diff --git a/build/PHPStan/Build/TurboAttributeCollector.php b/build/PHPStan/Build/TurboAttributeCollector.php
index fa0d80001fb..197a805ab7c 100644
--- a/build/PHPStan/Build/TurboAttributeCollector.php
+++ b/build/PHPStan/Build/TurboAttributeCollector.php
@@ -35,6 +35,7 @@
 use ReflectionClass;
 use RuntimeException;
 use Throwable;
+use function array_keys;
 use function class_exists;
 use function count;
 use function file_get_contents;
@@ -143,7 +144,7 @@ public function __construct(string $root)
 	 * the path) and merges the hardcoded vendored entries.
 	 *
 	 * @return array{
-	 *     pairs: array<string, array{string, bool, string}>,
+	 *     pairs: array<string, array{string, bool, string, list<class-string>}>,
 	 *     manifest: array<string, array{php: string, cpp: string, vendored?: bool}>,
 	 *     classMap: array<string, string>,
 	 *     referenced: array<string, string>,
@@ -195,6 +196,28 @@ public function collect(): array
 			}
 		}
 
+		foreach (array_keys($pairs) as $className) {
+			$reflection = new ReflectionClass($className);
+
+			// The stub shell extends the native class, and PHP is
+			// single-inheritance, so a parent of the shadowed class would
+			// silently disappear together with everything it declares.
+			$parent = $reflection->getParentClass();
+			if ($parent !== false) {
+				throw new RuntimeException(sprintf(
+					'%s cannot be shadowed by the turbo extension because it extends %s — the stub shell already extends the native class.',
+					$className,
+					$parent->getName(),
+				));
+			}
+
+			// Interfaces do survive, but only because they are re-declared on
+			// the stub: it inherits from the native class alone, so an
+			// interface left out here silently stops matching instanceof and
+			// DI type lookups.
+			$pairs[$className][3] = $reflection->getInterfaceNames();
+		}
+
 		ksort($pairs);
 		ksort($classMap);
 		ksort($referenced);
@@ -219,24 +242,74 @@ public function collect(): array
 		return ['pairs' => $pairs, 'manifest' => $manifest, 'classMap' => $classMap, 'referenced' => $referenced];
 	}
 
-	/** @param array<string, array{string, bool, string}> $pairs */
+	/**
+	 * Parent interfaces first, deduplicated, keyed by name to keep the order
+	 * stable across calls.
+	 *
+	 * @param class-string $interface
+	 * @param array<string, string> $files
+	 */
+	private static function collectInterfaceFiles(string $interface, array &$files): void
+	{
+		if (isset($files[$interface])) {
+			return;
+		}
+
+		$reflection = new ReflectionClass($interface);
+		foreach ($reflection->getInterfaceNames() as $parent) {
+			self::collectInterfaceFiles($parent, $files);
+		}
+
+		$fileName = $reflection->getFileName();
+		if ($fileName === false) {
+			return; // an engine interface, always declared
+		}
+
+		$files[$interface] = $fileName;
+	}
+
+	/** @param array<string, array{string, bool, string, list<class-string>}> $pairs */
 	public function renderStubs(array $pairs): string
 	{
 		$namespaces = [];
-		foreach ($pairs as $className => [$turboClass, $final]) {
+		foreach ($pairs as $className => [$turboClass, $final, $cppFile, $interfaces]) {
 			$pos = strrpos($className, '\\');
 			if ($pos === false) {
 				throw new RuntimeException(sprintf('%s is not a namespaced class name', $className));
 			}
+			$implements = '';
+			if (count($interfaces) > 0) {
+				$implements = ' implements \\' . implode(', \\', $interfaces);
+			}
 			$namespaces[substr($className, 0, $pos)][] = sprintf(
-				"\t%sclass %s extends \\%s {}",
+				"\t%sclass %s extends \\%s%s {}",
 				$final ? 'final ' : '',
 				substr($className, $pos + 1),
 				$turboClass,
+				$implements,
 			);
 		}
 
