fix(core): default missing composer.json "name" to __root__

Composer's RootPackageLoader assigns the root name "__root__" when
composer.json omits the "name" field. Mozart was failing deserialization
in that case, blocking any installer fixture with a nameless root
manifest. Apply the same serde default and unignore
update-to-empty-from-blank as the first green entry on the .test
scoreboard.

1 files changed, 7 insertions, 0 deletions

diff --git a/crates/mozart-core/src/package.rs b/crates/mozart-core/src/package.rs
index ce2ff12..5906c7e 100644
--- a/crates/mozart-core/src/package.rs
+++ b/crates/mozart-core/src/package.rs
@@ -458,6 +458,7 @@ delegate_complete_package!(RootPackageData => complete);
 /// and map directly to the JSON keys via serde.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RawPackageData {
+    #[serde(default = "default_root_package_name")]
     pub name: String,
 
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -531,6 +532,12 @@ pub struct RawRepository {
     pub url: String,
 }
 
+/// Default root-package name when `composer.json` omits the `name` field.
+/// Mirrors Composer's `RootPackageLoader` fallback.
+fn default_root_package_name() -> String {
+    "__root__".to_string()
+}
+
 impl RawPackageData {
     pub fn new(name: String) -> Self {
         Self {