feat(plugin): run plugin-provided installers through the RPC worker

A plugin can now hand an InstallerInterface implementation to
InstallationManager::addInstaller across the wire, and a legacy
composer-installer package is loaded as one; both are backed by a
PhpInstallerProxy forwarding the whole installer contract to the entity in
the PHP worker. An installer returning a real promise is an explicit error
until promises can cross the boundary.

InstallationManager takes installers as shared handles instead of boxes, so
the object identity removeInstaller and PluginManager's registeredPlugins
compare against survives registration, and holds them in a RefCell:
Installer::run keeps a shared borrow of the manager for the whole run, and a
plugin activated inside it registers its installer from there. The type
cache keys on the installer itself, like upstream, so re-entrant
registration cannot leave a stale index behind. InstallerInterface::supports
is fallible for the same reason getCapabilities and getCommands are: it
answers over RPC.

Cloning a proxy stub clones the Rust-side entity and rebinds the copy to the
fresh handle. Previously only the classes declaring __clone got a throwing
body, and the rest let two stubs share (and twice release) one handle.
Package entities answer with AnyPackage::dup, which already carries
BasePackage::__clone and the RootAliasPackage override; the others are an
explicit error.

The package proxy covers the whole PackageInterface surface; only the link
maps and the release date still lack a wire image for their value objects.
PluginManager gains a test-only seam for the reported Plugin API version,
and the three PluginInstallerTest cases that need it are ported.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

1 files changed, 37 insertions, 39 deletions

diff --git a/crates/shirabe/src/installer/installation_manager.rs b/crates/shirabe/src/installer/installation_manager.rs
index 31bfaa2c..439026b0 100644
--- a/crates/shirabe/src/installer/installation_manager.rs
+++ b/crates/shirabe/src/installer/installation_manager.rs
@@ -33,12 +33,12 @@ pub struct InstallationManager {
     /// Rc rather than Box so `get_installer` can hand out shareable handles: the download/cleanup
     /// futures collected for Loop::wait must own their installer beyond the loop iteration that
     /// created them (PHP closures capture $installer the same way).
-    installers: Vec<std::rc::Rc<dyn InstallerInterface>>,
-    /// Maps a package type to the index of its installer in `installers`. PHP caches the installer
-    /// instance itself; here we store an index instead. The index never dangles because both
-    /// `add_installer` and `remove_installer` clear the cache whenever `installers` changes.
+    /// RefCell so a plugin activated from inside `execute` — which holds a shared borrow of this
+    /// manager for the whole run — can still register its own installer.
+    installers: std::cell::RefCell<Vec<std::rc::Rc<dyn InstallerInterface>>>,
+    /// Maps a package type to its installer.
     /// RefCell so lookups can populate the cache through `&self` from concurrent operation chains.
-    cache: std::cell::RefCell<IndexMap<String, usize>>,
+    cache: std::cell::RefCell<IndexMap<String, std::rc::Rc<dyn InstallerInterface>>>,
     /// RefCell so mark_for_notification works through `&self` from concurrent operation chains.
     notifiable_packages: std::cell::RefCell<IndexMap<String, Vec<PackageInterfaceHandle>>>,
     loop_: std::rc::Rc<std::cell::RefCell<Loop>>,
@@ -69,7 +69,7 @@ impl InstallationManager {
         event_dispatcher: Option<std::rc::Rc<std::cell::RefCell<EventDispatcher>>>,
     ) -> Self {
         Self {
-            installers: vec![],
+            installers: std::cell::RefCell::new(vec![]),
             cache: std::cell::RefCell::new(IndexMap::new()),
             notifiable_packages: std::cell::RefCell::new(IndexMap::new()),
             loop_,
@@ -133,30 +133,25 @@ impl InstallationManager {
     }
 
