From 18d5dbfb7fff20ed04554e4754679092f533583f Mon Sep 17 00:00:00 2001
From: Micha Reiser <micha@reiser.io>
Date: Wed, 15 Jan 2025 09:03:38 +0100
Subject: [PATCH] Remove workspace support (#15472)

---
 _typos.toml                                   |  16 +-
 crates/red_knot/src/main.rs                   |  24 +-
 crates/red_knot/tests/file_watching.rs        | 419 ++++-----
 crates/red_knot_python_semantic/src/db.rs     |   2 +-
 .../src/module_resolver/resolver.rs           |   4 +-
 .../src/module_resolver/testing.rs            |   4 +-
 .../red_knot_python_semantic/src/program.rs   |  45 +-
 .../src/python_platform.rs                    |  11 +
 crates/red_knot_server/src/server/api.rs      |  12 +-
 .../server/api/notifications/did_change.rs    |   6 +-
 .../src/server/api/notifications/did_close.rs |   2 +-
 .../api/notifications/did_close_notebook.rs   |   2 +-
 .../src/server/api/notifications/did_open.rs  |   6 +-
 .../api/notifications/did_open_notebook.rs    |   6 +-
 .../src/server/api/requests/diagnostic.rs     |   6 +-
 .../red_knot_server/src/server/api/traits.rs  |   4 +-
 crates/red_knot_server/src/session.rs         |  58 +-
 crates/red_knot_test/src/db.rs                |   2 +-
 crates/red_knot_wasm/src/lib.rs               |  16 +-
 crates/red_knot_workspace/src/db.rs           |  63 +-
 crates/red_knot_workspace/src/db/changes.rs   | 121 ++-
 crates/red_knot_workspace/src/lib.rs          |   2 +-
 crates/red_knot_workspace/src/project.rs      | 459 ++++++++++
 .../src/{workspace => project}/files.rs       |  46 +-
 .../src/project/metadata.rs                   | 418 +++++++++
 .../src/{workspace => project}/pyproject.rs   |  55 +-
 .../pyproject/package_name.rs                 |   0
 .../src/{workspace => project}/settings.rs    |  25 +-
 ...ests__nested_projects_in_root_project.snap |  17 +
 ...tests__nested_projects_in_sub_project.snap |  17 +
 ...sted_projects_with_outer_knot_section.snap |  17 +
 ...nested_projects_without_knot_sections.snap |  17 +
 ...tadata__tests__project_with_pyproject.snap |  17 +
 ...ata__tests__project_without_pyproject.snap |  17 +
 crates/red_knot_workspace/src/watch.rs        |   4 +-
 ...orkspace_watcher.rs => project_watcher.rs} |  38 +-
 crates/red_knot_workspace/src/workspace.rs    | 665 --------------
 .../src/workspace/metadata.rs                 | 812 ------------------
 ...__tests__member_pattern_matching_file.snap |  34 -
 ...member_pattern_matching_hidden_folder.snap |  34 -
 ...ata__tests__package_without_pyproject.snap |  34 -
 ...pace__metadata__tests__single_package.snap |  34 -
 ...__metadata__tests__workspace_excluded.snap |  47 -
 ...e__metadata__tests__workspace_members.snap |  60 --
 crates/red_knot_workspace/tests/check.rs      |  28 +-
 crates/ruff_benchmark/benches/red_knot.rs     |  14 +-
 crates/ruff_db/src/files/file_root.rs         |  10 +-
 crates/ruff_graph/src/db.rs                   |   2 +-
 .../red_knot_check_invalid_syntax.rs          |   2 +-
 49 files changed, 1428 insertions(+), 2326 deletions(-)
 create mode 100644 crates/red_knot_workspace/src/project.rs
 rename crates/red_knot_workspace/src/{workspace => project}/files.rs (88%)
 create mode 100644 crates/red_knot_workspace/src/project/metadata.rs
 rename crates/red_knot_workspace/src/{workspace => project}/pyproject.rs (52%)
 rename crates/red_knot_workspace/src/{workspace => project}/pyproject/package_name.rs (100%)
 rename crates/red_knot_workspace/src/{workspace => project}/settings.rs (82%)
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_root_project.snap
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_sub_project.snap
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_with_outer_knot_section.snap
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_without_knot_sections.snap
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_with_pyproject.snap
 create mode 100644 crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_without_pyproject.snap
 rename crates/red_knot_workspace/src/watch/{workspace_watcher.rs => project_watcher.rs} (79%)
 delete mode 100644 crates/red_knot_workspace/src/workspace.rs
 delete mode 100644 crates/red_knot_workspace/src/workspace/metadata.rs
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_file.snap
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_hidden_folder.snap
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__package_without_pyproject.snap
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__single_package.snap
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_excluded.snap
 delete mode 100644 crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_members.snap

diff --git a/_typos.toml b/_typos.toml
index 48e4a4c375..7a6abdad8e 100644
--- a/_typos.toml
+++ b/_typos.toml
@@ -1,10 +1,9 @@
 [files]
 # https://github.com/crate-ci/typos/issues/868
 extend-exclude = [
-  "crates/red_knot_vendored/vendor/**/*",
-  "**/resources/**/*",
-  "**/snapshots/**/*",
-  "crates/red_knot_workspace/src/workspace/pyproject/package_name.rs"
+    "crates/red_knot_vendored/vendor/**/*",
+    "**/resources/**/*",
+    "**/snapshots/**/*",
 ]
 
 [default.extend-words]
@@ -21,7 +20,10 @@ Numer = "Numer" # Library name 'NumerBlox' in "Who's Using Ruff?"
 
 [default]
 extend-ignore-re = [
-  # Line ignore with trailing "spellchecker:disable-line"
-  "(?Rm)^.*#\\s*spellchecker:disable-line$",
-  "LICENSEs",
+    # Line ignore with trailing "spellchecker:disable-line"
+    "(?Rm)^.*#\\s*spellchecker:disable-line$",
+    "LICENSEs",
 ]
+
+[default.extend-identifiers]
+"FrIeNdLy" = "FrIeNdLy"
diff --git a/crates/red_knot/src/main.rs b/crates/red_knot/src/main.rs
index 49730267b2..7d5626aaed 100644
--- a/crates/red_knot/src/main.rs
+++ b/crates/red_knot/src/main.rs
@@ -8,11 +8,11 @@ use crossbeam::channel as crossbeam_channel;
 use python_version::PythonVersion;
 use red_knot_python_semantic::SitePackages;
 use red_knot_server::run_server;
-use red_knot_workspace::db::RootDatabase;
+use red_knot_workspace::db::ProjectDatabase;
+use red_knot_workspace::project::settings::Configuration;
+use red_knot_workspace::project::ProjectMetadata;
 use red_knot_workspace::watch;
-use red_knot_workspace::watch::WorkspaceWatcher;
-use red_knot_workspace::workspace::settings::Configuration;
-use red_knot_workspace::workspace::WorkspaceMetadata;
+use red_knot_workspace::watch::ProjectWatcher;
 use ruff_db::diagnostic::Diagnostic;
 use ruff_db::system::{OsSystem, System, SystemPath, SystemPathBuf};
 use salsa::plumbing::ZalsaDatabase;
@@ -165,7 +165,7 @@ fn run() -> anyhow::Result<ExitStatus> {
 
     let system = OsSystem::new(cwd.clone());
     let cli_configuration = args.to_configuration(&cwd);
-    let workspace_metadata = WorkspaceMetadata::discover(
+    let workspace_metadata = ProjectMetadata::discover(
         system.current_directory(),
         &system,
         Some(&cli_configuration),
@@ -173,7 +173,7 @@ fn run() -> anyhow::Result<ExitStatus> {
 
     // TODO: Use the `program_settings` to compute the key for the database's persistent
     //   cache and load the cache if it exists.
-    let mut db = RootDatabase::new(workspace_metadata, system)?;
+    let mut db = ProjectDatabase::new(workspace_metadata, system)?;
 
     let (main_loop, main_loop_cancellation_token) = MainLoop::new(cli_configuration);
 
@@ -226,7 +226,7 @@ struct MainLoop {
     receiver: crossbeam_channel::Receiver<MainLoopMessage>,
 
     /// The file system watcher, if running in watch mode.
-    watcher: Option<WorkspaceWatcher>,
+    watcher: Option<ProjectWatcher>,
 
     cli_configuration: Configuration,
 }
@@ -246,21 +246,21 @@ impl MainLoop {
         )
     }
 
-    fn watch(mut self, db: &mut RootDatabase) -> anyhow::Result<ExitStatus> {
+    fn watch(mut self, db: &mut ProjectDatabase) -> anyhow::Result<ExitStatus> {
         tracing::debug!("Starting watch mode");
         let sender = self.sender.clone();
         let watcher = watch::directory_watcher(move |event| {
             sender.send(MainLoopMessage::ApplyChanges(event)).unwrap();
         })?;
 
-        self.watcher = Some(WorkspaceWatcher::new(watcher, db));
+        self.watcher = Some(ProjectWatcher::new(watcher, db));
 
         self.run(db);
 
         Ok(ExitStatus::Success)
     }
 
-    fn run(mut self, db: &mut RootDatabase) -> ExitStatus {
+    fn run(mut self, db: &mut ProjectDatabase) -> ExitStatus {
         self.sender.send(MainLoopMessage::CheckWorkspace).unwrap();
 
         let result = self.main_loop(db);
@@ -270,7 +270,7 @@ impl MainLoop {
         result
     }
 
-    fn main_loop(&mut self, db: &mut RootDatabase) -> ExitStatus {
+    fn main_loop(&mut self, db: &mut ProjectDatabase) -> ExitStatus {
         // Schedule the first check.
         tracing::debug!("Starting main loop");
 
@@ -282,7 +282,7 @@ impl MainLoop {
                     let db = db.clone();
                     let sender = self.sender.clone();
 
-                    // Spawn a new task that checks the workspace. This needs to be done in a separate thread
+                    // Spawn a new task that checks the project. This needs to be done in a separate thread
                     // to prevent blocking the main loop here.
                     rayon::spawn(move || {
                         if let Ok(result) = db.check() {
diff --git a/crates/red_knot/tests/file_watching.rs b/crates/red_knot/tests/file_watching.rs
index 99229ffad9..22140811fa 100644
--- a/crates/red_knot/tests/file_watching.rs
+++ b/crates/red_knot/tests/file_watching.rs
@@ -5,18 +5,18 @@ use std::time::{Duration, Instant};
 
 use anyhow::{anyhow, Context};
 use red_knot_python_semantic::{resolve_module, ModuleName, Program, PythonVersion, SitePackages};
-use red_knot_workspace::db::{Db, RootDatabase};
-use red_knot_workspace::watch::{directory_watcher, ChangeEvent, WorkspaceWatcher};
-use red_knot_workspace::workspace::settings::{Configuration, SearchPathConfiguration};
-use red_knot_workspace::workspace::WorkspaceMetadata;
+use red_knot_workspace::db::{Db, ProjectDatabase};
+use red_knot_workspace::project::settings::{Configuration, SearchPathConfiguration};
+use red_knot_workspace::project::ProjectMetadata;
+use red_knot_workspace::watch::{directory_watcher, ChangeEvent, ProjectWatcher};
 use ruff_db::files::{system_path_to_file, File, FileError};
 use ruff_db::source::source_text;
 use ruff_db::system::{OsSystem, SystemPath, SystemPathBuf};
 use ruff_db::Upcast;
 
 struct TestCase {
-    db: RootDatabase,
-    watcher: Option<WorkspaceWatcher>,
+    db: ProjectDatabase,
+    watcher: Option<ProjectWatcher>,
     changes_receiver: crossbeam::channel::Receiver<Vec<ChangeEvent>>,
     /// The temporary directory that contains the test files.
     /// We need to hold on to it in the test case or the temp files get deleted.
@@ -26,15 +26,15 @@ struct TestCase {
 }
 
 impl TestCase {
-    fn workspace_path(&self, relative: impl AsRef<SystemPath>) -> SystemPathBuf {
-        SystemPath::absolute(relative, self.db.workspace().root(&self.db))
+    fn project_path(&self, relative: impl AsRef<SystemPath>) -> SystemPathBuf {
+        SystemPath::absolute(relative, self.db.project().root(&self.db))
     }
 
     fn root_path(&self) -> &SystemPath {
         &self.root_dir
     }
 
-    fn db(&self) -> &RootDatabase {
+    fn db(&self) -> &ProjectDatabase {
         &self.db
     }
 
@@ -150,7 +150,7 @@ impl TestCase {
     ) -> anyhow::Result<()> {
         let program = Program::get(self.db());
 
-        let new_settings = configuration.to_settings(self.db.workspace().root(&self.db));
+        let new_settings = configuration.to_settings(self.db.project().root(&self.db));
         self.configuration.search_paths = configuration;
 
         program.update_search_paths(&mut self.db, &new_settings)?;
@@ -163,9 +163,8 @@ impl TestCase {
         Ok(())
     }
 
-    fn collect_package_files(&self, path: &SystemPath) -> Vec<File> {
-        let package = self.db().workspace().package(self.db(), path).unwrap();
-        let files = package.files(self.db());
+    fn collect_project_files(&self) -> Vec<File> {
+        let files = self.db().project().files(self.db());
         let mut collected: Vec<_> = files.into_iter().collect();
         collected.sort_unstable_by_key(|file| file.path(self.db()).as_system_path().unwrap());
         collected
@@ -194,17 +193,17 @@ where
 }
 
 trait SetupFiles {
-    fn setup(self, root_path: &SystemPath, workspace_path: &SystemPath) -> anyhow::Result<()>;
+    fn setup(self, root_path: &SystemPath, project_path: &SystemPath) -> anyhow::Result<()>;
 }
 
 impl<const N: usize, P> SetupFiles for [(P, &'static str); N]
 where
     P: AsRef<SystemPath>,
 {
-    fn setup(self, _root_path: &SystemPath, workspace_path: &SystemPath) -> anyhow::Result<()> {
+    fn setup(self, _root_path: &SystemPath, project_path: &SystemPath) -> anyhow::Result<()> {
         for (relative_path, content) in self {
             let relative_path = relative_path.as_ref();
-            let absolute_path = workspace_path.join(relative_path);
+            let absolute_path = project_path.join(relative_path);
             if let Some(parent) = absolute_path.parent() {
                 std::fs::create_dir_all(parent).with_context(|| {
                     format!("Failed to create parent directory for file `{relative_path}`")
@@ -226,8 +225,8 @@ impl<F> SetupFiles for F
 where
     F: FnOnce(&SystemPath, &SystemPath) -> anyhow::Result<()>,
 {
-    fn setup(self, root_path: &SystemPath, workspace_path: &SystemPath) -> anyhow::Result<()> {
-        self(root_path, workspace_path)
+    fn setup(self, root_path: &SystemPath, project_path: &SystemPath) -> anyhow::Result<()> {
+        self(root_path, project_path)
     }
 }
 
@@ -235,7 +234,7 @@ fn setup<F>(setup_files: F) -> anyhow::Result<TestCase>
 where
     F: SetupFiles,
 {
-    setup_with_search_paths(setup_files, |_root, _workspace_path| {
+    setup_with_search_paths(setup_files, |_root, _project_path| {
         SearchPathConfiguration::default()
     })
 }
@@ -265,18 +264,18 @@ where
     .simplified()
     .to_path_buf();
 
-    let workspace_path = root_path.join("workspace");
+    let project_path = root_path.join("project");
 
-    std::fs::create_dir_all(workspace_path.as_std_path())
-        .with_context(|| format!("Failed to create workspace directory `{workspace_path}`"))?;
+    std::fs::create_dir_all(project_path.as_std_path())
+        .with_context(|| format!("Failed to create project directory `{project_path}`"))?;
 
     setup_files
-        .setup(&root_path, &workspace_path)
+        .setup(&root_path, &project_path)
         .context("Failed to setup test files")?;
 
-    let system = OsSystem::new(&workspace_path);
+    let system = OsSystem::new(&project_path);
 
-    let search_paths = create_search_paths(&root_path, &workspace_path);
+    let search_paths = create_search_paths(&root_path, &project_path);
 
     for path in search_paths
         .extra_paths
@@ -300,15 +299,15 @@ where
         search_paths,
     };
 
-    let workspace = WorkspaceMetadata::discover(&workspace_path, &system, Some(&configuration))?;
+    let project = ProjectMetadata::discover(&project_path, &system, Some(&configuration))?;
 
-    let db = RootDatabase::new(workspace, system)?;
+    let db = ProjectDatabase::new(project, system)?;
 
     let (sender, receiver) = crossbeam::channel::unbounded();
     let watcher = directory_watcher(move |events| sender.send(events).unwrap())
         .with_context(|| "Failed to create directory watcher")?;
 
