fix(install): honour config.allow-missing-requirements

Composer's Installer::doInstall prints the missing-requirement warnings
and continues when config.allow-missing-requirements is true, rather
than bailing with ERROR_LOCK_FILE_INVALID. Mozart was always bailing,
diverging on the install-from-incomplete-lock-with-ignore fixture.

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

2 files changed, 16 insertions, 4 deletions

diff --git a/crates/mozart/src/commands/install.rs b/crates/mozart/src/commands/install.rs
index 62a7d21..7a5ebe9 100644
--- a/crates/mozart/src/commands/install.rs
+++ b/crates/mozart/src/commands/install.rs
@@ -1204,9 +1204,21 @@ pub async fn run(
             for line in &missing {
                 console.info(line);
             }
-            return Err(mozart_core::exit_code::bail_silent(
-                mozart_core::exit_code::LOCK_FILE_INVALID,
-            ));
+            // Mirrors `Composer\Installer::doInstall()` lines 749-756: when
+            // `config.allow-missing-requirements` is true, print the warnings
+            // but proceed with what the lock already covers instead of
+            // bailing with ERROR_LOCK_FILE_INVALID.
+            let allow_missing = root_pkg
+                .extra_fields
+                .get("config")
+                .and_then(|v| v.get("allow-missing-requirements"))
+                .and_then(|v| v.as_bool())
+                .unwrap_or(false);
+            if !allow_missing {
+                return Err(mozart_core::exit_code::bail_silent(
+                    mozart_core::exit_code::LOCK_FILE_INVALID,
+                ));
+            }
         }
 
         let platform_problems = collect_install_platform_problems(
diff --git a/crates/mozart/tests/installer.rs b/crates/mozart/tests/installer.rs
index 7767f55..c411c10 100644
--- a/crates/mozart/tests/installer.rs
+++ b/crates/mozart/tests/installer.rs
@@ -261,7 +261,7 @@ installer_fixture!(install_dev);
 installer_fixture!(install_dev_using_dist);
 installer_fixture!(install_forces_reinstall_if_abandon_changes);
 installer_fixture!(install_from_incomplete_lock);
-installer_fixture!(install_from_incomplete_lock_with_ignore, ignore);
+installer_fixture!(install_from_incomplete_lock_with_ignore);
 installer_fixture!(install_from_lock_removes_package);
 installer_fixture!(install_funding_notice);
 installer_fixture!(install_funding_notice_env);