     /// Adds installer
-    pub fn add_installer(&mut self, installer: Box<dyn InstallerInterface>) {
-        array_unshift(&mut self.installers, std::rc::Rc::from(installer));
-        self.cache = std::cell::RefCell::new(IndexMap::new());
-    }
-
-    /// For testing only: adds an installer as a pre-built shared handle, so the caller keeps an
-    /// identity handle usable for PHP `assertSame`-style comparisons (`Rc::ptr_eq`) and for
-    /// `remove_installer`. `add_installer` cannot serve because `Rc::from(Box)` reallocates,
-    /// losing the caller's pointer identity.
-    pub fn __add_installer(&mut self, installer: std::rc::Rc<dyn InstallerInterface>) {
-        array_unshift(&mut self.installers, installer);
-        self.cache = std::cell::RefCell::new(IndexMap::new());
+    ///
+    /// The installer is taken as a shared handle: PHP hands over an object reference and both
+    /// sides keep the same identity afterwards, which `removeInstaller` and the plugin
+    /// manager's `registeredPlugins` bookkeeping compare against.
+    pub fn add_installer(&self, installer: std::rc::Rc<dyn InstallerInterface>) {
+        array_unshift(&mut self.installers.borrow_mut(), installer);
+        self.cache.borrow_mut().clear();
     }
 
     /// Removes installer
-    pub fn remove_installer(&mut self, installer: &dyn InstallerInterface) {
+    pub fn remove_installer(&self, installer: &dyn InstallerInterface) {
         let target = installer as *const dyn InstallerInterface as *const ();
-        let key = self
-            .installers
+        let mut installers = self.installers.borrow_mut();
+        let key = installers
             .iter()
             .position(|inst| &**inst as *const dyn InstallerInterface as *const () == target);
         if let Some(k) = key {
-            array_splice(&mut self.installers, k as i64, Some(1), vec![]);
-            self.cache = std::cell::RefCell::new(IndexMap::new());
+            array_splice(&mut installers, k as i64, Some(1), vec![]);
+            self.cache.borrow_mut().clear();
         }
     }
 
@@ -166,7 +161,9 @@ impl InstallationManager {
     /// disabling the PluginManager. This ensures that no third-party
     /// code is ever executed.
     pub fn disable_plugins(&mut self) {
-        for installer in self.installers.iter() {
+        // Cloned out: `disablePlugins` reaches into the plugin manager, which may reach back.
+        let installers = self.installers.borrow().clone();
+        for installer in installers.iter() {
             if let Some(plugin_installer) = installer.as_plugin_installer() {
                 plugin_installer.disable_plugins();
             }
@@ -180,17 +177,18 @@ impl InstallationManager {
     ) -> anyhow::Result<std::rc::Rc<dyn InstallerInterface>> {
         let r#type = strtolower(r#type);
 
-        if let Some(&index) = self.cache.borrow().get(&r#type) {
-            return Ok(self.installers[index].clone());
+        if let Some(installer) = self.cache.borrow().get(&r#type) {
+            return Ok(installer.clone());
         }
 
-        let index = self
-            .installers
-            .iter()
-            .position(|installer| installer.supports(&r#type));
-        if let Some(index) = index {
-            self.cache.borrow_mut().insert(r#type, index);
-            return Ok(self.installers[index].clone());
+        // Cloned out: a PHP-backed installer answers `supports` over RPC, and the plugin behind
+        // it can register a further installer from that call.
+        let installers = self.installers.borrow().clone();
+        for installer in installers {
+            if installer.supports(&r#type)? {
+                self.cache.borrow_mut().insert(r#type, installer.clone());
+                return Ok(installer);
+            }
         }
 
         Err(InvalidArgumentException {
@@ -1020,8 +1018,8 @@ pub trait InstallationManagerInterface: std::fmt::Debug {
         unimplemented!("as_any is only implemented for the concrete InstallationManager")
     }
 
-    fn add_installer(&mut self, installer: Box<dyn InstallerInterface>);
-    fn remove_installer(&mut self, installer: &dyn InstallerInterface);
+    fn add_installer(&self, installer: std::rc::Rc<dyn InstallerInterface>);
+    fn remove_installer(&self, installer: &dyn InstallerInterface);
     fn disable_plugins(&mut self);
     fn is_package_installed(
         &mut self,
@@ -1047,12 +1045,12 @@ impl InstallationManagerInterface for InstallationManager {
         self
     }
 
-    fn add_installer(&mut self, installer: Box<dyn InstallerInterface>) {
-        self.add_installer(installer);
+    fn add_installer(&self, installer: std::rc::Rc<dyn InstallerInterface>) {
+        InstallationManager::add_installer(self, installer);
     }
 
-    fn remove_installer(&mut self, installer: &dyn InstallerInterface) {
-        self.remove_installer(installer);
+    fn remove_installer(&self, installer: &dyn InstallerInterface) {
+        InstallationManager::remove_installer(self, installer);
     }
 
     fn disable_plugins(&mut self) {