refactor(registry): introduce Repository and InstallerExecutor traits

Sets up DI scaffolding for in-process installer E2E tests, mirroring how
Composer's PHPUnit suite swaps Packagist (FactoryMock) and the install
manager (InstallationManagerMock) without touching the network or filesystem.

Additions:
- Repository trait + RepositorySet (Composer's RepositoryInterface analog),
  with PackagistRepository, InlinePackageRepository, VcsRepository impls.
- InstallerExecutor trait (Composer's InstallationManager analog) with
  FilesystemExecutor extracted from install_from_lock.

install_from_lock now delegates per-package install/uninstall verbs to
FilesystemExecutor; console output orchestration stays in the caller so
existing --EXPECT-OUTPUT-shape assertions remain comparable. No behavior
change - all 136 enabled installer fixtures still pass.

Also tightens the installer_fixture\! ignore form to a single token
(installer_fixture\!(name, ignore)) for readability.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2 files changed, 306 insertions, 0 deletions

diff --git a/crates/mozart-registry/src/installer_executor/filesystem.rs b/crates/mozart-registry/src/installer_executor/filesystem.rs
new file mode 100644
index 0000000..82acc42
--- /dev/null
+++ b/crates/mozart-registry/src/installer_executor/filesystem.rs
@@ -0,0 +1,222 @@
+//! Production [`InstallerExecutor`] that touches the real filesystem.
+//!
+//! This is the verb behind `mozart install` / `mozart update` — it pulls
+//! dist archives via [`crate::downloader`], clones VCS sources via
+//! [`mozart_vcs`], and removes vendor directories. Test code substitutes a
+//! recording-only executor instead (added in a later step).
+
+use std::path::Path;
+
+use crate::cache::Cache;
+use crate::downloader;
+
+use super::{ExecuteContext, InstallerExecutor, PackageOperation};
+
+pub struct FilesystemExecutor {
+    files_cache: Cache,
+}
+
+impl FilesystemExecutor {
+    pub fn new(files_cache: Cache) -> Self {
+        Self { files_cache }
+    }
+}
+
+#[async_trait::async_trait]
+impl InstallerExecutor for FilesystemExecutor {
+    async fn install_package(
+        &mut self,
+        op: PackageOperation<'_>,
+        ctx: &ExecuteContext,
+    ) -> anyhow::Result<()> {
+        let pkg = op.package();
+
+        // Try source install if --prefer-source and source info is available.
+        if ctx.prefer_source
+            && let Some(source) = &pkg.source
+        {
+            return install_from_source(
+                &source.source_type,
+                &source.url,
+                source.reference.as_deref().unwrap_or("HEAD"),
+                &ctx.vendor_dir,
+                &pkg.name,
+            );
+        }
+
+        // A package with neither dist nor source has no install action.
+        // This covers Composer's `type: metapackage` (modeled explicitly as
+        // "no installer") and inline `type: package` definitions used in
+        // test fixtures that intentionally omit download metadata. Mozart
+        // records the operation and the installed.json entry but performs
+        // no filesystem work, mirroring Composer's MetapackageInstaller.
+        if pkg.dist.is_none() && pkg.source.is_none() {
+            return Ok(());
+        }
+
+        let dist = pkg.dist.as_ref().ok_or_else(|| {
+            anyhow::anyhow!(
+                "Package {} has no dist information. Use --prefer-source to install from VCS.",
+                pkg.name,
+            )
+        })?;
+
+        let mut progress = downloader::DownloadProgress::new(
+            !ctx.no_progress,
+            format!("{} ({})", pkg.name, pkg.version),
+        );
+
+        downloader::install_package(
+            &dist.url,
+            &dist.dist_type,
+            dist.shasum.as_deref(),
+            &ctx.vendor_dir,
+            &pkg.name,
+            Some(&mut progress),
+            &self.files_cache,
+        )
+        .await?;
+
+        progress.finish();
+        Ok(())
+    }
+
+    fn uninstall_package(&mut self, name: &str, ctx: &ExecuteContext) -> anyhow::Result<()> {
+        let pkg_dir = ctx.vendor_dir.join(name);
