fix: normalize config context loaded by jiti

src/index.ts

@@ -1,5 +1,5 @@
 import { getConfigExport, isConfigFunction } from './helpers.js';
-import { loadWithJiti } from './jiti.js';
+import { loadWithJiti, normalizeContext } from './jiti.js';
 import { JS_CONFIG_REGEXP, loadWithNative } from './native.js';
 import { resolveConfigPath } from './resolve.js';
 import type {
@@ -75,7 +75,10 @@ export async function loadConfig<
     }
   }
 
+  let usedJiti = false;
+
   if (!loadedConfig) {
+    usedJiti = true;
     loadedConfig = await loadWithJiti<Config, Params>(
       configPath,
       exportName,
@@ -93,14 +96,14 @@ export async function loadConfig<
     }
 
     return {
-      content: result,
+      content: usedJiti ? normalizeContext(result) : result,
       filePath: configPath,
       dependencies,
     };
   }
 
   return {
-    content: configExport,
+    content: usedJiti ? normalizeContext(configExport) : configExport,
     filePath: configPath,
     dependencies,
   };

src/jiti.ts

@@ -1,6 +1,29 @@
+import { normalize } from 'node:path';
 import { getConfigExport } from './helpers.js';
 import type { ConfigDefinition, LoadedConfig } from './types.js';
 
+type ConfigWithContext = { context: string };
+
+const hasContext = (config: unknown): config is ConfigWithContext =>
+  typeof config === 'object' &&
+  config !== null &&
+  typeof (config as ConfigWithContext).context === 'string';
+
+/**
+ * jiti exposes a POSIX-style `__dirname` on Windows, so a `context` built from
+ * it keeps forward slashes and no longer matches the native paths the bundler
+ * compares it against. Drop this once jiti stops rewriting `__dirname`.
+ */
+export const normalizeContext = <Config>(content: Config): Config => {
+  for (const config of Array.isArray(content) ? content : [content]) {
+    if (hasContext(config)) {
+      config.context = normalize(config.context);
+    }
+  }
+
+  return content;
+};
+
 export const loadWithJiti = async <Config, Params extends unknown[]>(
   configPath: string,
   exportName: string | false,

tests/normalize-context/demo.config.ts

@@ -0,0 +1 @@
+export default { context: 'D:/a/project', name: 'test' };

tests/normalize-context/function.config.ts

@@ -0,0 +1 @@
+export default () => ({ context: 'D:/a/project' });

tests/normalize-context/index.test.ts

@@ -0,0 +1,40 @@
+import { expect, test } from 'rstack/test';
+import { loadConfig } from '../../src/index';
+
+const __dirname = import.meta.dirname;
+
+const nativeContext =
+  process.platform === 'win32' ? 'D:\\a\\project' : 'D:/a/project';
+
+test('normalizes the context field of a jiti loaded config', async () => {
+  const result = await loadConfig<{ context: string; name: string }>({
+    cwd: __dirname,
+    path: 'demo.config.ts',
+    loader: 'jiti',
+  });
+
+  expect(result.content).toEqual({ context: nativeContext, name: 'test' });
+});
+
+test('normalizes the context field of a function config', async () => {
+  const result = await loadConfig<{ context: string }>({
+    cwd: __dirname,
+    path: 'function.config.ts',
+    loader: 'jiti',
+  });
+
+  expect(result.content.context).toBe(nativeContext);
+});
+
+test('normalizes the context field of every config in an array', async () => {
+  const result = await loadConfig<[{ context: string }, { name: string }]>({
+    cwd: __dirname,
+    path: 'multi.config.ts',
+    loader: 'jiti',
+  });
+
+  expect(result.content).toEqual([
+    { context: nativeContext },
+    { name: 'no-context' },
+  ]);
+});

tests/normalize-context/multi.config.ts

@@ -0,0 +1 @@
+export default [{ context: 'D:/a/project/src/..' }, { name: 'no-context' }];