diff --git a/tests/Instrument/Transformer/Php85AuditScratchTest.php b/tests/Instrument/Transformer/Php85AuditScratchTest.php
new file mode 100644
index 00000000..fbdc1106
--- /dev/null
+++ b/tests/Instrument/Transformer/Php85AuditScratchTest.php
@@ -0,0 +1,275 @@
+<?php
+
+declare(strict_types = 1);
+/*
+ * PHP 8.5 AUDIT HARNESS (temporary, lives only on the audit branch).
+ * Weaves PHP 8.1-8.5 feature fixtures from _files/audit through the real
+ * WeavingTransformer and validates that both the woven trait and the
+ * generated proxy still lint and preserve the feature under test.
+ */
+
+namespace Go\Instrument\Transformer;
+
+use Go\Aop\Advisor;
+use Go\Core\AdviceMatcherInterface;
+use Go\Core\AspectContainer;
+use Go\Core\AspectKernel;
+use Go\Core\AspectLoader;
+use Go\Instrument\ClassLoading\CachePathManager;
+use Go\VirtualFileSystem\FileSystem;
+use PHPUnit\Framework\Attributes\DataProvider;
+use PHPUnit\Framework\TestCase;
+use ReflectionClass;
+
+#[\PHPUnit\Framework\Attributes\AllowMockObjectsWithoutExpectations]
+class Php85AuditScratchTest extends TestCase
+{
+    private const FIXTURE_DIR = __DIR__ . '/../../Stubs';
+
+    /** Audit fixture stubs living in tests/Stubs alongside the general-purpose stubs. */
+    private const AUDIT_FIXTURES = [
+        'Collaborator',
+        'ConstAttr',
+        'ExprAttr',
+        'Php80ClassAttrPlain',
+        'Php80GlobalConstAttrArg',
+        'Php81EnumConstExprCases',
+        'Php81NewInInitializers',
+        'Php81NonScalarAttributeArgs',
+        'Php85CloneWith',
+        'Php85ClosuresInConstExpr',
+        'Php85ConstAttributes',
+        'Php85FinalPromotionAsymStatic',
+        'Php85NoDiscard',
+        'Php85PipeOperator',
+        'RichAttr',
+        'Status',
+    ];
+
+    protected static FileSystem $fileSystem;
+
+    protected WeavingTransformer $transformer;
+
+    protected ?AspectKernel $kernel;
+
+    protected ?CachePathManager $cachePathManager;
+
+    public static function setUpBeforeClass(): void
+    {
+        static::$fileSystem = FileSystem::mount('vfs');
+        if (!is_dir(self::outDir())) {
+            mkdir(self::outDir(), 0777, true);
+        }
+    }
+
+    private static function outDir(): string
+    {
+        return sys_get_temp_dir() . '/php85-audit-out';
+    }
+
+    public static function tearDownAfterClass(): void
+    {
+        static::$fileSystem->unmount();
+    }
+
+    public function setUp(): void
+    {
+        $container = $this->getContainerMock();
+        $loader    = $this
+            ->getMockBuilder(AspectLoader::class)
+            ->setConstructorArgs([$container])
+            ->getMock();
+
+        $this->kernel = $this->getKernelMock(
+            [
+                'appDir'        => dirname(__DIR__),
+                'cacheDir'      => 'vfs://',
+                'cacheFileMode' => 0770,
+                'includePaths'  => [],
+                'excludePaths'  => []
+            ],
+            $container
+        );
+        $this->cachePathManager = new CachePathManager($this->kernel);
+
+        $this->transformer = new WeavingTransformer(
+            $this->kernel,
+            $this->getInterceptEverythingMatcher(),
+            $this->cachePathManager,
+            $loader
+        );
+    }
+
+    /**
+     * @return array<string, array{string}>
+     */
+    public static function fixtureNames(): array
+    {
+        $names = [];
+        foreach (self::AUDIT_FIXTURES as $name) {
+            $names[$name] = [$name];
+        }
+
+        return $names;
+    }
+
+    /**
+     * Fixtures currently known to produce a broken weave, keyed to their tracking issue.
+     * A fix PR that resolves one of these MUST remove the entry (the test then asserts success).