-    let watcher = WorkspaceWatcher::new(watcher, &db);
+    let watcher = ProjectWatcher::new(watcher, &db);
     assert!(!watcher.has_errored_paths());
 
     let test_case = TestCase {
@@ -359,12 +358,12 @@ fn update_file(path: impl AsRef<SystemPath>, content: &str) -> anyhow::Result<()
 #[test]
 fn new_file() -> anyhow::Result<()> {
     let mut case = setup([("bar.py", "")])?;
-    let bar_path = case.workspace_path("bar.py");
+    let bar_path = case.project_path("bar.py");
     let bar_file = case.system_file(&bar_path).unwrap();
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
 
     assert_eq!(case.system_file(&foo_path), Err(FileError::NotFound));
-    assert_eq!(&case.collect_package_files(&bar_path), &[bar_file]);
+    assert_eq!(&case.collect_project_files(), &[bar_file]);
 
     std::fs::write(foo_path.as_std_path(), "print('Hello')")?;
 
@@ -374,7 +373,7 @@ fn new_file() -> anyhow::Result<()> {
 
     let foo = case.system_file(&foo_path).expect("foo.py to exist.");
 
-    assert_eq!(&case.collect_package_files(&bar_path), &[bar_file, foo]);
+    assert_eq!(&case.collect_project_files(), &[bar_file, foo]);
 
     Ok(())
 }
@@ -382,12 +381,12 @@ fn new_file() -> anyhow::Result<()> {
 #[test]
 fn new_ignored_file() -> anyhow::Result<()> {
     let mut case = setup([("bar.py", ""), (".ignore", "foo.py")])?;
-    let bar_path = case.workspace_path("bar.py");
+    let bar_path = case.project_path("bar.py");
     let bar_file = case.system_file(&bar_path).unwrap();
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
 
     assert_eq!(case.system_file(&foo_path), Err(FileError::NotFound));
-    assert_eq!(&case.collect_package_files(&bar_path), &[bar_file]);
+    assert_eq!(&case.collect_project_files(), &[bar_file]);
 
     std::fs::write(foo_path.as_std_path(), "print('Hello')")?;
 
@@ -396,7 +395,7 @@ fn new_ignored_file() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     assert!(case.system_file(&foo_path).is_ok());
-    assert_eq!(&case.collect_package_files(&bar_path), &[bar_file]);
+    assert_eq!(&case.collect_project_files(), &[bar_file]);
 
     Ok(())
 }
@@ -405,11 +404,11 @@ fn new_ignored_file() -> anyhow::Result<()> {
 fn changed_file() -> anyhow::Result<()> {
     let foo_source = "print('Hello, world!')";
     let mut case = setup([("foo.py", foo_source)])?;
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
 
     let foo = case.system_file(&foo_path)?;
     assert_eq!(source_text(case.db(), foo).as_str(), foo_source);
-    assert_eq!(&case.collect_package_files(&foo_path), &[foo]);
+    assert_eq!(&case.collect_project_files(), &[foo]);
 
     update_file(&foo_path, "print('Version 2')")?;
 
@@ -420,7 +419,7 @@ fn changed_file() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     assert_eq!(source_text(case.db(), foo).as_str(), "print('Version 2')");
-    assert_eq!(&case.collect_package_files(&foo_path), &[foo]);
+    assert_eq!(&case.collect_project_files(), &[foo]);
 
     Ok(())
 }
@@ -429,12 +428,12 @@ fn changed_file() -> anyhow::Result<()> {
 fn deleted_file() -> anyhow::Result<()> {
     let foo_source = "print('Hello, world!')";
     let mut case = setup([("foo.py", foo_source)])?;
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
 
     let foo = case.system_file(&foo_path)?;
 
     assert!(foo.exists(case.db()));
-    assert_eq!(&case.collect_package_files(&foo_path), &[foo]);
+    assert_eq!(&case.collect_project_files(), &[foo]);
 
     std::fs::remove_file(foo_path.as_std_path())?;
 
@@ -443,7 +442,7 @@ fn deleted_file() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     assert!(!foo.exists(case.db()));
-    assert_eq!(&case.collect_package_files(&foo_path), &[] as &[File]);
+    assert_eq!(&case.collect_project_files(), &[] as &[File]);
 
     Ok(())
 }
@@ -455,7 +454,7 @@ fn deleted_file() -> anyhow::Result<()> {
 fn move_file_to_trash() -> anyhow::Result<()> {
     let foo_source = "print('Hello, world!')";
     let mut case = setup([("foo.py", foo_source)])?;
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
 
     let trash_path = case.root_path().join(".trash");
     std::fs::create_dir_all(trash_path.as_std_path())?;
@@ -463,7 +462,7 @@ fn move_file_to_trash() -> anyhow::Result<()> {
     let foo = case.system_file(&foo_path)?;
 
     assert!(foo.exists(case.db()));
-    assert_eq!(&case.collect_package_files(&foo_path), &[foo]);
+    assert_eq!(&case.collect_project_files(), &[foo]);
 
     std::fs::rename(
         foo_path.as_std_path(),
@@ -475,58 +474,50 @@ fn move_file_to_trash() -> anyhow::Result<()> {
     case.apply_changes(changes);
 
     assert!(!foo.exists(case.db()));
-    assert_eq!(&case.collect_package_files(&foo_path), &[] as &[File]);
+    assert_eq!(&case.collect_project_files(), &[] as &[File]);
 
     Ok(())
 }
 
-/// Move a file from a non-workspace (non-watched) location into the workspace.
+/// Move a file from a non-project (non-watched) location into the project.
 #[test]
-fn move_file_to_workspace() -> anyhow::Result<()> {
+fn move_file_to_project() -> anyhow::Result<()> {
     let mut case = setup([("bar.py", "")])?;
-    let bar_path = case.workspace_path("bar.py");
+    let bar_path = case.project_path("bar.py");
     let bar = case.system_file(&bar_path).unwrap();
 
     let foo_path = case.root_path().join("foo.py");
     std::fs::write(foo_path.as_std_path(), "")?;
 
-    let foo_in_workspace_path = case.workspace_path("foo.py");
+    let foo_in_project = case.project_path("foo.py");
 
     assert!(case.system_file(&foo_path).is_ok());
-    assert_eq!(&case.collect_package_files(&bar_path), &[bar]);
-    assert!(case
-        .db()
-        .workspace()
-        .package(case.db(), &foo_path)
-        .is_none());
+    assert_eq!(&case.collect_project_files(), &[bar]);
 
-    std::fs::rename(foo_path.as_std_path(), foo_in_workspace_path.as_std_path())?;
+    std::fs::rename(foo_path.as_std_path(), foo_in_project.as_std_path())?;
 
     let changes = case.stop_watch(event_for_file("foo.py"));
 
     case.apply_changes(changes);
 
-    let foo_in_workspace = case.system_file(&foo_in_workspace_path)?;
+    let foo_in_project = case.system_file(&foo_in_project)?;
 
-    assert!(foo_in_workspace.exists(case.db()));
-    assert_eq!(
-        &case.collect_package_files(&foo_in_workspace_path),
-        &[bar, foo_in_workspace]
-    );
+    assert!(foo_in_project.exists(case.db()));
+    assert_eq!(&case.collect_project_files(), &[bar, foo_in_project]);
 
     Ok(())
 }
 
-/// Rename a workspace file.
+/// Rename a project file.
 #[test]
 fn rename_file() -> anyhow::Result<()> {
     let mut case = setup([("foo.py", "")])?;
-    let foo_path = case.workspace_path("foo.py");
-    let bar_path = case.workspace_path("bar.py");
+    let foo_path = case.project_path("foo.py");
+    let bar_path = case.project_path("bar.py");
 
     let foo = case.system_file(&foo_path)?;
 
-    assert_eq!(case.collect_package_files(&foo_path), [foo]);
+    assert_eq!(case.collect_project_files(), [foo]);
 
     std::fs::rename(foo_path.as_std_path(), bar_path.as_std_path())?;
 
@@ -539,15 +530,15 @@ fn rename_file() -> anyhow::Result<()> {
     let bar = case.system_file(&bar_path)?;
 
     assert!(bar.exists(case.db()));
-    assert_eq!(case.collect_package_files(&foo_path), [bar]);
+    assert_eq!(case.collect_project_files(), [bar]);
 
     Ok(())
 }
 
 #[test]
-fn directory_moved_to_workspace() -> anyhow::Result<()> {
+fn directory_moved_to_project() -> anyhow::Result<()> {
     let mut case = setup([("bar.py", "import sub.a")])?;
-    let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
+    let bar = case.system_file(case.project_path("bar.py")).unwrap();
 
     let sub_original_path = case.root_path().join("sub");
     let init_original_path = sub_original_path.join("__init__.py");
@@ -565,12 +556,9 @@ fn directory_moved_to_workspace() -> anyhow::Result<()> {
     );
 
     assert_eq!(sub_a_module, None);
-    assert_eq!(
-        case.collect_package_files(&case.workspace_path("bar.py")),
-        &[bar]
-    );
+    assert_eq!(case.collect_project_files(), &[bar]);
 
-    let sub_new_path = case.workspace_path("sub");
+    let sub_new_path = case.project_path("sub");
     std::fs::rename(sub_original_path.as_std_path(), sub_new_path.as_std_path())
         .with_context(|| "Failed to move sub directory")?;
 
@@ -592,10 +580,7 @@ fn directory_moved_to_workspace() -> anyhow::Result<()> {
     )
     .is_some());
 
-    assert_eq!(
-        case.collect_package_files(&case.workspace_path("bar.py")),
-        &[bar, init_file, a_file]
-    );
+    assert_eq!(case.collect_project_files(), &[bar, init_file, a_file]);
 
     Ok(())
 }
@@ -607,7 +592,7 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
         ("sub/__init__.py", ""),
         ("sub/a.py", ""),
     ])?;
-    let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
+    let bar = case.system_file(case.project_path("bar.py")).unwrap();
 
     assert!(resolve_module(
         case.db().upcast(),
@@ -615,7 +600,7 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
     )
     .is_some());
 
-    let sub_path = case.workspace_path("sub");
+    let sub_path = case.project_path("sub");
     let init_file = case
         .system_file(sub_path.join("__init__.py"))
         .expect("__init__.py to exist");
@@ -623,10 +608,7 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
         .system_file(sub_path.join("a.py"))
         .expect("a.py to exist");
 
-    assert_eq!(
-        case.collect_package_files(&case.workspace_path("bar.py")),
-        &[bar, init_file, a_file]
-    );
+    assert_eq!(case.collect_project_files(), &[bar, init_file, a_file]);
 
     std::fs::create_dir(case.root_path().join(".trash").as_std_path())?;
     let trashed_sub = case.root_path().join(".trash/sub");
@@ -647,10 +629,7 @@ fn directory_moved_to_trash() -> anyhow::Result<()> {
     assert!(!init_file.exists(case.db()));
     assert!(!a_file.exists(case.db()));
 
-    assert_eq!(
-        case.collect_package_files(&case.workspace_path("bar.py")),
-        &[bar]
-    );
+    assert_eq!(case.collect_project_files(), &[bar]);
 
     Ok(())
 }
@@ -663,7 +642,7 @@ fn directory_renamed() -> anyhow::Result<()> {
         ("sub/a.py", ""),
     ])?;
 
-    let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
+    let bar = case.system_file(case.project_path("bar.py")).unwrap();
 
     assert!(resolve_module(
         case.db().upcast(),
@@ -676,7 +655,7 @@ fn directory_renamed() -> anyhow::Result<()> {
     )
     .is_none());
 
-    let sub_path = case.workspace_path("sub");
+    let sub_path = case.project_path("sub");
     let sub_init = case
         .system_file(sub_path.join("__init__.py"))
         .expect("__init__.py to exist");
@@ -684,14 +663,11 @@ fn directory_renamed() -> anyhow::Result<()> {
         .system_file(sub_path.join("a.py"))
         .expect("a.py to exist");
 
-    assert_eq!(
-        case.collect_package_files(&sub_path),
-        &[bar, sub_init, sub_a]
-    );
+    assert_eq!(case.collect_project_files(), &[bar, sub_init, sub_a]);
 
-    let foo_baz = case.workspace_path("foo/baz");
+    let foo_baz = case.project_path("foo/baz");
 
-    std::fs::create_dir(case.workspace_path("foo").as_std_path())?;
+    std::fs::create_dir(case.project_path("foo").as_std_path())?;
     std::fs::rename(sub_path.as_std_path(), foo_baz.as_std_path())
         .with_context(|| "Failed to move the sub directory")?;
 
@@ -730,7 +706,7 @@ fn directory_renamed() -> anyhow::Result<()> {
     assert!(foo_baz_a.exists(case.db()));
 
     assert_eq!(
-        case.collect_package_files(&sub_path),
+        case.collect_project_files(),
         &[bar, foo_baz_init, foo_baz_a]
     );
 
@@ -745,7 +721,7 @@ fn directory_deleted() -> anyhow::Result<()> {
         ("sub/a.py", ""),
     ])?;
 
-    let bar = case.system_file(case.workspace_path("bar.py")).unwrap();
+    let bar = case.system_file(case.project_path("bar.py")).unwrap();
 
     assert!(resolve_module(
         case.db().upcast(),
@@ -753,7 +729,7 @@ fn directory_deleted() -> anyhow::Result<()> {
     )
     .is_some());
 
-    let sub_path = case.workspace_path("sub");
+    let sub_path = case.project_path("sub");
 
     let init_file = case
         .system_file(sub_path.join("__init__.py"))
@@ -761,10 +737,7 @@ fn directory_deleted() -> anyhow::Result<()> {
     let a_file = case
         .system_file(sub_path.join("a.py"))
         .expect("a.py to exist");
-    assert_eq!(
-        case.collect_package_files(&sub_path),
-        &[bar, init_file, a_file]
-    );
+    assert_eq!(case.collect_project_files(), &[bar, init_file, a_file]);
 
     std::fs::remove_dir_all(sub_path.as_std_path())
         .with_context(|| "Failed to remove the sub directory")?;
@@ -782,20 +755,20 @@ fn directory_deleted() -> anyhow::Result<()> {
 
     assert!(!init_file.exists(case.db()));
     assert!(!a_file.exists(case.db()));
-    assert_eq!(case.collect_package_files(&sub_path), &[bar]);
+    assert_eq!(case.collect_project_files(), &[bar]);
 
     Ok(())
 }
 
 #[test]
 fn search_path() -> anyhow::Result<()> {
-    let mut case = setup_with_search_paths(
-        [("bar.py", "import sub.a")],
-        |root_path, _workspace_path| SearchPathConfiguration {
-            site_packages: Some(SitePackages::Known(vec![root_path.join("site_packages")])),
-            ..SearchPathConfiguration::default()
-        },
-    )?;
+    let mut case =
+        setup_with_search_paths([("bar.py", "import sub.a")], |root_path, _project_path| {
+            SearchPathConfiguration {
+                site_packages: Some(SitePackages::Known(vec![root_path.join("site_packages")])),
+                ..SearchPathConfiguration::default()
+            }
+        })?;
 
     let site_packages = case.root_path().join("site_packages");
 
@@ -812,8 +785,8 @@ fn search_path() -> anyhow::Result<()> {
 
     assert!(resolve_module(case.db().upcast(), &ModuleName::new_static("a").unwrap()).is_some());
     assert_eq!(
-        case.collect_package_files(&case.workspace_path("bar.py")),
-        &[case.system_file(case.workspace_path("bar.py")).unwrap()]
+        case.collect_project_files(),
+        &[case.system_file(case.project_path("bar.py")).unwrap()]
     );
 
     Ok(())
@@ -823,7 +796,7 @@ fn search_path() -> anyhow::Result<()> {
 fn add_search_path() -> anyhow::Result<()> {
     let mut case = setup([("bar.py", "import sub.a")])?;
 
-    let site_packages = case.workspace_path("site_packages");
+    let site_packages = case.project_path("site_packages");
     std::fs::create_dir_all(site_packages.as_std_path())?;
 
     assert!(resolve_module(case.db().upcast(), &ModuleName::new_static("a").unwrap()).is_none());
@@ -848,13 +821,13 @@ fn add_search_path() -> anyhow::Result<()> {
 
 #[test]
 fn remove_search_path() -> anyhow::Result<()> {
-    let mut case = setup_with_search_paths(
-        [("bar.py", "import sub.a")],
-        |root_path, _workspace_path| SearchPathConfiguration {
-            site_packages: Some(SitePackages::Known(vec![root_path.join("site_packages")])),
-            ..SearchPathConfiguration::default()
-        },
-    )?;
+    let mut case =
+        setup_with_search_paths([("bar.py", "import sub.a")], |root_path, _project_path| {
+            SearchPathConfiguration {
+                site_packages: Some(SitePackages::Known(vec![root_path.join("site_packages")])),
+                ..SearchPathConfiguration::default()
+            }
+        })?;
 
