refactor(package): rename traits and switch dep maps to IndexMap

Rename Package/CompletePackage to PackageInterface/CompletePackageInterface
to mirror Composer's interface names, and split each into its own module
under crates/mozart-core/src/package/.

Switch dependency-link and metadata maps from BTreeMap to indexmap::IndexMap
so serialized JSON preserves the original key ordering rather than sorting
alphabetically — matching PHP associative-array semantics. The
--sort-packages behaviour in `require` is preserved via sort_unstable_keys.

29 files changed, 529 insertions, 553 deletions

diff --git a/crates/mozart-class-map-generator/Cargo.toml b/crates/mozart-class-map-generator/Cargo.toml
index 465b26c..e1bd1a3 100644
--- a/crates/mozart-class-map-generator/Cargo.toml
+++ b/crates/mozart-class-map-generator/Cargo.toml
@@ -5,6 +5,7 @@ edition.workspace = true
 
 [dependencies]
 anyhow.workspace = true
+indexmap.workspace = true
 regex.workspace = true
 
 [dev-dependencies]
diff --git a/crates/mozart-class-map-generator/src/classmap.rs b/crates/mozart-class-map-generator/src/classmap.rs
index e1631f4..17ca04a 100644
--- a/crates/mozart-class-map-generator/src/classmap.rs
+++ b/crates/mozart-class-map-generator/src/classmap.rs
@@ -133,18 +133,18 @@ pub fn path_to_static_expr(file: &Path, vendor_dir: &Path, project_dir: &Path) -
 ///
 /// Returns `(dynamic_classmap, static_classmap, psr_violations)`.
 pub fn scan_psr_for_classmap(
-    psr4: &BTreeMap<String, Vec<String>>,
-    psr0: &BTreeMap<String, Vec<String>>,
+    psr4: &indexmap::IndexMap<String, Vec<String>>,
+    psr0: &indexmap::IndexMap<String, Vec<String>>,
     vendor_dir: &Path,
     project_dir: &Path,
     excluded: &[String],
 ) -> (
-    BTreeMap<String, String>,
-    BTreeMap<String, String>,
+    indexmap::IndexMap<String, String>,
+    indexmap::IndexMap<String, String>,
     Vec<String>,
 ) {
-    let mut dyn_map: BTreeMap<String, String> = BTreeMap::new();
-    let mut static_map: BTreeMap<String, String> = BTreeMap::new();
+    let mut dyn_map = indexmap::IndexMap::new();
+    let mut static_map = indexmap::IndexMap::new();
     let mut violations: Vec<String> = Vec::new();
 
     // Helper: resolve a PHP path expression to an absolute path.
diff --git a/crates/mozart-core/src/autoload.rs b/crates/mozart-core/src/autoload.rs
index 7e8ead6..08a2859 100644
--- a/crates/mozart-core/src/autoload.rs
+++ b/crates/mozart-core/src/autoload.rs
@@ -8,7 +8,6 @@ use crate::repository::installed::InstalledPackages;
 use crate::repository::lockfile::LockedPackage;
 use indexmap::IndexSet;
 use mozart_class_map_generator::{scan_classmap_dirs, scan_psr_for_classmap};
-use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
 
 // Embed Composer PHP files from the submodule at compile time.
@@ -70,15 +69,15 @@ pub struct AutoloadConfig {
 pub struct AutoloadData {
     /// PSR-4: namespace prefix -> list of directory path expressions.
     /// Each path is a PHP expression string like `$vendorDir . '/psr/log/src'`.
-    pub psr4: BTreeMap<String, Vec<String>>,
+    pub psr4: indexmap::IndexMap<String, Vec<String>>,
     /// PSR-0: namespace prefix -> list of directory path expressions.
     /// (Empty in Phase 2.2, populated in 5.6.)
-    pub psr0: BTreeMap<String, Vec<String>>,
+    pub psr0: indexmap::IndexMap<String, Vec<String>>,
     /// Classmap entries: class name -> file path expression.
     /// (Empty in Phase 2.2, populated in 5.6.)
-    pub classmap: BTreeMap<String, String>,
+    pub classmap: indexmap::IndexMap<String, String>,
     /// Files to include on every request: file_identifier -> path expression.
-    pub files: BTreeMap<String, String>,
+    pub files: indexmap::IndexMap<String, String>,
 }
 
 /// Mirror of `Composer\ClassMapGenerator\ClassMap` — the return value
@@ -92,9 +91,9 @@ pub struct AutoloadData {
 /// summary — once `generate` is refactored to expose the full classmap
 /// these fields will hold the real entries.
 pub struct ClassMap {
-    map: BTreeMap<String, String>,
+    map: indexmap::IndexMap<String, String>,
     psr_violations: Vec<String>,
-    ambiguous_classes: BTreeMap<String, Vec<String>>,
+    ambiguous_classes: indexmap::IndexMap<String, Vec<String>>,
 }
 
 impl ClassMap {
@@ -126,7 +125,7 @@ impl ClassMap {
     }
 
     /// Read access to the underlying map (`getMap()` upstream).
-    pub fn map(&self) -> &BTreeMap<String, String> {
+    pub fn map(&self) -> &indexmap::IndexMap<String, String> {
         &self.map
     }
 
@@ -136,7 +135,7 @@ impl ClassMap {
     }
 
     /// Read access to the ambiguous-class records.
-    pub fn ambiguous_classes(&self) -> &BTreeMap<String, Vec<String>> {
+    pub fn ambiguous_classes(&self) -> &indexmap::IndexMap<String, Vec<String>> {
         &self.ambiguous_classes
     }
 }
@@ -282,9 +281,9 @@ impl AutoloadGeneratorExt for AutoloadGenerator {
             // for now and surface the limitation here rather than
             // silently writing files.
             return Ok(ClassMap {
-                map: BTreeMap::new(),
+                map: indexmap::IndexMap::new(),
                 psr_violations: Vec::new(),
-                ambiguous_classes: BTreeMap::new(),
+                ambiguous_classes: indexmap::IndexMap::new(),
             });
         }
 
@@ -297,7 +296,7 @@ impl AutoloadGeneratorExt for AutoloadGenerator {
         // command code that only branches on `count()` / `has_*()` works
         // today; refactoring `generate` to surface the full map is
         // tracked as follow-up work.
-        let mut map = BTreeMap::new();
+        let mut map = indexmap::IndexMap::new();
         for i in 0..result.class_count {
             map.insert(format!("__mozart_placeholder_{i}"), String::new());
         }
@@ -308,7 +307,7 @@ impl AutoloadGeneratorExt for AutoloadGenerator {
         } else {
             Vec::new()
         };
-        let mut ambiguous_classes = BTreeMap::new();
+        let mut ambiguous_classes = indexmap::IndexMap::new();
         if result.has_ambiguous_classes {
             ambiguous_classes.insert("__mozart_placeholder".to_string(), Vec::new());
         }
@@ -526,16 +525,16 @@ fn collect_autoloads(
     dev_mode: bool,
 ) -> (AutoloadData, AutoloadData) {
     let mut data = AutoloadData {
-        psr4: BTreeMap::new(),
-        psr0: BTreeMap::new(),
-        classmap: BTreeMap::new(),
-        files: BTreeMap::new(),
+        psr4: indexmap::IndexMap::new(),
+        psr0: indexmap::IndexMap::new(),
+        classmap: indexmap::IndexMap::new(),
+        files: indexmap::IndexMap::new(),
     };
     let mut static_data = AutoloadData {
-        psr4: BTreeMap::new(),
-        psr0: BTreeMap::new(),
-        classmap: BTreeMap::new(),
-        files: BTreeMap::new(),
+        psr4: indexmap::IndexMap::new(),
+        psr0: indexmap::IndexMap::new(),
+        classmap: indexmap::IndexMap::new(),
+        files: indexmap::IndexMap::new(),
     };
 
     // Process each installed package
@@ -703,7 +702,7 @@ fn generate_autoload_static(static_data: &AutoloadData, suffix: &str) -> String
     // $prefixLengthsPsr4 — group by first character of namespace
     if !static_data.psr4.is_empty() {
         // Group namespaces by first character, sorted reverse
-        let mut by_char: BTreeMap<char, Vec<(&String, usize)>> = BTreeMap::new();
+        let mut by_char: indexmap::IndexMap<_, Vec<_>> = indexmap::IndexMap::new();
 
         let mut sorted_ns: Vec<&String> = static_data.psr4.keys().collect();
         sorted_ns.sort_by(|a, b| b.cmp(a));
@@ -1278,11 +1277,11 @@ pub fn generate(config: &AutoloadConfig) -> anyhow::Result<GenerateResult> {
                 version_normalized: p.version_normalized.clone(),
                 source: None,
                 dist: None,
-                require: std::collections::BTreeMap::new(),
-                require_dev: std::collections::BTreeMap::new(),
-                conflict: std::collections::BTreeMap::new(),
-                provide: std::collections::BTreeMap::new(),
-                replace: std::collections::BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: p.package_type.clone(),
                 autoload: p.autoload.clone(),
@@ -1295,7 +1294,7 @@ pub fn generate(config: &AutoloadConfig) -> anyhow::Result<GenerateResult> {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: std::collections::BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             })
             .collect()
     };
@@ -1370,7 +1369,6 @@ pub fn generate(config: &AutoloadConfig) -> anyhow::Result<GenerateResult> {
 mod tests {
     use super::*;
     use crate::repository::installed::{InstalledPackageEntry, InstalledPackages};
-    use std::collections::BTreeMap;
     use tempfile::tempdir;
 
     fn make_installed_pkg(name: &str, version: &str) -> InstalledPackageEntry {
@@ -1386,7 +1384,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -1589,10 +1587,10 @@ mod tests {
     #[test]
     fn test_generate_autoload_psr4_empty() {
         let data = AutoloadData {
-            psr4: BTreeMap::new(),
-            psr0: BTreeMap::new(),
-            classmap: BTreeMap::new(),
-            files: BTreeMap::new(),
+            psr4: indexmap::IndexMap::new(),
+            psr0: indexmap::IndexMap::new(),
+            classmap: indexmap::IndexMap::new(),
+            files: indexmap::IndexMap::new(),
         };
         let output = generate_autoload_psr4(&data);
         assert!(output.contains("return array(\n);"));
diff --git a/crates/mozart-core/src/installer/installed_repo.rs b/crates/mozart-core/src/installer/installed_repo.rs
index 8361158..d7e4f83 100644
--- a/crates/mozart-core/src/installer/installed_repo.rs
+++ b/crates/mozart-core/src/installer/installed_repo.rs
@@ -17,7 +17,6 @@
 //!   or through a `provide` / `replace` link.
 
 use indexmap::IndexSet;
-use std::collections::BTreeMap;
 
 /// One installed package, in the shape `findPackagesWithReplacersAndProviders`
 /// needs. Mirrors the fields of `Composer\Package\PackageInterface` that the
@@ -33,9 +32,9 @@ pub struct InstalledCandidate {
     /// Original-case version, used in user-facing output.
     pub pretty_version: String,
     /// `provide` map: target package name → constraint string.
-    pub provides: BTreeMap<String, String>,
+    pub provides: indexmap::IndexMap<String, String>,
     /// `replace` map: target package name → constraint string.
-    pub replaces: BTreeMap<String, String>,
+    pub replaces: indexmap::IndexMap<String, String>,
 }
 
 #[derive(Debug, Clone, Default)]
@@ -106,8 +105,8 @@ mod tests {
             pretty_name: name.to_string(),
             version: version.to_string(),
             pretty_version: version.to_string(),
-            provides: BTreeMap::new(),
-            replaces: BTreeMap::new(),
+            provides: indexmap::IndexMap::new(),
+            replaces: indexmap::IndexMap::new(),
         }
     }
 
diff --git a/crates/mozart-core/src/package.rs b/crates/mozart-core/src/package.rs
index c6a3ae9..de88ffc 100644
--- a/crates/mozart-core/src/package.rs
+++ b/crates/mozart-core/src/package.rs
@@ -1,14 +1,18 @@
 use serde::de::{Deserializer, MapAccess, SeqAccess, Visitor};
 use serde::{Deserialize, Serialize};
-use std::collections::BTreeMap;
 use std::fmt;
 use std::fs;
 use std::path::Path;
 
 pub mod archiver;
+mod complete_package_interface;
 pub mod dumper;
+mod package_interface;
 pub mod version;
 
+pub use complete_package_interface::*;
+pub use package_interface::*;
+
 /// Package stability level.
 /// Higher value = less stable.
 /// Corresponds to `Composer\Package\BasePackage::STABILITY_*`.
@@ -62,8 +66,8 @@ pub struct Author {
 /// Autoload rule sets (PSR-4, PSR-0, classmap, files).
 #[derive(Debug, Clone, Default)]
 pub struct AutoloadRules {
-    pub psr4: BTreeMap<String, Vec<String>>,
-    pub psr0: BTreeMap<String, Vec<String>>,
+    pub psr4: indexmap::IndexMap<String, Vec<String>>,
+    pub psr0: indexmap::IndexMap<String, Vec<String>>,
     pub classmap: Vec<String>,
     pub files: Vec<String>,
 }
@@ -125,19 +129,19 @@ pub struct PackageData {
     pub dist_sha1_checksum: Option<String>,
 
     pub release_date: Option<String>,
-    pub extra: BTreeMap<String, serde_json::Value>,
+    pub extra: indexmap::IndexMap<String, serde_json::Value>,
     pub binaries: Vec<String>,
     pub dev: bool,
     pub stability: Stability,
     pub notification_url: Option<String>,
 
