fix(resolver): expose locked branch-alias entries in the pool

Composer's Locker::getLockedRepository runs each locked package through
ArrayLoader::load, which materializes any extra.branch-alias as a
separate AliasPackage in the locked repository. Mozart was only adding
the base locked package to the pool, so a `dev-master` locked entry
with branch alias `2.2.x-dev` was invisible to numeric root constraints
like `~2.1` on a partial update — the resolver bailed with "no matching
package found" even though Composer accepts the same lock. Surface
each branch-alias as a sibling pool entry pointing at the base via
is_alias_of.

2 files changed, 21 insertions, 1 deletions

diff --git a/crates/mozart-registry/src/resolver.rs b/crates/mozart-registry/src/resolver.rs
index 87a92e9..5dbe74f 100644
--- a/crates/mozart-registry/src/resolver.rs
+++ b/crates/mozart-registry/src/resolver.rs
@@ -1165,6 +1165,26 @@ pub async fn resolve(request: &ResolveRequest) -> Result<Vec<ResolvedPackage>, R
             is_alias_of: None,
         };
         builder.add_package(input);
+        // Also expose each `extra.branch-alias` entry as a separate pool
+        // package, mirroring `Composer\Package\Locker::getLockedRepository`
+        // (which calls `ArrayLoader::load`, which materializes the
+        // branch-alias via `getBranchAlias`). Without this, a `dev-master`
+        // locked package with branch alias `2.2.x-dev` is only visible
+        // under `dev-master` in the pool, so root requires like `~2.1`
+        // see no candidate and the resolver fails on a partial update.
+        for (alias_pretty, alias_normalized) in &locked.branch_aliases {
+            builder.add_package(PoolPackageInput {
+                name: locked_name_lower.clone(),
+                version: alias_normalized.clone(),
+                pretty_version: alias_pretty.clone(),
+                requires: make_pool_links(&locked_name_lower, alias_normalized, &locked.requires),
+                replaces: make_pool_links(&locked_name_lower, alias_normalized, &locked.replaces),
+                provides: make_pool_links(&locked_name_lower, alias_normalized, &locked.provides),
+                conflicts: make_pool_links(&locked_name_lower, alias_normalized, &locked.conflicts),
+                is_fixed: false,
+                is_alias_of: Some(locked.version_normalized.clone()),
+            });
+        }
     }
 
     // Scan VCS repositories and collect packages from them
diff --git a/crates/mozart/tests/installer.rs b/crates/mozart/tests/installer.rs
index 729e9db..b1c1968 100644
--- a/crates/mozart/tests/installer.rs
+++ b/crates/mozart/tests/installer.rs
@@ -314,7 +314,7 @@ installer_fixture!(partial_update_downgrades_non_allow_listed_unstable);
 installer_fixture!(partial_update_forces_dev_reference_from_lock_for_non_updated_packages);
 installer_fixture!(partial_update_from_lock);
 installer_fixture!(partial_update_from_lock_with_root_alias);
-installer_fixture!(partial_update_installs_from_lock_even_missing, ignore);
+installer_fixture!(partial_update_installs_from_lock_even_missing);
 installer_fixture!(partial_update_keeps_older_dep_if_still_required);
 installer_fixture!(partial_update_keeps_older_dep_if_still_required_with_provide);
 installer_fixture!(partial_update_loads_root_aliases_for_path_repos);