6 files changed, 20 insertions, 6 deletions
diff --git a/crates/mozart/src/commands/create_project.rs b/crates/mozart/src/commands/create_project.rs
index 13a2bb2..fc0efee 100644
--- a/crates/mozart/src/commands/create_project.rs
+++ b/crates/mozart/src/commands/create_project.rs
@@ -464,6 +464,7 @@ pub async fn execute(
         repositories: std::sync::Arc::new(
             mozart_registry::repository::RepositorySet::with_packagist(repo_cache.clone()),
         ),
+        previous_lock: None,
     })
     .await?;
 
diff --git a/crates/mozart/src/commands/install.rs b/crates/mozart/src/commands/install.rs
index 58a01b4..017c08e 100644
--- a/crates/mozart/src/commands/install.rs
+++ b/crates/mozart/src/commands/install.rs
@@ -206,12 +206,19 @@ pub fn compute_operations<'a>(
         ops.push((pkg, action));
     }
 
-    // Compute removals: packages in installed but not in locked
+    // Compute removals: packages in installed but not in locked. Iterate
+    // installed.json in reverse, mirroring Composer's
+    // `Transaction::calculateOperations`, which seeds `removeMap` from
+    // `presentPackages` in order and then `array_unshift`s each entry onto
+    // `operations` — flipping the iteration order. Without the flip, two
+    // co-orphaned packages emit removals in the wrong order vs Composer's
+    // trace.
     let locked_names: IndexSet<String> = locked.iter().map(|p| p.name.to_lowercase()).collect();
 
     let removals: Vec<String> = installed
         .packages
         .iter()
+        .rev()
         .filter(|p| !locked_names.contains(&p.name.to_lowercase()))
         .map(|p| p.name.clone())
         .collect();
diff --git a/crates/mozart/src/commands/remove.rs b/crates/mozart/src/commands/remove.rs
index 3ffe04a..eb6ee4a 100644
--- a/crates/mozart/src/commands/remove.rs
+++ b/crates/mozart/src/commands/remove.rs
@@ -376,6 +376,7 @@ pub async fn execute(
         repositories: std::sync::Arc::new(
             mozart_registry::repository::RepositorySet::with_packagist(repo_cache.clone()),
         ),
+        previous_lock: old_lock.clone(),
     })
     .await?;
 
@@ -619,6 +620,7 @@ async fn remove_unused(
         repositories: std::sync::Arc::new(
             mozart_registry::repository::RepositorySet::with_packagist(repo_cache.clone()),
         ),
+        previous_lock: Some(old_lock.clone()),
     })
     .await?;
 
@@ -934,6 +936,7 @@ mod tests {
                     ),
                 ),
             ),
+            previous_lock: None,
         })
         .await
         .expect("initial lock file generation should succeed");
@@ -994,6 +997,7 @@ mod tests {
                     ),
                 ),
             ),
+            previous_lock: Some(initial_lock.clone()),
         })
         .await
         .expect("post-remove lock file generation should succeed");
diff --git a/crates/mozart/src/commands/require.rs b/crates/mozart/src/commands/require.rs
index 45ad759..110bd1a 100644
--- a/crates/mozart/src/commands/require.rs
+++ b/crates/mozart/src/commands/require.rs
@@ -765,6 +765,7 @@ pub async fn execute(
         repositories: std::sync::Arc::new(
             mozart_registry::repository::RepositorySet::with_packagist(repo_cache.clone()),
         ),
+        previous_lock: old_lock.clone(),
     })
     .await?;
 
@@ -1095,6 +1096,7 @@ mod tests {
                     ),
                 ),
             ),
+            previous_lock: None,
         })
         .await
         .expect("Lock file generation should succeed");
@@ -1168,6 +1170,7 @@ mod tests {
                     ),
                 ),
             ),
+            previous_lock: None,
         })
         .await
         .expect("Lock file generation should succeed");
diff --git a/crates/mozart/src/commands/update.rs b/crates/mozart/src/commands/update.rs
index 5cf05c4..43825f2 100644
--- a/crates/mozart/src/commands/update.rs
+++ b/crates/mozart/src/commands/update.rs
@@ -1290,6 +1290,7 @@ pub async fn run(
         composer_json: composer_json.clone(),
         include_dev: dev_mode,
         repositories: repositories.clone(),
+        previous_lock: old_lock.clone(),
     })
     .await?;
 
@@ -2285,6 +2286,7 @@ mod tests {
                     ),
                 ),
             ),
+            previous_lock: None,
         })
         .await
         .expect("Lock file generation should succeed");
diff --git a/crates/mozart/tests/installer.rs b/crates/mozart/tests/installer.rs
index f6324b6..06c7581 100644
--- a/crates/mozart/tests/installer.rs
+++ b/crates/mozart/tests/installer.rs
@@ -373,10 +373,7 @@ installer_fixture!(update_allow_list_with_dependencies_alias, ignore);
 installer_fixture!(update_allow_list_with_dependencies_new_requirement);
 installer_fixture!(update_allow_list_with_dependencies_require_new);
 installer_fixture!(update_allow_list_with_dependencies_require_new_replace);
-installer_fixture!(
-    update_allow_list_with_dependencies_require_new_replace_mutual,
-    ignore
-);
+installer_fixture!(update_allow_list_with_dependencies_require_new_replace_mutual);
 installer_fixture!(update_allow_list_with_dependency_conflict);
 installer_fixture!(update_changes_url, ignore);
 installer_fixture!(update_dev_ignores_providers);
@@ -403,7 +400,7 @@ installer_fixture!(update_picks_up_change_of_vcs_type);
 installer_fixture!(update_prefer_lowest_stable);
 installer_fixture!(update_reference);
 installer_fixture!(update_reference_picks_latest);
-installer_fixture!(update_removes_unused_locked_dep, ignore);
+installer_fixture!(update_removes_unused_locked_dep);
 installer_fixture!(update_requiring_decision_reverts_and_learning_positive_literals);
 installer_fixture!(update_security_advisory_matching_direct_dependency, ignore);
 installer_fixture!(