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, 113 insertions, 0 deletions

diff --git a/crates/shirabe-php-rpc/php/guards/Composer/Package/Locker.php b/crates/shirabe-php-rpc/php/guards/Composer/Package/Locker.php
new file mode 100644
index 00000000..4009f162
--- /dev/null
+++ b/crates/shirabe-php-rpc/php/guards/Composer/Package/Locker.php
@@ -0,0 +1,113 @@
+<?php
+
+// Generated by scripts/plugin-stub-generator; do not edit by hand.
+// Guard for Composer\Package\Locker.
+// 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\Package;
+
+use Composer\Json\JsonFile;
+use Composer\Installer\InstallationManager;
+use Composer\Repository\LockArrayRepository;
+use Composer\Util\ProcessExecutor;
+use Composer\IO\IOInterface;
+
+class Locker
+{
+    public function __construct(IOInterface $io, JsonFile $lockFile, InstallationManager $installationManager, string $composerFileContents, ?ProcessExecutor $process = null)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, '__construct');
+    }
+
+    public function getJsonFile(): JsonFile
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getJsonFile');
+    }
+
+    public static function getContentHash(string $composerFileContents): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getContentHash');
+    }
+
+    public function isLocked(): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isLocked');
+    }
+
+    public function isFresh(): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isFresh');
+    }
+
+    public function getLockedRepository(bool $withDevReqs = false): LockArrayRepository
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getLockedRepository');
+    }
+
+    public function getDevPackageNames(): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getDevPackageNames');
+    }
+
+    public function getPlatformRequirements(bool $withDevReqs = false): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPlatformRequirements');
+    }
+
+    public function getMinimumStability(): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getMinimumStability');
+    }
+
+    public function getStabilityFlags(): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getStabilityFlags');
+    }
+
+    public function getPreferStable(): ?bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPreferStable');
+    }
+
+    public function getPreferLowest(): ?bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPreferLowest');
+    }
+
+    public function getPlatformOverrides(): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPlatformOverrides');
+    }
+
+    public function getAliases(): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getAliases');
+    }
+
+    public function getPluginApi()
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getPluginApi');
+    }
+
+    public function getLockData(): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getLockData');
+    }
+
+    public function setLockData(array $packages, ?array $devPackages, array $platformReqs, array $platformDevReqs, array $aliases, string $minimumStability, array $stabilityFlags, bool $preferStable, bool $preferLowest, array $platformOverrides, bool $write = true): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'setLockData');
+    }
+
+    public function updateHash(JsonFile $composerJson, ?callable $dataProcessor = null): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'updateHash');
+    }
+
+    public function getMissingRequirementInfo(RootPackageInterface $package, bool $includeDev): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getMissingRequirementInfo');
+    }
+}