     // dependency links
-    pub requires: BTreeMap<String, Link>,
-    pub conflicts: BTreeMap<String, Link>,
-    pub provides: BTreeMap<String, Link>,
-    pub replaces: BTreeMap<String, Link>,
-    pub dev_requires: BTreeMap<String, Link>,
-    pub suggests: BTreeMap<String, String>,
+    pub requires: indexmap::IndexMap<String, Link>,
+    pub conflicts: indexmap::IndexMap<String, Link>,
+    pub provides: indexmap::IndexMap<String, Link>,
+    pub replaces: indexmap::IndexMap<String, Link>,
+    pub dev_requires: indexmap::IndexMap<String, Link>,
+    pub suggests: indexmap::IndexMap<String, String>,
 
     // autoload
     pub autoload: AutoloadRules,
@@ -157,7 +161,7 @@ pub struct CompletePackageData {
     pub license: Vec<String>,
     pub keywords: Vec<String>,
     pub authors: Vec<Author>,
-    pub scripts: BTreeMap<String, Vec<String>>,
+    pub scripts: indexmap::IndexMap<String, Vec<String>>,
     pub support: Support,
     pub funding: Vec<Funding>,
     pub repositories: Vec<serde_json::Value>,
@@ -175,105 +179,55 @@ pub struct RootPackageData {
 
     pub minimum_stability: Stability,
     pub prefer_stable: bool,
-    pub stability_flags: BTreeMap<String, Stability>,
-    pub config: BTreeMap<String, serde_json::Value>,
-    pub references: BTreeMap<String, String>,
+    pub stability_flags: indexmap::IndexMap<String, Stability>,
+    pub config: indexmap::IndexMap<String, serde_json::Value>,
+    pub references: indexmap::IndexMap<String, String>,
     pub aliases: Vec<VersionAlias>,
 }
 
-/// Accessor for `PackageData` fields.
-/// Corresponds to `Composer\Package\PackageInterface`.
-pub trait Package {
-    fn name(&self) -> &str;
-    fn pretty_name(&self) -> &str;
-    fn version(&self) -> &str;
-    fn pretty_version(&self) -> &str;
-    fn package_type(&self) -> &str;
-    fn target_dir(&self) -> Option<&str>;
-    fn source_type(&self) -> Option<&str>;
-    fn source_url(&self) -> Option<&str>;
-    fn source_reference(&self) -> Option<&str>;
-    fn dist_type(&self) -> Option<&str>;
-    fn dist_url(&self) -> Option<&str>;
-    fn dist_reference(&self) -> Option<&str>;
-    fn dist_sha1_checksum(&self) -> Option<&str>;
-    fn release_date(&self) -> Option<&str>;
-    fn extra(&self) -> &BTreeMap<String, serde_json::Value>;
-    fn binaries(&self) -> &[String];
-    fn is_dev(&self) -> bool;
-    fn stability(&self) -> Stability;
-    fn notification_url(&self) -> Option<&str>;
-    fn requires(&self) -> &BTreeMap<String, Link>;
-    fn conflicts(&self) -> &BTreeMap<String, Link>;
-    fn provides(&self) -> &BTreeMap<String, Link>;
-    fn replaces(&self) -> &BTreeMap<String, Link>;
-    fn dev_requires(&self) -> &BTreeMap<String, Link>;
-    fn suggests(&self) -> &BTreeMap<String, String>;
-    fn autoload(&self) -> &AutoloadRules;
-    fn dev_autoload(&self) -> &AutoloadRules;
-    fn is_default_branch(&self) -> bool;
-}
-
-/// Accessor for `CompletePackageData` fields.
-/// Corresponds to `Composer\Package\CompletePackageInterface`.
-pub trait CompletePackage: Package {
-    fn description(&self) -> Option<&str>;
-    fn homepage(&self) -> Option<&str>;
-    fn license(&self) -> &[String];
-    fn keywords(&self) -> &[String];
-    fn authors(&self) -> &[Author];
-    fn scripts(&self) -> &BTreeMap<String, Vec<String>>;
-    fn support(&self) -> &Support;
-    fn funding(&self) -> &[Funding];
-    fn repositories(&self) -> &[serde_json::Value];
-    fn abandoned(&self) -> Option<&str>;
-    fn archive_name(&self) -> Option<&str>;
-    fn archive_excludes(&self) -> &[String];
-}
-
 /// Accessor for `RootPackageData` fields.
 /// Corresponds to `Composer\Package\RootPackageInterface`.
-pub trait RootPackage: CompletePackage {
+pub trait RootPackage: CompletePackageInterface {
     fn minimum_stability(&self) -> Stability;
     fn prefer_stable(&self) -> bool;
-    fn stability_flags(&self) -> &BTreeMap<String, Stability>;
-    fn config(&self) -> &BTreeMap<String, serde_json::Value>;
-    fn references(&self) -> &BTreeMap<String, String>;
+    fn stability_flags(&self) -> &indexmap::IndexMap<String, Stability>;
+    fn config(&self) -> &indexmap::IndexMap<String, serde_json::Value>;
+    fn references(&self) -> &indexmap::IndexMap<String, String>;
     fn aliases(&self) -> &[VersionAlias];
 }
 
 /// Implements `Package` trait by delegating to an inner `PackageData` field.
 macro_rules! delegate_package {
     ($type:ty => $($path:ident).+) => {
-        impl Package for $type {
-            fn name(&self)               -> &str                                 { &self.$($path).+.name                          }
-            fn pretty_name(&self)        -> &str                                 { &self.$($path).+.pretty_name                   }
-            fn version(&self)            -> &str                                 { &self.$($path).+.version                       }
-            fn pretty_version(&self)     -> &str                                 { &self.$($path).+.pretty_version                }
-            fn package_type(&self)       -> &str                                 { &self.$($path).+.package_type                  }
-            fn target_dir(&self)         -> Option<&str>                         {  self.$($path).+.target_dir.as_deref()         }
-            fn source_type(&self)        -> Option<&str>                         {  self.$($path).+.source_type.as_deref()        }
-            fn source_url(&self)         -> Option<&str>                         {  self.$($path).+.source_url.as_deref()         }
-            fn source_reference(&self)   -> Option<&str>                         {  self.$($path).+.source_reference.as_deref()   }
-            fn dist_type(&self)          -> Option<&str>                         {  self.$($path).+.dist_type.as_deref()          }
-            fn dist_url(&self)           -> Option<&str>                         {  self.$($path).+.dist_url.as_deref()           }
-            fn dist_reference(&self)     -> Option<&str>                         {  self.$($path).+.dist_reference.as_deref()     }
-            fn dist_sha1_checksum(&self) -> Option<&str>                         {  self.$($path).+.dist_sha1_checksum.as_deref() }
-            fn release_date(&self)       -> Option<&str>                         {  self.$($path).+.release_date.as_deref()       }
-            fn extra(&self)              -> &BTreeMap<String, serde_json::Value> { &self.$($path).+.extra                         }
-            fn binaries(&self)           -> &[String]                            { &self.$($path).+.binaries                      }
-            fn is_dev(&self)             -> bool                                 {  self.$($path).+.dev                           }
-            fn stability(&self)          -> Stability                            {  self.$($path).+.stability                     }
-            fn notification_url(&self)   -> Option<&str>                         {  self.$($path).+.notification_url.as_deref()   }
-            fn requires(&self)           -> &BTreeMap<String, Link>              { &self.$($path).+.requires                      }
-            fn conflicts(&self)          -> &BTreeMap<String, Link>              { &self.$($path).+.conflicts                     }
-            fn provides(&self)           -> &BTreeMap<String, Link>              { &self.$($path).+.provides                      }
-            fn replaces(&self)           -> &BTreeMap<String, Link>              { &self.$($path).+.replaces                      }
-            fn dev_requires(&self)       -> &BTreeMap<String, Link>              { &self.$($path).+.dev_requires                  }
-            fn suggests(&self)           -> &BTreeMap<String, String>            { &self.$($path).+.suggests                      }
-            fn autoload(&self)           -> &AutoloadRules                       { &self.$($path).+.autoload                      }
-            fn dev_autoload(&self)       -> &AutoloadRules                       { &self.$($path).+.dev_autoload                  }
-            fn is_default_branch(&self)  -> bool                                 {  self.$($path).+.is_default_branch             }
+        impl PackageInterface for $type {
+            fn name(&self)               -> &str                                           { &self.$($path).+.name                          }
+            fn pretty_name(&self)        -> &str                                           { &self.$($path).+.pretty_name                   }
+            fn version(&self)            -> &str                                           { &self.$($path).+.version                       }
+            fn pretty_version(&self)     -> &str                                           { &self.$($path).+.pretty_version                }
+            fn package_type(&self)       -> &str                                           { &self.$($path).+.package_type                  }
+            fn target_dir(&self)         -> Option<&str>                                   {  self.$($path).+.target_dir.as_deref()         }
+            fn source_type(&self)        -> Option<&str>                                   {  self.$($path).+.source_type.as_deref()        }
+            fn source_url(&self)         -> Option<&str>                                   {  self.$($path).+.source_url.as_deref()         }
+            fn source_reference(&self)   -> Option<&str>                                   {  self.$($path).+.source_reference.as_deref()   }
+            fn dist_type(&self)          -> Option<&str>                                   {  self.$($path).+.dist_type.as_deref()          }
+            fn dist_url(&self)           -> Option<&str>                                   {  self.$($path).+.dist_url.as_deref()           }
+            fn dist_reference(&self)     -> Option<&str>                                   {  self.$($path).+.dist_reference.as_deref()     }
+            fn dist_sha1_checksum(&self) -> Option<&str>                                   {  self.$($path).+.dist_sha1_checksum.as_deref() }
+            fn release_date(&self)       -> Option<&str>                                   {  self.$($path).+.release_date.as_deref()       }
+            fn extra(&self)              -> &indexmap::IndexMap<String, serde_json::Value> { &self.$($path).+.extra                         }
+            fn binaries(&self)           -> &[String]                                      { &self.$($path).+.binaries                      }
+            fn is_dev(&self)             -> bool                                           {  self.$($path).+.dev                           }
+            fn stability(&self)          -> Stability                                      {  self.$($path).+.stability                     }
+            fn notification_url(&self)   -> Option<&str>                                   {  self.$($path).+.notification_url.as_deref()   }
+            fn requires(&self)           -> &indexmap::IndexMap<String, Link>              { &self.$($path).+.requires                      }
+            fn conflicts(&self)          -> &indexmap::IndexMap<String, Link>              { &self.$($path).+.conflicts                     }
+            fn provides(&self)           -> &indexmap::IndexMap<String, Link>              { &self.$($path).+.provides                      }
+            fn replaces(&self)           -> &indexmap::IndexMap<String, Link>              { &self.$($path).+.replaces                      }
+            fn dev_requires(&self)       -> &indexmap::IndexMap<String, Link>              { &self.$($path).+.dev_requires                  }
+            fn suggests(&self)           -> &indexmap::IndexMap<String, String>            { &self.$($path).+.suggests                      }
+            fn autoload(&self)           -> &AutoloadRules                                 { &self.$($path).+.autoload                      }
+            fn dev_autoload(&self)       -> &AutoloadRules                                 { &self.$($path).+.dev_autoload                  }
+            fn is_default_branch(&self)  -> bool                                           {  self.$($path).+.is_default_branch             }
         }
     };
 }
@@ -281,24 +235,24 @@ macro_rules! delegate_package {
 /// Implements `CompletePackage` trait by delegating to an inner `CompletePackageData` field.
 macro_rules! delegate_complete_package {
     ($type:ty => $($path:ident).+) => {
-        impl CompletePackage for $type {
-            fn description(&self)      -> Option<&str>                   {  self.$($path).+.description.as_deref()  }
-            fn homepage(&self)         -> Option<&str>                   {  self.$($path).+.homepage.as_deref()     }
-            fn license(&self)          -> &[String]                      { &self.$($path).+.license                 }
-            fn keywords(&self)         -> &[String]                      { &self.$($path).+.keywords                }
-            fn authors(&self)          -> &[Author]                      { &self.$($path).+.authors                 }
-            fn scripts(&self)          -> &BTreeMap<String, Vec<String>> { &self.$($path).+.scripts                 }
-            fn support(&self)          -> &Support                       { &self.$($path).+.support                 }
-            fn funding(&self)          -> &[Funding]                     { &self.$($path).+.funding                 }
-            fn repositories(&self)     -> &[serde_json::Value]           { &self.$($path).+.repositories            }
-            fn abandoned(&self)        -> Option<&str>                   {  self.$($path).+.abandoned.as_deref()    }
-            fn archive_name(&self)     -> Option<&str>                   {  self.$($path).+.archive_name.as_deref() }
-            fn archive_excludes(&self) -> &[String]                      { &self.$($path).+.archive_excludes        }
+        impl CompletePackageInterface for $type {
+            fn description(&self)      -> Option<&str>                             {  self.$($path).+.description.as_deref()  }
+            fn homepage(&self)         -> Option<&str>                             {  self.$($path).+.homepage.as_deref()     }
+            fn license(&self)          -> &[String]                                { &self.$($path).+.license                 }
+            fn keywords(&self)         -> &[String]                                { &self.$($path).+.keywords                }
+            fn authors(&self)          -> &[Author]                                { &self.$($path).+.authors                 }
+            fn scripts(&self)          -> &indexmap::IndexMap<String, Vec<String>> { &self.$($path).+.scripts                 }
+            fn support(&self)          -> &Support                                 { &self.$($path).+.support                 }
+            fn funding(&self)          -> &[Funding]                               { &self.$($path).+.funding                 }
+            fn repositories(&self)     -> &[serde_json::Value]                     { &self.$($path).+.repositories            }
+            fn abandoned(&self)        -> Option<&str>                             {  self.$($path).+.abandoned.as_deref()    }
+            fn archive_name(&self)     -> Option<&str>                             {  self.$($path).+.archive_name.as_deref() }
+            fn archive_excludes(&self) -> &[String]                                { &self.$($path).+.archive_excludes        }
         }
     };
 }
 