 		$blocks = [];
+
+		// The stubs are declared before the Composer autoloader registers, so
+		// the interfaces they re-declare have to be required here — parents
+		// first, since an interface extending another needs it at declaration
+		// time. Interfaces without a file are the engine's own.
+		$interfaceFiles = [];
+		foreach ($pairs as $pair) {
+			foreach ($pair[3] as $interface) {
+				self::collectInterfaceFiles($interface, $interfaceFiles);
+			}
+		}
+		if (count($interfaceFiles) > 0) {
+			$requires = [];
+			foreach ($interfaceFiles as $file) {
+				$requires[] = sprintf("\trequire_once __DIR__ . '/../%s';", $this->relativize($file));
+			}
+			$blocks[] = sprintf("namespace {\n\n%s\n\n}", implode("\n", $requires));
+		}
+
 		foreach ($namespaces as $namespace => $declarations) {
 			$blocks[] = sprintf("namespace %s {\n\n%s\n\n}", $namespace, implode("\n", $declarations));
 		}
@@ -250,7 +323,8 @@ public function renderStubs(array $pairs): string
 // ShadowedByTurboExtension attribute (plus the hardcoded vendored
 // PhpParser\NodeTraverser) with the phpstan_turbo extension's native
 // implementation. Required by PHPStan\Turbo\TurboExtensionEnabler before
-// the Composer autoloader registers.
+// the Composer autoloader registers — hence the interface sources required
+// below, which the autoloader cannot resolve yet.
 
 %s
 
diff --git a/build/generate-turbo-stubs.php b/build/generate-turbo-stubs.php
index ecd98134bc9..7fa288f4277 100644
--- a/build/generate-turbo-stubs.php
+++ b/build/generate-turbo-stubs.php
@@ -7,7 +7,8 @@
  *
  * - vendor/turbo-stubs.php: one empty stub shell per shadowed class,
  *   extending the phpstan_turbo extension's native counterpart the attribute
- *   names. TurboExtensionEnabler requires the file before the Composer
+ *   names and repeating the class's own implements clause.
+ *   TurboExtensionEnabler requires the file before the Composer
  *   autoloader registers, so with the extension active every reference to
  *   the original class name transparently resolves to the native
  *   implementation.
diff --git a/src/DependencyInjection/Configurator.php b/src/DependencyInjection/Configurator.php
index 7865956266b..d31fa7e97af 100644
--- a/src/DependencyInjection/Configurator.php
+++ b/src/DependencyInjection/Configurator.php
@@ -105,7 +105,12 @@ public function loadContainer(): string
 			is_file($attributesPhp) ? hash_file('sha256', $attributesPhp) : 'attributes-missing',
 			NeonAdapter::CACHE_KEY,
 			$this->getAllConfigFilesHashes(),
-			var_export(TurboExtensionEnabler::isLoaded(), true),
+			// the stubs, not the extension: a shadowed service class is
+			// reflected while the container compiles, so a container built
+			// against the stub shells must not be reused by a run that loaded
+			// the extension but left it inactive (version mismatch,
+			// PHPSTAN_TURBO=0) and reflects the PHP implementations instead
+			var_export(TurboExtensionEnabler::isActive(), true),
 		];
 
 		$className = $loader->load(
diff --git a/src/Turbo/ShadowedByTurboExtension.php b/src/Turbo/ShadowedByTurboExtension.php
index 45b1ed6e2c7..adaedecc627 100644
--- a/src/Turbo/ShadowedByTurboExtension.php
+++ b/src/Turbo/ShadowedByTurboExtension.php
@@ -12,7 +12,9 @@
  *
  * On composer dump-autoload, build/generate-turbo-stubs.php collects these
  * attributes and generates vendor/turbo-stubs.php — an empty stub shell per
- * class extending the native one — which TurboExtensionEnabler declares
+ * class extending the native one and repeating its implements clause (a
+ * parent class is rejected: the shell has no inheritance slot left for it)
+ * — which TurboExtensionEnabler declares
  * before the Composer autoloader registers when the extension is active,
  * plus vendor/turbo-shadowed-classes.json — the manifest of shadowed pairs
  * read by the enabler, the compiler's preload builder, and the parity
diff --git a/src/Turbo/TurboExtensionEnabler.php b/src/Turbo/TurboExtensionEnabler.php
index c41df8b63c8..691c31e90ce 100644
--- a/src/Turbo/TurboExtensionEnabler.php
+++ b/src/Turbo/TurboExtensionEnabler.php
@@ -20,7 +20,7 @@ final class TurboExtensionEnabler
 	 * version is the short SHA of the last commit touching turbo-ext/src/,
 	 * enforced by the phar.yml turbo-version job.
 	 */
-	public const EXPECTED_EXTENSION_VERSION = '2d4b432';
+	public const EXPECTED_EXTENSION_VERSION = 'e9ce4dc';
 