     // Remove site packages from the search path settings.
     let site_packages = case.root_path().join("site_packages");
@@ -876,8 +849,8 @@ fn remove_search_path() -> anyhow::Result<()> {
 #[test]
 fn changed_versions_file() -> anyhow::Result<()> {
     let mut case = setup_with_search_paths(
-        |root_path: &SystemPath, workspace_path: &SystemPath| {
-            std::fs::write(workspace_path.join("bar.py").as_std_path(), "import sub.a")?;
+        |root_path: &SystemPath, project_path: &SystemPath| {
+            std::fs::write(project_path.join("bar.py").as_std_path(), "import sub.a")?;
             std::fs::create_dir_all(root_path.join("typeshed/stdlib").as_std_path())?;
             std::fs::write(root_path.join("typeshed/stdlib/VERSIONS").as_std_path(), "")?;
             std::fs::write(
@@ -887,7 +860,7 @@ fn changed_versions_file() -> anyhow::Result<()> {
 
             Ok(())
         },
-        |root_path, _workspace_path| SearchPathConfiguration {
+        |root_path, _project_path| SearchPathConfiguration {
             typeshed: Some(root_path.join("typeshed")),
             ..SearchPathConfiguration::default()
         },
@@ -915,11 +888,11 @@ fn changed_versions_file() -> anyhow::Result<()> {
     Ok(())
 }
 
-/// Watch a workspace that contains two files where one file is a hardlink to another.
+/// Watch a project that contains two files where one file is a hardlink to another.
 ///
 /// Setup:
 /// ```text
-/// - workspace
+/// - project
 ///   |- foo.py
 ///   |- bar.py (hard link to foo.py)
 /// ```
@@ -935,22 +908,22 @@ fn changed_versions_file() -> anyhow::Result<()> {
 /// I haven't found any documentation that states the notification behavior on Windows but what
 /// we're seeing is that Windows only emits a single event, similar to Linux.
 #[test]
-fn hard_links_in_workspace() -> anyhow::Result<()> {
-    let mut case = setup(|_root: &SystemPath, workspace: &SystemPath| {
-        let foo_path = workspace.join("foo.py");
+fn hard_links_in_project() -> anyhow::Result<()> {
+    let mut case = setup(|_root: &SystemPath, project: &SystemPath| {
+        let foo_path = project.join("foo.py");
         std::fs::write(foo_path.as_std_path(), "print('Version 1')")?;
 
         // Create a hardlink to `foo`
-        let bar_path = workspace.join("bar.py");
+        let bar_path = project.join("bar.py");
         std::fs::hard_link(foo_path.as_std_path(), bar_path.as_std_path())
             .context("Failed to create hard link from foo.py -> bar.py")?;
 
         Ok(())
     })?;
 
-    let foo_path = case.workspace_path("foo.py");
+    let foo_path = case.project_path("foo.py");
     let foo = case.system_file(&foo_path).unwrap();
-    let bar_path = case.workspace_path("bar.py");
+    let bar_path = case.project_path("bar.py");
     let bar = case.system_file(&bar_path).unwrap();
 
     assert_eq!(source_text(case.db(), foo).as_str(), "print('Version 1')");
@@ -973,12 +946,12 @@ fn hard_links_in_workspace() -> anyhow::Result<()> {
     Ok(())
 }
 
-/// Watch a workspace that contains one file that is a hardlink to a file outside the workspace.
+/// Watch a project that contains one file that is a hardlink to a file outside the project.
 ///
 /// Setup:
 /// ```text
 /// - foo.py
-/// - workspace
+/// - project
 ///   |- bar.py (hard link to /foo.py)
 /// ```
 ///
@@ -996,7 +969,7 @@ fn hard_links_in_workspace() -> anyhow::Result<()> {
 /// [source](https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-readdirectorychangesw)
 ///
 /// My interpretation of this is that Windows doesn't support observing changes made to
-/// hard linked files outside the workspace.
+/// hard linked files outside the project.
 #[test]
 #[cfg_attr(
     target_os = "linux",
@@ -1006,13 +979,13 @@ fn hard_links_in_workspace() -> anyhow::Result<()> {
     target_os = "windows",
     ignore = "windows doesn't support observing changes to hard linked files."
 )]
-fn hard_links_to_target_outside_workspace() -> anyhow::Result<()> {
-    let mut case = setup(|root: &SystemPath, workspace: &SystemPath| {
+fn hard_links_to_target_outside_project() -> anyhow::Result<()> {
+    let mut case = setup(|root: &SystemPath, project: &SystemPath| {
         let foo_path = root.join("foo.py");
         std::fs::write(foo_path.as_std_path(), "print('Version 1')")?;
 
         // Create a hardlink to `foo`
-        let bar_path = workspace.join("bar.py");
+        let bar_path = project.join("bar.py");
         std::fs::hard_link(foo_path.as_std_path(), bar_path.as_std_path())
             .context("Failed to create hard link from foo.py -> bar.py")?;
 
@@ -1021,7 +994,7 @@ fn hard_links_to_target_outside_workspace() -> anyhow::Result<()> {
 
     let foo_path = case.root_path().join("foo.py");
     let foo = case.system_file(&foo_path).unwrap();
-    let bar_path = case.workspace_path("bar.py");
+    let bar_path = case.project_path("bar.py");
     let bar = case.system_file(&bar_path).unwrap();
 
     assert_eq!(source_text(case.db(), foo).as_str(), "print('Version 1')");
@@ -1044,13 +1017,13 @@ mod unix {
     //! Tests that make use of unix specific file-system features.
     use super::*;
 
-    /// Changes the metadata of the only file in the workspace.
+    /// Changes the metadata of the only file in the project.
     #[test]
     fn changed_metadata() -> anyhow::Result<()> {
         use std::os::unix::fs::PermissionsExt;
 
         let mut case = setup([("foo.py", "")])?;
-        let foo_path = case.workspace_path("foo.py");
+        let foo_path = case.project_path("foo.py");
 
         let foo = case.system_file(&foo_path)?;
         assert_eq!(
@@ -1086,14 +1059,14 @@ mod unix {
         Ok(())
     }
 
-    /// A workspace path is a symlink to a file outside the workspace.
+    /// A project path is a symlink to a file outside the project.
     ///
     /// Setup:
     /// ```text
     /// - bar
     ///   |- baz.py
     ///
-    /// - workspace
+    /// - project
     ///   |- bar -> /bar
     /// ```
     ///
@@ -1115,7 +1088,7 @@ mod unix {
         ignore = "FSEvents doesn't emit change events for symlinked directories outside of the watched paths."
     )]
     fn symlink_target_outside_watched_paths() -> anyhow::Result<()> {
-        let mut case = setup(|root: &SystemPath, workspace: &SystemPath| {
+        let mut case = setup(|root: &SystemPath, project: &SystemPath| {
             // Set up the symlink target.
             let link_target = root.join("bar");
             std::fs::create_dir_all(link_target.as_std_path())
@@ -1124,8 +1097,8 @@ mod unix {
             std::fs::write(baz_original.as_std_path(), "def baz(): ...")
                 .context("Failed to write link target file")?;
 
-            // Create a symlink inside the workspace
-            let bar = workspace.join("bar");
+            // Create a symlink inside the project
+            let bar = project.join("bar");
             std::os::unix::fs::symlink(link_target.as_std_path(), bar.as_std_path())
                 .context("Failed to create symlink to bar package")?;
 
@@ -1137,7 +1110,7 @@ mod unix {
             &ModuleName::new_static("bar.baz").unwrap(),
         )
         .expect("Expected bar.baz to exist in site-packages.");
-        let baz_workspace = case.workspace_path("bar/baz.py");
+        let baz_project = case.project_path("bar/baz.py");
 
         assert_eq!(
             source_text(case.db(), baz.file()).as_str(),
@@ -1145,7 +1118,7 @@ mod unix {
         );
         assert_eq!(
             baz.file().path(case.db()).as_system_path(),
-            Some(&*baz_workspace)
+            Some(&*baz_project)
         );
 
         let baz_original = case.root_path().join("bar/baz.py");
@@ -1164,7 +1137,7 @@ mod unix {
         );
 
         // Write to the symlink source.
-        update_file(baz_workspace, "def baz(): print('Version 3')")
+        update_file(baz_project, "def baz(): print('Version 3')")
             .context("Failed to update bar/baz.py")?;
 
         let changes = case.stop_watch(event_for_file("baz.py"));
@@ -1179,14 +1152,14 @@ mod unix {
         Ok(())
     }
 
-    /// Workspace contains a symlink to another directory inside the workspace.
+    /// Project contains a symlink to another directory inside the project.
     /// Changes to files in the symlinked directory should be reflected
     /// to all files.
     ///
     /// Setup:
     /// ```text
-    /// - workspace
-    ///   | - bar -> /workspace/patched/bar
+    /// - project
+    ///   | - bar -> /project/patched/bar
     ///   |
     ///   | - patched
     ///   |   |-- bar
@@ -1195,10 +1168,10 @@ mod unix {
     ///   |-- foo.py
     /// ```
     #[test]
-    fn symlink_inside_workspace() -> anyhow::Result<()> {
-        let mut case = setup(|_root: &SystemPath, workspace: &SystemPath| {
+    fn symlink_inside_project() -> anyhow::Result<()> {
+        let mut case = setup(|_root: &SystemPath, project: &SystemPath| {
             // Set up the symlink target.
-            let link_target = workspace.join("patched/bar");
+            let link_target = project.join("patched/bar");
             std::fs::create_dir_all(link_target.as_std_path())
                 .context("Failed to create link target directory")?;
             let baz_original = link_target.join("baz.py");
@@ -1206,8 +1179,8 @@ mod unix {
                 .context("Failed to write link target file")?;
 
             // Create a symlink inside site-packages
-            let bar_in_workspace = workspace.join("bar");
-            std::os::unix::fs::symlink(link_target.as_std_path(), bar_in_workspace.as_std_path())
+            let bar_in_project = project.join("bar");
+            std::os::unix::fs::symlink(link_target.as_std_path(), bar_in_project.as_std_path())
                 .context("Failed to create symlink to bar package")?;
 
             Ok(())
@@ -1218,9 +1191,9 @@ mod unix {
             &ModuleName::new_static("bar.baz").unwrap(),
         )
         .expect("Expected bar.baz to exist in site-packages.");
-        let bar_baz = case.workspace_path("bar/baz.py");
+        let bar_baz = case.project_path("bar/baz.py");
 
-        let patched_bar_baz = case.workspace_path("patched/bar/baz.py");
+        let patched_bar_baz = case.project_path("patched/bar/baz.py");
         let patched_bar_baz_file = case.system_file(&patched_bar_baz).unwrap();
 
         assert_eq!(
@@ -1279,7 +1252,7 @@ mod unix {
     /// - site-packages
     ///   | - bar/baz.py
     ///
-    /// - workspace
+    /// - project
     ///   |-- .venv/lib/python3.12/site-packages -> /site-packages
     ///   |
     ///   |-- foo.py
@@ -1287,7 +1260,7 @@ mod unix {
     #[test]
     fn symlinked_module_search_path() -> anyhow::Result<()> {
         let mut case = setup_with_search_paths(
-            |root: &SystemPath, workspace: &SystemPath| {
+            |root: &SystemPath, project: &SystemPath| {
                 // Set up the symlink target.
                 let site_packages = root.join("site-packages");
                 let bar = site_packages.join("bar");
@@ -1298,7 +1271,7 @@ mod unix {
                     .context("Failed to write baz.py")?;
 
                 // Symlink the site packages in the venv to the global site packages
-                let venv_site_packages = workspace.join(".venv/lib/python3.12/site-packages");
+                let venv_site_packages = project.join(".venv/lib/python3.12/site-packages");
                 std::fs::create_dir_all(venv_site_packages.parent().unwrap())
                     .context("Failed to create .venv directory")?;
                 std::os::unix::fs::symlink(
@@ -1309,9 +1282,9 @@ mod unix {
 
                 Ok(())
             },
-            |_root, workspace| SearchPathConfiguration {
+            |_root, project| SearchPathConfiguration {
                 site_packages: Some(SitePackages::Known(vec![
-                    workspace.join(".venv/lib/python3.12/site-packages")
+                    project.join(".venv/lib/python3.12/site-packages")
                 ])),
                 ..SearchPathConfiguration::default()
             },
@@ -1323,7 +1296,7 @@ mod unix {
         )
         .expect("Expected bar.baz to exist in site-packages.");
         let baz_site_packages_path =
-            case.workspace_path(".venv/lib/python3.12/site-packages/bar/baz.py");
+            case.project_path(".venv/lib/python3.12/site-packages/bar/baz.py");
         let baz_site_packages = case.system_file(&baz_site_packages_path).unwrap();
         let baz_original = case.root_path().join("site-packages/bar/baz.py");
         let baz_original_file = case.system_file(&baz_original).unwrap();
@@ -1372,13 +1345,15 @@ mod unix {
 }
 
 #[test]
-fn nested_packages_delete_root() -> anyhow::Result<()> {
-    let mut case = setup(|root: &SystemPath, workspace_root: &SystemPath| {
+fn nested_projects_delete_root() -> anyhow::Result<()> {
+    let mut case = setup(|root: &SystemPath, project_root: &SystemPath| {
         std::fs::write(
-            workspace_root.join("pyproject.toml").as_std_path(),
+            project_root.join("pyproject.toml").as_std_path(),
             r#"
             [project]
             name = "inner"
+
+            [tool.knot]
             "#,
         )?;
 
@@ -1387,120 +1362,24 @@ fn nested_packages_delete_root() -> anyhow::Result<()> {
             r#"
             [project]
             name = "outer"
+
+            [tool.knot]
             "#,
         )?;
 
         Ok(())
     })?;
 
-    assert_eq!(
-        case.db().workspace().root(case.db()),
-        &*case.workspace_path("")
-    );
+    assert_eq!(case.db().project().root(case.db()), &*case.project_path(""));
 
-    std::fs::remove_file(case.workspace_path("pyproject.toml").as_std_path())?;
+    std::fs::remove_file(case.project_path("pyproject.toml").as_std_path())?;
 
     let changes = case.stop_watch(ChangeEvent::is_deleted);
 
     case.apply_changes(changes);
 
-    // It should now pick up the outer workspace.
-    assert_eq!(case.db().workspace().root(case.db()), case.root_path());
-
-    Ok(())
-}
-
-#[test]
-fn added_package() -> anyhow::Result<()> {
-    let mut case = setup([
-        (
-            "pyproject.toml",
-            r#"
-            [project]
-            name = "inner"
-
-            [tool.knot.workspace]
-            members = ["packages/*"]
-            "#,
-        ),
-        (
-            "packages/a/pyproject.toml",
-            r#"
-            [project]
-            name = "a"
-            "#,
-        ),
-    ])?;
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 2);
-
-    std::fs::create_dir(case.workspace_path("packages/b").as_std_path())
-        .context("failed to create folder for package 'b'")?;
-
-    // It seems that the file watcher won't pick up on file changes shortly after the folder
-    // was created... I suspect this is because most file watchers don't support recursive
-    // file watching. Instead, file-watching libraries manually implement recursive file watching
-    // by setting a watcher for each directory. But doing this obviously "lags" behind.
-    case.take_watch_changes();
-
-    std::fs::write(
-        case.workspace_path("packages/b/pyproject.toml")
-            .as_std_path(),
-        r#"
-            [project]
-            name = "b"
-            "#,
-    )
-    .context("failed to write pyproject.toml for package b")?;
-
-    let changes = case.stop_watch(event_for_file("pyproject.toml"));
-
-    case.apply_changes(changes);
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 3);
-
-    Ok(())
-}
-
-#[test]
-fn removed_package() -> anyhow::Result<()> {
-    let mut case = setup([
-        (
-            "pyproject.toml",
-            r#"
-            [project]
-            name = "inner"
-
-            [tool.knot.workspace]
-            members = ["packages/*"]
-            "#,
-        ),
-        (
-            "packages/a/pyproject.toml",
-            r#"
-            [project]
-            name = "a"
-            "#,
-        ),
-        (
-            "packages/b/pyproject.toml",
-            r#"
-            [project]
-            name = "b"
-            "#,
-        ),
-    ])?;
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 3);
-
-    std::fs::remove_dir_all(case.workspace_path("packages/b").as_std_path())
-        .context("failed to remove package 'b'")?;
-
-    let changes = case.stop_watch(ChangeEvent::is_deleted);
-
-    case.apply_changes(changes);
-
-    assert_eq!(case.db().workspace().packages(case.db()).len(), 2);
+    // It should now pick up the outer project.
+    assert_eq!(case.db().project().root(case.db()), case.root_path());
 