-impl Package for PackageData {
+impl PackageInterface for PackageData {
     fn name(&self) -> &str {
         &self.name
     }
@@ -341,7 +295,7 @@ impl Package for PackageData {
     fn release_date(&self) -> Option<&str> {
         self.release_date.as_deref()
     }
-    fn extra(&self) -> &BTreeMap<String, serde_json::Value> {
+    fn extra(&self) -> &indexmap::IndexMap<String, serde_json::Value> {
         &self.extra
     }
     fn binaries(&self) -> &[String] {
@@ -356,22 +310,22 @@ impl Package for PackageData {
     fn notification_url(&self) -> Option<&str> {
         self.notification_url.as_deref()
     }
-    fn requires(&self) -> &BTreeMap<String, Link> {
+    fn requires(&self) -> &indexmap::IndexMap<String, Link> {
         &self.requires
     }
-    fn conflicts(&self) -> &BTreeMap<String, Link> {
+    fn conflicts(&self) -> &indexmap::IndexMap<String, Link> {
         &self.conflicts
     }
-    fn provides(&self) -> &BTreeMap<String, Link> {
+    fn provides(&self) -> &indexmap::IndexMap<String, Link> {
         &self.provides
     }
-    fn replaces(&self) -> &BTreeMap<String, Link> {
+    fn replaces(&self) -> &indexmap::IndexMap<String, Link> {
         &self.replaces
     }
-    fn dev_requires(&self) -> &BTreeMap<String, Link> {
+    fn dev_requires(&self) -> &indexmap::IndexMap<String, Link> {
         &self.dev_requires
     }
-    fn suggests(&self) -> &BTreeMap<String, String> {
+    fn suggests(&self) -> &indexmap::IndexMap<String, String> {
         &self.suggests
     }
     fn autoload(&self) -> &AutoloadRules {
@@ -385,7 +339,7 @@ impl Package for PackageData {
     }
 }
 
-impl CompletePackage for CompletePackageData {
+impl CompletePackageInterface for CompletePackageData {
     fn description(&self) -> Option<&str> {
         self.description.as_deref()
     }
@@ -401,7 +355,7 @@ impl CompletePackage for CompletePackageData {
     fn authors(&self) -> &[Author] {
         &self.authors
     }
-    fn scripts(&self) -> &BTreeMap<String, Vec<String>> {
+    fn scripts(&self) -> &indexmap::IndexMap<String, Vec<String>> {
         &self.scripts
     }
     fn support(&self) -> &Support {
@@ -431,13 +385,13 @@ impl RootPackage for RootPackageData {
     fn prefer_stable(&self) -> bool {
         self.prefer_stable
     }
-    fn stability_flags(&self) -> &BTreeMap<String, Stability> {
+    fn stability_flags(&self) -> &indexmap::IndexMap<String, Stability> {
         &self.stability_flags
     }
-    fn config(&self) -> &BTreeMap<String, serde_json::Value> {
+    fn config(&self) -> &indexmap::IndexMap<String, serde_json::Value> {
         &self.config
     }
-    fn references(&self) -> &BTreeMap<String, String> {
+    fn references(&self) -> &indexmap::IndexMap<String, String> {
         &self.references
     }
     fn aliases(&self) -> &[VersionAlias] {
@@ -489,23 +443,23 @@ pub struct RawPackageData {
     pub minimum_stability: Option<String>,
 
     #[serde(default)]
-    pub require: BTreeMap<String, String>,
+    pub require: indexmap::IndexMap<String, String>,
 
     #[serde(
         rename = "require-dev",
         default,
-        skip_serializing_if = "BTreeMap::is_empty"
+        skip_serializing_if = "indexmap::IndexMap::is_empty"
     )]
-    pub require_dev: BTreeMap<String, String>,
+    pub require_dev: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub conflict: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub conflict: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub provide: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub provide: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub replace: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub replace: indexmap::IndexMap<String, String>,
 
     /// `repositories` accepts either a JSON array or a JSON object keyed by
     /// repository name. Composer iterates `foreach ($repoConfigs as ...)` in
@@ -525,7 +479,7 @@ pub struct RawPackageData {
     pub bin: Vec<String>,
 
     #[serde(flatten)]
-    pub extra_fields: BTreeMap<String, serde_json::Value>,
+    pub extra_fields: indexmap::IndexMap<String, serde_json::Value>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -539,7 +493,7 @@ pub struct RawAuthor {
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct RawAutoload {
     #[serde(rename = "psr-4")]
-    pub psr4: BTreeMap<String, String>,
+    pub psr4: indexmap::IndexMap<String, String>,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -653,15 +607,15 @@ impl RawPackageData {
             license: None,
             authors: Vec::new(),
             minimum_stability: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             repositories: Vec::new(),
             autoload: None,
             bin: Vec::new(),
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -696,9 +650,9 @@ impl RootPackageData {
     pub fn from_raw(raw: RawPackageData) -> Self {
         fn make_links(
             source: &str,
-            deps: BTreeMap<String, String>,
+            deps: indexmap::IndexMap<String, String>,
             description: &str,
-        ) -> BTreeMap<String, Link> {
+        ) -> indexmap::IndexMap<String, Link> {
             deps.into_iter()
                 .map(|(target, constraint)| {
                     let normalized = target.to_lowercase();
@@ -745,7 +699,7 @@ impl RootPackageData {
             })
             .unwrap_or_default();
 
-        let extra: BTreeMap<String, serde_json::Value> = raw
+        let extra: indexmap::IndexMap<String, serde_json::Value> = raw
             .extra_fields
             .get("extra")
             .and_then(|v| v.as_object())
@@ -783,7 +737,7 @@ impl RootPackageData {
             })
             .unwrap_or_default();
 
-        let scripts: BTreeMap<String, Vec<String>> = raw
+        let scripts: indexmap::IndexMap<String, Vec<String>> = raw
             .extra_fields
             .get("scripts")
             .and_then(|v| v.as_object())
@@ -841,7 +795,7 @@ impl RootPackageData {
             })
             .unwrap_or_default();
 
-        let config: BTreeMap<String, serde_json::Value> = raw
+        let config: indexmap::IndexMap<String, serde_json::Value> = raw
             .extra_fields
             .get("config")
             .and_then(|v| v.as_object())
@@ -882,7 +836,7 @@ impl RootPackageData {
             provides,
             replaces,
             dev_requires,
-            suggests: BTreeMap::new(),
+            suggests: indexmap::IndexMap::new(),
             autoload,
             dev_autoload: AutoloadRules::default(),
             is_default_branch: false,
@@ -908,9 +862,9 @@ impl RootPackageData {
             complete: complete_data,
             minimum_stability,
             prefer_stable,
-            stability_flags: BTreeMap::new(),
+            stability_flags: indexmap::IndexMap::new(),
             config,
-            references: BTreeMap::new(),
+            references: indexmap::IndexMap::new(),
             aliases: Vec::new(),
         }
     }
@@ -976,7 +930,7 @@ mod tests {
             security_advisories: None,
         }];
 
-        let mut psr4 = BTreeMap::new();
+        let mut psr4 = indexmap::IndexMap::new();
         psr4.insert("Acme\\Full\\".to_string(), "src/".to_string());
         raw.autoload = Some(RawAutoload { psr4 });
 
diff --git a/crates/mozart-core/src/package/complete_package_interface.rs b/crates/mozart-core/src/package/complete_package_interface.rs
new file mode 100644
index 0000000..c321309
--- /dev/null
+++ b/crates/mozart-core/src/package/complete_package_interface.rs
@@ -0,0 +1,17 @@
+use crate::package::{Author, Funding, PackageInterface, Support};
+
+/// ref: \Composer\Package\CompletePackageInterface
+pub trait CompletePackageInterface: PackageInterface {
+    fn description(&self) -> Option<&str>;
+    fn homepage(&self) -> Option<&str>;
+    fn license(&self) -> &[String];
+    fn keywords(&self) -> &[String];
+    fn authors(&self) -> &[Author];
+    fn scripts(&self) -> &indexmap::IndexMap<String, Vec<String>>;
+    fn support(&self) -> &Support;
+    fn funding(&self) -> &[Funding];
+    fn repositories(&self) -> &[serde_json::Value];
+    fn abandoned(&self) -> Option<&str>;
+    fn archive_name(&self) -> Option<&str>;
+    fn archive_excludes(&self) -> &[String];
+}
diff --git a/crates/mozart-core/src/package/package_interface.rs b/crates/mozart-core/src/package/package_interface.rs
new file mode 100644
index 0000000..7006657
--- /dev/null
+++ b/crates/mozart-core/src/package/package_interface.rs
@@ -0,0 +1,33 @@
+use crate::package::{AutoloadRules, Link, Stability};
+
+/// ref: \Composer\Package\PackageInterface
+pub trait PackageInterface {
+    fn name(&self) -> &str;
+    fn pretty_name(&self) -> &str;
+    fn version(&self) -> &str;
+    fn pretty_version(&self) -> &str;
+    fn package_type(&self) -> &str;
+    fn target_dir(&self) -> Option<&str>;
+    fn source_type(&self) -> Option<&str>;
+    fn source_url(&self) -> Option<&str>;
+    fn source_reference(&self) -> Option<&str>;
+    fn dist_type(&self) -> Option<&str>;
+    fn dist_url(&self) -> Option<&str>;
+    fn dist_reference(&self) -> Option<&str>;
+    fn dist_sha1_checksum(&self) -> Option<&str>;
+    fn release_date(&self) -> Option<&str>;
+    fn extra(&self) -> &indexmap::IndexMap<String, serde_json::Value>;
+    fn binaries(&self) -> &[String];
+    fn is_dev(&self) -> bool;
+    fn stability(&self) -> Stability;
+    fn notification_url(&self) -> Option<&str>;
+    fn requires(&self) -> &indexmap::IndexMap<String, Link>;
+    fn conflicts(&self) -> &indexmap::IndexMap<String, Link>;
+    fn provides(&self) -> &indexmap::IndexMap<String, Link>;
+    fn replaces(&self) -> &indexmap::IndexMap<String, Link>;
+    fn dev_requires(&self) -> &indexmap::IndexMap<String, Link>;
+    fn suggests(&self) -> &indexmap::IndexMap<String, String>;
+    fn autoload(&self) -> &AutoloadRules;
+    fn dev_autoload(&self) -> &AutoloadRules;
+    fn is_default_branch(&self) -> bool;
+}
diff --git a/crates/mozart-core/src/repository/browse_repos.rs b/crates/mozart-core/src/repository/browse_repos.rs
index 83a40f1..a174637 100644
--- a/crates/mozart-core/src/repository/browse_repos.rs
+++ b/crates/mozart-core/src/repository/browse_repos.rs
@@ -8,8 +8,8 @@
 //! `CompletePackageInterface` (`getSupport()['source']`,
 //! `getSourceUrl()`, `getHomepage()`).
 
-use super::super::package::Package as _;
-use super::super::package::{CompletePackage as _, RootPackageData};
+use super::super::package::PackageInterface as _;
+use super::super::package::{CompletePackageInterface as _, RootPackageData};
 use super::cache::Cache;
 use super::installed::{InstalledPackageEntry, InstalledPackages};
 use super::lockfile::LockedPackage;
@@ -167,7 +167,6 @@ impl BrowseRepos {
 mod tests {
     use super::*;
     use crate::package::RawPackageData;
-    use std::collections::BTreeMap;
 
     fn locked(
         name: &str,
@@ -185,11 +184,11 @@ mod tests {
                 reference: None,
             }),
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: None,
             autoload: None,
@@ -202,7 +201,7 @@ mod tests {
             support: support_source.map(|s| serde_json::json!({"source": s})),
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -240,7 +239,7 @@ mod tests {
             aliases: vec![],
             homepage: Some("https://vendor.example.com".to_string()),
             support: Some(serde_json::json!({"source": "https://github.com/vendor/pkg"})),
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         };
         let view = CompletePackageView::from(&entry);
         assert_eq!(
diff --git a/crates/mozart-core/src/repository/installed.rs b/crates/mozart-core/src/repository/installed.rs
index 422f79f..4bee0e5 100644
--- a/crates/mozart-core/src/repository/installed.rs
+++ b/crates/mozart-core/src/repository/installed.rs
@@ -1,7 +1,6 @@
 use crate::installer::HasSuggests;
 use crate::package::to_json_pretty;
 use serde::{Deserialize, Serialize};
-use std::collections::BTreeMap;
 use std::fs;
 use std::path::Path;
 
@@ -56,7 +55,7 @@ pub struct InstalledPackageEntry {
     pub support: Option<serde_json::Value>,
 
     #[serde(flatten)]
-    pub extra_fields: BTreeMap<String, serde_json::Value>,
+    pub extra_fields: indexmap::IndexMap<String, serde_json::Value>,
 }
 
 impl HasSuggests for InstalledPackageEntry {
@@ -215,7 +214,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
diff --git a/crates/mozart-core/src/repository/lockfile.rs b/crates/mozart-core/src/repository/lockfile.rs
index 146506d..cde7530 100644
--- a/crates/mozart-core/src/repository/lockfile.rs
+++ b/crates/mozart-core/src/repository/lockfile.rs
@@ -2,12 +2,12 @@ use super::packagist::{PackagistDist, PackagistSource, PackagistVersion};
 use super::repository::RepositorySet;
 use super::resolver::ResolvedPackage;
 use crate::installer::HasSuggests;
-use crate::package::Package as _;
+use crate::package::PackageInterface as _;
 use crate::package::{Link, RawPackageData, to_json_pretty};
 use indexmap::IndexMap;
 use indexmap::IndexSet;
 use serde::{Deserialize, Serialize};
-use std::collections::{BTreeMap, VecDeque};
+use std::collections::VecDeque;
 use std::fs;
 use std::path::Path;
 