+     */
+    private const KNOWN_GAPS = [
+        // #598-#603 are all fixed on master. Remaining follow-ups (#615/#616, fixed by PR #617):
+        // #[\Attribute] on a trait only became a compile error in PHP 8.5,
+        // so these three are gaps on 8.5+ but weave cleanly on 8.4
+        'ConstAttr'               => 'https://github.com/goaop/framework/issues/615',
+        'ExprAttr'                => 'https://github.com/goaop/framework/issues/615',
+        'RichAttr'                => 'https://github.com/goaop/framework/issues/615',
+        // new-in-initializer default copied onto the proxy hook property
+        'Php81NewInInitializers'  => 'https://github.com/goaop/framework/issues/616',
+    ];
+
+    /** Fixtures whose KNOWN_GAPS entry applies only on PHP >= 8.5 (see above). */
+    private const GAP_ONLY_ON_85 = ['ConstAttr' => true, 'ExprAttr' => true, 'RichAttr' => true];
+
+    #[DataProvider('fixtureNames')]
+    public function testWeaveAndLint(string $name): void
+    {
+        // 8.5-only syntax cannot lint (nor natively reflect) on older runtimes
+        if (str_starts_with($name, 'Php85') && PHP_VERSION_ID < 80500) {
+            $this->markTestSkipped('Fixture uses PHP 8.5 syntax');
+        }
+
+        $problems = $this->weaveAndCollectProblems($name);
+
+        $isKnownGap = isset(self::KNOWN_GAPS[$name])
+            && (!isset(self::GAP_ONLY_ON_85[$name]) || PHP_VERSION_ID >= 80500);
+
+        if ($isKnownGap) {
+            $issue = self::KNOWN_GAPS[$name];
+            $this->assertNotSame(
+                [],
+                $problems,
+                "$name weaves cleanly now — the gap tracked in $issue looks fixed. " .
+                'Remove it from KNOWN_GAPS so this stays asserted.'
+            );
+            $this->addToAssertionCount(1);
+
+            return;
+        }
+
+        $this->assertSame([], $problems, "$name should weave cleanly:\n" . implode("\n---\n", $problems));
+    }
+
+    /**
+     * @return list<string> Problems encountered (transform exception or lint failures); empty = clean weave
+     */
+    private function weaveAndCollectProblems(string $name): array
+    {
+        $metadata = $this->loadAuditMetadata($name);
+
+        try {
+            $this->transformer->transform($metadata);
+        } catch (\Throwable $e) {
+            file_put_contents(self::outDir() . "/$name.ERROR.txt", (string) $e);
+
+            return ["TRANSFORM ERROR: {$e->getMessage()}"];
+        }
+
+        $problems = [];
+        $woven    = $metadata->source;
+        file_put_contents(self::outDir() . "/$name-woven.php", $woven);
+        $problems = [...$problems, ...$this->lintProblems(self::outDir() . "/$name-woven.php", "$name woven trait")];
+
+        if (preg_match_all("/AOP_CACHE_DIR . '(.+)';$/m", $woven, $matches)) {
+            foreach ($matches[1] as $i => $proxyPath) {
+                $proxyContent = (string) file_get_contents('vfs://' . $proxyPath);
+                $suffix       = $i > 0 ? "-$i" : '';
+                file_put_contents(self::outDir() . "/$name-proxy$suffix.php", $proxyContent);
+                $problems = [...$problems, ...$this->lintProblems(self::outDir() . "/$name-proxy$suffix.php", "$name proxy #$i")];
+            }
+        }
+
+        return $problems;
+    }
+
+    /**
+     * @return list<string>
+     */
+    private function lintProblems(string $file, string $label): array
+    {
+        exec(escapeshellarg(PHP_BINARY) . ' -l ' . escapeshellarg($file) . ' 2>&1', $output, $code);
+        if ($code !== 0) {
+            return ["$label does not lint:\n" . implode("\n", $output)];
+        }
+
+        return [];
+    }
+
+    private function getInterceptEverythingMatcher(): AdviceMatcherInterface
+    {
+        $mock = $this->createMock(AdviceMatcherInterface::class);
+        $mock
+            ->method('getAdvicesForClass')
+            ->willReturnCallback(function (ReflectionClass $refClass) {
+                $advices = [];
+                foreach ($refClass->getMethods() as $method) {
+                    if ($method->getDeclaringClass()->name !== $refClass->name) {
+                        continue;
+                    }
+                    $advisorId = "advisor.{$refClass->name}->{$method->name}";
+                    $advices[AspectContainer::METHOD_PREFIX][$method->name][$advisorId] = true;
+                }
+                foreach ($refClass->getProperties() as $property) {
+                    if ($property->getDeclaringClass()->name !== $refClass->name) {
+                        continue;
+                    }
+                    // Mirror the real AdviceMatcher gates (static/readonly/hooked are not interceptable)
+                    if ($property->isStatic() || $property->isReadOnly() || $property->hasHooks()) {
+                        continue;
+                    }
+                    $advisorId = "advisor.{$refClass->name}->{$property->name}";
+                    $advices[AspectContainer::PROPERTY_PREFIX][$property->name][$advisorId] = true;
+                }
+                return $advices;
+            });
+        $mock->method('getAdvicesForFunctions')->willReturn([]);
+
+        return $mock;
+    }
+
+    protected function getKernelMock(array $options, AspectContainer $container): AspectKernel
+    {
+        $mock = $this->getMockBuilder(AspectKernel::class)
+            ->disableOriginalConstructor()
+            ->onlyMethods(['configureAop', 'getOptions', 'getContainer', 'hasFeature'])