     Ok(())
 }
diff --git a/crates/red_knot_python_semantic/src/db.rs b/crates/red_knot_python_semantic/src/db.rs
index 6f251bd371..65e23b1129 100644
--- a/crates/red_knot_python_semantic/src/db.rs
+++ b/crates/red_knot_python_semantic/src/db.rs
@@ -180,7 +180,7 @@ pub(crate) mod tests {
 
             Program::from_settings(
                 &db,
-                &ProgramSettings {
+                ProgramSettings {
                     python_version: self.python_version,
                     python_platform: self.python_platform,
                     search_paths,
diff --git a/crates/red_knot_python_semantic/src/module_resolver/resolver.rs b/crates/red_knot_python_semantic/src/module_resolver/resolver.rs
index 954ded4262..057d24a386 100644
--- a/crates/red_knot_python_semantic/src/module_resolver/resolver.rs
+++ b/crates/red_knot_python_semantic/src/module_resolver/resolver.rs
@@ -1294,7 +1294,7 @@ mod tests {
 
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version: PythonVersion::PY38,
                 python_platform: PythonPlatform::default(),
                 search_paths: SearchPathSettings {
@@ -1800,7 +1800,7 @@ not_a_directory
 
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version: PythonVersion::default(),
                 python_platform: PythonPlatform::default(),
                 search_paths: SearchPathSettings {
diff --git a/crates/red_knot_python_semantic/src/module_resolver/testing.rs b/crates/red_knot_python_semantic/src/module_resolver/testing.rs
index 365dec2893..acdee3d3c1 100644
--- a/crates/red_knot_python_semantic/src/module_resolver/testing.rs
+++ b/crates/red_knot_python_semantic/src/module_resolver/testing.rs
@@ -232,7 +232,7 @@ impl TestCaseBuilder<MockedTypeshed> {
 
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version,
                 python_platform,
                 search_paths: SearchPathSettings {
@@ -290,7 +290,7 @@ impl TestCaseBuilder<VendoredTypeshed> {
 
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version,
                 python_platform,
                 search_paths: SearchPathSettings {
diff --git a/crates/red_knot_python_semantic/src/program.rs b/crates/red_knot_python_semantic/src/program.rs
index be2cf081b7..3b2487fede 100644
--- a/crates/red_knot_python_semantic/src/program.rs
+++ b/crates/red_knot_python_semantic/src/program.rs
@@ -1,14 +1,13 @@
+use crate::module_resolver::SearchPaths;
 use crate::python_platform::PythonPlatform;
 use crate::python_version::PythonVersion;
+use crate::Db;
+
 use anyhow::Context;
+use ruff_db::system::{SystemPath, SystemPathBuf};
 use salsa::Durability;
 use salsa::Setter;
 
-use ruff_db::system::{SystemPath, SystemPathBuf};
-
-use crate::module_resolver::SearchPaths;
-use crate::Db;
-
 #[salsa::input(singleton)]
 pub struct Program {
     pub python_version: PythonVersion,
@@ -21,25 +20,51 @@ pub struct Program {
 }
 
 impl Program {
-    pub fn from_settings(db: &dyn Db, settings: &ProgramSettings) -> anyhow::Result<Self> {
+    pub fn from_settings(db: &dyn Db, settings: ProgramSettings) -> anyhow::Result<Self> {
         let ProgramSettings {
             python_version,
             python_platform,
             search_paths,
         } = settings;
 
-        tracing::info!("Python version: Python {python_version}");
+        tracing::info!("Python version: Python {python_version}, platform: {python_platform}");
 
-        let search_paths = SearchPaths::from_settings(db, search_paths)
+        let search_paths = SearchPaths::from_settings(db, &search_paths)
             .with_context(|| "Invalid search path settings")?;
 
         Ok(
-            Program::builder(*python_version, python_platform.clone(), search_paths)
+            Program::builder(python_version, python_platform, search_paths)
                 .durability(Durability::HIGH)
                 .new(db),
         )
     }
 
+    pub fn update_from_settings(
+        self,
+        db: &mut dyn Db,
+        settings: ProgramSettings,
+    ) -> anyhow::Result<()> {
+        let ProgramSettings {
+            python_version,
+            python_platform,
+            search_paths,
+        } = settings;
+
+        if &python_platform != self.python_platform(db) {
+            tracing::debug!("Updating python platform: `{python_platform:?}`");
+            self.set_python_platform(db).to(python_platform);
+        }
+
+        if python_version != self.python_version(db) {
+            tracing::debug!("Updating python version: Python {python_version}");
+            self.set_python_version(db).to(python_version);
+        }
+
+        self.update_search_paths(db, &search_paths)?;
+
+        Ok(())
+    }
+
     pub fn update_search_paths(
         self,
         db: &mut dyn Db,
@@ -77,7 +102,7 @@ pub struct SearchPathSettings {
     /// or pyright's stubPath configuration setting.
     pub extra_paths: Vec<SystemPathBuf>,
 
-    /// The root of the workspace, used for finding first-party modules.
+    /// The root of the project, used for finding first-party modules.
     pub src_root: SystemPathBuf,
 
     /// Optional path to a "custom typeshed" directory on disk for us to use for standard-library types.
diff --git a/crates/red_knot_python_semantic/src/python_platform.rs b/crates/red_knot_python_semantic/src/python_platform.rs
index 672db29459..9711e433b3 100644
--- a/crates/red_knot_python_semantic/src/python_platform.rs
+++ b/crates/red_knot_python_semantic/src/python_platform.rs
@@ -1,3 +1,5 @@
+use std::fmt::{Display, Formatter};
+
 /// The target platform to assume when resolving types.
 #[derive(Debug, Clone, Default, PartialEq, Eq)]
 #[cfg_attr(
@@ -17,3 +19,12 @@ pub enum PythonPlatform {
     #[cfg_attr(feature = "serde", serde(untagged))]
     Identifier(String),
 }
+
+impl Display for PythonPlatform {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            PythonPlatform::All => f.write_str("all"),
+            PythonPlatform::Identifier(name) => f.write_str(name),
+        }
+    }
+}
diff --git a/crates/red_knot_server/src/server/api.rs b/crates/red_knot_server/src/server/api.rs
index ee56e1fe64..9638c14e8c 100644
--- a/crates/red_knot_server/src/server/api.rs
+++ b/crates/red_knot_server/src/server/api.rs
@@ -86,13 +86,11 @@ fn background_request_task<'a, R: traits::BackgroundDocumentRequestHandler>(
             return Box::new(|_, _| {});
         };
         let db = match path {
-            AnySystemPath::System(path) => {
-                match session.workspace_db_for_path(path.as_std_path()) {
-                    Some(db) => db.clone(),
-                    None => session.default_workspace_db().clone(),
-                }
-            }
-            AnySystemPath::SystemVirtual(_) => session.default_workspace_db().clone(),
+            AnySystemPath::System(path) => match session.project_db_for_path(path.as_std_path()) {
+                Some(db) => db.clone(),
+                None => session.default_project_db().clone(),
+            },
+            AnySystemPath::SystemVirtual(_) => session.default_project_db().clone(),
         };
 
         let Some(snapshot) = session.take_snapshot(url) else {
diff --git a/crates/red_knot_server/src/server/api/notifications/did_change.rs b/crates/red_knot_server/src/server/api/notifications/did_change.rs
index b22989a6c8..abd7167918 100644
--- a/crates/red_knot_server/src/server/api/notifications/did_change.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_change.rs
@@ -36,14 +36,14 @@ impl SyncNotificationHandler for DidChangeTextDocumentHandler {
 
         match path {
             AnySystemPath::System(path) => {
-                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                let db = match session.project_db_for_path_mut(path.as_std_path()) {
                     Some(db) => db,
-                    None => session.default_workspace_db_mut(),
+                    None => session.default_project_db_mut(),
                 };
                 db.apply_changes(vec![ChangeEvent::file_content_changed(path)], None);
             }
             AnySystemPath::SystemVirtual(virtual_path) => {
-                let db = session.default_workspace_db_mut();
+                let db = session.default_project_db_mut();
                 db.apply_changes(vec![ChangeEvent::ChangedVirtual(virtual_path)], None);
             }
         }
diff --git a/crates/red_knot_server/src/server/api/notifications/did_close.rs b/crates/red_knot_server/src/server/api/notifications/did_close.rs
index 87afef9747..b353f27f60 100644
--- a/crates/red_knot_server/src/server/api/notifications/did_close.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_close.rs
@@ -34,7 +34,7 @@ impl SyncNotificationHandler for DidCloseTextDocumentHandler {
             .with_failure_code(ErrorCode::InternalError)?;
 
         if let AnySystemPath::SystemVirtual(virtual_path) = path {
-            let db = session.default_workspace_db_mut();
+            let db = session.default_project_db_mut();
             db.apply_changes(vec![ChangeEvent::DeletedVirtual(virtual_path)], None);
         }
 
diff --git a/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs b/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs
index 3d96f83eef..fa8f5d4a8a 100644
--- a/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_close_notebook.rs
@@ -33,7 +33,7 @@ impl SyncNotificationHandler for DidCloseNotebookHandler {
             .with_failure_code(lsp_server::ErrorCode::InternalError)?;
 
         if let AnySystemPath::SystemVirtual(virtual_path) = path {
-            let db = session.default_workspace_db_mut();
+            let db = session.default_project_db_mut();
             db.apply_changes(vec![ChangeEvent::DeletedVirtual(virtual_path)], None);
         }
 
diff --git a/crates/red_knot_server/src/server/api/notifications/did_open.rs b/crates/red_knot_server/src/server/api/notifications/did_open.rs
index 2bc5dc03c4..9e1377a8d7 100644
--- a/crates/red_knot_server/src/server/api/notifications/did_open.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_open.rs
@@ -33,14 +33,14 @@ impl SyncNotificationHandler for DidOpenTextDocumentHandler {
 
         match path {
             AnySystemPath::System(path) => {
-                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                let db = match session.project_db_for_path_mut(path.as_std_path()) {
                     Some(db) => db,
-                    None => session.default_workspace_db_mut(),
+                    None => session.default_project_db_mut(),
                 };
                 db.apply_changes(vec![ChangeEvent::Opened(path)], None);
             }
             AnySystemPath::SystemVirtual(virtual_path) => {
-                let db = session.default_workspace_db_mut();
+                let db = session.default_project_db_mut();
                 db.files().virtual_file(db, &virtual_path);
             }
         }
diff --git a/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs b/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs
index edbff7e022..5a74e77172 100644
--- a/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs
+++ b/crates/red_knot_server/src/server/api/notifications/did_open_notebook.rs
@@ -41,14 +41,14 @@ impl SyncNotificationHandler for DidOpenNotebookHandler {
 
         match path {
             AnySystemPath::System(path) => {
-                let db = match session.workspace_db_for_path_mut(path.as_std_path()) {
+                let db = match session.project_db_for_path_mut(path.as_std_path()) {
                     Some(db) => db,
-                    None => session.default_workspace_db_mut(),
+                    None => session.default_project_db_mut(),
                 };
                 db.apply_changes(vec![ChangeEvent::Opened(path)], None);
             }
             AnySystemPath::SystemVirtual(virtual_path) => {
-                let db = session.default_workspace_db_mut();
+                let db = session.default_project_db_mut();
                 db.files().virtual_file(db, &virtual_path);
             }
         }
diff --git a/crates/red_knot_server/src/server/api/requests/diagnostic.rs b/crates/red_knot_server/src/server/api/requests/diagnostic.rs
index d208535807..3c4e35e0a7 100644
--- a/crates/red_knot_server/src/server/api/requests/diagnostic.rs
+++ b/crates/red_knot_server/src/server/api/requests/diagnostic.rs
@@ -11,7 +11,7 @@ use crate::edit::ToRangeExt;
 use crate::server::api::traits::{BackgroundDocumentRequestHandler, RequestHandler};
 use crate::server::{client::Notifier, Result};
 use crate::session::DocumentSnapshot;
-use red_knot_workspace::db::{Db, RootDatabase};
+use red_knot_workspace::db::{Db, ProjectDatabase};
 use ruff_db::diagnostic::Severity;
 use ruff_db::source::{line_index, source_text};
 
@@ -28,7 +28,7 @@ impl BackgroundDocumentRequestHandler for DocumentDiagnosticRequestHandler {
 
     fn run_with_snapshot(
         snapshot: DocumentSnapshot,
-        db: RootDatabase,
+        db: ProjectDatabase,
         _notifier: Notifier,
         _params: DocumentDiagnosticParams,
     ) -> Result<DocumentDiagnosticReportResult> {
@@ -46,7 +46,7 @@ impl BackgroundDocumentRequestHandler for DocumentDiagnosticRequestHandler {
     }
 }
 
-fn compute_diagnostics(snapshot: &DocumentSnapshot, db: &RootDatabase) -> Vec<Diagnostic> {
+fn compute_diagnostics(snapshot: &DocumentSnapshot, db: &ProjectDatabase) -> Vec<Diagnostic> {
     let Some(file) = snapshot.file(db) else {
         tracing::info!(
             "No file found for snapshot for `{}`",
diff --git a/crates/red_knot_server/src/server/api/traits.rs b/crates/red_knot_server/src/server/api/traits.rs
index 03006d0abb..bbd11b1358 100644
--- a/crates/red_knot_server/src/server/api/traits.rs
+++ b/crates/red_knot_server/src/server/api/traits.rs
@@ -5,7 +5,7 @@ use crate::session::{DocumentSnapshot, Session};
 
 use lsp_types::notification::Notification as LSPNotification;
 use lsp_types::request::Request;
-use red_knot_workspace::db::RootDatabase;
+use red_knot_workspace::db::ProjectDatabase;
 
 /// A supertrait for any server request handler.
 pub(super) trait RequestHandler {
@@ -34,7 +34,7 @@ pub(super) trait BackgroundDocumentRequestHandler: RequestHandler {
 
     fn run_with_snapshot(
         snapshot: DocumentSnapshot,
-        db: RootDatabase,
+        db: ProjectDatabase,
         notifier: Notifier,
         params: <<Self as RequestHandler>::RequestType as Request>::Params,
     ) -> super::Result<<<Self as RequestHandler>::RequestType as Request>::Result>;
diff --git a/crates/red_knot_server/src/session.rs b/crates/red_knot_server/src/session.rs
index ca4e129959..b6d2a0833e 100644
--- a/crates/red_knot_server/src/session.rs
+++ b/crates/red_knot_server/src/session.rs
@@ -8,8 +8,8 @@ use std::sync::Arc;
 use anyhow::anyhow;
 use lsp_types::{ClientCapabilities, TextDocumentContentChangeEvent, Url};
 
-use red_knot_workspace::db::RootDatabase;
-use red_knot_workspace::workspace::WorkspaceMetadata;
+use red_knot_workspace::db::ProjectDatabase;
+use red_knot_workspace::project::ProjectMetadata;
 use ruff_db::files::{system_path_to_file, File};
 use ruff_db::system::SystemPath;
 use ruff_db::Db;
@@ -28,7 +28,7 @@ pub(crate) mod index;
 mod settings;
 
 // TODO(dhruvmanila): In general, the server shouldn't use any salsa queries directly and instead
-// should use methods on `RootDatabase`.
+// should use methods on `ProjectDatabase`.
 