@@ -76,27 +76,27 @@ pub struct LockedPackage {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub dist: Option<LockedDist>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub require: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub require: indexmap::IndexMap<String, String>,
 
     #[serde(
         rename = "require-dev",
         default,
-        skip_serializing_if = "BTreeMap::is_empty"
+        skip_serializing_if = "indexmap::IndexMap::is_empty"
     )]
-    pub require_dev: BTreeMap<String, String>,
+    pub require_dev: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub conflict: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub conflict: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub provide: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub provide: indexmap::IndexMap<String, String>,
 
-    #[serde(default, skip_serializing_if = "BTreeMap::is_empty")]
-    pub replace: BTreeMap<String, String>,
+    #[serde(default, skip_serializing_if = "indexmap::IndexMap::is_empty")]
+    pub replace: indexmap::IndexMap<String, String>,
 
     #[serde(skip_serializing_if = "Option::is_none")]
-    pub suggest: Option<BTreeMap<String, String>>,
+    pub suggest: Option<indexmap::IndexMap<String, String>>,
 
     #[serde(rename = "type", skip_serializing_if = "Option::is_none")]
     pub package_type: Option<String>,
@@ -133,7 +133,7 @@ pub struct LockedPackage {
 
     /// Catch-all for extra fields we don't explicitly model
     #[serde(flatten)]
-    pub extra_fields: BTreeMap<String, serde_json::Value>,
+    pub extra_fields: indexmap::IndexMap<String, serde_json::Value>,
 }
 
 impl HasSuggests for LockedPackage {
@@ -231,9 +231,9 @@ impl LockFile {
         ];
 
         // Collect relevant keys into a BTreeMap (auto-sorted by key)
-        let mut filtered: BTreeMap<&str, &serde_json::Value> = BTreeMap::new();
-        for key in &relevant_keys {
-            if let Some(v) = obj.get(*key) {
+        let mut filtered = std::collections::BTreeMap::new();
+        for key in relevant_keys {
+            if let Some(v) = obj.get(key) {
                 filtered.insert(key, v);
             }
         }
@@ -396,7 +396,7 @@ pub fn locked_package_branch_aliases(pkg: &LockedPackage) -> Vec<LockAlias> {
 }
 
 fn check_requirement_set(
-    requires: &BTreeMap<String, Link>,
+    requires: &IndexMap<String, Link>,
     description: &str,
     pool: &[LockedSearchEntry],
     messages: &mut Vec<String>,
@@ -626,10 +626,10 @@ fn packagist_dist_to_locked(pd: &PackagistDist) -> LockedDist {
 /// `dev` after stripping the reference are left out (matching the
 /// `'dev' === VersionParser::parseStability(...)` guard in PHP).
 fn extract_root_references(
-    require: &BTreeMap<String, String>,
-    require_dev: &BTreeMap<String, String>,
-) -> BTreeMap<String, String> {
-    let mut out = BTreeMap::new();
+    require: &IndexMap<String, String>,
+    require_dev: &IndexMap<String, String>,
+) -> indexmap::IndexMap<String, String> {
+    let mut out = indexmap::IndexMap::new();
     for (name, raw_constraint) in require.iter().chain(require_dev.iter()) {
         if let Some(reference) = parse_inline_reference(raw_constraint) {
             out.insert(name.to_lowercase(), reference);
@@ -730,7 +730,7 @@ fn rewrite_known_dist_url_reference(url: &str, reference: &str) -> String {
 
 /// Convert a `PackagistVersion` to a `LockedPackage`.
 fn packagist_version_to_locked_package(name: &str, pv: &PackagistVersion) -> LockedPackage {
-    let mut extra_fields: BTreeMap<String, serde_json::Value> = BTreeMap::new();
+    let mut extra_fields = indexmap::IndexMap::new();
 
     if let Some(extra) = &pv.extra {
         extra_fields.insert("extra".to_string(), extra.clone());
@@ -808,8 +808,8 @@ fn packagist_version_to_locked_package(name: &str, pv: &PackagistVersion) -> Loc
 /// declares `provide: { provided/pkg: 1.0.0 }`.
 fn classify_dev_packages(
     resolved: &[ResolvedPackage],
-    require: &BTreeMap<String, String>,
-    _require_dev: &BTreeMap<String, String>,
+    require: &IndexMap<String, String>,
+    _require_dev: &IndexMap<String, String>,
     requires_by_name: &IndexMap<String, Vec<String>>,
     providers_by_name: &IndexMap<String, Vec<String>>,
 ) -> IndexSet<String> {
@@ -874,7 +874,7 @@ fn is_platform_name(name: &str) -> bool {
 ///
 /// Filters the map to include only platform package keys (`php`, `ext-*`, `lib-*`, etc.)
 /// and returns them as a JSON object.
-fn extract_platform_requirements(requirements: &BTreeMap<String, String>) -> serde_json::Value {
+fn extract_platform_requirements(requirements: &IndexMap<String, String>) -> serde_json::Value {
     let map: serde_json::Map<String, serde_json::Value> = requirements
         .iter()
         .filter(|(k, _)| is_platform_name(k))
@@ -920,12 +920,12 @@ pub async fn generate_lock_file(request: &LockFileGenerationRequest) -> anyhow::
     // resolver picked a new commit at the same version label) still get
     // their ref refreshed.
     struct PreservedRelationships {
-        require: BTreeMap<String, String>,
-        require_dev: BTreeMap<String, String>,
-        conflict: BTreeMap<String, String>,
-        provide: BTreeMap<String, String>,
-        replace: BTreeMap<String, String>,
-        suggest: Option<BTreeMap<String, String>>,
+        require: indexmap::IndexMap<String, String>,
+        require_dev: indexmap::IndexMap<String, String>,
+        conflict: indexmap::IndexMap<String, String>,
+        provide: indexmap::IndexMap<String, String>,
+        replace: indexmap::IndexMap<String, String>,
+        suggest: Option<indexmap::IndexMap<String, String>>,
     }
     let mut preserved_rel: IndexMap<String, PreservedRelationships> = IndexMap::new();
     if let Some(prev) = &request.previous_lock {
@@ -1229,11 +1229,11 @@ mod tests {
                 reference: Some("abc123".to_string()),
                 shasum: Some("".to_string()),
             }),
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -1246,7 +1246,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
 
         lock.write_to_file(&path).unwrap();
@@ -1320,15 +1320,15 @@ mod tests {
     fn make_packagist_version(
         version: &str,
         version_normalized: &str,
-        require: BTreeMap<String, String>,
+        require: indexmap::IndexMap<String, String>,
     ) -> PackagistVersion {
         PackagistVersion {
             version: version.to_string(),
             version_normalized: version_normalized.to_string(),
             require,
-            replace: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            conflict: BTreeMap::new(),
+            replace: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
             dist: Some(super::super::packagist::PackagistDist {
                 dist_type: "zip".to_string(),
                 url: format!("https://example.com/{version}.zip"),
@@ -1340,7 +1340,7 @@ mod tests {
                 url: "https://github.com/example/pkg.git".to_string(),
                 reference: Some("deadbeef".to_string()),
             }),
-            require_dev: BTreeMap::new(),
+            require_dev: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: Some(serde_json::json!({"psr-4": {"Example\\": "src/"}})),
@@ -1366,7 +1366,7 @@ mod tests {
 
     #[test]
     fn test_packagist_version_to_locked_package() {
-        let pv = make_packagist_version("1.2.3", "1.2.3.0", BTreeMap::new());
+        let pv = make_packagist_version("1.2.3", "1.2.3.0", indexmap::IndexMap::new());
         let locked = packagist_version_to_locked_package("example/pkg", &pv);
 
         assert_eq!(locked.name, "example/pkg");
@@ -1414,13 +1414,13 @@ mod tests {
         let pv = PackagistVersion {
             version: "1.0.0".to_string(),
             version_normalized: "1.0.0.0".to_string(),
-            require: BTreeMap::new(),
-            replace: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            conflict: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
             dist: None,
             source: None,
-            require_dev: BTreeMap::new(),
+            require_dev: indexmap::IndexMap::new(),
             suggest: None,
             package_type: None,
             autoload: None,
@@ -1484,16 +1484,16 @@ mod tests {
             },
         ];
 
-        let mut require = BTreeMap::new();
+        let mut require = indexmap::IndexMap::new();
         require.insert("vendor/a".to_string(), "^1.0".to_string());
 
-        let mut require_dev = BTreeMap::new();
+        let mut require_dev = indexmap::IndexMap::new();
         require_dev.insert("vendor/b".to_string(), "^1.0".to_string());
 
         let mut metadata: IndexMap<String, PackagistVersion> = IndexMap::new();
 
         // A requires C
-        let mut a_require = BTreeMap::new();
+        let mut a_require = indexmap::IndexMap::new();
         a_require.insert("vendor/c".to_string(), "^1.0".to_string());
         metadata.insert(
             "vendor/a".to_string(),
@@ -1501,7 +1501,7 @@ mod tests {
         );
 
         // B requires D
-        let mut b_require = BTreeMap::new();
+        let mut b_require = indexmap::IndexMap::new();
         b_require.insert("vendor/d".to_string(), "^1.0".to_string());
         metadata.insert(
             "vendor/b".to_string(),
@@ -1511,11 +1511,11 @@ mod tests {
         // C and D have no deps
         metadata.insert(
             "vendor/c".to_string(),
-            make_packagist_version("1.0.0", "1.0.0.0", BTreeMap::new()),
+            make_packagist_version("1.0.0", "1.0.0.0", indexmap::IndexMap::new()),
         );
         metadata.insert(
             "vendor/d".to_string(),
-            make_packagist_version("1.0.0", "1.0.0.0", BTreeMap::new()),
+            make_packagist_version("1.0.0", "1.0.0.0", indexmap::IndexMap::new()),
         );
 
         let requires_by_name: IndexMap<String, Vec<String>> = metadata
@@ -1577,16 +1577,16 @@ mod tests {
             },
         ];
 
-        let mut require = BTreeMap::new();
+        let mut require = indexmap::IndexMap::new();
         require.insert("vendor/a".to_string(), "^1.0".to_string());
 
-        let mut require_dev = BTreeMap::new();
+        let mut require_dev = indexmap::IndexMap::new();
         require_dev.insert("vendor/b".to_string(), "^1.0".to_string());
 
         let mut metadata: IndexMap<String, PackagistVersion> = IndexMap::new();
 
         // A requires C
-        let mut a_require = BTreeMap::new();
+        let mut a_require = indexmap::IndexMap::new();
         a_require.insert("vendor/c".to_string(), "^1.0".to_string());
         metadata.insert(
             "vendor/a".to_string(),
@@ -1594,7 +1594,7 @@ mod tests {
         );
 
         // B also requires C
-        let mut b_require = BTreeMap::new();
+        let mut b_require = indexmap::IndexMap::new();
         b_require.insert("vendor/c".to_string(), "^1.0".to_string());
         metadata.insert(
             "vendor/b".to_string(),
@@ -1604,7 +1604,7 @@ mod tests {
         // C has no deps
         metadata.insert(
             "vendor/c".to_string(),
-            make_packagist_version("1.0.0", "1.0.0.0", BTreeMap::new()),
+            make_packagist_version("1.0.0", "1.0.0.0", indexmap::IndexMap::new()),
         );
 
         let requires_by_name: IndexMap<String, Vec<String>> = metadata
@@ -1636,7 +1636,7 @@ mod tests {
 
     #[test]
     fn test_extract_platform_requirements() {
-        let mut requirements = BTreeMap::new();
+        let mut requirements = indexmap::IndexMap::new();
         requirements.insert("php".to_string(), ">=8.1".to_string());
         requirements.insert("ext-json".to_string(), "*".to_string());
         requirements.insert("ext-mbstring".to_string(), "*".to_string());
@@ -1669,7 +1669,7 @@ mod tests {
 
     #[test]
     fn test_extract_platform_requirements_empty() {
-        let requirements = BTreeMap::new();
+        let requirements = indexmap::IndexMap::new();
         let platform = extract_platform_requirements(&requirements);
         assert_eq!(platform, serde_json::json!({}));
     }
@@ -1729,11 +1729,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -1746,7 +1746,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             },
             LockedPackage {
                 name: "vendor/alpha".to_string(),
@@ -1754,11 +1754,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -1771,7 +1771,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             },
         ];
 
@@ -1892,11 +1892,11 @@ mod tests {
             version_normalized: None,
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -1909,7 +1909,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
diff --git a/crates/mozart-core/src/repository/packagist.rs b/crates/mozart-core/src/repository/packagist.rs
index 199ff51..91b47df 100644
--- a/crates/mozart-core/src/repository/packagist.rs
+++ b/crates/mozart-core/src/repository/packagist.rs
@@ -55,13 +55,13 @@ pub struct PackagistVersion {
     pub version: String,
     pub version_normalized: String,
     #[serde(default, deserialize_with = "deserialize_unset_as_default")]
-    pub require: BTreeMap<String, String>,
+    pub require: indexmap::IndexMap<String, String>,
     #[serde(default, deserialize_with = "deserialize_unset_as_default")]
-    pub replace: BTreeMap<String, String>,
+    pub replace: indexmap::IndexMap<String, String>,
     #[serde(default, deserialize_with = "deserialize_unset_as_default")]
-    pub provide: BTreeMap<String, String>,
+    pub provide: indexmap::IndexMap<String, String>,
     #[serde(default, deserialize_with = "deserialize_unset_as_default")]
-    pub conflict: BTreeMap<String, String>,
+    pub conflict: indexmap::IndexMap<String, String>,
     #[serde(default, deserialize_with = "deserialize_unset_as_none")]
     pub dist: Option<PackagistDist>,
     #[serde(default, deserialize_with = "deserialize_unset_as_none")]
@@ -72,10 +72,10 @@ pub struct PackagistVersion {
         default,
         deserialize_with = "deserialize_unset_as_default"
     )]
-    pub require_dev: BTreeMap<String, String>,
+    pub require_dev: indexmap::IndexMap<String, String>,
 