+        if pkg_dir.exists() {
+            std::fs::remove_dir_all(&pkg_dir)?;
+        }
+        Ok(())
+    }
+
+    fn cleanup_after_uninstalls(&mut self, ctx: &ExecuteContext) -> anyhow::Result<()> {
+        cleanup_empty_vendor_dirs(&ctx.vendor_dir)
+    }
+}
+
+/// Remove empty vendor namespace directories left behind after package
+/// removals. Skips the `composer/` and `bin/` directories. Mirrors the
+/// post-uninstall cleanup Composer does in `LibraryInstaller::removeCode`.
+fn cleanup_empty_vendor_dirs(vendor_dir: &Path) -> anyhow::Result<()> {
+    if let Ok(entries) = std::fs::read_dir(vendor_dir) {
+        for entry in entries.flatten() {
+            let path = entry.path();
+            if path.is_dir() {
+                let name = entry.file_name().to_string_lossy().to_string();
+                if name == "composer" || name == "bin" {
+                    continue;
+                }
+                if std::fs::read_dir(&path)?.next().is_none() {
+                    std::fs::remove_dir(&path)?;
+                }
+            }
+        }
+    }
+    Ok(())
+}
+
+/// Install a package from VCS source (git/svn/hg). Lifted from the previous
+/// `commands/install.rs::install_from_source`. Mirrors the per-driver
+/// dispatch in `Composer\Downloader\VcsDownloader::install`.
+fn install_from_source(
+    source_type: &str,
+    url: &str,
+    reference: &str,
+    vendor_dir: &Path,
+    package_name: &str,
+) -> anyhow::Result<()> {
+    let target = vendor_dir.join(package_name);
+    if target.exists() {
+        std::fs::remove_dir_all(&target)?;
+    }
+
+    match source_type {
+        "git" => {
+            let process = mozart_vcs::process::ProcessExecutor::new();
+            let git_util = mozart_vcs::util::git::GitUtil::new(
+                process,
+                vendor_dir.join(".cache").join("git"),
+            );
+            let downloader = mozart_vcs::downloader::git::GitDownloader::new(git_util);
+            use mozart_vcs::downloader::VcsDownloader;
+            downloader.download(url, reference, &target)?;
+            downloader.install(url, reference, &target)?;
+        }
+        "svn" => {
+            let process = mozart_vcs::process::ProcessExecutor::new();
+            let svn_util = mozart_vcs::util::svn::SvnUtil::new(process);
+            let downloader = mozart_vcs::downloader::svn::SvnDownloader::new(svn_util);
+            use mozart_vcs::downloader::VcsDownloader;
+            downloader.install(url, reference, &target)?;
+        }
+        "hg" => {
+            let process = mozart_vcs::process::ProcessExecutor::new();
+            let hg_util = mozart_vcs::util::hg::HgUtil::new(process);
+            let downloader = mozart_vcs::downloader::hg::HgDownloader::new(hg_util);
+            use mozart_vcs::downloader::VcsDownloader;
+            downloader.install(url, reference, &target)?;
+        }
+        _ => {
+            anyhow::bail!("Unsupported source type for VCS install: {}", source_type);
+        }
+    }
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    fn make_executor() -> FilesystemExecutor {
+        FilesystemExecutor::new(Cache::new(std::env::temp_dir().join("__no_cache"), false))
+    }
+
+    #[test]
+    fn cleanup_after_uninstalls_removes_empty_namespace_dirs() {
+        let dir = tempdir().unwrap();
+        let vendor_dir = dir.path().join("vendor");
+        std::fs::create_dir_all(&vendor_dir).unwrap();
+
+        let empty_ns = vendor_dir.join("old-vendor");
+        std::fs::create_dir_all(&empty_ns).unwrap();
+
+        let nonempty_ns = vendor_dir.join("psr");
+        std::fs::create_dir_all(nonempty_ns.join("log")).unwrap();
+
+        std::fs::create_dir_all(vendor_dir.join("composer")).unwrap();
+
+        let mut exec = make_executor();
+        exec.cleanup_after_uninstalls(&ExecuteContext {
+            vendor_dir: vendor_dir.clone(),
+            no_progress: true,
+            prefer_source: false,
+        })
+        .unwrap();
+
+        assert!(!empty_ns.exists());
+        assert!(vendor_dir.join("psr").exists());
+        assert!(vendor_dir.join("composer").exists());
+    }
+
+    #[test]
