feat(plugin): guard Rust-owned classes the worker has no proxy for

The worker's autoloader fell through to the real Composer source for every
Rust-owned FQCN without a proxy stub, so plugin code doing `new Filesystem()`
or subclassing `LibraryInstaller` silently ran on a second instance the Rust
side never sees. An unimplemented part of the plugin API has to fail with an
explicit error naming it, not quietly work on a disconnected copy.

The stub generator now emits a guard class for each of those FQCNs: the real
declaration, hierarchy and constants, with every constructor and method
raising an explicit error. References satisfied by the declaration alone
(`instanceof`, `X::class`, `Link::TYPE_REQUIRE`) keep working. Two FQCNs stay
resolvable to the real class, each listed with the worker-side mechanism that
makes a natively constructed instance correct.

The error had nowhere to go: `Installer::run` dropped the `Result` of both
`dispatch_script` calls, so an exception from a listener ended in exit 0.
Both propagate now, the way the exception does upstream.

Three real-plugin E2E comparisons stop at a guard and are ignored, each
naming the class it needs.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 167 insertions, 0 deletions

diff --git a/crates/shirabe-php-rpc/php/guards/Composer/Util/Filesystem.php b/crates/shirabe-php-rpc/php/guards/Composer/Util/Filesystem.php
new file mode 100644
index 00000000..6d8dbb24
--- /dev/null
+++ b/crates/shirabe-php-rpc/php/guards/Composer/Util/Filesystem.php
@@ -0,0 +1,167 @@
+<?php
+
+// Generated by scripts/plugin-stub-generator; do not edit by hand.
+// Guard for Composer\Util\Filesystem.
+// The Rust side owns this class and the worker has no proxy for it, so this
+// declaration shadows the real one: the constants and the hierarchy stay, while
+// constructing it or calling anything on it raises an explicit error.
+
+namespace Composer\Util;
+
+class Filesystem
+{
+    public function __construct(?ProcessExecutor $executor = null)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, '__construct');
+    }
+
+    public function remove(string $file)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'remove');
+    }
+
+    public function isDirEmpty(string $dir)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isDirEmpty');
+    }
+
+    public function emptyDirectory(string $dir, bool $ensureDirectoryExists = true)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'emptyDirectory');
+    }
+
+    public function removeDirectory(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'removeDirectory');
+    }
+
+    public function removeDirectoryAsync(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'removeDirectoryAsync');
+    }
+
+    public function removeDirectoryPhp(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'removeDirectoryPhp');
+    }
+
+    public function ensureDirectoryExists(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'ensureDirectoryExists');
+    }
+
+    public function unlink(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'unlink');
+    }
+
+    public function rmdir(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'rmdir');
+    }
+
+    public function copyThenRemove(string $source, string $target)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'copyThenRemove');
+    }
+
+    public function copy(string $source, string $target)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'copy');
+    }
+
+    public function rename(string $source, string $target)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'rename');
+    }
+
+    public function findShortestPath(string $from, string $to, bool $directories = false, bool $preferRelative = false)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'findShortestPath');
+    }
+
+    public function findShortestPathCode(string $from, string $to, bool $directories = false, bool $staticCode = false, bool $preferRelative = false)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'findShortestPathCode');
+    }
+
+    public function isAbsolutePath(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isAbsolutePath');
+    }
+
+    public function size(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'size');
+    }
+
+    public function normalizePath(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'normalizePath');
+    }
+
+    public static function trimTrailingSlash(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'trimTrailingSlash');
+    }
+
+    public static function isLocalPath(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isLocalPath');
+    }
+
+    public static function getPlatformPath(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPlatformPath');
+    }
+
+    public static function isReadable(string $path)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isReadable');
+    }
+
+    protected function directorySize(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'directorySize');
+    }
+
+    protected function getProcess()
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getProcess');
+    }
+
+    public function relativeSymlink(string $target, string $link)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'relativeSymlink');
+    }
+
+    public function isSymlinkedDirectory(string $directory)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isSymlinkedDirectory');
+    }
+
+    public function junction(string $target, string $junction)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'junction');
+    }
+
+    public function isJunction(string $junction)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isJunction');
+    }
+
+    public function removeJunction(string $junction)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'removeJunction');
+    }
+
+    public function filePutContentsIfModified(string $path, string $content)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'filePutContentsIfModified');
+    }
+
+    public function safeCopy(string $source, string $target): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'safeCopy');
+    }
+}