     #[serde(default, deserialize_with = "deserialize_unset_as_none")]
-    pub suggest: Option<BTreeMap<String, String>>,
+    pub suggest: Option<indexmap::IndexMap<String, String>>,
 
     #[serde(
         rename = "type",
@@ -160,17 +160,17 @@ impl PackagistVersion {
     ///
     /// Returns a map from branch name (e.g. `"dev-master"`) to alias target
     /// (e.g. `"2.x-dev"`). Returns an empty map when no aliases are declared.
-    pub fn branch_aliases(&self) -> BTreeMap<String, String> {
+    pub fn branch_aliases(&self) -> indexmap::IndexMap<String, String> {
         let Some(extra) = &self.extra else {
-            return BTreeMap::new();
+            return indexmap::IndexMap::new();
         };
 
         let Some(branch_alias) = extra.get("branch-alias") else {
-            return BTreeMap::new();
+            return indexmap::IndexMap::new();
         };
 
         let Some(map) = branch_alias.as_object() else {
-            return BTreeMap::new();
+            return indexmap::IndexMap::new();
         };
 
         map.iter()
diff --git a/crates/mozart-core/src/repository/vcs_bridge.rs b/crates/mozart-core/src/repository/vcs_bridge.rs
index 18a8420..79c0c5b 100644
--- a/crates/mozart-core/src/repository/vcs_bridge.rs
+++ b/crates/mozart-core/src/repository/vcs_bridge.rs
@@ -10,7 +10,6 @@ use crate::repository::resolver::{parse_normalized, version_stability};
 use crate::repository::vcs::DriverConfig;
 use crate::vcs::repository::{VcsPackageVersion, VcsRepository};
 use indexmap::IndexMap;
-use std::collections::BTreeMap;
 
 /// Scan all VCS-type repositories and collect package versions.
 ///
@@ -191,7 +190,7 @@ pub fn vcs_to_packagist_version(vpkg: &VcsPackageVersion) -> PackagistVersion {
 }
 
 /// Extract a dependency map from composer.json JSON.
-fn extract_dep_map(json: &serde_json::Value, key: &str) -> BTreeMap<String, String> {
+fn extract_dep_map(json: &serde_json::Value, key: &str) -> indexmap::IndexMap<String, String> {
     json.get(key)
         .and_then(|v| v.as_object())
         .map(|obj| {
diff --git a/crates/mozart-core/src/repository_utils.rs b/crates/mozart-core/src/repository_utils.rs
index b16a0d6..7a797c4 100644
--- a/crates/mozart-core/src/repository_utils.rs
+++ b/crates/mozart-core/src/repository_utils.rs
@@ -19,7 +19,7 @@ use std::collections::BTreeSet;
 /// `package_name` only in that case.
 pub trait Required {
     fn package_name(&self) -> &str;
-    fn requires(&self) -> &std::collections::BTreeMap<String, String>;
+    fn requires(&self) -> &indexmap::IndexMap<String, String>;
     fn package_names(&self) -> Option<Vec<&str>> {
         None
     }
@@ -38,8 +38,8 @@ pub trait Required {
 /// discovered, matching PHP's `$bucket[] = $candidate;` push pattern.
 pub fn filter_required_packages<P, V>(
     packages: &[P],
-    requirer_requires: &std::collections::BTreeMap<String, V>,
-    requirer_dev_requires: Option<&std::collections::BTreeMap<String, V>>,
+    requirer_requires: &indexmap::IndexMap<String, V>,
+    requirer_dev_requires: Option<&indexmap::IndexMap<String, V>>,
 ) -> Vec<usize>
 where
     P: Required,
@@ -78,24 +78,23 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::BTreeMap;
 
     struct Pkg {
         name: String,
-        requires: BTreeMap<String, String>,
+        requires: indexmap::IndexMap<String, String>,
     }
 
     impl Required for Pkg {
         fn package_name(&self) -> &str {
             &self.name
         }
-        fn requires(&self) -> &BTreeMap<String, String> {
+        fn requires(&self) -> &indexmap::IndexMap<String, String> {
             &self.requires
         }
     }
 
     fn pkg(name: &str, requires: &[&str]) -> Pkg {
-        let mut r = BTreeMap::new();
+        let mut r = indexmap::IndexMap::new();
         for n in requires {
             r.insert(n.to_string(), "*".to_string());
         }
@@ -105,8 +104,8 @@ mod tests {
         }
     }
 
-    fn root_requires(names: &[&str]) -> BTreeMap<String, String> {
-        let mut m = BTreeMap::new();
+    fn root_requires(names: &[&str]) -> indexmap::IndexMap<String, String> {
+        let mut m = indexmap::IndexMap::new();
         for n in names {
             m.insert(n.to_string(), "*".to_string());
         }
@@ -167,7 +166,7 @@ mod tests {
     #[test]
     fn empty_requires_yields_nothing() {
         let packages = vec![pkg("a/a", &[]), pkg("b/b", &[])];
-        let root: BTreeMap<String, String> = BTreeMap::new();
+        let root: indexmap::IndexMap<_, ()> = indexmap::IndexMap::new();
         let kept = filter_required_packages(&packages, &root, None);
         assert!(kept.is_empty());
     }
diff --git a/crates/mozart/src/commands/audit.rs b/crates/mozart/src/commands/audit.rs
index 0b84ccf..f543cb4 100644
--- a/crates/mozart/src/commands/audit.rs
+++ b/crates/mozart/src/commands/audit.rs
@@ -194,8 +194,6 @@ fn load_locked_packages(working_dir: &Path, no_dev: bool) -> anyhow::Result<Vec<
 
 #[cfg(test)]
 mod tests {
-    use std::collections::BTreeMap;
-
     use super::*;
     use mozart_core::repository::lockfile::{LockFile, LockedPackage};
 
@@ -242,7 +240,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
         installed.write(&vendor_dir).unwrap();
 
@@ -273,7 +271,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
         installed.upsert(mozart_core::repository::installed::InstalledPackageEntry {
             name: "phpunit/phpunit".to_string(),
@@ -287,7 +285,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
         installed
             .dev_package_names
@@ -315,11 +313,11 @@ mod tests {
                 version_normalized: Some("3.0.0.0".to_string()),
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -332,7 +330,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             }],
             packages_dev: None,
             aliases: vec![],
@@ -370,11 +368,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -387,7 +385,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             }],
             packages_dev: Some(vec![LockedPackage {
                 name: "phpunit/phpunit".to_string(),
@@ -395,11 +393,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -412,7 +410,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             }]),
             aliases: vec![],
             minimum_stability: "stable".to_string(),
diff --git a/crates/mozart/src/commands/browse.rs b/crates/mozart/src/commands/browse.rs
index e3eae22..957f4bc 100644
--- a/crates/mozart/src/commands/browse.rs
+++ b/crates/mozart/src/commands/browse.rs
@@ -4,7 +4,7 @@ use mozart_core::console::IoInterface;
 use mozart_core::console_writeln;
 use mozart_core::console_writeln_error;
 use mozart_core::exit_code;
-use mozart_core::package::Package as _;
+use mozart_core::package::PackageInterface as _;
 use mozart_core::repository::browse_repos::{BrowseRepos, CompletePackageView};
 use mozart_core::repository::cache::{Cache, build_cache_config};
 use mozart_core::repository::installed::InstalledPackages;
diff --git a/crates/mozart/src/commands/bump.rs b/crates/mozart/src/commands/bump.rs
index 351be01..2d6eea8 100644
--- a/crates/mozart/src/commands/bump.rs
+++ b/crates/mozart/src/commands/bump.rs
@@ -3,7 +3,7 @@ use clap::Args;
 use indexmap::IndexMap;
 use mozart_core::composer::LocalRepository;
 use mozart_core::console::IoInterface;
-use mozart_core::package::{Link, Package as _};
+use mozart_core::package::PackageInterface as _;
 use mozart_core::{console_writeln, console_writeln_error};
 use std::collections::BTreeMap;
 use std::path::Path;
@@ -151,7 +151,7 @@ pub async fn do_bump(
         }
     }
 
-    let mut tasks: Vec<(&'static str, &BTreeMap<String, Link>)> = Vec::new();
+    let mut tasks = Vec::new();
     if !dev_only {
         tasks.push(("require", composer.package().requires()));
     }
@@ -386,11 +386,11 @@ mod tests {
             version_normalized: Some(format!("{version}.0")),
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: None,
             autoload: None,
@@ -403,7 +403,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
diff --git a/crates/mozart/src/commands/check_platform_reqs.rs b/crates/mozart/src/commands/check_platform_reqs.rs
index 2dbcd3b..f6731d7 100644
--- a/crates/mozart/src/commands/check_platform_reqs.rs
+++ b/crates/mozart/src/commands/check_platform_reqs.rs
@@ -3,7 +3,6 @@ use mozart_core::console::IoInterface;
 use mozart_core::console_writeln;
 use mozart_core::console_writeln_error;
 use mozart_core::installer::{InstalledCandidate, InstalledRepoLite};
-use std::collections::BTreeMap;
 use std::path::Path;
 
 #[derive(Args)]
@@ -75,7 +74,7 @@ pub async fn execute(
     let installed_path = vendor_dir.join("composer/installed.json");
 
     let mut installed_repo = InstalledRepoLite::new();
-    let mut requires: BTreeMap<String, Vec<Link>> = BTreeMap::new();
+    let mut requires = indexmap::IndexMap::new();
 
     if args.lock {
         if !lock_path.exists() {
@@ -141,8 +140,8 @@ pub async fn execute(
             pretty_name: pkg.name,
             version: pkg.version.clone(),
             pretty_version: pkg.version,
-            provides: BTreeMap::new(),
-            replaces: BTreeMap::new(),
+            provides: indexmap::IndexMap::new(),
+            replaces: indexmap::IndexMap::new(),
         });
     }
 
@@ -251,7 +250,7 @@ fn load_lock(
     lock_path: &Path,
     no_dev: bool,
     repo: &mut InstalledRepoLite,
-    requires: &mut BTreeMap<String, Vec<Link>>,
+    requires: &mut indexmap::IndexMap<String, Vec<Link>>,
 ) -> anyhow::Result<()> {
     let lock = mozart_core::repository::lockfile::LockFile::read_from_file(lock_path)?;
 
@@ -282,7 +281,7 @@ fn load_installed(
     installed: &mozart_core::repository::installed::InstalledPackages,
     no_dev: bool,
     repo: &mut InstalledRepoLite,
-    requires: &mut BTreeMap<String, Vec<Link>>,
+    requires: &mut indexmap::IndexMap<String, Vec<Link>>,
 ) {
     let dev_names: indexmap::IndexSet<String> = installed
         .dev_package_names
@@ -334,10 +333,10 @@ fn add_root_as_candidate(
 }
 
 fn string_map_from_extra(
-    extra: &BTreeMap<String, serde_json::Value>,
+    extra: &indexmap::IndexMap<String, serde_json::Value>,
     key: &str,
-) -> BTreeMap<String, String> {
-    let mut out: BTreeMap<String, String> = BTreeMap::new();
+) -> indexmap::IndexMap<String, String> {
+    let mut out = indexmap::IndexMap::new();
     if let Some(val) = extra.get(key)
         && let Some(obj) = val.as_object()
     {
@@ -351,7 +350,7 @@ fn string_map_from_extra(
 }
 
 fn push_platform_link(
-    requires: &mut BTreeMap<String, Vec<Link>>,
+    requires: &mut indexmap::IndexMap<String, Vec<Link>>,
     source: &str,
     target: &str,
     constraint: &str,
@@ -470,7 +469,6 @@ fn print_table(
 mod tests {
     use super::*;
     use mozart_core::console::Console;
-    use std::collections::BTreeMap;
     use tempfile::tempdir;
 
     fn test_console() -> std::sync::Arc<std::sync::Mutex<Box<dyn IoInterface>>> {
@@ -481,22 +479,26 @@ mod tests {
 
     fn write_lock(
         path: &Path,
-        packages: &[(&str, BTreeMap<String, String>)],
-        dev_packages: &[(&str, BTreeMap<String, String>)],
+        packages: &[(&str, indexmap::IndexMap<String, String>)],
+        dev_packages: &[(&str, indexmap::IndexMap<String, String>)],
     ) {
         write_lock_with(path, packages, dev_packages, &[]);
     }
 
     fn write_lock_with(
         path: &Path,
-        packages: &[(&str, BTreeMap<String, String>)],
-        dev_packages: &[(&str, BTreeMap<String, String>)],
-        provides: &[(&str, BTreeMap<String, String>, BTreeMap<String, String>)], // (name, provide, replace)
+        packages: &[(&str, indexmap::IndexMap<String, String>)],
+        dev_packages: &[(&str, indexmap::IndexMap<String, String>)],
+        provides: &[(
+            &str,
+            indexmap::IndexMap<String, String>,
+            indexmap::IndexMap<String, String>,
+        )], // (name, provide, replace)
     ) {
         let make_pkg = |name: &str,
-                        require: BTreeMap<String, String>,
-                        provide: BTreeMap<String, String>,
-                        replace: BTreeMap<String, String>| {
+                        require: indexmap::IndexMap<String, String>,
+                        provide: indexmap::IndexMap<String, String>,
+                        replace: indexmap::IndexMap<String, String>| {
             serde_json::json!({
                 "name": name,
                 "version": "1.0.0",
@@ -508,15 +510,34 @@ mod tests {
 
         let mut pkgs_json: Vec<serde_json::Value> = packages
             .iter()
-            .map(|(name, req)| make_pkg(name, req.clone(), BTreeMap::new(), BTreeMap::new()))
+            .map(|(name, req)| {
+                make_pkg(
+                    name,
+                    req.clone(),
+                    indexmap::IndexMap::new(),
+                    indexmap::IndexMap::new(),
+                )
+            })
             .collect();
         for (name, prov, repl) in provides {
-            pkgs_json.push(make_pkg(name, BTreeMap::new(), prov.clone(), repl.clone()));
+            pkgs_json.push(make_pkg(
+                name,
+                indexmap::IndexMap::new(),
+                prov.clone(),
+                repl.clone(),
+            ));
         }
 
         let dev_pkgs_json: Vec<serde_json::Value> = dev_packages
             .iter()
-            .map(|(name, req)| make_pkg(name, req.clone(), BTreeMap::new(), BTreeMap::new()))
+            .map(|(name, req)| {
+                make_pkg(
+                    name,
+                    req.clone(),
+                    indexmap::IndexMap::new(),
+                    indexmap::IndexMap::new(),
+                )
+            })
             .collect();
 
         let lock_json = serde_json::json!({
@@ -565,7 +586,7 @@ mod tests {
         let dir = tempdir().unwrap();
         let lock_path = dir.path().join("composer.lock");
 