 /// The global state for the LSP
 pub struct Session {
@@ -41,8 +41,9 @@ pub struct Session {
     /// [`index_mut`]: Session::index_mut
     index: Option<Arc<index::Index>>,
 
-    /// Maps workspace root paths to their respective databases.
-    workspaces: BTreeMap<PathBuf, RootDatabase>,
+    /// Maps workspace folders to their respective project databases.
+    projects_by_workspace_folder: BTreeMap<PathBuf, ProjectDatabase>,
+
     /// The global position encoding, negotiated during LSP initialization.
     position_encoding: PositionEncoding,
     /// Tracks what LSP features the client supports and doesn't support.
@@ -68,14 +69,14 @@ impl Session {
             let system = LSPSystem::new(index.clone());
 
             // TODO(dhruvmanila): Get the values from the client settings
-            let metadata = WorkspaceMetadata::discover(system_path, &system, None)?;
+            let metadata = ProjectMetadata::discover(system_path, &system, None)?;
             // TODO(micha): Handle the case where the program settings are incorrect more gracefully.
-            workspaces.insert(path, RootDatabase::new(metadata, system)?);
+            workspaces.insert(path, ProjectDatabase::new(metadata, system)?);
         }
 
         Ok(Self {
             position_encoding,
-            workspaces,
+            projects_by_workspace_folder: workspaces,
             index: Some(index),
             resolved_client_capabilities: Arc::new(ResolvedClientCapabilities::new(
                 client_capabilities,
@@ -87,38 +88,41 @@ impl Session {
     // and `default_workspace_db_mut` but the borrow checker doesn't allow that.
     // https://github.com/astral-sh/ruff/pull/13041#discussion_r1726725437
 
-    /// Returns a reference to the workspace [`RootDatabase`] corresponding to the given path, if
+    /// Returns a reference to the project's [`ProjectDatabase`] corresponding to the given path, if
     /// any.
-    pub(crate) fn workspace_db_for_path(&self, path: impl AsRef<Path>) -> Option<&RootDatabase> {
-        self.workspaces
+    pub(crate) fn project_db_for_path(&self, path: impl AsRef<Path>) -> Option<&ProjectDatabase> {
+        self.projects_by_workspace_folder
             .range(..=path.as_ref().to_path_buf())
             .next_back()
             .map(|(_, db)| db)
     }
 
-    /// Returns a mutable reference to the workspace [`RootDatabase`] corresponding to the given
+    /// Returns a mutable reference to the project [`ProjectDatabase`] corresponding to the given
     /// path, if any.
-    pub(crate) fn workspace_db_for_path_mut(
+    pub(crate) fn project_db_for_path_mut(
         &mut self,
         path: impl AsRef<Path>,
-    ) -> Option<&mut RootDatabase> {
-        self.workspaces
+    ) -> Option<&mut ProjectDatabase> {
+        self.projects_by_workspace_folder
             .range_mut(..=path.as_ref().to_path_buf())
             .next_back()
             .map(|(_, db)| db)
     }
 
-    /// Returns a reference to the default workspace [`RootDatabase`]. The default workspace is the
-    /// minimum root path in the workspace map.
-    pub(crate) fn default_workspace_db(&self) -> &RootDatabase {
-        // SAFETY: Currently, red knot only support a single workspace.
-        self.workspaces.values().next().unwrap()
+    /// Returns a reference to the default project [`ProjectDatabase`]. The default project is the
+    /// minimum root path in the project map.
+    pub(crate) fn default_project_db(&self) -> &ProjectDatabase {
+        // SAFETY: Currently, red knot only support a single project.
+        self.projects_by_workspace_folder.values().next().unwrap()
     }
 
-    /// Returns a mutable reference to the default workspace [`RootDatabase`].
-    pub(crate) fn default_workspace_db_mut(&mut self) -> &mut RootDatabase {
-        // SAFETY: Currently, red knot only support a single workspace.
-        self.workspaces.values_mut().next().unwrap()
+    /// Returns a mutable reference to the default project [`ProjectDatabase`].
+    pub(crate) fn default_project_db_mut(&mut self) -> &mut ProjectDatabase {
+        // SAFETY: Currently, red knot only support a single project.
+        self.projects_by_workspace_folder
+            .values_mut()
+            .next()
+            .unwrap()
     }
 
     pub fn key_from_url(&self, url: Url) -> DocumentKey {
@@ -187,7 +191,7 @@ impl Session {
     fn index_mut(&mut self) -> MutIndexGuard {
         let index = self.index.take().unwrap();
 
-        for db in self.workspaces.values_mut() {
+        for db in self.projects_by_workspace_folder.values_mut() {
             // Remove the `index` from each database. This drops the count of `Arc<Index>` down to 1
             db.system_mut()
                 .as_any_mut()
@@ -232,7 +236,7 @@ impl Drop for MutIndexGuard<'_> {
     fn drop(&mut self) {
         if let Some(index) = self.index.take() {
             let index = Arc::new(index);
-            for db in self.session.workspaces.values_mut() {
+            for db in self.session.projects_by_workspace_folder.values_mut() {
                 db.system_mut()
                     .as_any_mut()
                     .downcast_mut::<LSPSystem>()
@@ -267,7 +271,7 @@ impl DocumentSnapshot {
         self.position_encoding
     }
 
-    pub(crate) fn file(&self, db: &RootDatabase) -> Option<File> {
+    pub(crate) fn file(&self, db: &ProjectDatabase) -> Option<File> {
         match url_to_any_system_path(self.document_ref.file_url()).ok()? {
             AnySystemPath::System(path) => system_path_to_file(db, path).ok(),
             AnySystemPath::SystemVirtual(virtual_path) => db
diff --git a/crates/red_knot_test/src/db.rs b/crates/red_knot_test/src/db.rs
index 851025712b..7bf706d404 100644
--- a/crates/red_knot_test/src/db.rs
+++ b/crates/red_knot_test/src/db.rs
@@ -38,7 +38,7 @@ impl Db {
 
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version: PythonVersion::default(),
                 python_platform: PythonPlatform::default(),
                 search_paths: SearchPathSettings::new(db.workspace_root.clone()),
diff --git a/crates/red_knot_wasm/src/lib.rs b/crates/red_knot_wasm/src/lib.rs
index ca41654f4c..b4a2cc7f39 100644
--- a/crates/red_knot_wasm/src/lib.rs
+++ b/crates/red_knot_wasm/src/lib.rs
@@ -3,9 +3,9 @@ use std::any::Any;
 use js_sys::Error;
 use wasm_bindgen::prelude::*;
 
-use red_knot_workspace::db::{Db, RootDatabase};
-use red_knot_workspace::workspace::settings::Configuration;
-use red_knot_workspace::workspace::WorkspaceMetadata;
+use red_knot_workspace::db::{Db, ProjectDatabase};
+use red_knot_workspace::project::settings::Configuration;
+use red_knot_workspace::project::ProjectMetadata;
 use ruff_db::diagnostic::Diagnostic;
 use ruff_db::files::{system_path_to_file, File};
 use ruff_db::system::walk_directory::WalkDirectoryBuilder;
@@ -33,7 +33,7 @@ pub fn run() {
 
 #[wasm_bindgen]
 pub struct Workspace {
-    db: RootDatabase,
+    db: ProjectDatabase,
     system: WasmSystem,
 }
 
@@ -42,7 +42,7 @@ impl Workspace {
     #[wasm_bindgen(constructor)]
     pub fn new(root: &str, settings: &Settings) -> Result<Workspace, Error> {
         let system = WasmSystem::new(SystemPath::new(root));
-        let workspace = WorkspaceMetadata::discover(
+        let workspace = ProjectMetadata::discover(
             SystemPath::new(root),
             &system,
             Some(&Configuration {
@@ -52,7 +52,7 @@ impl Workspace {
         )
         .map_err(into_error)?;
 
-        let db = RootDatabase::new(workspace, system.clone()).map_err(into_error)?;
+        let db = ProjectDatabase::new(workspace, system.clone()).map_err(into_error)?;
 
         Ok(Self { db, system })
     }
@@ -67,7 +67,7 @@ impl Workspace {
         let file = system_path_to_file(&self.db, path).expect("File to exist");
         file.sync(&mut self.db);
 
-        self.db.workspace().open_file(&mut self.db, file);
+        self.db.project().open_file(&mut self.db, file);
 
         Ok(FileHandle {
             file,
@@ -95,7 +95,7 @@ impl Workspace {
     pub fn close_file(&mut self, file_id: &FileHandle) -> Result<(), Error> {
         let file = file_id.file;
 
-        self.db.workspace().close_file(&mut self.db, file);
+        self.db.project().close_file(&mut self.db, file);
         self.system
             .fs
             .remove_file(&file_id.path)
diff --git a/crates/red_knot_workspace/src/db.rs b/crates/red_knot_workspace/src/db.rs
index e30a39b9fb..14d49ec351 100644
--- a/crates/red_knot_workspace/src/db.rs
+++ b/crates/red_knot_workspace/src/db.rs
@@ -1,7 +1,7 @@
 use std::panic::RefUnwindSafe;
 use std::sync::Arc;
 
-use crate::workspace::{check_file, Workspace, WorkspaceMetadata};
+use crate::project::{check_file, Project, ProjectMetadata};
 use crate::DEFAULT_LINT_REGISTRY;
 use red_knot_python_semantic::lint::{LintRegistry, RuleSelection};
 use red_knot_python_semantic::{Db as SemanticDb, Program};
@@ -17,28 +17,28 @@ mod changes;
 
 #[salsa::db]
 pub trait Db: SemanticDb + Upcast<dyn SemanticDb> {
-    fn workspace(&self) -> Workspace;
+    fn project(&self) -> Project;
 }
 
 #[salsa::db]
 #[derive(Clone)]
-pub struct RootDatabase {
-    workspace: Option<Workspace>,
-    storage: salsa::Storage<RootDatabase>,
+pub struct ProjectDatabase {
+    project: Option<Project>,
+    storage: salsa::Storage<ProjectDatabase>,
     files: Files,
     system: Arc<dyn System + Send + Sync + RefUnwindSafe>,
     rule_selection: Arc<RuleSelection>,
 }
 
-impl RootDatabase {
-    pub fn new<S>(workspace: WorkspaceMetadata, system: S) -> anyhow::Result<Self>
+impl ProjectDatabase {
+    pub fn new<S>(project_metadata: ProjectMetadata, system: S) -> anyhow::Result<Self>
     where
         S: System + 'static + Send + Sync + RefUnwindSafe,
     {
         let rule_selection = RuleSelection::from_registry(&DEFAULT_LINT_REGISTRY);
 
         let mut db = Self {
-            workspace: None,
+            project: None,
             storage: salsa::Storage::default(),
             files: Files::default(),
             system: Arc::new(system),
@@ -46,16 +46,17 @@ impl RootDatabase {
         };
 
         // Initialize the `Program` singleton
-        Program::from_settings(&db, workspace.settings().program())?;
+        let program_settings = project_metadata.to_program_settings();
+        Program::from_settings(&db, program_settings)?;
 
-        db.workspace = Some(Workspace::from_metadata(&db, workspace));
+        db.project = Some(Project::from_metadata(&db, project_metadata));
 
         Ok(db)
     }
 
-    /// Checks all open files in the workspace and its dependencies.
+    /// Checks all open files in the project and its dependencies.
     pub fn check(&self) -> Result<Vec<Box<dyn Diagnostic>>, Cancelled> {
-        self.with_db(|db| db.workspace().check(db))
+        self.with_db(|db| db.project().check(db))
     }
 
     pub fn check_file(&self, file: File) -> Result<Vec<Box<dyn Diagnostic>>, Cancelled> {
@@ -77,13 +78,13 @@ impl RootDatabase {
 
     pub(crate) fn with_db<F, T>(&self, f: F) -> Result<T, Cancelled>
     where
-        F: FnOnce(&RootDatabase) -> T + std::panic::UnwindSafe,
+        F: FnOnce(&ProjectDatabase) -> T + std::panic::UnwindSafe,
     {
         Cancelled::catch(|| f(self))
     }
 }
 
-impl Upcast<dyn SemanticDb> for RootDatabase {
+impl Upcast<dyn SemanticDb> for ProjectDatabase {
     fn upcast(&self) -> &(dyn SemanticDb + 'static) {
         self
     }
@@ -93,7 +94,7 @@ impl Upcast<dyn SemanticDb> for RootDatabase {
     }
 }
 
-impl Upcast<dyn SourceDb> for RootDatabase {
+impl Upcast<dyn SourceDb> for ProjectDatabase {
     fn upcast(&self) -> &(dyn SourceDb + 'static) {
         self
     }
@@ -104,13 +105,13 @@ impl Upcast<dyn SourceDb> for RootDatabase {
 }
 
 #[salsa::db]
-impl SemanticDb for RootDatabase {
+impl SemanticDb for ProjectDatabase {
     fn is_file_open(&self, file: File) -> bool {
-        let Some(workspace) = &self.workspace else {
+        let Some(project) = &self.project else {
             return false;
         };
 
-        workspace.is_file_open(self, file)
+        project.is_file_open(self, file)
     }
 
     fn rule_selection(&self) -> &RuleSelection {
@@ -123,7 +124,7 @@ impl SemanticDb for RootDatabase {
 }
 
 #[salsa::db]
-impl SourceDb for RootDatabase {
+impl SourceDb for ProjectDatabase {
     fn vendored(&self) -> &VendoredFileSystem {
         red_knot_vendored::file_system()
     }
@@ -138,7 +139,7 @@ impl SourceDb for RootDatabase {
 }
 
 #[salsa::db]
-impl salsa::Database for RootDatabase {
+impl salsa::Database for ProjectDatabase {
     fn salsa_event(&self, event: &dyn Fn() -> Event) {
         if !tracing::enabled!(tracing::Level::TRACE) {
             return;
@@ -154,9 +155,9 @@ impl salsa::Database for RootDatabase {
 }
 
 #[salsa::db]
-impl Db for RootDatabase {
-    fn workspace(&self) -> Workspace {
-        self.workspace.unwrap()
+impl Db for ProjectDatabase {
+    fn project(&self) -> Project {
+        self.project.unwrap()
     }
 }
 
@@ -174,7 +175,7 @@ pub(crate) mod tests {
     use ruff_db::{Db as SourceDb, Upcast};
 
     use crate::db::Db;
-    use crate::workspace::{Workspace, WorkspaceMetadata};
+    use crate::project::{Project, ProjectMetadata};
     use crate::DEFAULT_LINT_REGISTRY;
 
     #[salsa::db]
@@ -186,11 +187,11 @@ pub(crate) mod tests {
         system: TestSystem,
         vendored: VendoredFileSystem,
         rule_selection: RuleSelection,
-        workspace: Option<Workspace>,
+        project: Option<Project>,
     }
 
     impl TestDb {
-        pub(crate) fn new(workspace: WorkspaceMetadata) -> Self {
+        pub(crate) fn new(project: ProjectMetadata) -> Self {
             let mut db = Self {
                 storage: salsa::Storage::default(),
                 system: TestSystem::default(),
@@ -198,11 +199,11 @@ pub(crate) mod tests {
                 files: Files::default(),
                 events: Arc::default(),
                 rule_selection: RuleSelection::from_registry(&DEFAULT_LINT_REGISTRY),
-                workspace: None,
+                project: None,
             };
 
-            let workspace = Workspace::from_metadata(&db, workspace);
-            db.workspace = Some(workspace);
+            let project = Project::from_metadata(&db, project);
+            db.project = Some(project);
             db
         }
     }
@@ -280,8 +281,8 @@ pub(crate) mod tests {
 
     #[salsa::db]
     impl Db for TestDb {
-        fn workspace(&self) -> Workspace {
-            self.workspace.unwrap()
+        fn project(&self) -> Project {
+            self.project.unwrap()
         }
     }
 
diff --git a/crates/red_knot_workspace/src/db/changes.rs b/crates/red_knot_workspace/src/db/changes.rs
index a5ee5b3936..bdeaf3c25a 100644
--- a/crates/red_knot_workspace/src/db/changes.rs
+++ b/crates/red_knot_workspace/src/db/changes.rs
@@ -1,8 +1,7 @@
-use crate::db::{Db, RootDatabase};
-use crate::watch;
+use crate::db::{Db, ProjectDatabase};
+use crate::project::settings::Configuration;
+use crate::project::{Project, ProjectMetadata};
 use crate::watch::{ChangeEvent, CreatedKind, DeletedKind};
-use crate::workspace::settings::Configuration;
-use crate::workspace::{Workspace, WorkspaceMetadata};
 use red_knot_python_semantic::Program;
 use ruff_db::files::{system_path_to_file, File, Files};
 use ruff_db::system::walk_directory::WalkState;
@@ -10,25 +9,24 @@ use ruff_db::system::SystemPath;
 use ruff_db::Db as _;
 use rustc_hash::FxHashSet;
 
-impl RootDatabase {
+impl ProjectDatabase {
     #[tracing::instrument(level = "debug", skip(self, changes, base_configuration))]
     pub fn apply_changes(
         &mut self,
-        changes: Vec<watch::ChangeEvent>,
+        changes: Vec<ChangeEvent>,
         base_configuration: Option<&Configuration>,
     ) {
-        let mut workspace = self.workspace();
-        let workspace_path = workspace.root(self).to_path_buf();
+        let mut project = self.project();
+        let project_path = project.root(self).to_path_buf();
         let program = Program::get(self);
         let custom_stdlib_versions_path = program
             .custom_stdlib_search_path(self)
             .map(|path| path.join("VERSIONS"));
 
-        let mut workspace_change = false;
+        // Are there structural changes to the project
+        let mut project_changed = false;
         // Changes to a custom stdlib path's VERSIONS
         let mut custom_stdlib_change = false;
-        // Packages that need reloading
-        let mut changed_packages = FxHashSet::default();
         // Paths that were added
         let mut added_paths = FxHashSet::default();
 
@@ -36,13 +34,13 @@ impl RootDatabase {
         let mut synced_files = FxHashSet::default();
         let mut synced_recursively = FxHashSet::default();
 
-        let mut sync_path = |db: &mut RootDatabase, path: &SystemPath| {
+        let mut sync_path = |db: &mut ProjectDatabase, path: &SystemPath| {
             if synced_files.insert(path.to_path_buf()) {
                 File::sync_path(db, path);
             }
         };
 