+    fn cleanup_after_uninstalls_preserves_bin_dir() {
+        let dir = tempdir().unwrap();
+        let vendor_dir = dir.path().join("vendor");
+        std::fs::create_dir_all(&vendor_dir).unwrap();
+
+        let bin_dir = vendor_dir.join("bin");
+        std::fs::create_dir_all(&bin_dir).unwrap();
+
+        let mut exec = make_executor();
+        exec.cleanup_after_uninstalls(&ExecuteContext {
+            vendor_dir: vendor_dir.clone(),
+            no_progress: true,
+            prefer_source: false,
+        })
+        .unwrap();
+
+        assert!(bin_dir.exists());
+    }
+}
diff --git a/crates/mozart-registry/src/installer_executor/mod.rs b/crates/mozart-registry/src/installer_executor/mod.rs
new file mode 100644
index 0000000..fde4c49
--- /dev/null
+++ b/crates/mozart-registry/src/installer_executor/mod.rs
@@ -0,0 +1,84 @@
+//! Installation execution abstraction.
+//!
+//! Mirrors `Composer\Installer\InstallationManager`: the per-operation
+//! side-effect surface (download, extract, remove from vendor/) lives behind
+//! a trait so test code can substitute a recording-only implementation
+//! (Composer's `InstallationManagerMock`) without going anywhere near the
+//! filesystem or the network.
+//!
+//! The orchestration loop (computing operations from lock vs installed,
+//! emitting console messages, writing `installed.json`, generating the
+//! autoloader) stays in the caller. The executor is purely the verb —
+//! "install this package" / "uninstall this package" — so test traces match
+//! Composer's `(string) $operation` byte-for-byte without the executor
+//! having to also reproduce console formatting.
+
+use std::path::PathBuf;
+
+use crate::lockfile::LockedPackage;
+
+pub mod filesystem;
+
+pub use filesystem::FilesystemExecutor;
+
+/// One install or update operation handed to [`InstallerExecutor::install_package`].
+#[derive(Debug, Clone, Copy)]
+pub enum PackageOperation<'a> {
+    /// First-time install. The whole package directory is created from
+    /// `package.dist`/`package.source`.
+    Install { package: &'a LockedPackage },
+    /// Replace an existing install with a new version. `from_version` is the
+    /// pretty version that was installed before.
+    Update {
+        from_version: &'a str,
+        package: &'a LockedPackage,
+    },
+}
+
+impl<'a> PackageOperation<'a> {
+    pub fn package(&self) -> &'a LockedPackage {
+        match self {
+            PackageOperation::Install { package }
+            | PackageOperation::Update { package, .. } => package,
+        }
+    }
+}
+
+/// Per-call configuration shared across executor methods. Owned by the
+/// caller (typically `install_from_lock`) so the executor sees a consistent
+/// view across an entire install/update run.
+#[derive(Debug, Clone)]
+pub struct ExecuteContext {
+    pub vendor_dir: PathBuf,
+    /// Suppress download progress bars.
+    pub no_progress: bool,
+    /// Prefer cloning from VCS source over downloading dist archives.
+    pub prefer_source: bool,
+}
+
+/// Side-effect surface for install/update/uninstall operations.
+///
+/// Implementations are stateful — `&mut self` lets a recorder accumulate
+/// trace lines and lets the filesystem implementation hold long-lived
+/// handles (caches, progress bars). All methods return `anyhow::Result` so
+/// callers can short-circuit on the first failure, mirroring Composer's
+/// fail-fast `InstallationManager::execute`.
+#[async_trait::async_trait]
+pub trait InstallerExecutor: Send + Sync {
+    /// Perform side effects for one install or update operation.
+    async fn install_package(
+        &mut self,
+        op: PackageOperation<'_>,
+        ctx: &ExecuteContext,
+    ) -> anyhow::Result<()>;
+
+    /// Perform side effects for one uninstall.
+    fn uninstall_package(&mut self, name: &str, ctx: &ExecuteContext) -> anyhow::Result<()>;
+
+    /// Hook called once after every uninstall has run. Default no-op.
+    /// Composer cleans up empty namespace directories here; the recorder
+    /// has no work to do.
+    fn cleanup_after_uninstalls(&mut self, _ctx: &ExecuteContext) -> anyhow::Result<()> {
+        Ok(())
+    }
+}