-        let mut pkg_require = BTreeMap::new();
+        let mut pkg_require = indexmap::IndexMap::new();
         pkg_require.insert("php".to_string(), ">=8.1".to_string());
         pkg_require.insert("ext-json".to_string(), "*".to_string());
         pkg_require.insert("monolog/monolog".to_string(), "^3.0".to_string()); // not platform
@@ -573,7 +594,7 @@ mod tests {
         write_lock(&lock_path, &[("vendor/pkg", pkg_require)], &[]);
 
         let mut repo = InstalledRepoLite::new();
-        let mut requires: BTreeMap<String, Vec<Link>> = BTreeMap::new();
+        let mut requires = indexmap::IndexMap::new();
         load_lock(&lock_path, false, &mut repo, &mut requires).unwrap();
 
         assert!(requires.contains_key("php"));
@@ -591,10 +612,10 @@ mod tests {
         let dir = tempdir().unwrap();
         let lock_path = dir.path().join("composer.lock");
 
-        let mut prod_require = BTreeMap::new();
+        let mut prod_require = indexmap::IndexMap::new();
         prod_require.insert("php".to_string(), ">=8.0".to_string());
 
-        let mut dev_require = BTreeMap::new();
+        let mut dev_require = indexmap::IndexMap::new();
         dev_require.insert("ext-xdebug".to_string(), "*".to_string());
 
         write_lock(
@@ -604,13 +625,13 @@ mod tests {
         );
 
         let mut repo = InstalledRepoLite::new();
-        let mut requires: BTreeMap<String, Vec<Link>> = BTreeMap::new();
+        let mut requires = indexmap::IndexMap::new();
         load_lock(&lock_path, true, &mut repo, &mut requires).unwrap();
         assert!(requires.contains_key("php"));
         assert!(!requires.contains_key("ext-xdebug"));
 
         let mut repo2 = InstalledRepoLite::new();
-        let mut requires2: BTreeMap<String, Vec<Link>> = BTreeMap::new();
+        let mut requires2 = indexmap::IndexMap::new();
         load_lock(&lock_path, false, &mut repo2, &mut requires2).unwrap();
         assert!(requires2.contains_key("ext-xdebug"));
     }
@@ -626,10 +647,10 @@ mod tests {
             pretty_name: "vendor/pkg".into(),
             version: "1.0.0".into(),
             pretty_version: "1.0.0".into(),
-            provides: BTreeMap::new(),
-            replaces: BTreeMap::new(),
+            provides: indexmap::IndexMap::new(),
+            replaces: indexmap::IndexMap::new(),
         });
-        let mut polyfill_provides = BTreeMap::new();
+        let mut polyfill_provides = indexmap::IndexMap::new();
         polyfill_provides.insert("ext-mbstring".to_string(), "*".to_string());
         repo.add_candidate(InstalledCandidate {
             name: "symfony/polyfill-mbstring".into(),
@@ -637,7 +658,7 @@ mod tests {
             version: "1.30.0".into(),
             pretty_version: "1.30.0".into(),
             provides: polyfill_provides,
-            replaces: BTreeMap::new(),
+            replaces: indexmap::IndexMap::new(),
         });
 
         let candidates = repo.find_with_replacers_and_providers("ext-mbstring");
@@ -652,7 +673,7 @@ mod tests {
 
     #[test]
     fn test_replacer_candidate_satisfies_require() {
-        let mut replaces = BTreeMap::new();
+        let mut replaces = indexmap::IndexMap::new();
         replaces.insert("ext-mbstring".to_string(), "1.0".to_string());
 
         let mut repo = InstalledRepoLite::new();
@@ -661,7 +682,7 @@ mod tests {
             pretty_name: "vendor/legacy-replacement".into(),
             version: "2.0.0".into(),
             pretty_version: "2.0.0".into(),
-            provides: BTreeMap::new(),
+            provides: indexmap::IndexMap::new(),
             replaces,
         });
 
diff --git a/crates/mozart/src/commands/dependency.rs b/crates/mozart/src/commands/dependency.rs
index 70d1644..5766b08 100644
--- a/crates/mozart/src/commands/dependency.rs
+++ b/crates/mozart/src/commands/dependency.rs
@@ -9,7 +9,6 @@ use indexmap::IndexSet;
 use mozart_core::console::IoInterface;
 use mozart_core::console_format;
 use mozart_core::console_writeln;
-use std::collections::BTreeMap;
 use std::path::Path;
 
 /// Inputs for [`do_execute`], collected from the `depends` / `prohibits` CLI args.
@@ -160,11 +159,11 @@ pub struct PackageInfo {
     pub name: String,
     pub version: String,
     /// Runtime requirements (`require` section).
-    pub require: BTreeMap<String, String>,
+    pub require: indexmap::IndexMap<String, String>,
     /// Dev requirements (`require-dev`) — only non-empty for the root package.
-    pub require_dev: BTreeMap<String, String>,
+    pub require_dev: indexmap::IndexMap<String, String>,
     /// Conflict declarations (`conflict` section).
-    pub conflict: BTreeMap<String, String>,
+    pub conflict: indexmap::IndexMap<String, String>,
     /// Whether this is the root `composer.json` package.
     pub is_root: bool,
 }
@@ -218,9 +217,9 @@ pub fn load_packages(working_dir: &Path, locked: bool) -> Result<Vec<PackageInfo
         packages.push(PackageInfo {
             name: pp.name.clone(),
             version: pp.version.clone(),
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
             is_root: false,
         });
     }
@@ -230,7 +229,7 @@ pub fn load_packages(working_dir: &Path, locked: bool) -> Result<Vec<PackageInfo
         && let Ok(root) = mozart_core::package::read_from_file(&composer_json_path)
     {
         // Extract conflict from extra_fields if present
-        let conflict: BTreeMap<String, String> = root
+        let conflict = root
             .extra_fields
             .get("conflict")
             .and_then(|v| v.as_object())
@@ -267,7 +266,7 @@ fn load_from_lockfile(lock_path: &Path) -> Result<Vec<PackageInfo>> {
             name: pkg.name.clone(),
             version: pkg.version.clone(),
             require: pkg.require.clone(),
-            require_dev: BTreeMap::new(), // locked packages don't expose require-dev
+            require_dev: indexmap::IndexMap::new(), // locked packages don't expose require-dev
             conflict: pkg.conflict.clone(),
             is_root: false,
         });
@@ -279,7 +278,7 @@ fn load_from_lockfile(lock_path: &Path) -> Result<Vec<PackageInfo>> {
                 name: pkg.name.clone(),
                 version: pkg.version.clone(),
                 require: pkg.require.clone(),
-                require_dev: BTreeMap::new(),
+                require_dev: indexmap::IndexMap::new(),
                 conflict: pkg.conflict.clone(),
                 is_root: false,
             });
@@ -325,7 +324,7 @@ fn load_from_installed(working_dir: &Path) -> Result<Vec<PackageInfo>> {
                 name: p.name.clone(),
                 version: p.version.clone(),
                 require,
-                require_dev: BTreeMap::new(),
+                require_dev: indexmap::IndexMap::new(),
                 conflict,
                 is_root: false,
             }
@@ -367,7 +366,7 @@ fn get_dependents_forward(
     let needle_set: IndexSet<String> = needles.iter().map(|n| n.to_lowercase()).collect();
 
     // Build name→PackageInfo lookup
-    let pkg_map: BTreeMap<String, &PackageInfo> = packages
+    let pkg_map: indexmap::IndexMap<_, _> = packages
         .iter()
         .map(|p| (p.name.to_lowercase(), p))
         .collect();
@@ -448,7 +447,7 @@ fn collect_direct_requires(packages: &[PackageInfo], needle: &str) -> Vec<Depend
 fn recurse_dependents(
     packages: &[PackageInfo],
     needle: &str,
-    pkg_map: &BTreeMap<String, &PackageInfo>,
+    pkg_map: &indexmap::IndexMap<String, &PackageInfo>,
     visited: &mut IndexSet<String>,
     _original_needles: &IndexSet<String>,
 ) -> Vec<DependencyResult> {
@@ -760,7 +759,7 @@ mod tests {
                 .iter()
                 .map(|(k, v)| (k.to_string(), v.to_string()))
                 .collect(),
-            require_dev: BTreeMap::new(),
+            require_dev: indexmap::IndexMap::new(),
             conflict: conflict
                 .iter()
                 .map(|(k, v)| (k.to_string(), v.to_string()))
diff --git a/crates/mozart/src/commands/diagnose.rs b/crates/mozart/src/commands/diagnose.rs
index a1d655f..6b2817a 100644
--- a/crates/mozart/src/commands/diagnose.rs
+++ b/crates/mozart/src/commands/diagnose.rs
@@ -8,7 +8,7 @@ use mozart_core::console::IoInterface;
 use mozart_core::console_writeln;
 use mozart_core::factory::create_config;
 use mozart_core::http::HttpDownloader;
-use mozart_core::package::CompletePackage as _;
+use mozart_core::package::CompletePackageInterface as _;
 use std::borrow::Cow;
 use std::path::Path;
 
diff --git a/crates/mozart/src/commands/exec.rs b/crates/mozart/src/commands/exec.rs
index f2a9c55..1078158 100644
--- a/crates/mozart/src/commands/exec.rs
+++ b/crates/mozart/src/commands/exec.rs
@@ -1,6 +1,6 @@
 use crate::composer::Composer;
 use clap::Args;
-use mozart_core::package::Package as _;
+use mozart_core::package::PackageInterface as _;
 use mozart_core::{console::IoInterface, console_writeln};
 use std::path::{Path, PathBuf};
 
diff --git a/crates/mozart/src/commands/init.rs b/crates/mozart/src/commands/init.rs
index 0e16054..4598d39 100644
--- a/crates/mozart/src/commands/init.rs
+++ b/crates/mozart/src/commands/init.rs
@@ -425,7 +425,7 @@ async fn build_interactive(
             "Would you like to define your dev dependencies (require-dev) interactively [<comment>yes</comment>]?"
         ))
     {
-        let all_required: BTreeMap<String, String> = require
+        let all_required: indexmap::IndexMap<_, _> = require
             .iter()
             .chain(require_dev.iter())
             .map(|(k, v)| (k.clone(), v.clone()))
@@ -493,7 +493,7 @@ async fn build_interactive(
 /// Returns a map of package name → version constraint selected by the user.
 async fn interactive_search_packages(
     label: &str,
-    already_required: &BTreeMap<String, String>,
+    already_required: &indexmap::IndexMap<String, String>,
     preferred_stability: Stability,
     repo_cache: &mozart_core::repository::cache::Cache,
     io: &std::sync::Arc<std::sync::Mutex<Box<dyn IoInterface>>>,
@@ -749,8 +749,8 @@ fn get_git_config_value(key: &str) -> Option<String> {
     get_git_config().get(key).cloned().filter(|v| !v.is_empty())
 }
 
-fn parse_requirements(reqs: &[String]) -> anyhow::Result<BTreeMap<String, String>> {
-    let mut map = BTreeMap::new();
+fn parse_requirements(reqs: &[String]) -> anyhow::Result<indexmap::IndexMap<String, String>> {
+    let mut map = indexmap::IndexMap::new();
     for req in reqs {
         let (name, version) =
             validation::parse_require_string(req).map_err(|e| anyhow::anyhow!(e))?;
@@ -761,7 +761,7 @@ fn parse_requirements(reqs: &[String]) -> anyhow::Result<BTreeMap<String, String
 
 fn build_autoload(path: &str, package_name: &str) -> Option<RawAutoload> {
     let namespace = validation::namespace_from_package_name(package_name)?;
-    let mut psr4 = BTreeMap::new();
+    let mut psr4 = indexmap::IndexMap::new();
     psr4.insert(format!("{namespace}\\"), path.to_string());
     Some(RawAutoload { psr4 })
 }
diff --git a/crates/mozart/src/commands/install.rs b/crates/mozart/src/commands/install.rs
index 54256e2..709b934 100644
--- a/crates/mozart/src/commands/install.rs
+++ b/crates/mozart/src/commands/install.rs
@@ -2,7 +2,7 @@ use clap::Args;
 use indexmap::IndexSet;
 use mozart_core::console::IoInterface;
 use mozart_core::console_format;
-use mozart_core::package::{Package as _, RootPackage as _, RootPackageData};
+use mozart_core::package::{PackageInterface as _, RootPackage as _, RootPackageData};
 use mozart_core::repository::installed;
 use mozart_core::repository::installer_executor::{
     Action, ExecuteContext, FilesystemExecutor, InstallerExecutor, PackageOperation,
@@ -11,7 +11,6 @@ use mozart_core::repository::installer_executor::{
     locked_to_installed_entry, previously_installed_alias_versions,
 };
 use mozart_core::repository::lockfile;
-use std::collections::BTreeMap;
 use std::path::Path;
 
