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, 145 insertions, 0 deletions

diff --git a/crates/shirabe-php-rpc/php/guards/Composer/DependencyResolver/Decisions.php b/crates/shirabe-php-rpc/php/guards/Composer/DependencyResolver/Decisions.php
new file mode 100644
index 00000000..21d44992
--- /dev/null
+++ b/crates/shirabe-php-rpc/php/guards/Composer/DependencyResolver/Decisions.php
@@ -0,0 +1,145 @@
+<?php
+
+// Generated by scripts/plugin-stub-generator; do not edit by hand.
+// Guard for Composer\DependencyResolver\Decisions.
+// 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\DependencyResolver;
+
+class Decisions implements \Iterator, \Countable
+{
+    public const DECISION_LITERAL = 0;
+    public const DECISION_REASON = 1;
+
+    public function __construct(Pool $pool)
+    {
+        \ShirabeUnsupportedClass::fail(self::class, '__construct');
+    }
+
+    public function decide(int $literal, int $level, Rule $why): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'decide');
+    }
+
+    public function satisfy(int $literal): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'satisfy');
+    }
+
+    public function conflict(int $literal): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'conflict');
+    }
+
+    public function decided(int $literalOrPackageId): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'decided');
+    }
+
+    public function undecided(int $literalOrPackageId): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'undecided');
+    }
+
+    public function decidedInstall(int $literalOrPackageId): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'decidedInstall');
+    }
+
+    public function decisionLevel(int $literalOrPackageId): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'decisionLevel');
+    }
+
+    public function decisionRule(int $literalOrPackageId): Rule
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'decisionRule');
+    }
+
+    public function atOffset(int $queueOffset): array
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'atOffset');
+    }
+
+    public function validOffset(int $queueOffset): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'validOffset');
+    }
+
+    public function lastReason(): Rule
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'lastReason');
+    }
+
+    public function lastLiteral(): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'lastLiteral');
+    }
+
+    public function reset(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'reset');
+    }
+
+    public function resetToOffset(int $offset): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'resetToOffset');
+    }
+
+    public function revertLast(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'revertLast');
+    }
+
+    public function count(): int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'count');
+    }
+
+    public function rewind(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'rewind');
+    }
+
+    public function current()
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'current');
+    }
+
+    public function key(): ?int
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'key');
+    }
+
+    public function next(): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'next');
+    }
+
+    public function valid(): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'valid');
+    }
+
+    public function isEmpty(): bool
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'isEmpty');
+    }
+
+    protected function addDecision(int $literal, int $level): void
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'addDecision');
+    }
+
+    public function toString(?Pool $pool = null): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, 'toString');
+    }
+
+    public function __toString(): string
+    {
+        \ShirabeUnsupportedClass::fail(self::class, '__toString');
+    }
+}