 	private static bool $typeCombinatorCacheEnabled = false;
 
diff --git a/turbo-ext/CLAUDE.md b/turbo-ext/CLAUDE.md
index 35bd68784c9..5ac6b02b315 100644
--- a/turbo-ext/CLAUDE.md
+++ b/turbo-ext/CLAUDE.md
@@ -21,9 +21,12 @@ being ≥0.5% faster is. When the estimate is marginal, don't port.
    `grep "\$this->foo"` in double quotes sends `\$` to grep and silently
    matches nothing — use single quotes). Run the full test suite now, before
    any native work.
-2. **Check it is not a DI service** (rule 6 in README — this is fatal and
-   was measured at 617 broken tests). Value classes and manually-instantiated
-   classes are safe.
+2. **Check it has no parent class** — the stub shell extends the native
+   class and PHP is single-inheritance, so the collector rejects it. If it is
+   a DI service, its native `__construct` arginfo must declare the real
+   parameter class names (rule 6 in README): Nette autowires by reflecting
+   the constructor, and erased types fail container compilation for every
+   shadowed service at once.
 3. **Implement natively**: one class per `.cpp` in `src/`, namespace
    `PHPStanTurbo`, class **non-final**, `instanceof`-style checks instead of
    exact class-entry comparisons. Hot classes are registered with the raw
diff --git a/turbo-ext/README.md b/turbo-ext/README.md
index a62acb3b47c..630b721846f 100644
--- a/turbo-ext/README.md
+++ b/turbo-ext/README.md
@@ -56,6 +56,12 @@ Every shadowed piece of PHP code follows the same three steps:
    per class, `final class Foo extends \PHPStanTurbo\Foo {}` (shadowed
    classes living in vendor/ cannot carry the attribute and are hardcoded in
    `build/TurboAttributeCollector.php`; currently `PhpParser\NodeTraverser`).
+   The shell repeats the class's own `implements` clause, because it inherits
+   from the native class alone — an interface left off it silently stops
+   matching `instanceof` and DI type lookups — and `require`s the interface
+   sources, which the autoloader cannot yet provide at that point. A parent
+   class cannot survive the same way (PHP is single-inheritance), so the
+   collector rejects a shadowed class that has one.
    When the extension
    is enabled, `PHPStan\Turbo\TurboExtensionEnabler` `require`s that file
    *before* the Composer autoloader registers. All PHP code keeps calling
@@ -336,9 +342,13 @@ Measured in the July 2026 benchmarks (callback-free absorptions gained
    call is exactly the per-element boundary cost these rules forbid. (The
    extension originally hosted its lifecycle in PHP-CPP; it is a plain Zend
    module since the Windows port.)
-6. **Never shadow a DI-service class.** Nette's `getByType()` normalizes
-   requested types through reflection to the real class name and breaks
-   containers cached in the other mode.
+6. **A shadowed DI-service class has to stay autowirable.** Nette reflects
+   `__construct` while it compiles the container, so the native arginfo must
+   declare the real parameter class names — erasing them fails container
+   compilation for every shadowed service at once. (Aliasing a service class
+   is what genuinely cannot work: `getByType()` normalizes the requested type
+   through reflection to the real class name. The stub shells are subclasses
+   carrying the original name, so that does not apply to them.)
 7. **Every port must prove itself**: interleaved A/B benchmark on a long run
    (user CPU, result cache cleared) plus a byte-identical output diff. Ports
    measuring ≤0.5% get reverted — the failure mode is silent no-gain, and
diff --git a/turbo-ext/src/NodeTraverser.cpp b/turbo-ext/src/NodeTraverser.cpp
index 22b7cb0aa20..4c6a991646e 100644
--- a/turbo-ext/src/NodeTraverser.cpp
+++ b/turbo-ext/src/NodeTraverser.cpp
@@ -877,13 +877,16 @@ void pt_register_node_traverser()
 		}
 	});
 
