fix(plugin): resolve review findings in the plugin activation flow

InstallationManager::execute now takes &self (the mock recorder moved
into a RefCell) and its callers hold only shared borrows: plugin
registration inside a batch re-enters the same manager handle through
Composer::getInstallationManager()->getInstallPath(), which panicked
on the RefCell re-borrow under the &mut shape — the same re-entrancy
the repository side already fixed, unreachable from the ported tests
because they call PluginInstaller::install directly like PHPUnit does.

The worker-side InstalledVersions mirror now matches the full tail of
FilesystemRepository::write: unconditional reload plus the
reflection-based selfDir/installedIsLocalDir restore. The previous
class_exists(false) guard rested on a lazy-load assumption that does
not hold in the worker (its real ClassLoader only knows the Composer
checkout's vendor dir, so a later lazy load would read the checkout's
installed.php, not the project's); the mirror is now skipped only when
the class is not autoloadable at all, i.e. no plugin runtime and hence
no observer code. Boot-time seeding stays TODO(plugin).

Also from the review: registered_plugins entries are removed only
after the deactivate/uninstall loop (PHP unsets last, and a throw must
leave the entry observable); extra.class keeps associative-array
values and fails loudly on non-strings instead of silently dropping
them; the two discarded write() results now propagate (they carry the
reload-push failure); register_package's allow-plugins skip message is
DEBUG like the addPlugin side; the loader-eviction divergence of
REGISTERED_LOADERS and the lossy UTF-8 spots carry searchable
markers; the test-only proxy downcast follows the __ naming rule; the
R-table dispatch clones the entity out instead of holding the table
borrow across the handler; the IO/PartialComposer stubs turn a
plugin-side `new NullIO()` into an explicit error instead of an
ArgumentCountError; and the empty() emulation covers float 0.0.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/docs/dev/php-rpc.md b/docs/dev/php-rpc.md
index c43fdfd5..f8f42e90 100644
--- a/docs/dev/php-rpc.md
+++ b/docs/dev/php-rpc.md
@@ -122,9 +122,10 @@ function; an unknown name is an explicit error. Notable internal helpers:
 - `__shirabe_composer_require` — the body of `\Composer\Autoload\composerRequire`, sharing
   its `$GLOBALS['__composer_autoload_files']` guard (files-autoload entries of plugin
   packages).
-- `__shirabe_installed_versions_reload` — mirrors `FilesystemRepository::write`'s in-process
-  `InstalledVersions::reload($versions)` into the worker; guarded by
-  `class_exists(..., false)` so an unloaded class keeps its upstream lazy-load behavior.
+- `__shirabe_installed_versions_reload` — mirrors the tail of `FilesystemRepository::write`
+  (the unconditional `InstalledVersions::reload($versions)` plus the reflection-based
+  `selfDir`/`installedIsLocalDir` restore) into the worker; skipped only when the class is not
+  even autoloadable there, i.e. no Composer PHP runtime and therefore no observer code.
 - `__shirabe_get_property` — for testing only: reads a public property of a P-table entity.
 - `__shirabe_oracle_roundtrip` — codec oracle support for tests.