Use new util for watching

packages/ember-auto-import/ts/auto-import.ts

@@ -26,8 +26,10 @@ import type { TransformOptions } from '@babel/core';
 import { MARKER } from './analyzer-syntax';
 import path from 'path';
 import funnel from 'broccoli-funnel';
+import makeDebug from 'debug';
 
 const debugTree = buildDebugCallback('ember-auto-import');
+const debugWatch = makeDebug('ember-auto-import:watch');
 
 // This interface must be stable across all versions of ember-auto-import that
 // speak the same leader-election protocol. So don't change this unless you know
@@ -244,6 +246,7 @@ function depsFor(allAppTree: Node, packages: Set<Package>) {
     let watched = pkg.watchedDirectories;
     if (watched) {
       deps = deps.concat(watched.map((dir) => new WatchedDir(dir)));
+      debugWatch(`Adding watched directories: ${watched.join(', ')}`);
     }
   }
   return deps;

packages/ember-auto-import/ts/package.ts

@@ -14,6 +14,7 @@ import type { PluginItem, TransformOptions } from '@babel/core';
 import { MacrosConfig } from '@embroider/macros/src/node';
 import minimatch from 'minimatch';
 import { stripQuery } from './util';
+import { getWatchedDirectories } from './watch-utils';
 
 // from child addon instance to their parent package
 const parentCache: WeakMap<AddonInstance, Package> = new WeakMap();
@@ -514,13 +515,15 @@ export default class Package {
           for (let name of names) {
             let path = resolvePackagePath(name, cursor);
             if (!path) {
-              return undefined;
+              return [];
             }
             cursor = dirname(path);
           }
-          return cursor;
+          return getWatchedDirectories(cursor).map((relativeDir) =>
+            join(cursor, relativeDir)
+          );
         })
-        .filter(Boolean) as string[];
+        .flat();
     }
   }