+	static const reg::Arg voidReturn = { "", MAY_BE_VOID, nullptr };
+	static const reg::Arg arrayReturn = reg::arrayArg("");
+
 	cls.method("addVisitor", reg::Public, 1, { reg::obj("visitor", NODE_VISITOR_CLASS) }, [](INTERNAL_FUNCTION_PARAMETERS) {
 		zval *visitor;
 		ZEND_PARSE_PARAMETERS_START(1, 1)
 			Z_PARAM_OBJECT(visitor)
 		ZEND_PARSE_PARAMETERS_END();
 		NodeTraverser(Z_OBJ_P(ZEND_THIS)).addVisitor(zv::Ref(visitor));
-	});
+	}, &voidReturn);
 
 	cls.method("removeVisitor", reg::Public, 1, { reg::obj("visitor", NODE_VISITOR_CLASS) }, [](INTERNAL_FUNCTION_PARAMETERS) {
 		zval *visitor;
@@ -891,7 +894,7 @@ void pt_register_node_traverser()
 			Z_PARAM_OBJECT(visitor)
 		ZEND_PARSE_PARAMETERS_END();
 		NodeTraverser(Z_OBJ_P(ZEND_THIS)).removeVisitor(zv::Ref(visitor));
-	});
+	}, &voidReturn);
 
 	cls.method("traverse", reg::Public, 1, { reg::arrayArg("nodes") }, [](INTERNAL_FUNCTION_PARAMETERS) {
 		HashTable *nodes;
@@ -904,7 +907,7 @@ void pt_register_node_traverser()
 			RETURN_THROWS();
 		}
 		result.intoReturnValue(return_value);
-	});
+	}, &arrayReturn);
 
 	pt_ce_node_traverser = cls.register_();
 }
diff --git a/turbo-ext/src/reg.h b/turbo-ext/src/reg.h
index dc103002dba..2e0c2f561f1 100644
--- a/turbo-ext/src/reg.h
+++ b/turbo-ext/src/reg.h
@@ -116,14 +116,16 @@ class Class
 	 * requiredArgs is ZEND_BEGIN_ARG_INFO_EX's required_num_args; args carry
 	 * name/type/by-ref/variadic exactly as the ZEND_ARG_* macros would.
 	 */
-	Class &method(const char *methodName, uint32_t flags, uint32_t requiredArgs, std::initializer_list<Arg> args, zif_handler handler)
+	Class &method(const char *methodName, uint32_t flags, uint32_t requiredArgs, std::initializer_list<Arg> args, zif_handler handler, const Arg *returns = NULL)
 	{
 		/* arginfo array: slot 0 is the return-info slot carrying the
-		 * required-args count, exactly as ZEND_BEGIN_ARG_INFO_EX emits */
+		 * required-args count, exactly as ZEND_BEGIN_ARG_INFO_EX emits.
+		 * A declared return type goes in the same slot's type — needed only
+		 * where the engine enforces it (implementing a userland interface). */
 		auto *argInfo = (zend_internal_arg_info *) pemalloc(sizeof(zend_internal_arg_info) * (args.size() + 1), 1);
 		argInfo[0].name = (const char *) (uintptr_t) requiredArgs;
-		argInfo[0].type.ptr = NULL;
-		argInfo[0].type.type_mask = 0;
+		argInfo[0].type.ptr = returns != NULL ? (void *) returns->className : NULL;
+		argInfo[0].type.type_mask = returns != NULL ? returns->typeMask : 0;
 		argInfo[0].default_value = NULL;
 		size_t i = 1;
 		for (const Arg &arg : args) {