 #[derive(Args)]
@@ -212,7 +211,7 @@ fn verify_lock_platform_problems(
 /// `provide` is intentionally excluded — `getNames(false)` excludes it, and
 /// virtual `provide` targets allow multiple co-installed providers.
 fn verify_lock_same_name_problems(lock: &lockfile::LockFile, dev_mode: bool) -> Vec<String> {
-    let mut providers: BTreeMap<String, Vec<String>> = BTreeMap::new();
+    let mut providers: indexmap::IndexMap<_, Vec<_>> = indexmap::IndexMap::new();
 
     let mut all_pkgs: Vec<&lockfile::LockedPackage> = lock.packages.iter().collect();
     if dev_mode {
@@ -397,8 +396,8 @@ fn combine_platform_requirements(
     root: &RootPackageData,
     lock: &lockfile::LockFile,
     dev_mode: bool,
-) -> BTreeMap<String, String> {
-    let mut combined: BTreeMap<String, String> = BTreeMap::new();
+) -> indexmap::IndexMap<String, String> {
+    let mut combined = indexmap::IndexMap::new();
 
     if let Some(obj) = lock.platform.as_object() {
         for (name, val) in obj {
@@ -434,7 +433,7 @@ fn combine_platform_requirements(
 }
 
 fn check_platform_requirements_against(
-    combined: &BTreeMap<String, String>,
+    combined: &indexmap::IndexMap<String, String>,
     platform: &[mozart_core::platform::PlatformPackage],
     ignore_platform_reqs: bool,
     ignore_platform_req: &[String],
@@ -1081,7 +1080,6 @@ pub async fn run(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::BTreeMap;
     use tempfile::tempdir;
 
     fn make_locked_package(name: &str, version: &str) -> lockfile::LockedPackage {
@@ -1091,11 +1089,11 @@ mod tests {
             version_normalized: None,
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -1108,7 +1106,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -1125,7 +1123,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -1506,9 +1504,10 @@ mod tests {
 
     #[test]
     fn check_platform_requirements_reports_missing_extension() {
-        let combined: BTreeMap<String, String> = [("ext-foo".to_string(), "^10".to_string())]
-            .into_iter()
-            .collect();
+        let combined: indexmap::IndexMap<String, String> =
+            [("ext-foo".to_string(), "^10".to_string())]
+                .into_iter()
+                .collect();
         let platform = vec![pp("php", "8.2.0")];
         let problems = check_platform_requirements_against(&combined, &platform, false, &[]);
 
@@ -1521,7 +1520,7 @@ mod tests {
 
     #[test]
     fn check_platform_requirements_reports_unsatisfied_php() {
-        let combined: BTreeMap<String, String> = [("php".to_string(), "^20".to_string())]
+        let combined: indexmap::IndexMap<String, String> = [("php".to_string(), "^20".to_string())]
             .into_iter()
             .collect();
         let platform = vec![pp("php", "8.2.0")];
@@ -1536,9 +1535,10 @@ mod tests {
 
     #[test]
     fn check_platform_requirements_satisfied_returns_empty() {
-        let combined: BTreeMap<String, String> = [("php".to_string(), "^8.0".to_string())]
-            .into_iter()
-            .collect();
+        let combined: indexmap::IndexMap<String, String> =
+            [("php".to_string(), "^8.0".to_string())]
+                .into_iter()
+                .collect();
         let platform = vec![pp("php", "8.2.0")];
         let problems = check_platform_requirements_against(&combined, &platform, false, &[]);
 
@@ -1547,9 +1547,10 @@ mod tests {
 
     #[test]
     fn check_platform_requirements_ignore_platform_reqs_short_circuits() {
-        let combined: BTreeMap<String, String> = [("ext-foo".to_string(), "^10".to_string())]
-            .into_iter()
-            .collect();
+        let combined: indexmap::IndexMap<String, String> =
+            [("ext-foo".to_string(), "^10".to_string())]
+                .into_iter()
+                .collect();
         let platform: Vec<mozart_core::platform::PlatformPackage> = vec![];
         let problems = check_platform_requirements_against(&combined, &platform, true, &[]);
 
@@ -1558,7 +1559,7 @@ mod tests {
 
     #[test]
     fn check_platform_requirements_specific_ignore_filters_named_packages() {
-        let combined: BTreeMap<String, String> = [
+        let combined: indexmap::IndexMap<String, String> = [
             ("ext-foo".to_string(), "^10".to_string()),
             ("ext-bar".to_string(), "^10".to_string()),
         ]
diff --git a/crates/mozart/src/commands/licenses.rs b/crates/mozart/src/commands/licenses.rs
index 73f2018..0e4ea0b 100644
--- a/crates/mozart/src/commands/licenses.rs
+++ b/crates/mozart/src/commands/licenses.rs
@@ -4,14 +4,13 @@ use indexmap::IndexMap;
 use mozart_core::console::IoInterface;
 use mozart_core::console::hyperlink;
 use mozart_core::console_writeln;
-use mozart_core::package::Package as _;
+use mozart_core::package::PackageInterface as _;
 use mozart_core::package_info;
 use mozart_core::package_info::PackageUrls;
 use mozart_core::package_sorter::sort_packages_alphabetically;
 use mozart_core::repository_utils;
 use mozart_core::repository_utils::Required;
 use serde::Serialize as _;
-use std::collections::BTreeMap;
 
 #[derive(Args)]
 pub struct LicensesArgs {
@@ -38,7 +37,7 @@ struct LicenseEntry {
     name: String,
     version: String,
     licenses: Vec<String>,
-    requires: BTreeMap<String, String>,
+    requires: indexmap::IndexMap<String, String>,
     support_source: Option<String>,
     source_url: Option<String>,
     homepage: Option<String>,
@@ -48,7 +47,7 @@ impl Required for LicenseEntry {
     fn package_name(&self) -> &str {
         &self.name
     }
-    fn requires(&self) -> &BTreeMap<String, String> {
+    fn requires(&self) -> &indexmap::IndexMap<String, String> {
         &self.requires
     }
 }
@@ -144,7 +143,7 @@ fn read_root_licenses(composer_json_path: &std::path::Path) -> anyhow::Result<Ve
 
 fn load_installed_entries<V>(
     working_dir: &std::path::Path,
-    root_requires: &BTreeMap<String, V>,
+    root_requires: &indexmap::IndexMap<String, V>,
     no_dev: bool,
 ) -> anyhow::Result<Vec<LicenseEntry>> {
     let vendor_dir = working_dir.join("vendor");
@@ -453,7 +452,6 @@ fn tally_licenses(entries: &[LicenseEntry]) -> Vec<(String, usize)> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::BTreeMap;
 
     fn entry(name: &str, licenses: &[&str]) -> LicenseEntry {
         LicenseEntry {
@@ -461,7 +459,7 @@ mod tests {
             name: name.to_lowercase(),
             version: "1.0.0".to_string(),
             licenses: licenses.iter().map(|s| s.to_string()).collect(),
-            requires: BTreeMap::new(),
+            requires: indexmap::IndexMap::new(),
             support_source: None,
             source_url: None,
             homepage: None,
@@ -547,7 +545,7 @@ mod tests {
     #[test]
     fn installed_to_entry_extracts_require_and_license() {
         use mozart_core::repository::installed::InstalledPackageEntry;
-        let mut extra = BTreeMap::new();
+        let mut extra = indexmap::IndexMap::new();
         extra.insert("license".to_string(), serde_json::json!(["MIT"]));
         extra.insert(
             "require".to_string(),
@@ -587,7 +585,7 @@ mod tests {
             aliases: vec![],
             homepage: Some("https://example.com/".to_string()),
             support: Some(serde_json::json!({"source": "https://github.com/v/p"})),
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         };
         let e = installed_to_entry(&pkg);
         assert_eq!(e.support_source.as_deref(), Some("https://github.com/v/p"));
@@ -630,7 +628,7 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
         installed.upsert(mozart_core::repository::installed::InstalledPackageEntry {
             name: "b/b".to_string(),
@@ -644,11 +642,11 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         });
         installed.write(&vendor_dir).unwrap();
 
-        let mut root_req = BTreeMap::new();
+        let mut root_req = indexmap::IndexMap::new();
         root_req.insert("a/a".to_string(), "*".to_string());
 
         let kept = load_installed_entries(working_dir, &root_req, true).unwrap();
@@ -679,11 +677,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -696,7 +694,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             }],
             packages_dev: Some(vec![LockedPackage {
                 name: "phpunit/phpunit".to_string(),
@@ -704,11 +702,11 @@ mod tests {
                 version_normalized: None,
                 source: None,
                 dist: None,
-                require: BTreeMap::new(),
-                require_dev: BTreeMap::new(),
-                conflict: BTreeMap::new(),
-                provide: BTreeMap::new(),
-                replace: BTreeMap::new(),
+                require: indexmap::IndexMap::new(),
+                require_dev: indexmap::IndexMap::new(),
+                conflict: indexmap::IndexMap::new(),
+                provide: indexmap::IndexMap::new(),
+                replace: indexmap::IndexMap::new(),
                 suggest: None,
                 package_type: None,
                 autoload: None,
@@ -721,7 +719,7 @@ mod tests {
                 support: None,
                 funding: None,
                 time: None,
-                extra_fields: BTreeMap::new(),
+                extra_fields: indexmap::IndexMap::new(),
             }]),
             aliases: vec![],
             minimum_stability: "stable".to_string(),
diff --git a/crates/mozart/src/commands/remove.rs b/crates/mozart/src/commands/remove.rs
index 5bb3be3..938a5d1 100644
--- a/crates/mozart/src/commands/remove.rs
+++ b/crates/mozart/src/commands/remove.rs
@@ -154,7 +154,7 @@ pub async fn execute(
         if args.dev {
             if composer.require_dev.contains_key(&name) {
                 console_writeln!(io, "<info>Removing {name} from require-dev</info>");
-                composer.require_dev.remove(&name);
+                composer.require_dev.shift_remove(&name);
                 packages_removed.push(name);
             } else {
                 io.lock().unwrap().info(&console_format!(
@@ -163,11 +163,11 @@ pub async fn execute(
             }
         } else if composer.require.contains_key(&name) {
             console_writeln!(io, "<info>Removing {name} from require</info>");
-            composer.require.remove(&name);
+            composer.require.shift_remove(&name);
             packages_removed.push(name);
         } else if composer.require_dev.contains_key(&name) {
             console_writeln!(io, "<info>Removing {name} from require-dev</info>");
-            composer.require_dev.remove(&name);
+            composer.require_dev.shift_remove(&name);
             packages_removed.push(name);
         } else {
             io.lock().unwrap().info(&console_format!(
@@ -682,7 +682,6 @@ mod tests {
     use super::*;
     use mozart_core::package::RawPackageData;
     use mozart_core::repository::lockfile;
-    use std::collections::BTreeMap;
 
     fn make_locked_package(name: &str, version: &str) -> lockfile::LockedPackage {
         lockfile::LockedPackage {
@@ -691,11 +690,11 @@ mod tests {
             version_normalized: Some(format!("{}.0", version)),
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -708,7 +707,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -746,7 +745,7 @@ mod tests {
 
         assert!(composer.require.contains_key("psr/log"));
 
-        composer.require.remove("psr/log");
+        composer.require.shift_remove("psr/log");
 
         assert!(
             !composer.require.contains_key("psr/log"),
@@ -771,7 +770,7 @@ mod tests {
 
         assert!(composer.require_dev.contains_key("phpunit/phpunit"));
 
-        composer.require_dev.remove("phpunit/phpunit");
+        composer.require_dev.shift_remove("phpunit/phpunit");
 
         assert!(
             !composer.require_dev.contains_key("phpunit/phpunit"),
@@ -792,8 +791,8 @@ mod tests {
             .insert("psr/log".to_string(), "^3.0".to_string());
 
         let name = "nonexistent/package";
-        let found_in_require = composer.require.remove(name).is_some();
-        let found_in_require_dev = composer.require_dev.remove(name).is_some();
+        let found_in_require = composer.require.shift_remove(name).is_some();
+        let found_in_require_dev = composer.require_dev.shift_remove(name).is_some();
 
         assert!(!found_in_require);
         assert!(!found_in_require_dev);
@@ -814,9 +813,9 @@ mod tests {
             .insert("phpunit/phpunit".to_string(), "^11.0".to_string());
 
         let name = "psr/log";
-        let removed_from_require = composer.require.remove(name).is_some();
+        let removed_from_require = composer.require.shift_remove(name).is_some();
         let removed_from_dev = if !removed_from_require {
-            composer.require_dev.remove(name).is_some()
+            composer.require_dev.shift_remove(name).is_some()
         } else {
             false
         };
@@ -842,9 +841,9 @@ mod tests {
             .insert("phpunit/phpunit".to_string(), "^11.0".to_string());
 
         let name = "phpunit/phpunit";
-        let removed_from_require = composer.require.remove(name).is_some();
+        let removed_from_require = composer.require.shift_remove(name).is_some();
         let removed_from_dev = if !removed_from_require {
-            composer.require_dev.remove(name).is_some()
+            composer.require_dev.shift_remove(name).is_some()
         } else {
             false
         };
@@ -894,8 +893,8 @@ mod tests {
 
