An installation without compiled DI metadata serves requests

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+
+- Read the di.xml files through the runtime loader of Magento when the installation has no compiled metadata, so a developer-mode install serves requests.
+
 ## 0.2.0-rc5
 
 - Use Credis when the PHP Redis extension is unavailable; phpredis remains the preferred transport when installed.

src/FastBoot/Model/ObjectManager/AreaConfigLoader.php

@@ -8,6 +8,7 @@
 use GraphCommerce\FastBootCache\Model\Release;
 use Magento\Framework\App\Area;
 use Magento\Framework\App\Filesystem\DirectoryList;
+use Magento\Framework\App\ObjectManager\ConfigLoader;
 use Magento\Framework\App\ObjectManager\ConfigLoader\Compiled;
 use Magento\Framework\ObjectManager\ConfigLoaderInterface;
 
@@ -17,7 +18,9 @@
  * global one it already holds: 15 000 arguments replaced by themselves on
  * every request. This loader hands the object manager only the entries the
  * area changes, from a file under var/cache/fastboot/metadata that follows
- * an immutable release identity (or the source hashes without one).
+ * an immutable release identity (or the source hashes without one). An
+ * installation without compiled metadata reads the di.xml files through the
+ * runtime loader of Magento.
  */
 class AreaConfigLoader implements ConfigLoaderInterface
 {
@@ -30,6 +33,7 @@ public function __construct(
         private readonly DirectoryList $directoryList,
         private readonly Feature $feature,
         private readonly Release $release,
+        private readonly ConfigLoader $runtimeLoader,
     ) {
     }
 
@@ -40,9 +44,10 @@ public function load($area, bool $rebuild = false)
         }
         $areaFile = Compiled::getFilePath($area);
         $globalFile = Compiled::getFilePath(Area::AREA_GLOBAL);
-        if ($area === Area::AREA_GLOBAL || !is_file($areaFile) || !is_file($globalFile)
-            || !$this->feature->on(self::SWITCH)
-        ) {
+        if (!is_file($areaFile) || !is_file($globalFile)) {
+            return $this->loaded[$area] = $this->runtimeLoader->load($area);
+        }
+        if ($area === Area::AREA_GLOBAL || !$this->feature->on(self::SWITCH)) {
             return $this->loaded[$area] = include $areaFile;
         }
         $release = $this->release->id();

src/FastBoot/Test/Unit/Model/AreaConfigLoaderTest.php

@@ -8,12 +8,33 @@
 use GraphCommerce\FastBootCache\Model\Feature;
 use GraphCommerce\FastBootCache\Model\Release;
 use Magento\Framework\App\Filesystem\DirectoryList;
+use Magento\Framework\App\ObjectManager\ConfigLoader;
 use PHPUnit\Framework\Attributes\PreserveGlobalState;
 use PHPUnit\Framework\Attributes\RunInSeparateProcess;
 use PHPUnit\Framework\TestCase;
 
 class AreaConfigLoaderTest extends TestCase
 {
+    #[RunInSeparateProcess]
+    #[PreserveGlobalState(false)]
+    public function testInstallationWithoutCompiledMetadataUsesTheRuntimeLoader(): void
+    {
+        $root = sys_get_temp_dir().'/fastboot-area-'.bin2hex(random_bytes(8));
+        define('BP', $root);
+        $calls = 0;
+        $runtime = $this->createStub(ConfigLoader::class);
+        $runtime->method('load')->willReturnCallback(static function (string $area) use (&$calls): array {
+            $calls++;
+            return ['arguments' => ['runtime' => $area]];
+        });
+        $feature = $this->createStub(Feature::class);
+        $feature->method('on')->willReturn(true);
+        $loader = new AreaConfigLoader($this->createStub(DirectoryList::class), $feature, $this->createStub(Release::class), $runtime);
+        self::assertSame(['arguments' => ['runtime' => 'graphql']], $loader->load('graphql'));
+        self::assertSame(['arguments' => ['runtime' => 'graphql']], $loader->load('graphql'));
+        self::assertSame(1, $calls);
+    }
+
     #[RunInSeparateProcess]
     #[PreserveGlobalState(false)]
     public function testCorruptArtifactsRepairAndPreparationRebuildsChangedMetadata(): void
@@ -34,7 +55,7 @@ public function testCorruptArtifactsRepairAndPreparationRebuildsChangedMetadata(
         $feature->method('on')->willReturn(true);
         $release = $this->createStub(Release::class);
         $release->method('id')->willReturn('deployed-build');
-        $loader = fn () => new AreaConfigLoader($directory, $feature, $release);
+        $loader = fn () => new AreaConfigLoader($directory, $feature, $release, $this->createStub(ConfigLoader::class));
         $expected = ['arguments' => ['changed' => ['x' => 2]]];
         try {
             self::assertSame($expected, $loader()->load('graphql'));