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diff --git a/crates/mozart/src/composer.rs b/crates/mozart/src/composer.rs
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+++ b/crates/mozart/src/composer.rs
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+//! Composer-equivalent root state: composer.json + effective config +
+//! the manager objects commands look up off the root [`Composer`].
+//!
+//! Mirrors the role of `Composer\Composer` / `Composer\PartialComposer`
+//! (PHP) — a state container with getters for the merged [`Config`], the
+//! root [`RawPackageData`], the [`RepositoryManager`], and the
+//! [`InstallationManager`]. Wiring lives in [`crate::factory`], the same
+//! split as upstream's `Composer\Factory::createComposer`.
+//!
+//! See `Composer\Command\BaseCommand::requireComposer()` /
+//! `Composer\Command\BaseCommand::tryComposer()` for the upstream contract
+//! that [`Composer::require`] and [`Composer::try_load`] are modelled on.
+
+use std::path::{Path, PathBuf};
+
+use crate::factory::create_composer;
+use mozart_core::composer::{AutoloadGenerator, InstallationManager, Locker, RepositoryManager};
+use mozart_core::config::Config;
+use mozart_core::package::RawPackageData;
+use mozart_registry::download_manager::DownloadManager;
+
+/// Project-level Composer state. Mirrors `Composer\PartialComposer` /
+/// `Composer\Composer` in PHP, exposing the subset of getters command
+/// handlers need today: config, root package, repository manager,
+/// installation manager, autoload generator, and locker. More
+/// managers (download, …) can be layered on as commands need them.
+pub struct Composer {
+    project_dir: PathBuf,
+    config: Config,
+    package: RawPackageData,
+    repository_manager: RepositoryManager,
+    installation_manager: InstallationManager,
+    download_manager: DownloadManager,
+    autoload_generator: AutoloadGenerator,
+    locker: Locker,
+}
+
+impl Composer {
+    /// All-args constructor used by [`crate::factory::create_composer`].
+    /// Mirrors the PHP pattern of `new Composer()` followed by
+    /// `setConfig` / `setPackage` / `setRepositoryManager` /
+    /// `setInstallationManager` / `setAutoloadGenerator` / `setLocker`,
+    /// collapsed into a single immutable build.
+    #[allow(clippy::too_many_arguments)]
+    pub fn new(
+        project_dir: PathBuf,
+        config: Config,
+        package: RawPackageData,
+        repository_manager: RepositoryManager,
+        installation_manager: InstallationManager,
+        download_manager: DownloadManager,
+        autoload_generator: AutoloadGenerator,
+        locker: Locker,
+    ) -> Self {
+        Self {
+            project_dir,
+            config,
+            package,
+            repository_manager,
+            installation_manager,
+            download_manager,
+            autoload_generator,
+            locker,
+        }
+    }
+
+    /// Load Composer state for `project_dir`, requiring a composer.json.
+    /// Mirrors `BaseCommand::requireComposer()`, which delegates to
+    /// `Factory::createComposer` after asserting the file exists.
+    pub fn require(project_dir: impl Into<PathBuf>) -> anyhow::Result<Self> {
+        let project_dir = project_dir.into();
+        let composer_json = project_dir.join("composer.json");
+        if !composer_json.exists() {
+            anyhow::bail!(
+                "Composer could not find a composer.json file in {}",
+                project_dir.display()
+            );
+        }
+        create_composer(project_dir, &composer_json)
+    }
+
+    /// Load Composer state for `project_dir`, returning `None` if no
+    /// composer.json exists. Other I/O or parse errors still propagate.
+    /// Mirrors `BaseCommand::tryComposer()`.
+    pub fn try_load(project_dir: impl Into<PathBuf>) -> anyhow::Result<Option<Self>> {
+        let project_dir = project_dir.into();
+        let composer_json = project_dir.join("composer.json");
+        if !composer_json.exists() {
+            return Ok(None);
+        }
+        create_composer(project_dir, &composer_json).map(Some)
+    }
+
+    /// Load Composer state keyed on a specific `composer.json` file, deriving
+    /// the project directory from `file.parent()`. Mirrors
+    /// `ValidateCommand::createComposerInstance($file)` — Composer keys
+    /// instances on a file rather than a directory for non-default paths.
+    pub fn try_load_from_file(file: &Path) -> anyhow::Result<Option<Self>> {
+        let project_dir = file
+            .parent()
+            .map(Path::to_path_buf)
+            .unwrap_or_else(|| PathBuf::from("."));
+        Self::try_load(project_dir)
+    }
+
+    pub fn project_dir(&self) -> &Path {
+        &self.project_dir
+    }
+
+    pub fn config(&self) -> &Config {
+        &self.config
+    }
+
+    /// Root package loaded from the project's `composer.json`. Mirrors
+    /// `Composer::getPackage()`; ideally this would return a fully
+    /// resolved `RootPackageInterface` equivalent, but Mozart does not
+    /// yet have a `RootPackageLoader` port — for now callers see the
+    /// raw, pre-normalised JSON shape.
+    pub fn package(&self) -> &RawPackageData {
+        &self.package
+    }
+
+    /// Mirror of `Composer::getRepositoryManager()`.
+    pub fn repository_manager(&self) -> &RepositoryManager {
+        &self.repository_manager
+    }
+
+    /// Mirror of `Composer::getInstallationManager()`.
+    pub fn installation_manager(&self) -> &InstallationManager {
+        &self.installation_manager
+    }
+
+    pub fn download_manager(&self) -> &DownloadManager {
+        &self.download_manager
+    }
+
+    /// Mirror of `Composer::getAutoloadGenerator()`.
+    ///
+    /// Returned by shared reference because Mozart's
+    /// [`AutoloadGenerator`] is stateless — per-call toggles live on
+    /// [`AutoloadDumpOptions`] passed into `dump()`, not on the
+    /// generator itself. Diverges from PHP's
+    /// `$composer->getAutoloadGenerator()->setDryRun(...)` chain.
+    pub fn autoload_generator(&self) -> &AutoloadGenerator {
+        &self.autoload_generator
+    }
+
+    /// Mirror of `Composer::getLocker()`.
+    pub fn locker(&self) -> &Locker {
+        &self.locker
+    }
+}