-        let mut sync_recursively = |db: &mut RootDatabase, path: &SystemPath| {
+        let mut sync_recursively = |db: &mut ProjectDatabase, path: &SystemPath| {
             if synced_recursively.insert(path.to_path_buf()) {
                 Files::sync_recursively(db, path);
             }
@@ -54,19 +52,8 @@ impl RootDatabase {
                     path.file_name(),
                     Some(".gitignore" | ".ignore" | "ruff.toml" | ".ruff.toml" | "pyproject.toml")
                 ) {
-                    // Changes to ignore files or settings can change the workspace structure or add/remove files
-                    // from packages.
-                    if let Some(package) = workspace.package(self, path) {
-                        if package.root(self) == workspace.root(self)
-                            || matches!(change, ChangeEvent::Deleted { .. })
-                        {
-                            workspace_change = true;
-                        }
-
-                        changed_packages.insert(package);
-                    } else {
-                        workspace_change = true;
-                    }
+                    // Changes to ignore files or settings can change the project structure or add/remove files.
+                    project_changed = true;
 
                     continue;
                 }
@@ -77,10 +64,11 @@ impl RootDatabase {
             }
 
             match change {
-                watch::ChangeEvent::Changed { path, kind: _ }
-                | watch::ChangeEvent::Opened(path) => sync_path(self, &path),
+                ChangeEvent::Changed { path, kind: _ } | ChangeEvent::Opened(path) => {
+                    sync_path(self, &path);
+                }
 
-                watch::ChangeEvent::Created { kind, path } => {
+                ChangeEvent::Created { kind, path } => {
                     match kind {
                         CreatedKind::File => sync_path(self, &path),
                         CreatedKind::Directory | CreatedKind::Any => {
@@ -97,7 +85,7 @@ impl RootDatabase {
                     }
                 }
 
-                watch::ChangeEvent::Deleted { kind, path } => {
+                ChangeEvent::Deleted { kind, path } => {
                     let is_file = match kind {
                         DeletedKind::File => true,
                         DeletedKind::Directory => {
@@ -113,10 +101,8 @@ impl RootDatabase {
                     if is_file {
                         sync_path(self, &path);
 
-                        if let Some(package) = workspace.package(self, &path) {
-                            if let Some(file) = self.files().try_system(self, &path) {
-                                package.remove_file(self, file);
-                            }
+                        if let Some(file) = self.files().try_system(self, &path) {
+                            project.remove_file(self, file);
                         }
                     } else {
                         sync_recursively(self, &path);
@@ -128,69 +114,68 @@ impl RootDatabase {
                             custom_stdlib_change = true;
                         }
 
-                        if let Some(package) = workspace.package(self, &path) {
-                            changed_packages.insert(package);
-                        } else {
-                            workspace_change = true;
-                        }
+                        // Perform a full-reload in case the deleted directory contained the pyproject.toml.
+                        // We may want to make this more clever in the future, to e.g. iterate over the
+                        // indexed files and remove the once that start with the same path, unless
+                        // the deleted path is the project configuration.
+                        project_changed = true;
                     }
                 }
 
-                watch::ChangeEvent::CreatedVirtual(path)
-                | watch::ChangeEvent::ChangedVirtual(path) => {
+                ChangeEvent::CreatedVirtual(path) | ChangeEvent::ChangedVirtual(path) => {
                     File::sync_virtual_path(self, &path);
                 }
 
-                watch::ChangeEvent::DeletedVirtual(path) => {
+                ChangeEvent::DeletedVirtual(path) => {
                     if let Some(virtual_file) = self.files().try_virtual_file(&path) {
                         virtual_file.close(self);
                     }
                 }
 
-                watch::ChangeEvent::Rescan => {
-                    workspace_change = true;
+                ChangeEvent::Rescan => {
+                    project_changed = true;
                     Files::sync_all(self);
                     break;
                 }
             }
         }
 
-        if workspace_change {
-            match WorkspaceMetadata::discover(&workspace_path, self.system(), base_configuration) {
+        if project_changed {
+            match ProjectMetadata::discover(&project_path, self.system(), base_configuration) {
                 Ok(metadata) => {
-                    if metadata.root() == workspace.root(self) {
-                        tracing::debug!("Reloading workspace after structural change");
-                        // TODO: Handle changes in the program settings.
-                        workspace.reload(self, metadata);
+                    let program_settings = metadata.to_program_settings();
+
+                    let program = Program::get(self);
+                    if let Err(error) = program.update_from_settings(self, program_settings) {
+                        tracing::error!("Failed to update the program settings, keeping the old program settings: {error}");
+                    };
+
+                    if metadata.root() == project.root(self) {
+                        tracing::debug!("Reloading project after structural change");
+                        project.reload(self, metadata);
                     } else {
-                        tracing::debug!("Replace workspace after structural change");
-                        workspace = Workspace::from_metadata(self, metadata);
-                        self.workspace = Some(workspace);
+                        tracing::debug!("Replace project after structural change");
+                        project = Project::from_metadata(self, metadata);
+                        self.project = Some(project);
                     }
                 }
                 Err(error) => {
                     tracing::error!(
-                        "Failed to load workspace, keeping old workspace configuration: {error}"
+                        "Failed to load project, keeping old project configuration: {error}"
                     );
                 }
             }
 
             return;
         } else if custom_stdlib_change {
-            let search_paths = workspace.search_path_settings(self).clone();
+            let search_paths = project.metadata(self).to_program_settings().search_paths;
+
             if let Err(error) = program.update_search_paths(self, &search_paths) {
                 tracing::error!("Failed to set the new search paths: {error}");
             }
         }
 
-        let mut added_paths = added_paths.into_iter().filter(|path| {
-            let Some(package) = workspace.package(self, path) else {
-                return false;
-            };
-
-            // Skip packages that need reloading
-            !changed_packages.contains(&package)
-        });
+        let mut added_paths = added_paths.into_iter();
 
         // Use directory walking to discover newly added files.
         if let Some(path) = added_paths.next() {
@@ -221,18 +206,12 @@ impl RootDatabase {
             });
 
             for path in added_paths.into_inner().unwrap() {
-                let package = workspace.package(self, &path);
                 let file = system_path_to_file(self, &path);
 
-                if let (Some(package), Ok(file)) = (package, file) {
-                    package.add_file(self, file);
+                if let Ok(file) = file {
+                    project.add_file(self, file);
                 }
             }
         }
-
-        // Reload
-        for package in changed_packages {
-            package.reload_files(self);
-        }
     }
 }
diff --git a/crates/red_knot_workspace/src/lib.rs b/crates/red_knot_workspace/src/lib.rs
index 7a7503bf85..5ae74bf0e5 100644
--- a/crates/red_knot_workspace/src/lib.rs
+++ b/crates/red_knot_workspace/src/lib.rs
@@ -2,8 +2,8 @@ use red_knot_python_semantic::lint::{LintRegistry, LintRegistryBuilder};
 use red_knot_python_semantic::register_lints;
 
 pub mod db;
+pub mod project;
 pub mod watch;
-pub mod workspace;
 
 pub static DEFAULT_LINT_REGISTRY: std::sync::LazyLock<LintRegistry> =
     std::sync::LazyLock::new(default_lints_registry);
diff --git a/crates/red_knot_workspace/src/project.rs b/crates/red_knot_workspace/src/project.rs
new file mode 100644
index 0000000000..5401b54783
--- /dev/null
+++ b/crates/red_knot_workspace/src/project.rs
@@ -0,0 +1,459 @@
+#![allow(clippy::ref_option)]
+
+use crate::db::Db;
+use crate::db::ProjectDatabase;
+use crate::project::files::{Index, Indexed, IndexedFiles, IndexedIter};
+pub use metadata::{ProjectDiscoveryError, ProjectMetadata};
+
+use red_knot_python_semantic::types::check_types;
+use ruff_db::diagnostic::{Diagnostic, DiagnosticId, ParseDiagnostic, Severity};
+use ruff_db::parsed::parsed_module;
+use ruff_db::source::{source_text, SourceTextError};
+use ruff_db::system::FileType;
+use ruff_db::{
+    files::{system_path_to_file, File},
+    system::{walk_directory::WalkState, SystemPath},
+};
+use ruff_python_ast::PySourceType;
+use ruff_text_size::TextRange;
+use rustc_hash::{FxBuildHasher, FxHashSet};
+use salsa::{Durability, Setter as _};
+use std::borrow::Cow;
+use std::sync::Arc;
+
+mod files;
+mod metadata;
+mod pyproject;
+pub mod settings;
+
+/// The project as a Salsa ingredient.
+///
+/// ## How is a project different from a program?
+/// There are two (related) motivations:
+///
+/// 1. Program is defined in `ruff_db` and it can't reference the settings types for the linter and formatter
+///    without introducing a cyclic dependency. The project is defined in a higher level crate
+///    where it can reference these setting types.
+/// 2. Running `ruff check` with different target versions results in different programs (settings) but
+///    it remains the same project. That's why program is a narrowed view of the project only
+///    holding on to the most fundamental settings required for checking.
+#[salsa::input]
+pub struct Project {
+    /// The files that are open in the project.
+    ///
+    /// Setting the open files to a non-`None` value changes `check` to only check the
+    /// open files rather than all files in the project.
+    #[return_ref]
+    #[default]
+    open_fileset: Option<Arc<FxHashSet<File>>>,
+
+    /// The first-party files of this project.
+    #[default]
+    #[return_ref]
+    file_set: IndexedFiles,
+
+    /// The metadata describing the project, including the unresolved configuration.
+    #[return_ref]
+    pub metadata: ProjectMetadata,
+}
+
+impl Project {
+    pub fn from_metadata(db: &dyn Db, metadata: ProjectMetadata) -> Self {
+        Project::builder(metadata)
+            .durability(Durability::MEDIUM)
+            .open_fileset_durability(Durability::LOW)
+            .file_set_durability(Durability::LOW)
+            .new(db)
+    }
+
+    pub fn root(self, db: &dyn Db) -> &SystemPath {
+        self.metadata(db).root()
+    }
+
+    pub fn name(self, db: &dyn Db) -> &str {
+        self.metadata(db).name()
+    }
+
+    pub fn reload(self, db: &mut dyn Db, metadata: ProjectMetadata) {
+        tracing::debug!("Reloading project");
+        assert_eq!(self.root(db), metadata.root());
+
+        if &metadata != self.metadata(db) {
+            self.set_metadata(db).to(metadata);
+        }
+
+        self.reload_files(db);
+    }
+
+    /// Checks all open files in the project and its dependencies.
+    pub fn check(self, db: &ProjectDatabase) -> Vec<Box<dyn Diagnostic>> {
+        let project_span = tracing::debug_span!("Project::check");
+        let _span = project_span.enter();
+
+        tracing::debug!("Checking project '{name}'", name = self.name(db));
+        let result = Arc::new(std::sync::Mutex::new(Vec::new()));
+        let inner_result = Arc::clone(&result);
+
+        let db = db.clone();
+        let project_span = project_span.clone();
+
+        rayon::scope(move |scope| {
+            let files = ProjectFiles::new(&db, self);
+            for file in &files {
+                let result = inner_result.clone();
+                let db = db.clone();
+                let project_span = project_span.clone();
+
+                scope.spawn(move |_| {
+                    let check_file_span = tracing::debug_span!(parent: &project_span, "check_file", file=%file.path(&db));
+                    let _entered = check_file_span.entered();
+
+                    let file_diagnostics = check_file(&db, file);
+                    result.lock().unwrap().extend(file_diagnostics);
+                });
+            }
+        });
+
+        Arc::into_inner(result).unwrap().into_inner().unwrap()
+    }
+
+    /// Opens a file in the project.
+    ///
+    /// This changes the behavior of `check` to only check the open files rather than all files in the project.
+    pub fn open_file(self, db: &mut dyn Db, file: File) {
+        tracing::debug!("Opening file `{}`", file.path(db));
+
+        let mut open_files = self.take_open_files(db);
+        open_files.insert(file);
+        self.set_open_files(db, open_files);
+    }
+
+    /// Closes a file in the project.
+    pub fn close_file(self, db: &mut dyn Db, file: File) -> bool {
+        tracing::debug!("Closing file `{}`", file.path(db));
+
+        let mut open_files = self.take_open_files(db);
+        let removed = open_files.remove(&file);
+
+        if removed {
+            self.set_open_files(db, open_files);
+        }
+
+        removed
+    }
+
+    /// Returns the open files in the project or `None` if the entire project should be checked.
+    pub fn open_files(self, db: &dyn Db) -> Option<&FxHashSet<File>> {
+        self.open_fileset(db).as_deref()
+    }
+
+    /// Sets the open files in the project.
+    ///
+    /// This changes the behavior of `check` to only check the open files rather than all files in the project.
+    #[tracing::instrument(level = "debug", skip(self, db))]
+    pub fn set_open_files(self, db: &mut dyn Db, open_files: FxHashSet<File>) {
+        tracing::debug!("Set open project files (count: {})", open_files.len());
+
+        self.set_open_fileset(db).to(Some(Arc::new(open_files)));
+    }
+
+    /// This takes the open files from the project and returns them.
+    ///
+    /// This changes the behavior of `check` to check all files in the project instead of just the open files.
+    fn take_open_files(self, db: &mut dyn Db) -> FxHashSet<File> {
+        tracing::debug!("Take open project files");
+
+        // Salsa will cancel any pending queries and remove its own reference to `open_files`
+        // so that the reference counter to `open_files` now drops to 1.
+        let open_files = self.set_open_fileset(db).to(None);
+
+        if let Some(open_files) = open_files {
+            Arc::try_unwrap(open_files).unwrap()
+        } else {
+            FxHashSet::default()
+        }
+    }
+
+    /// Returns `true` if the file is open in the project.
+    ///
+    /// A file is considered open when:
+    /// * explicitly set as an open file using [`open_file`](Self::open_file)
+    /// * It has a [`SystemPath`] and belongs to a package's `src` files
+    /// * It has a [`SystemVirtualPath`](ruff_db::system::SystemVirtualPath)
+    pub fn is_file_open(self, db: &dyn Db, file: File) -> bool {
+        if let Some(open_files) = self.open_files(db) {
+            open_files.contains(&file)
+        } else if file.path(db).is_system_path() {
+            self.contains_file(db, file)
+        } else {
+            file.path(db).is_system_virtual_path()
+        }
+    }
+
+    /// Returns `true` if `file` is a first-party file part of this package.
+    pub fn contains_file(self, db: &dyn Db, file: File) -> bool {
+        self.files(db).contains(&file)
+    }
+
+    #[tracing::instrument(level = "debug", skip(db))]
+    pub fn remove_file(self, db: &mut dyn Db, file: File) {
+        tracing::debug!(
+            "Removing file `{}` from project `{}`",
+            file.path(db),
+            self.name(db)
+        );
+
+        let Some(mut index) = IndexedFiles::indexed_mut(db, self) else {
+            return;
+        };
+
+        index.remove(file);
+    }
+
+    pub fn add_file(self, db: &mut dyn Db, file: File) {
+        tracing::debug!(
+            "Adding file `{}` to project `{}`",
+            file.path(db),
+            self.name(db)
+        );
+
+        let Some(mut index) = IndexedFiles::indexed_mut(db, self) else {
+            return;
+        };
+
+        index.insert(file);
+    }
+
+    /// Returns the files belonging to this project.
+    pub fn files(self, db: &dyn Db) -> Indexed<'_> {
+        let files = self.file_set(db);
+
+        let indexed = match files.get() {
+            Index::Lazy(vacant) => {
+                let _entered =
+                    tracing::debug_span!("Project::index_files", package = %self.name(db))
+                        .entered();
+
+                let files = discover_project_files(db, self);
+                tracing::info!("Found {} files in project `{}`", files.len(), self.name(db));
+                vacant.set(files)
+            }
+            Index::Indexed(indexed) => indexed,
+        };
+
+        indexed
+    }
+
+    pub fn reload_files(self, db: &mut dyn Db) {
+        tracing::debug!("Reloading files for project `{}`", self.name(db));
+
+        if !self.file_set(db).is_lazy() {
+            // Force a re-index of the files in the next revision.
+            self.set_file_set(db).to(IndexedFiles::lazy());
+        }
+    }
+}
+
+pub(super) fn check_file(db: &dyn Db, file: File) -> Vec<Box<dyn Diagnostic>> {
+    let mut diagnostics: Vec<Box<dyn Diagnostic>> = Vec::new();
+    // Abort checking if there are IO errors.
+    let source = source_text(db.upcast(), file);
+
+    if let Some(read_error) = source.read_error() {
+        diagnostics.push(Box::new(IOErrorDiagnostic {
+            file,
+            error: read_error.clone(),
+        }));
+        return diagnostics;
+    }
+
+    let parsed = parsed_module(db.upcast(), file);
+    diagnostics.extend(parsed.errors().iter().map(|error| {
+        let diagnostic: Box<dyn Diagnostic> = Box::new(ParseDiagnostic::new(file, error.clone()));
+        diagnostic
+    }));
+
+    diagnostics.extend(check_types(db.upcast(), file).iter().map(|diagnostic| {
+        let boxed: Box<dyn Diagnostic> = Box::new(diagnostic.clone());
+        boxed
+    }));
+
+    diagnostics.sort_unstable_by_key(|diagnostic| diagnostic.range().unwrap_or_default().start());
+
+    diagnostics
+}
+
+fn discover_project_files(db: &dyn Db, project: Project) -> FxHashSet<File> {
+    let paths = std::sync::Mutex::new(Vec::new());
+
+    db.system().walk_directory(project.root(db)).run(|| {
+        Box::new(|entry| {
+            match entry {
+                Ok(entry) => {
+                    // Skip over any non python files to avoid creating too many entries in `Files`.
+                    match entry.file_type() {
+                        FileType::File => {
+                            if entry
+                                .path()
+                                .extension()
+                                .and_then(PySourceType::try_from_extension)
+                                .is_some()
+                            {
+                                let mut paths = paths.lock().unwrap();
+                                paths.push(entry.into_path());
+                            }
+                        }
+                        FileType::Directory | FileType::Symlink => {}
+                    }
+                }
+                Err(error) => {
+                    // TODO Handle error
+                    tracing::error!("Failed to walk path: {error}");
+                }
+            }
+
+            WalkState::Continue
+        })
+    });
+
+    let paths = paths.into_inner().unwrap();
+    let mut files = FxHashSet::with_capacity_and_hasher(paths.len(), FxBuildHasher);
+
+    for path in paths {
+        // If this returns `None`, then the file was deleted between the `walk_directory` call and now.
+        // We can ignore this.
+        if let Ok(file) = system_path_to_file(db.upcast(), &path) {
+            files.insert(file);
+        }
+    }
+
+    files
+}
+
+#[derive(Debug)]
+enum ProjectFiles<'a> {
+    OpenFiles(&'a FxHashSet<File>),
+    Indexed(Indexed<'a>),
+}
+
+impl<'a> ProjectFiles<'a> {
+    fn new(db: &'a dyn Db, project: Project) -> Self {
+        if let Some(open_files) = project.open_files(db) {
+            ProjectFiles::OpenFiles(open_files)
+        } else {
+            ProjectFiles::Indexed(project.files(db))
+        }
+    }
+}
+
+impl<'a> IntoIterator for &'a ProjectFiles<'a> {
+    type Item = File;
+    type IntoIter = ProjectFilesIter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        match self {
+            ProjectFiles::OpenFiles(files) => ProjectFilesIter::OpenFiles(files.iter()),
+            ProjectFiles::Indexed(indexed) => ProjectFilesIter::Indexed {
+                files: indexed.into_iter(),
+            },
+        }
+    }
+}
+
+enum ProjectFilesIter<'db> {
+    OpenFiles(std::collections::hash_set::Iter<'db, File>),
+    Indexed { files: IndexedIter<'db> },
+}
+
+impl Iterator for ProjectFilesIter<'_> {
+    type Item = File;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            ProjectFilesIter::OpenFiles(files) => files.next().copied(),
+            ProjectFilesIter::Indexed { files } => files.next(),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct IOErrorDiagnostic {
+    file: File,
+    error: SourceTextError,
+}
+
+impl Diagnostic for IOErrorDiagnostic {
+    fn id(&self) -> DiagnosticId {
+        DiagnosticId::Io
+    }
+
+    fn message(&self) -> Cow<str> {
+        self.error.to_string().into()
+    }
+
+    fn file(&self) -> File {
+        self.file
+    }
+
+    fn range(&self) -> Option<TextRange> {
+        None
+    }
+
+    fn severity(&self) -> Severity {
+        Severity::Error
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::db::tests::TestDb;
+    use crate::project::{check_file, ProjectMetadata};
+    use red_knot_python_semantic::types::check_types;
+    use ruff_db::diagnostic::Diagnostic;
+    use ruff_db::files::system_path_to_file;
+    use ruff_db::source::source_text;
+    use ruff_db::system::{DbWithTestSystem, SystemPath, SystemPathBuf};
+    use ruff_db::testing::assert_function_query_was_not_run;
+    use ruff_python_ast::name::Name;
+
+    #[test]
+    fn check_file_skips_type_checking_when_file_cant_be_read() -> ruff_db::system::Result<()> {
+        let project = ProjectMetadata::new(Name::new_static("test"), SystemPathBuf::from("/"));
+        let mut db = TestDb::new(project);
+        let path = SystemPath::new("test.py");
+
+        db.write_file(path, "x = 10")?;
+        let file = system_path_to_file(&db, path).unwrap();
+
+        // Now the file gets deleted before we had a chance to read its source text.
+        db.memory_file_system().remove_file(path)?;
+        file.sync(&mut db);
+
+        assert_eq!(source_text(&db, file).as_str(), "");
+        assert_eq!(
+            check_file(&db, file)
+                .into_iter()
+                .map(|diagnostic| diagnostic.message().into_owned())
+                .collect::<Vec<_>>(),
+            vec!["Failed to read file: No such file or directory".to_string()]
+        );
+
+        let events = db.take_salsa_events();
+        assert_function_query_was_not_run(&db, check_types, file, &events);
+
+        // The user now creates a new file with an empty text. The source text
+        // content returned by `source_text` remains unchanged, but the diagnostics should get updated.
+        db.write_file(path, "").unwrap();
+
+        assert_eq!(source_text(&db, file).as_str(), "");
+        assert_eq!(
+            check_file(&db, file)
+                .into_iter()
+                .map(|diagnostic| diagnostic.message().into_owned())
+                .collect::<Vec<_>>(),
+            vec![] as Vec<String>
+        );
+
+        Ok(())
+    }
+}
diff --git a/crates/red_knot_workspace/src/workspace/files.rs b/crates/red_knot_workspace/src/project/files.rs
similarity index 88%
rename from crates/red_knot_workspace/src/workspace/files.rs
rename to crates/red_knot_workspace/src/project/files.rs
index e434fb7f72..01ab9ad2de 100644
--- a/crates/red_knot_workspace/src/workspace/files.rs
+++ b/crates/red_knot_workspace/src/project/files.rs
@@ -8,12 +8,12 @@ use salsa::Setter;
 use ruff_db::files::File;
 
