diff --git a/packages/compat/src/compat-app-builder.ts b/packages/compat/src/compat-app-builder.ts
index d5b3051c4..fa101ade7 100644
--- a/packages/compat/src/compat-app-builder.ts
+++ b/packages/compat/src/compat-app-builder.ts
@@ -292,6 +292,7 @@ export class CompatAppBuilder {
           // that the last one wins. Our resolver's order is the order to
           // search, so first one wins.
           .reverse(),
+        isLazy: appFiles.engine.package.isLazyEngine(),
       })),
       amdCompatibility: this.options.amdCompatibility,
 
@@ -526,7 +527,7 @@ export class CompatAppBuilder {
 
     html.insertStyleLink(html.styles, `assets/${this.origAppPackage.name}.css`);
 
-    const parentEngine = appFiles.find(e => !e.engine.parent)!;
+    const parentEngine = appFiles.find(e => e.engine.isApp)!;
     let vendorJS = this.implicitScriptsAsset(prepared, parentEngine, emberENV);
     if (vendorJS) {
       html.insertScriptTag(html.implicitScripts, vendorJS.relativePath);
@@ -659,13 +660,12 @@ export class CompatAppBuilder {
     }
   }
 
-  private partitionEngines(appJSPath: string): Engine[] {
+  private partitionEngines(): Engine[] {
     let queue: Engine[] = [
       {
         package: this.appPackageWithMovedDeps,
         addons: new Map(),
-        parent: undefined,
-        sourcePath: appJSPath,
+        isApp: true,
         modulePrefix: this.modulePrefix(),
         appRelativePath: '.',
       },
@@ -684,8 +684,7 @@ export class CompatAppBuilder {
           queue.push({
             package: addon,
             addons: new Map(),
-            parent: current,
-            sourcePath: addon.root,
+            isApp: !current,
             modulePrefix: addon.name,
             appRelativePath: explicitRelative(this.root, addon.root),
           });
@@ -719,8 +718,8 @@ export class CompatAppBuilder {
 
   private updateAppJS(appJSPath: string): AppFiles[] {
     if (!this.engines) {
-      this.engines = this.partitionEngines(appJSPath).map(engine => {
-        if (engine.sourcePath === appJSPath) {
+      this.engines = this.partitionEngines().map(engine => {
+        if (engine.isApp) {
           // this is the app. We have more to do for the app than for other
           // engines.
           let fastbootSync: SyncDir | undefined;
@@ -741,7 +740,7 @@ export class CompatAppBuilder {
           // their files, not doing any actual copying or building.
           return {
             engine,
-            appSync: new SyncDir(engine.sourcePath, undefined),
+            appSync: new SyncDir(engine.package.root, undefined),
 
             // AFAIK, we've never supported a fastboot overlay directory in an
             // engine. But if we do need that, it would go here.
@@ -1226,7 +1225,7 @@ export class CompatAppBuilder {
     let styles = [];
     // only import styles from engines with a parent (this excludeds the parent application) as their styles
     // will be inserted via a direct <link> tag.
-    if (appFiles.engine.parent && appFiles.engine.package.isLazyEngine()) {
+    if (!appFiles.engine.isApp && appFiles.engine.package.isLazyEngine()) {
       let implicitStyles = this.impliedAssets('implicit-styles', appFiles);
       for (let style of implicitStyles) {
         styles.push({
diff --git a/packages/compat/tests/audit.test.ts b/packages/compat/tests/audit.test.ts
index d8474cf03..478c7b7b2 100644
--- a/packages/compat/tests/audit.test.ts
+++ b/packages/compat/tests/audit.test.ts
@@ -48,6 +48,7 @@ describe('audit', function () {
           fastbootFiles: {},
           activeAddons: [],
           root: app.baseDir,
+          isLazy: false,
         },
       ],
       resolvableExtensions,
diff --git a/packages/core/src/app-files.ts b/packages/core/src/app-files.ts
index 4bd825ed2..d3ec4fa6b 100644
--- a/packages/core/src/app-files.ts
+++ b/packages/core/src/app-files.ts
@@ -204,12 +204,10 @@ export interface Engine {
   package: Package;
   // the set of active addons in the engine. For each one we keep track of a file that can resolve the addon, because we'll need that later.
   addons: Map<AddonPackage, string>;
-  // the parent engine, if any
-  parent: Engine | undefined;
-  // where the engine's own V2 code comes from
-  sourcePath: string;
+  // is this the top-level engine?
+  isApp: boolean;
   // runtime name for the engine's own module namespace
   modulePrefix: string;
-  // this is destPath but relative to the app itself
+  // TODO: remove this after we remove the stage2 entrypoint
   appRelativePath: string;
 }
diff --git a/packages/core/src/module-resolver.ts b/packages/core/src/module-resolver.ts
index 53d4b2aa7..65a51d5c2 100644
--- a/packages/core/src/module-resolver.ts
+++ b/packages/core/src/module-resolver.ts
@@ -95,11 +95,14 @@ export interface Options {
   amdCompatibility: Required<UserOptions['amdCompatibility']>;
 }
 
-interface EngineConfig {
+// TODO: once we can remove the stage2 entrypoint this type can get streamlined
+// to the parts we actually need
+export interface EngineConfig {
   packageName: string;
   activeAddons: { name: string; root: string; canResolveFromFile: string }[];
   fastbootFiles: { [appName: string]: { localFilename: string; shadowedFilename: string | undefined } };
   root: string;
+  isLazy: boolean;
 }
 
 type MergeEntry =
diff --git a/tests/scenarios/compat-resolver-test.ts b/tests/scenarios/compat-resolver-test.ts
index 485c365da..cf6b46f28 100644
--- a/tests/scenarios/compat-resolver-test.ts
+++ b/tests/scenarios/compat-resolver-test.ts
@@ -81,6 +81,7 @@ Scenarios.fromProject(() => new Project())
                 root: app.dir,
                 activeAddons: [],
                 fastbootFiles: {},
+                isLazy: false,
               },
             ],
             modulePrefix: 'my-app',
diff --git a/tests/scenarios/core-resolver-test.ts b/tests/scenarios/core-resolver-test.ts
index b1c0dceee..96b25a5aa 100644
--- a/tests/scenarios/core-resolver-test.ts
+++ b/tests/scenarios/core-resolver-test.ts
@@ -101,6 +101,7 @@ Scenarios.fromProject(() => new Project())
             engines: [
               {
                 packageName: 'my-app',
+                isLazy: false,
                 root: app.dir,
                 fastbootFiles: opts?.fastbootFiles ?? {},
                 activeAddons: [