         // A glob-style name: not a valid exact package name, not in require either.
         let name = "vendor/*";
-        let found =
-            composer.require.remove(name).is_some() || composer.require_dev.remove(name).is_some();
+        let found = composer.require.shift_remove(name).is_some()
+            || composer.require_dev.shift_remove(name).is_some();
 
         // Should NOT be found (falls through to "not required" warning), not panicked/bailed.
         assert!(!found, "glob name should not match any package");
@@ -1001,7 +1000,7 @@ mod tests {
             .write_to_file(&lock_path)
             .expect("should write initial lock file");
 
-        composer.require.remove("psr/log");
+        composer.require.shift_remove("psr/log");
         package::write_to_file(&composer, &composer_path).unwrap();
 
         let request2 = ResolveRequest {
@@ -1084,7 +1083,7 @@ mod tests {
         std::fs::write(&composer_path, content).unwrap();
 
         let mut composer: RawPackageData = serde_json::from_str(content).unwrap();
-        composer.require.remove("psr/log");
+        composer.require.shift_remove("psr/log");
         package::write_to_file(&composer, &composer_path).unwrap();
 
         assert!(
diff --git a/crates/mozart/src/commands/require.rs b/crates/mozart/src/commands/require.rs
index 3d5fcd6..f92442c 100644
--- a/crates/mozart/src/commands/require.rs
+++ b/crates/mozart/src/commands/require.rs
@@ -1026,9 +1026,9 @@ pub async fn execute(
     // Remove from the opposite section before inserting into the target.
     for pkg in &inconsistent {
         if args.dev {
-            raw.require.remove(pkg.as_str());
+            raw.require.shift_remove(pkg.as_str());
         } else {
-            raw.require_dev.remove(pkg.as_str());
+            raw.require_dev.shift_remove(pkg.as_str());
         }
     }
 
@@ -1066,10 +1066,8 @@ pub async fn execute(
     let sort_packages = args.sort_packages || config_sort_packages;
 
     if sort_packages {
-        let sorted_require: std::collections::BTreeMap<_, _> = raw.require.clone();
-        raw.require = sorted_require;
-        let sorted_dev: std::collections::BTreeMap<_, _> = raw.require_dev.clone();
-        raw.require_dev = sorted_dev;
+        raw.require.sort_unstable_keys();
+        raw.require_dev.sort_unstable_keys();
     }
 
     // --- Write composer.json (unless --dry-run) ---
@@ -1129,7 +1127,6 @@ pub async fn execute(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::BTreeMap;
 
     fn make_locked_package(name: &str, version: &str) -> lockfile::LockedPackage {
         lockfile::LockedPackage {
@@ -1138,11 +1135,11 @@ mod tests {
             version_normalized: Some(format!("{}.0", version)),
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -1155,7 +1152,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
@@ -1176,35 +1173,6 @@ mod tests {
         }
     }
 
-    /// Verify that --sort-packages sorts both require and require-dev maps.
-    #[test]
-    fn test_sort_packages_sorts_both_sections() {
-        use mozart_core::package::RawPackageData;
-
-        let mut raw = RawPackageData::new("test/project".to_string());
-        raw.require
-            .insert("z/package".to_string(), "^1.0".to_string());
-        raw.require
-            .insert("a/package".to_string(), "^2.0".to_string());
-        raw.require
-            .insert("m/package".to_string(), "^3.0".to_string());
-        raw.require_dev
-            .insert("z/dev".to_string(), "^1.0".to_string());
-        raw.require_dev
-            .insert("a/dev".to_string(), "^2.0".to_string());
-
-        let sorted_require: BTreeMap<String, String> = raw.require.clone();
-        raw.require = sorted_require;
-        let sorted_dev: BTreeMap<String, String> = raw.require_dev.clone();
-        raw.require_dev = sorted_dev;
-
-        let require_keys: Vec<_> = raw.require.keys().collect();
-        assert_eq!(require_keys, vec!["a/package", "m/package", "z/package"]);
-
-        let dev_keys: Vec<_> = raw.require_dev.keys().collect();
-        assert_eq!(dev_keys, vec!["a/dev", "z/dev"]);
-    }
-
     /// Verify that compute_update_changes produces correct Install entries for new packages.
     #[test]
     fn test_require_change_report_new_packages() {
diff --git a/crates/mozart/src/commands/show.rs b/crates/mozart/src/commands/show.rs
index d0a2218..81eaaad 100644
--- a/crates/mozart/src/commands/show.rs
+++ b/crates/mozart/src/commands/show.rs
@@ -6,7 +6,6 @@ use mozart_core::console_writeln;
 use mozart_core::console_writeln_error;
 use mozart_core::matches_wildcard;
 use mozart_core::platform::is_platform_package;
-use std::collections::BTreeMap;
 use std::path::Path;
 
 #[derive(Default, Args)]
@@ -255,15 +254,15 @@ struct PackageDetail {
     support: Option<serde_json::Value>,
     /// A13: autoload rules.
     autoload: Option<serde_json::Value>,
-    require: BTreeMap<String, String>,
-    require_dev: BTreeMap<String, String>,
+    require: indexmap::IndexMap<String, String>,
+    require_dev: indexmap::IndexMap<String, String>,
     /// A12: conflict links.
-    conflict: BTreeMap<String, String>,
+    conflict: indexmap::IndexMap<String, String>,
     /// A12: provide links.
-    provide: BTreeMap<String, String>,
+    provide: indexmap::IndexMap<String, String>,
     /// A12: replace links.
-    replace: BTreeMap<String, String>,
-    suggest: BTreeMap<String, String>,
+    replace: indexmap::IndexMap<String, String>,
+    suggest: indexmap::IndexMap<String, String>,
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
@@ -1132,7 +1131,7 @@ async fn print_package_detail(
 /// Print a named section of package links (requires, conflict, etc.).
 fn print_links_section(
     label: &str,
-    links: &BTreeMap<String, String>,
+    links: &indexmap::IndexMap<String, String>,
     io: std::sync::Arc<std::sync::Mutex<Box<dyn IoInterface>>>,
 ) {
     if links.is_empty() {
@@ -2077,7 +2076,7 @@ fn get_installed_release_date(
 fn get_installed_link_map(
     pkg: &mozart_core::repository::installed::InstalledPackageEntry,
     key: &str,
-) -> BTreeMap<String, String> {
+) -> indexmap::IndexMap<String, String> {
     pkg.extra_fields
         .get(key)
         .and_then(|v| v.as_object())
@@ -2092,7 +2091,7 @@ fn get_installed_link_map(
 /// Extract a map of `{package: reason}` from an installed package's suggest field.
 fn get_installed_suggest_map(
     pkg: &mozart_core::repository::installed::InstalledPackageEntry,
-) -> BTreeMap<String, String> {
+) -> indexmap::IndexMap<String, String> {
     pkg.extra_fields
         .get("suggest")
         .and_then(|v| v.as_object())
@@ -2268,8 +2267,7 @@ mod tests {
 
     #[test]
     fn test_get_installed_description_present() {
-        use std::collections::BTreeMap;
-        let mut extra = BTreeMap::new();
+        let mut extra = indexmap::IndexMap::new();
         extra.insert(
             "description".to_string(),
             serde_json::Value::String("A logging library".to_string()),
@@ -2293,7 +2291,6 @@ mod tests {
 
     #[test]
     fn test_get_installed_description_absent() {
-        use std::collections::BTreeMap;
         let pkg = mozart_core::repository::installed::InstalledPackageEntry {
             name: "psr/log".to_string(),
             version: "3.0.0".to_string(),
@@ -2306,15 +2303,14 @@ mod tests {
             aliases: vec![],
             homepage: None,
             support: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         };
         assert_eq!(get_installed_description(&pkg), "");
     }
 
     #[test]
     fn test_get_installed_keywords() {
-        use std::collections::BTreeMap;
-        let mut extra = BTreeMap::new();
+        let mut extra = indexmap::IndexMap::new();
         extra.insert(
             "keywords".to_string(),
             serde_json::json!(["log", "psr3", "logging"]),
diff --git a/crates/mozart/src/commands/suggests.rs b/crates/mozart/src/commands/suggests.rs
index b882f5c..ca8e5fe 100644
--- a/crates/mozart/src/commands/suggests.rs
+++ b/crates/mozart/src/commands/suggests.rs
@@ -235,11 +235,10 @@ fn build_root_info(root: Option<&mozart_core::package::RawPackageData>) -> RootI
 mod tests {
     use super::*;
     use mozart_core::installer::{HasSuggests, InstalledRepoLite, RootInfo};
-    use std::collections::BTreeMap;
 
     fn make_locked_package(
         name: &str,
-        suggest: Option<BTreeMap<String, String>>,
+        suggest: Option<indexmap::IndexMap<String, String>>,
     ) -> mozart_core::repository::lockfile::LockedPackage {
         mozart_core::repository::lockfile::LockedPackage {
             name: name.to_string(),
@@ -247,11 +246,11 @@ mod tests {
             version_normalized: None,
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest,
             package_type: None,
             autoload: None,
@@ -264,15 +263,15 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
     fn make_installed_entry(
         name: &str,
-        suggest: Option<BTreeMap<String, String>>,
+        suggest: Option<indexmap::IndexMap<String, String>>,
     ) -> mozart_core::repository::installed::InstalledPackageEntry {
-        let mut extra_fields: BTreeMap<String, serde_json::Value> = BTreeMap::new();
+        let mut extra_fields = indexmap::IndexMap::new();
         if let Some(s) = suggest {
             let map: serde_json::Map<String, serde_json::Value> = s
                 .into_iter()
@@ -322,7 +321,7 @@ mod tests {
 
     #[test]
     fn locked_package_implements_has_suggests() {
-        let mut suggest = BTreeMap::new();
+        let mut suggest = indexmap::IndexMap::new();
         suggest.insert("ext-intl".to_string(), "for i18n".to_string());
         suggest.insert("ext-redis".to_string(), "for cache".to_string());
         let pkg = make_locked_package("vendor/a", Some(suggest));
@@ -333,7 +332,7 @@ mod tests {
 
     #[test]
     fn installed_entry_reads_suggest_from_extra_fields() {
-        let mut suggest = BTreeMap::new();
+        let mut suggest = indexmap::IndexMap::new();
         suggest.insert("ext-redis".to_string(), "for cache".to_string());
         let entry = make_installed_entry("vendor/cache", Some(suggest));
         let pairs = entry.suggests();
@@ -413,15 +412,15 @@ mod tests {
             license: None,
             authors: vec![],
             minimum_stability: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             repositories: vec![],
             autoload: None,
             bin: vec![],
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         };
         root.require.insert("vendor/a".into(), "^1.0".into());
         root.require_dev.insert("vendor/b".into(), "^2.0".into());
@@ -437,7 +436,7 @@ mod tests {
         let console = console();
         let mut reporter = SuggestedPackagesReporter::new(&console);
 
-        let mut suggest = BTreeMap::new();
+        let mut suggest = indexmap::IndexMap::new();
         suggest.insert("ext-intl".to_string(), "for i18n".to_string());
         suggest.insert("vendor/optional".to_string(), "Optional".to_string());
         let pkg = make_locked_package("vendor/a", Some(suggest));
@@ -452,7 +451,7 @@ mod tests {
         let console = console();
         let mut reporter = SuggestedPackagesReporter::new(&console);
 
-        let mut suggest = BTreeMap::new();
+        let mut suggest = indexmap::IndexMap::new();
         suggest.insert("vendor/already-here".to_string(), "".to_string());
         suggest.insert("vendor/not-here".to_string(), "".to_string());
         let pkg = make_locked_package("vendor/a", Some(suggest));
diff --git a/crates/mozart/src/commands/update.rs b/crates/mozart/src/commands/update.rs
index f482272..334e221 100644
--- a/crates/mozart/src/commands/update.rs
+++ b/crates/mozart/src/commands/update.rs
@@ -1803,7 +1803,6 @@ pub async fn run(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use std::collections::BTreeMap;
 
     fn make_locked_package(name: &str, version: &str) -> lockfile::LockedPackage {
         lockfile::LockedPackage {
@@ -1812,11 +1811,11 @@ mod tests {
             version_normalized: Some(format!("{}.0", version)),
             source: None,
             dist: None,
-            require: BTreeMap::new(),
-            require_dev: BTreeMap::new(),
-            conflict: BTreeMap::new(),
-            provide: BTreeMap::new(),
-            replace: BTreeMap::new(),
+            require: indexmap::IndexMap::new(),
+            require_dev: indexmap::IndexMap::new(),
+            conflict: indexmap::IndexMap::new(),
+            provide: indexmap::IndexMap::new(),
+            replace: indexmap::IndexMap::new(),
             suggest: None,
             package_type: Some("library".to_string()),
             autoload: None,
@@ -1829,7 +1828,7 @@ mod tests {
             support: None,
             funding: None,
             time: None,
-            extra_fields: BTreeMap::new(),
+            extra_fields: indexmap::IndexMap::new(),
         }
     }
 
diff --git a/crates/mozart/src/factory.rs b/crates/mozart/src/factory.rs
index 41f157a..581b53a 100644
--- a/crates/mozart/src/factory.rs
+++ b/crates/mozart/src/factory.rs
@@ -368,7 +368,7 @@ mod tests {
             r#"{"name": "acme/app", "require": {"vendor/pkg": "^1.0"}}"#,
         );
 
-        use mozart_core::package::Package;
+        use mozart_core::package::PackageInterface;
         let composer = Composer::require(io(), dir.path()).unwrap();
         assert_eq!(composer.package().name(), "acme/app");
         assert_eq!(