 use crate::db::Db;
-use crate::workspace::Package;
+use crate::project::Project;
 
 /// Cheap cloneable hash set of files.
 type FileSet = Arc<FxHashSet<File>>;
 
-/// The indexed files of a package.
+/// The indexed files of a project.
 ///
 /// The indexing happens lazily, but the files are then cached for subsequent reads.
 ///
@@ -24,11 +24,11 @@ type FileSet = Arc<FxHashSet<File>>;
 /// the indexed files must go through `IndexedMut`, which uses the Salsa setter `package.set_file_set` to
 /// ensure that Salsa always knows when the set of indexed files have changed.
 #[derive(Debug)]
-pub struct PackageFiles {
+pub struct IndexedFiles {
     state: std::sync::Mutex<State>,
 }
 
-impl PackageFiles {
+impl IndexedFiles {
     pub fn lazy() -> Self {
         Self {
             state: std::sync::Mutex::new(State::Lazy),
@@ -60,7 +60,7 @@ impl PackageFiles {
     /// Returns a mutable view on the index that allows cheap in-place mutations.
     ///
     /// The changes are automatically written back to the database once the view is dropped.
-    pub(super) fn indexed_mut(db: &mut dyn Db, package: Package) -> Option<IndexedMut> {
+    pub(super) fn indexed_mut(db: &mut dyn Db, project: Project) -> Option<IndexedMut> {
         // Calling `zalsa_mut` cancels all pending salsa queries. This ensures that there are no pending
         // reads to the file set.
         // TODO: Use a non-internal API instead https://salsa.zulipchat.com/#narrow/stream/333573-salsa-3.2E0/topic/Expose.20an.20API.20to.20cancel.20other.20queries
@@ -79,7 +79,7 @@ impl PackageFiles {
         //   all clones must have been dropped at this point and the `Indexed`
         //   can't outlive the database (constrained by the `db` lifetime).
         let state = {
-            let files = package.file_set(db);
+            let files = project.file_set(db);
             let mut locked = files.state.lock().unwrap();
             std::mem::replace(&mut *locked, State::Lazy)
         };
@@ -93,14 +93,14 @@ impl PackageFiles {
 
         Some(IndexedMut {
             db: Some(db),
-            package,
+            project,
             files: indexed,
             did_change: false,
         })
     }
 }
 
-impl Default for PackageFiles {
+impl Default for IndexedFiles {
     fn default() -> Self {
         Self::lazy()
     }
@@ -142,7 +142,7 @@ impl<'db> LazyFiles<'db> {
 /// The indexed files of a package.
 ///
 /// Note: This type is intentionally non-cloneable. Making it cloneable requires
-/// revisiting the locking behavior in [`PackageFiles::indexed_mut`].
+/// revisiting the locking behavior in [`IndexedFiles::indexed_mut`].
 #[derive(Debug, PartialEq, Eq)]
 pub struct Indexed<'db> {
     files: FileSet,
@@ -169,13 +169,13 @@ impl<'a> IntoIterator for &'a Indexed<'_> {
     }
 }
 
-/// A Mutable view of a package's indexed files.
+/// A Mutable view of a project's indexed files.
 ///
 /// Allows in-place mutation of the files without deep cloning the hash set.
 /// The changes are written back when the mutable view is dropped or by calling [`Self::set`] manually.
 pub(super) struct IndexedMut<'db> {
     db: Option<&'db mut dyn Db>,
-    package: Package,
+    project: Project,
     files: FileSet,
     did_change: bool,
 }
@@ -212,12 +212,12 @@ impl IndexedMut<'_> {
 
         if self.did_change {
             // If there are changes, set the new file_set to trigger a salsa revision change.
-            self.package
+            self.project
                 .set_file_set(db)
-                .to(PackageFiles::indexed(files));
+                .to(IndexedFiles::indexed(files));
         } else {
             // The `indexed_mut` replaced the `state` with Lazy. Restore it back to the indexed state.
-            *self.package.file_set(db).state.lock().unwrap() = State::Indexed(files);
+            *self.project.file_set(db).state.lock().unwrap() = State::Indexed(files);
         }
     }
 }
@@ -234,30 +234,24 @@ mod tests {
 
     use crate::db::tests::TestDb;
     use crate::db::Db;
-    use crate::workspace::files::Index;
-    use crate::workspace::WorkspaceMetadata;
+    use crate::project::files::Index;
+    use crate::project::ProjectMetadata;
     use ruff_db::files::system_path_to_file;
     use ruff_db::system::{DbWithTestSystem, SystemPathBuf};
     use ruff_python_ast::name::Name;
 
     #[test]
     fn re_entrance() -> anyhow::Result<()> {
-        let metadata = WorkspaceMetadata::single_package(
-            Name::new_static("test"),
-            SystemPathBuf::from("/test"),
-        );
+        let metadata = ProjectMetadata::new(Name::new_static("test"), SystemPathBuf::from("/test"));
         let mut db = TestDb::new(metadata);
 
         db.write_file("test.py", "")?;
 
-        let package = db
-            .workspace()
-            .package(&db, "/test")
-            .expect("test package to exist");
+        let project = db.project();
 
         let file = system_path_to_file(&db, "test.py").unwrap();
 
-        let files = match package.file_set(&db).get() {
+        let files = match project.file_set(&db).get() {
             Index::Lazy(lazy) => lazy.set(FxHashSet::from_iter([file])),
             Index::Indexed(files) => files,
         };
@@ -265,7 +259,7 @@ mod tests {
         // Calling files a second time should not dead-lock.
         // This can e.g. happen when `check_file` iterates over all files and
         // `is_file_open` queries the open files.
-        let files_2 = package.file_set(&db).get();
+        let files_2 = project.file_set(&db).get();
 
