fix: handle @babel/traverse CJS-ESM interop in .mts files

@babel/traverse is a CJS package that exports { default: fn }.
In Node ESM (.mts), `import traverse from '@babel/traverse'`
resolves to the module object, not the function, causing
"traverse is not a function" at runtime.

Use `_traverse.default ?? _traverse` to unwrap correctly.

Author: jdalton

.config/vitest.config.isolated.mts

@@ -30,6 +30,9 @@ const isCoverageEnabled =
 export default defineConfig({
   cacheDir: './.cache/vitest',
   test: {
+    deps: {
+      interopDefault: false,
+    },
     globals: false,
     environment: 'node',
     // Only include tests that need isolation

.config/vitest.config.mts

@@ -25,6 +25,9 @@ if (isCoverageEnabled) {
 export default defineConfig({
   cacheDir: './.cache/vitest',
   test: {
+    deps: {
+      interopDefault: false,
+    },
     globals: false,
     environment: 'node',
     include: ['test/**/*.test.{js,ts,mjs,mts,cjs}'],

scripts/generate-sdk.mts

@@ -15,7 +15,7 @@ import path from 'node:path'
 import process from 'node:process'
 
 import { parse } from '@babel/parser'
-import traverse from '@babel/traverse'
+import _traverse from '@babel/traverse'
 import * as t from '@babel/types'
 import MagicString from 'magic-string'
 
@@ -26,6 +26,10 @@ import { spawn } from '@socketsecurity/lib/spawn'
 import { getRootPath } from './utils/path-helpers.mts'
 import { runCommand } from './utils/run-command.mts'
 
+// CJS interop: @babel/traverse exports { default: fn } from CJS.
+// @ts-expect-error -- runtime CJS has .default, types don't expose it.
+const traverse: typeof _traverse = _traverse.default
+
 const OPENAPI_URL = 'https://api.socket.dev/v0/openapi'
 
 const rootPath = getRootPath(import.meta.url)

test/unit/bundle-validation.test.mts

@@ -8,9 +8,13 @@ import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
 import { parse } from '@babel/parser'
-import { default as traverse } from '@babel/traverse'
+import _traverse from '@babel/traverse'
 import { describe, expect, it } from 'vitest'
 
+// CJS interop: @babel/traverse exports { default: fn } from CJS.
+// @ts-expect-error -- runtime CJS has .default, types don't expose it.
+const traverse: typeof _traverse = _traverse.default
+
 const __dirname = path.dirname(fileURLToPath(import.meta.url))
 const packagePath = path.resolve(__dirname, '../..')
 const distPath = path.join(packagePath, 'dist')