+            ->getMock();
+
+        $mock->method('getOptions')->willReturn($options);
+        $mock->method('getContainer')->willReturn($container);
+
+        return $mock;
+    }
+
+    private function loadAuditMetadata(string $name): StreamMetaData
+    {
+        $fileName = self::FIXTURE_DIR . '/' . $name . '.php';
+        $stream   = fopen('php://filter/string.tolower/resource=' . $fileName, 'r');
+        $source   = file_get_contents($fileName);
+        $metadata = new StreamMetaData($stream, $source);
+        fclose($stream);
+
+        return $metadata;
+    }
+
+    private function getContainerMock(): AspectContainer
+    {
+        $container = $this->createMock(AspectContainer::class);
+        $container
+            ->method('getServicesByInterface')
+            ->willReturnMap([
+                [Advisor::class, []]
+            ]);
+
+        return $container;
+    }
+}
diff --git a/tests/Stubs/Collaborator.php b/tests/Stubs/Collaborator.php
new file mode 100644
index 00000000..ca9e5775
--- /dev/null
+++ b/tests/Stubs/Collaborator.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Collaborator
+{
+    public function __construct(public string $tag = 'default')
+    {
+    }
+}
diff --git a/tests/Stubs/ConstAttr.php b/tests/Stubs/ConstAttr.php
new file mode 100644
index 00000000..d2381b7f
--- /dev/null
+++ b/tests/Stubs/ConstAttr.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[\Attribute(\Attribute::TARGET_CONSTANT | \Attribute::TARGET_CLASS_CONSTANT)]
+class ConstAttr
+{
+    public function __construct(public string $reason = '')
+    {
+    }
+}
diff --git a/tests/Stubs/ExprAttr.php b/tests/Stubs/ExprAttr.php
new file mode 100644
index 00000000..42465dc0
--- /dev/null
+++ b/tests/Stubs/ExprAttr.php
@@ -0,0 +1,13 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[\Attribute(\Attribute::TARGET_ALL)]
+class ExprAttr
+{
+    public function __construct(public mixed $value = null)
+    {
+    }
+}
diff --git a/tests/Stubs/Php80ClassAttrPlain.php b/tests/Stubs/Php80ClassAttrPlain.php
new file mode 100644
index 00000000..4cd358b9
--- /dev/null
+++ b/tests/Stubs/Php80ClassAttrPlain.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[ExprAttr]
+class Php80ClassAttrPlain
+{
+    public function run(): int
+    {
+        return 42;
+    }
+}
diff --git a/tests/Stubs/Php80GlobalConstAttrArg.php b/tests/Stubs/Php80GlobalConstAttrArg.php
new file mode 100644
index 00000000..430152c2
--- /dev/null
+++ b/tests/Stubs/Php80GlobalConstAttrArg.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php80GlobalConstAttrArg
+{
+    #[ExprAttr(PHP_INT_MAX)]
+    public function limited(): int
+    {
+        return PHP_INT_MAX;
+    }
+}
diff --git a/tests/Stubs/Php81EnumConstExprCases.php b/tests/Stubs/Php81EnumConstExprCases.php
new file mode 100644
index 00000000..96501ebf
--- /dev/null
+++ b/tests/Stubs/Php81EnumConstExprCases.php
@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+enum Php81EnumConstExprCases: int
+{
+    private const int SHIFT = 2;
+
+    case Negative = -1;
+    case Shifted = 1 << 2;
+    case FromConst = self::SHIFT + 10;
+
+    public function describe(): string
+    {
+        return $this->name . '=' . $this->value;
+    }
+}
diff --git a/tests/Stubs/Php81NewInInitializers.php b/tests/Stubs/Php81NewInInitializers.php
new file mode 100644
index 00000000..a596a4a9
--- /dev/null
+++ b/tests/Stubs/Php81NewInInitializers.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php81NewInInitializers
+{
+    public function __construct(
+        private Collaborator $service = new Collaborator('ctor-default'),
+    ) {
+    }
+
+    public function run(Collaborator $helper = new Collaborator('method-default')): string
+    {
+        static $memo = new \ArrayObject();
+
+        return $this->service->tag . '/' . $helper->tag;
+    }
+}
diff --git a/tests/Stubs/Php81NonScalarAttributeArgs.php b/tests/Stubs/Php81NonScalarAttributeArgs.php
new file mode 100644
index 00000000..a870d35b
--- /dev/null
+++ b/tests/Stubs/Php81NonScalarAttributeArgs.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[RichAttr(Status::Active, new \ArrayObject([1, 2]))]
+class Php81NonScalarAttributeArgs
+{
+    #[RichAttr(Status::Disabled, 123)]
+    public function tagged(#[RichAttr(Status::Active)] int $x = 8): int
+    {
+        return $x;
+    }
+}
diff --git a/tests/Stubs/Php85CloneWith.php b/tests/Stubs/Php85CloneWith.php
new file mode 100644
index 00000000..1cbaef4e
--- /dev/null
+++ b/tests/Stubs/Php85CloneWith.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php85CloneWith
+{
+    public function __construct(
+        public string $name = 'initial',
+        public int $count = 0,
+    ) {
+    }
+
+    public function withName(string $name): static
+    {
+        return clone($this, ['name' => $name]);
+    }
+
+    public function bump(): static
+    {
+        return clone($this, ['count' => $this->count + 1, 'name' => $this->name . '+']);
+    }
+}
diff --git a/tests/Stubs/Php85ClosuresInConstExpr.php b/tests/Stubs/Php85ClosuresInConstExpr.php
new file mode 100644
index 00000000..0742f3f6
--- /dev/null
+++ b/tests/Stubs/Php85ClosuresInConstExpr.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[ExprAttr(static function (int $x): int { return $x * 2; })]
+class Php85ClosuresInConstExpr
+{
+    public const \Closure UPPER = strtoupper(...);
+
+    public const \Closure DOUBLER = static function (int $x): int {
+        return $x * 2;
+    };
+
+    #[ExprAttr(strlen(...))]
