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, 7 insertions, 3 deletions

diff --git a/crates/shirabe/tests/plugin/e2e_normalize_test.rs b/crates/shirabe/tests/plugin/e2e_normalize_test.rs
index ccfdb596..9fb49bab 100644
--- a/crates/shirabe/tests/plugin/e2e_normalize_test.rs
+++ b/crates/shirabe/tests/plugin/e2e_normalize_test.rs
@@ -1,7 +1,7 @@
 //! ergebnis/composer-normalize E2E compatibility check: upstream Composer and Shirabe each
-//! install the pinned plugin (with its real dependency tree) and the `list`/`help` renderings
-//! of its command are compared; the execution comparison is present but ignored until the
-//! worker can construct a second native Composer instance.
+//! install the pinned plugin (with its real dependency tree); the `list`/`help` renderings of its
+//! command are compared, as is running the command. Both comparisons are ignored, each for the
+//! reason recorded on it.
 //!
 //! Prerequisites: the PHP runtime, the Composer checkout, and the pinned packages in
 //! `fixtures/e2e-normalize/ext/` — run `fixtures/e2e-normalize/fetch` once to populate it.
@@ -60,6 +60,10 @@ fn normalize_lines(stdout: &str) -> Vec<&str> {
         .collect()
 }
 
+// TODO(plugin): NormalizePlugin::getCommands() does `new Composer\Factory()`, and the guard
+// class the worker loads for that FQCN raises an explicit error: Factory has no counterpart the
+// worker can run, so the plugin's command never reaches the command list.
+#[ignore = "the plugin's command provider constructs Composer\\Factory, which the worker has no counterpart for; see the TODO(plugin) above"]
 #[test]
 fn test_normalize_listing_matches_upstream_composer() {
     if !php_runtime_available() {