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, 114 insertions, 0 deletions

diff --git a/crates/shirabe-php-rpc/php/guards/Composer/Util/ProcessExecutor.php b/crates/shirabe-php-rpc/php/guards/Composer/Util/ProcessExecutor.php
new file mode 100644
index 00000000..405905e8
--- /dev/null
+++ b/crates/shirabe-php-rpc/php/guards/Composer/Util/ProcessExecutor.php
@@ -0,0 +1,114 @@
+<?php
+
+// Generated by scripts/plugin-stub-generator; do not edit by hand.
+// Guard for Composer\Util\ProcessExecutor.
+// 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;
+
+use Composer\IO\IOInterface;
+use React\Promise\PromiseInterface;
+
+class ProcessExecutor
+{
+    private const STATUS_QUEUED = 1;
+    private const STATUS_STARTED = 2;
+    private const STATUS_COMPLETED = 3;
+    private const STATUS_FAILED = 4;
+    private const STATUS_ABORTED = 5;
+    private const BUILTIN_CMD_COMMANDS = [
+        'assoc', 'break', 'call', 'cd', 'chdir', 'cls', 'color', 'copy', 'date',
+        'del', 'dir', 'echo', 'endlocal', 'erase', 'exit', 'for', 'ftype', 'goto',
+        'help', 'if', 'label', 'md', 'mkdir', 'mklink', 'move', 'path', 'pause',
+        'popd', 'prompt', 'pushd', 'rd', 'rem', 'ren', 'rename', 'rmdir', 'set',
+        'setlocal', 'shift', 'start', 'time', 'title', 'type', 'ver', 'vol',
+    ];
+    private const GIT_CMDS_NEED_GIT_DIR = [
+        ['show'],
+        ['log'],
+        ['branch'],
+        ['remote', 'set-url'],
+    ];
+
+    public function __construct(?IOInterface $io = null)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, '__construct');
+    }
+
+    public function execute($command, &$output = null, ?string $cwd = null): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'execute');
+    }
+
+    public function executeTty($command, ?string $cwd = null): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'executeTty');
+    }
+
+    public function executeAsync($command, ?string $cwd = null): PromiseInterface
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'executeAsync');
+    }
+
+    protected function outputHandler(string $type, string $buffer): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'outputHandler');
+    }
+
+    public function setMaxJobs(int $maxJobs): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'setMaxJobs');
+    }
+
+    public function resetMaxJobs(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'resetMaxJobs');
+    }
+
+    public function wait($index = null): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'wait');
+    }
+
+    public function enableAsync(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'enableAsync');
+    }
+
+    public function countActiveJobs($index = null): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'countActiveJobs');
+    }
+
+    public function splitLines(?string $output): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'splitLines');
+    }
+
+    public function getErrorOutput(): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getErrorOutput');
+    }
+
+    public static function getTimeout(): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'getTimeout');
+    }
+
+    public static function setTimeout(int $timeout): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'setTimeout');
+    }
+
+    public static function escape($argument): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'escape');
+    }
+
+    public function requiresGitDirEnv($command): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'requiresGitDirEnv');
+    }
+}