+    public function withClosureDefaults(
+        \Closure $normalizer = trim(...),
+        \Closure $mapper = static function (int $v): int {
+            return $v + 1;
+        },
+    ): string {
+        return ($normalizer)(' hello ');
+    }
+}
diff --git a/tests/Stubs/Php85ConstAttributes.php b/tests/Stubs/Php85ConstAttributes.php
new file mode 100644
index 00000000..dc55349e
--- /dev/null
+++ b/tests/Stubs/Php85ConstAttributes.php
@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php85ConstAttributes
+{
+    #[ConstAttr('class constant attribute')]
+    public const string LABEL = 'label';
+
+    #[\Deprecated(message: 'use LABEL')]
+    public const string OLD_LABEL = 'old';
+
+    public function getLabel(): string
+    {
+        return self::LABEL;
+    }
+}
diff --git a/tests/Stubs/Php85FinalPromotionAsymStatic.php b/tests/Stubs/Php85FinalPromotionAsymStatic.php
new file mode 100644
index 00000000..0b23d671
--- /dev/null
+++ b/tests/Stubs/Php85FinalPromotionAsymStatic.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php85FinalPromotionAsymStatic
+{
+    public static private(set) int $instances = 0;
+
+    public function __construct(
+        final public string $identity = 'anon',
+        public private(set) int $version = 1,
+    ) {
+        self::$instances++;
+    }
+
+    public function describe(): string
+    {
+        return $this->identity . '#' . $this->version;
+    }
+}
diff --git a/tests/Stubs/Php85NoDiscard.php b/tests/Stubs/Php85NoDiscard.php
new file mode 100644
index 00000000..f2d266d2
--- /dev/null
+++ b/tests/Stubs/Php85NoDiscard.php
@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php85NoDiscard
+{
+    #[\NoDiscard('result must be used')]
+    public function computeTotal(int $a, int $b): int
+    {
+        return $a + $b;
+    }
+
+    public function caller(): int
+    {
+        return $this->computeTotal(1, 2);
+    }
+}
diff --git a/tests/Stubs/Php85PipeOperator.php b/tests/Stubs/Php85PipeOperator.php
new file mode 100644
index 00000000..dd9b7596
--- /dev/null
+++ b/tests/Stubs/Php85PipeOperator.php
@@ -0,0 +1,21 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+class Php85PipeOperator
+{
+    public function transform(string $input): string
+    {
+        return $input
+            |> trim(...)
+            |> (fn(string $x) => strtoupper($x))
+            |> strrev(...);
+    }
+
+    public function withNewOnRhs(string $value): \ArrayObject
+    {
+        return [$value] |> (fn(array $items) => new \ArrayObject($items));
+    }
+}
diff --git a/tests/Stubs/RichAttr.php b/tests/Stubs/RichAttr.php
new file mode 100644
index 00000000..e67e19f9
--- /dev/null
+++ b/tests/Stubs/RichAttr.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+#[\Attribute(\Attribute::TARGET_ALL)]
+class RichAttr
+{
+    public function __construct(
+        public mixed $value = null,
+        public mixed $extra = null,
+    ) {
+    }
+}
diff --git a/tests/Stubs/Status.php b/tests/Stubs/Status.php
new file mode 100644
index 00000000..f7d9790d
--- /dev/null
+++ b/tests/Stubs/Status.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Go\Stubs;
+
+enum Status: string
+{
+    case Active = 'active';
+    case Disabled = 'disabled';
+}