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>

1 files changed, 58 insertions, 0 deletions

diff --git a/crates/mozart-registry/src/repository/packagist_repo.rs b/crates/mozart-registry/src/repository/packagist_repo.rs
new file mode 100644
index 0000000..17208c1
--- /dev/null
+++ b/crates/mozart-registry/src/repository/packagist_repo.rs
@@ -0,0 +1,58 @@
+//! [`Repository`] backed by the live Packagist HTTP API.
+//!
+//! Wraps the existing [`crate::packagist::fetch_package_versions`] so the
+//! resolver sees the same data either through this trait or via the legacy
+//! direct call. Construction takes ownership of the [`Cache`] handle so
+//! callers no longer thread it through `ResolveRequest` / `LockFileGenerationRequest`.
+
+use super::{LoadResult, NamedPackagistVersion, PackageQuery, Repository};
+use crate::cache::Cache;
+use crate::packagist;
+
+pub struct PackagistRepository {
+    id: String,
+    cache: Cache,
+}
+
+impl PackagistRepository {
+    pub fn new(cache: Cache) -> Self {
+        Self {
+            id: "packagist.org".to_string(),
+            cache,
+        }
+    }
+}
+
+#[async_trait::async_trait]
+impl Repository for PackagistRepository {
+    fn id(&self) -> &str {
+        &self.id
+    }
+
+    async fn load_packages(&self, queries: &[PackageQuery<'_>]) -> anyhow::Result<LoadResult> {
+        let mut result = LoadResult::default();
+        for query in queries {
+            // Mirror the existing transitive-loop tolerance: a 404 / network
+            // failure for one name is not fatal — it just means this repo
+            // contributes nothing for that name. `RepositorySet` falls
+            // through, and the solver fails later if no repo knows it.
+            let versions =
+                match packagist::fetch_package_versions(query.name, &self.cache).await {
+                    Ok(v) => v,
+                    Err(_) => continue,
+                };
+            // `fetch_package_versions` returning Ok counts as "this repo
+            // authoritatively knows the name", even if the version list is
+            // empty (matches Composer `ArrayRepository::loadPackages` which
+            // adds the name to `namesFound` regardless of constraint match).
+            result.names_found.push(query.name.to_string());
+            for version in versions {
+                result.packages.push(NamedPackagistVersion {
+                    name: query.name.to_string(),
+                    version,
+                });
+            }
+        }
+        Ok(result)
+    }
+}