <variable>ms on 1 files using 1 threads.
 --- STDERR ---------
-Failed to load configuration file.
-<cwd>/vite.config.ts
-Expected a \`fmt\` field in the default export.
+
 --------------------"
 `;
 

apps/oxfmt/test/cli/vite_config/vite_config.test.ts

@@ -11,8 +11,8 @@ describe("vite_config", () => {
     expect(snapshot).toMatchSnapshot();
   });
 
-  it("error: no fmt field in vite.config.ts", async () => {
-    const cwd = join(fixturesDir, "error_no_fmt_field");
+  it("missing fmt field in vite.config.ts falls back to default config", async () => {
+    const cwd = join(fixturesDir, "missing_fmt_field");
     const snapshot = await runAndSnapshot(cwd, [["--check", "test.ts"]]);
     expect(snapshot).toMatchSnapshot();
   });

apps/oxlint/src-js/js_config.ts

@@ -111,7 +111,10 @@ export async function loadJsConfigs(paths: string[]): Promise<string> {
         }
 
         if (pathBasename(path) === VITE_CONFIG_NAME) {
-          config = (config as Record<string, unknown>)[VITE_OXLINT_CONFIG_FIELD] ?? {};
+          config =
+            VITE_OXLINT_CONFIG_FIELD in config
+              ? (config as Record<string, unknown>)[VITE_OXLINT_CONFIG_FIELD]
+              : {};
           if (typeof config !== "object" || config === null || Array.isArray(config)) {
             throw new Error(
               `The \`${VITE_OXLINT_CONFIG_FIELD}\` field in the default export must be an object.`,