         match files_2 {
             Index::Lazy(_) => {
diff --git a/crates/red_knot_workspace/src/project/metadata.rs b/crates/red_knot_workspace/src/project/metadata.rs
new file mode 100644
index 0000000000..c4fa860bd2
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/metadata.rs
@@ -0,0 +1,418 @@
+use ruff_db::system::{System, SystemPath, SystemPathBuf};
+use ruff_python_ast::name::Name;
+
+use crate::project::pyproject::{PyProject, PyProjectError};
+use crate::project::settings::Configuration;
+use red_knot_python_semantic::ProgramSettings;
+use thiserror::Error;
+
+#[derive(Debug, PartialEq, Eq)]
+#[cfg_attr(test, derive(serde::Serialize))]
+pub struct ProjectMetadata {
+    pub(super) name: Name,
+
+    pub(super) root: SystemPathBuf,
+
+    /// The resolved settings for this project.
+    pub(super) configuration: Configuration,
+}
+
+impl ProjectMetadata {
+    /// Creates a project with the given name and root that uses the default configuration options.
+    pub fn new(name: Name, root: SystemPathBuf) -> Self {
+        Self {
+            name,
+            root,
+            configuration: Configuration::default(),
+        }
+    }
+
+    /// Loads a project from a `pyproject.toml` file.
+    pub(crate) fn from_pyproject(
+        pyproject: PyProject,
+        root: SystemPathBuf,
+        base_configuration: Option<&Configuration>,
+    ) -> Self {
+        let name = pyproject.project.and_then(|project| project.name);
+        let name = name
+            .map(|name| Name::new(&*name))
+            .unwrap_or_else(|| Name::new(root.file_name().unwrap_or("root")));
+
+        // TODO: load configuration from pyrpoject.toml
+        let mut configuration = Configuration::default();
+
+        if let Some(base_configuration) = base_configuration {
+            configuration.extend(base_configuration.clone());
+        }
+
+        Self {
+            name,
+            root,
+            configuration,
+        }
+    }
+
+    /// Discovers the closest project at `path` and returns its metadata.
+    ///
+    /// The algorithm traverses upwards in the `path`'s ancestor chain and uses the following precedence
+    /// the resolve the project's root.
+    ///
+    /// 1. The closest `pyproject.toml` with a `tool.knot` section.
+    /// 1. The closest `pyproject.toml`.
+    /// 1. Fallback to use `path` as the root and use the default settings.
+    pub fn discover(
+        path: &SystemPath,
+        system: &dyn System,
+        base_configuration: Option<&Configuration>,
+    ) -> Result<ProjectMetadata, ProjectDiscoveryError> {
+        tracing::debug!("Searching for a project in '{path}'");
+
+        if !system.is_directory(path) {
+            return Err(ProjectDiscoveryError::NotADirectory(path.to_path_buf()));
+        }
+
+        let mut closest_project: Option<ProjectMetadata> = None;
+
+        for ancestor in path.ancestors() {
+            let pyproject_path = ancestor.join("pyproject.toml");
+            if let Ok(pyproject_str) = system.read_to_string(&pyproject_path) {
+                let pyproject = PyProject::from_str(&pyproject_str).map_err(|error| {
+                    ProjectDiscoveryError::InvalidPyProject {
+                        path: pyproject_path,
+                        source: Box::new(error),
+                    }
+                })?;
+
+                let has_knot_section = pyproject.knot().is_some();
+                let metadata = ProjectMetadata::from_pyproject(
+                    pyproject,
+                    ancestor.to_path_buf(),
+                    base_configuration,
+                );
+
+                if has_knot_section {
+                    let project_root = ancestor;
+                    tracing::debug!("Found project at '{}'", project_root);
+
+                    return Ok(metadata);
+                }
+
+                // Not a project itself, keep looking for an enclosing project.
+                if closest_project.is_none() {
+                    closest_project = Some(metadata);
+                }
+            }
+        }
+
+        // No project found, but maybe a pyproject.toml was found.
+        let metadata = if let Some(closest_project) = closest_project {
+            tracing::debug!(
+                "Project without `tool.knot` section: '{}'",
+                closest_project.root()
+            );
+
+            closest_project
+        } else {
+            tracing::debug!("The ancestor directories contain no `pyproject.toml`. Falling back to a virtual project.");
+
+            // Create a package with a default configuration
+            Self {
+                name: path.file_name().unwrap_or("root").into(),
+                root: path.to_path_buf(),
+                // TODO create the configuration from the pyproject toml
+                configuration: base_configuration.cloned().unwrap_or_default(),
+            }
+        };
+
+        Ok(metadata)
+    }
+
+    pub fn root(&self) -> &SystemPath {
+        &self.root
+    }
+
+    pub fn name(&self) -> &str {
+        &self.name
+    }
+
+    pub fn configuration(&self) -> &Configuration {
+        &self.configuration
+    }
+
+    pub fn to_program_settings(&self) -> ProgramSettings {
+        self.configuration.to_program_settings(self.root())
+    }
+}
+
+#[derive(Debug, Error)]
+pub enum ProjectDiscoveryError {
+    #[error("project path '{0}' is not a directory")]
+    NotADirectory(SystemPathBuf),
+
+    #[error("{path} is not a valid `pyproject.toml`: {source}")]
+    InvalidPyProject {
+        source: Box<PyProjectError>,
+        path: SystemPathBuf,
+    },
+}
+
+#[cfg(test)]
+mod tests {
+    //! Integration tests for project discovery
+
+    use crate::snapshot_project;
+    use anyhow::{anyhow, Context};
+    use insta::assert_ron_snapshot;
+    use ruff_db::system::{SystemPathBuf, TestSystem};
+
+    use crate::project::{ProjectDiscoveryError, ProjectMetadata};
+
+    #[test]
+    fn project_without_pyproject() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([(root.join("foo.py"), ""), (root.join("bar.py"), "")])
+            .context("Failed to write files")?;
+
+        let project = ProjectMetadata::discover(&root, &system, None)
+            .context("Failed to discover project")?;
+
+        assert_eq!(project.root(), &*root);
+
+        snapshot_project!(project);
+
+        Ok(())
+    }
+
+    #[test]
+    fn project_with_pyproject() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "backend"
+
+                    "#,
+                ),
+                (root.join("db/__init__.py"), ""),
+            ])
+            .context("Failed to write files")?;
+
+        let project = ProjectMetadata::discover(&root, &system, None)
+            .context("Failed to discover project")?;
+
+        assert_eq!(project.root(), &*root);
+        snapshot_project!(project);
+
+        // Discovering the same package from a subdirectory should give the same result
+        let from_src = ProjectMetadata::discover(&root.join("db"), &system, None)
+            .context("Failed to discover project from src sub-directory")?;
+
+        assert_eq!(from_src, project);
+
+        Ok(())
+    }
+
+    #[test]
+    fn project_with_invalid_pyproject() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "backend"
+
+                    [tool.knot
+                    "#,
+                ),
+                (root.join("db/__init__.py"), ""),
+            ])
+            .context("Failed to write files")?;
+
+        let Err(error) = ProjectMetadata::discover(&root, &system, None) else {
+            return Err(anyhow!("Expected project discovery to fail because of invalid syntax in the pyproject.toml"));
+        };
+
+        assert_error_eq(
+            &error,
+            r#"/app/pyproject.toml is not a valid `pyproject.toml`: TOML parse error at line 5, column 31
+  |
+5 |                     [tool.knot
+  |                               ^
+invalid table header
+expected `.`, `]`
+"#,
+        );
+
+        Ok(())
+    }
+
+    #[test]
+    fn nested_projects_in_sub_project() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "project-root"
+
+                    [tool.knot]
+                    "#,
+                ),
+                (
+                    root.join("packages/a/pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "nested-project"
+
+                    [tool.knot]
+                    "#,
+                ),
+            ])
+            .context("Failed to write files")?;
+
+        let sub_project = ProjectMetadata::discover(&root.join("packages/a"), &system, None)?;
+
+        snapshot_project!(sub_project);
+
+        Ok(())
+    }
+
+    #[test]
+    fn nested_projects_in_root_project() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "project-root"
+
+                    [tool.knot]
+                    "#,
+                ),
+                (
+                    root.join("packages/a/pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "nested-project"
+
+                    [tool.knot]
+                    "#,
+                ),
+            ])
+            .context("Failed to write files")?;
+
+        let root = ProjectMetadata::discover(&root, &system, None)?;
+
+        snapshot_project!(root);
+
+        Ok(())
+    }
+
+    #[test]
+    fn nested_projects_without_knot_sections() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "project-root"
+                    "#,
+                ),
+                (
+                    root.join("packages/a/pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "nested-project"
+                    "#,
+                ),
+            ])
+            .context("Failed to write files")?;
+
+        let sub_project = ProjectMetadata::discover(&root.join("packages/a"), &system, None)?;
+
+        snapshot_project!(sub_project);
+
+        Ok(())
+    }
+
+    #[test]
+    fn nested_projects_with_outer_knot_section() -> anyhow::Result<()> {
+        let system = TestSystem::default();
+        let root = SystemPathBuf::from("/app");
+
+        system
+            .memory_file_system()
+            .write_files([
+                (
+                    root.join("pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "project-root"
+
+                    [tool.knot]
+                    "#,
+                ),
+                (
+                    root.join("packages/a/pyproject.toml"),
+                    r#"
+                    [project]
+                    name = "nested-project"
+                    "#,
+                ),
+            ])
+            .context("Failed to write files")?;
+
+        let root = ProjectMetadata::discover(&root.join("packages/a"), &system, None)?;
+
+        snapshot_project!(root);
+
+        Ok(())
+    }
+
+    #[track_caller]
+    fn assert_error_eq(error: &ProjectDiscoveryError, message: &str) {
+        assert_eq!(error.to_string().replace('\\', "/"), message);
+    }
+
+    /// Snapshots a project but with all paths using unix separators.
+    #[macro_export]
+    macro_rules! snapshot_project {
+    ($project:expr) => {{
+        assert_ron_snapshot!($project,{
+            ".root" => insta::dynamic_redaction(|content, _content_path| {
+                content.as_str().unwrap().replace("\\", "/")
+            }),
+        });
+    }};
+}
+}
diff --git a/crates/red_knot_workspace/src/workspace/pyproject.rs b/crates/red_knot_workspace/src/project/pyproject.rs
similarity index 52%
rename from crates/red_knot_workspace/src/workspace/pyproject.rs
rename to crates/red_knot_workspace/src/project/pyproject.rs
index 9f74774863..8cae133094 100644
--- a/crates/red_knot_workspace/src/workspace/pyproject.rs
+++ b/crates/red_knot_workspace/src/project/pyproject.rs
@@ -4,9 +4,7 @@ use pep440_rs::{Version, VersionSpecifiers};
 use serde::Deserialize;
 use thiserror::Error;
 
-use crate::workspace::metadata::WorkspaceDiscoveryError;
 pub(crate) use package_name::PackageName;
-use ruff_db::system::SystemPath;
 
 /// A `pyproject.toml` as specified in PEP 517.
 #[derive(Deserialize, Debug, Default, Clone)]
@@ -19,11 +17,8 @@ pub(crate) struct PyProject {
 }
 
 impl PyProject {
-    pub(crate) fn workspace(&self) -> Option<&Workspace> {
-        self.tool
-            .as_ref()
-            .and_then(|tool| tool.knot.as_ref())
-            .and_then(|knot| knot.workspace.as_ref())
+    pub(crate) fn knot(&self) -> Option<&Knot> {
+        self.tool.as_ref().and_then(|tool| tool.knot.as_ref())
     }
 }
 
@@ -62,47 +57,9 @@ pub(crate) struct Tool {
     pub knot: Option<Knot>,
 }
 
+// TODO(micha): Remove allow once we add knot settings.
+//  We can't use a unit struct here or deserializing `[tool.knot]` fails.
+#[allow(clippy::empty_structs_with_brackets)]
 #[derive(Deserialize, Debug, Clone, PartialEq, Eq)]
 #[serde(rename_all = "kebab-case", deny_unknown_fields)]
-pub(crate) struct Knot {
-    pub(crate) workspace: Option<Workspace>,
-}
-
-#[derive(Deserialize, Debug, Clone, PartialEq, Eq)]
-#[serde(rename_all = "kebab-case", deny_unknown_fields)]
-pub(crate) struct Workspace {
-    pub(crate) members: Option<Vec<String>>,
-    pub(crate) exclude: Option<Vec<String>>,
-}
-
-impl Workspace {
-    pub(crate) fn members(&self) -> &[String] {
-        self.members.as_deref().unwrap_or_default()
-    }
-
-    pub(crate) fn exclude(&self) -> &[String] {
-        self.exclude.as_deref().unwrap_or_default()
-    }
-
-    pub(crate) fn is_excluded(
-        &self,
-        path: &SystemPath,
-        workspace_root: &SystemPath,
-    ) -> Result<bool, WorkspaceDiscoveryError> {
-        for exclude in self.exclude() {
-            let full_glob =
-                glob::Pattern::new(workspace_root.join(exclude).as_str()).map_err(|error| {
-                    WorkspaceDiscoveryError::InvalidMembersPattern {
-                        raw_glob: exclude.clone(),
-                        source: error,
-                    }
-                })?;
-
-            if full_glob.matches_path(path.as_std_path()) {
-                return Ok(true);
-            }
-        }
-
-        Ok(false)
-    }
-}
+pub(crate) struct Knot {}
diff --git a/crates/red_knot_workspace/src/workspace/pyproject/package_name.rs b/crates/red_knot_workspace/src/project/pyproject/package_name.rs
similarity index 100%
rename from crates/red_knot_workspace/src/workspace/pyproject/package_name.rs
rename to crates/red_knot_workspace/src/project/pyproject/package_name.rs
diff --git a/crates/red_knot_workspace/src/workspace/settings.rs b/crates/red_knot_workspace/src/project/settings.rs
similarity index 82%
rename from crates/red_knot_workspace/src/workspace/settings.rs
rename to crates/red_knot_workspace/src/project/settings.rs
index c924e9ec9b..c5dea766b2 100644
--- a/crates/red_knot_workspace/src/workspace/settings.rs
+++ b/crates/red_knot_workspace/src/project/settings.rs
@@ -1,4 +1,3 @@
-use crate::workspace::PackageMetadata;
 use red_knot_python_semantic::{
     ProgramSettings, PythonPlatform, PythonVersion, SearchPathSettings, SitePackages,
 };
@@ -9,17 +8,17 @@ use ruff_db::system::{SystemPath, SystemPathBuf};
 /// The main difference to [`Configuration`] is that default values are filled in.
 #[derive(Debug, Clone, PartialEq, Eq)]
 #[cfg_attr(test, derive(serde::Serialize))]
-pub struct WorkspaceSettings {
+pub struct ProjectSettings {
     pub(super) program: ProgramSettings,
 }
 
-impl WorkspaceSettings {
+impl ProjectSettings {
     pub fn program(&self) -> &ProgramSettings {
         &self.program
     }
 }
 
-/// The configuration for the workspace or a package.
+/// The configuration for the project or a package.
 #[derive(Debug, Default, Clone, PartialEq, Eq)]
 #[cfg_attr(test, derive(serde::Serialize))]
 pub struct Configuration {
@@ -34,17 +33,11 @@ impl Configuration {
         self.search_paths.extend(with.search_paths);
     }
 
-    pub fn to_workspace_settings(
-        &self,
-        workspace_root: &SystemPath,
-        _packages: &[PackageMetadata],
-    ) -> WorkspaceSettings {
-        WorkspaceSettings {
-            program: ProgramSettings {
-                python_version: self.python_version.unwrap_or_default(),
-                python_platform: PythonPlatform::default(),
-                search_paths: self.search_paths.to_settings(workspace_root),
-            },
+    pub(super) fn to_program_settings(&self, first_party_root: &SystemPath) -> ProgramSettings {
+        ProgramSettings {
+            python_version: self.python_version.unwrap_or_default(),
+            python_platform: PythonPlatform::default(),
+            search_paths: self.search_paths.to_settings(first_party_root),
         }
     }
 }
@@ -57,7 +50,7 @@ pub struct SearchPathConfiguration {
     /// or pyright's stubPath configuration setting.
     pub extra_paths: Option<Vec<SystemPathBuf>>,
 
-    /// The root of the workspace, used for finding first-party modules.
+    /// The root of the project, used for finding first-party modules.
     pub src_root: Option<SystemPathBuf>,
 
     /// Optional path to a "typeshed" directory on disk for us to use for standard-library types.
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_root_project.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_root_project.snap
new file mode 100644
index 0000000000..1d2577dd70
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_root_project.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: root
+---
+ProjectMetadata(
+  name: Name("project-root"),
+  root: "/app",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_sub_project.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_sub_project.snap
new file mode 100644
index 0000000000..65e51376cb
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_in_sub_project.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: sub_project
+---
+ProjectMetadata(
+  name: Name("nested-project"),
+  root: "/app/packages/a",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_with_outer_knot_section.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_with_outer_knot_section.snap
new file mode 100644
index 0000000000..1d2577dd70
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_with_outer_knot_section.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: root
+---
+ProjectMetadata(
+  name: Name("project-root"),
+  root: "/app",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_without_knot_sections.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_without_knot_sections.snap
new file mode 100644
index 0000000000..65e51376cb
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__nested_projects_without_knot_sections.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: sub_project
+---
+ProjectMetadata(
+  name: Name("nested-project"),
+  root: "/app/packages/a",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_with_pyproject.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_with_pyproject.snap
new file mode 100644
index 0000000000..00ce8e31eb
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_with_pyproject.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: project
+---
+ProjectMetadata(
+  name: Name("backend"),
+  root: "/app",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_without_pyproject.snap b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_without_pyproject.snap
new file mode 100644
index 0000000000..69b4594491
--- /dev/null
+++ b/crates/red_knot_workspace/src/project/snapshots/red_knot_workspace__project__metadata__tests__project_without_pyproject.snap
@@ -0,0 +1,17 @@
+---
+source: crates/red_knot_workspace/src/project/metadata.rs
+expression: project
+---
+ProjectMetadata(
+  name: Name("app"),
+  root: "/app",
+  configuration: Configuration(
+    python_version: None,
+    search_paths: SearchPathConfiguration(
+      extra_paths: None,
+      src_root: None,
+      typeshed: None,
+      site_packages: None,
+    ),
+  ),
+)
diff --git a/crates/red_knot_workspace/src/watch.rs b/crates/red_knot_workspace/src/watch.rs
index 65e0149165..fe5db5a1ed 100644
--- a/crates/red_knot_workspace/src/watch.rs
+++ b/crates/red_knot_workspace/src/watch.rs
@@ -1,9 +1,9 @@
+pub use project_watcher::ProjectWatcher;
 use ruff_db::system::{SystemPath, SystemPathBuf, SystemVirtualPathBuf};
 pub use watcher::{directory_watcher, EventHandler, Watcher};
-pub use workspace_watcher::WorkspaceWatcher;
 
+mod project_watcher;
 mod watcher;
-mod workspace_watcher;
 
 /// Classification of a file system change event.
 ///
diff --git a/crates/red_knot_workspace/src/watch/workspace_watcher.rs b/crates/red_knot_workspace/src/watch/project_watcher.rs
similarity index 79%
rename from crates/red_knot_workspace/src/watch/workspace_watcher.rs
rename to crates/red_knot_workspace/src/watch/project_watcher.rs
index a76f09e585..25b4f6f08d 100644
--- a/crates/red_knot_workspace/src/watch/workspace_watcher.rs
+++ b/crates/red_knot_workspace/src/watch/project_watcher.rs
@@ -8,11 +8,11 @@ use ruff_cache::{CacheKey, CacheKeyHasher};
 use ruff_db::system::{SystemPath, SystemPathBuf};
 use ruff_db::{Db as _, Upcast};
 
-use crate::db::{Db, RootDatabase};
+use crate::db::{Db, ProjectDatabase};
 use crate::watch::Watcher;
 
-/// Wrapper around a [`Watcher`] that watches the relevant paths of a workspace.
-pub struct WorkspaceWatcher {
+/// Wrapper around a [`Watcher`] that watches the relevant paths of a project.
+pub struct ProjectWatcher {
     watcher: Watcher,
 
     /// The paths that need to be watched. This includes paths for which setting up file watching failed.
@@ -25,9 +25,9 @@ pub struct WorkspaceWatcher {
     cache_key: Option<u64>,
 }
 
-impl WorkspaceWatcher {
-    /// Create a new workspace watcher.
-    pub fn new(watcher: Watcher, db: &RootDatabase) -> Self {
+impl ProjectWatcher {
+    /// Create a new project watcher.
+    pub fn new(watcher: Watcher, db: &ProjectDatabase) -> Self {
         let mut watcher = Self {
             watcher,
             watched_paths: Vec::new(),
@@ -40,11 +40,11 @@ impl WorkspaceWatcher {
         watcher
     }
 
-    pub fn update(&mut self, db: &RootDatabase) {
+    pub fn update(&mut self, db: &ProjectDatabase) {
         let search_paths: Vec<_> = system_module_search_paths(db.upcast()).collect();
-        let workspace_path = db.workspace().root(db).to_path_buf();
+        let project_path = db.project().root(db).to_path_buf();
 
-        let new_cache_key = Self::compute_cache_key(&workspace_path, &search_paths);
+        let new_cache_key = Self::compute_cache_key(&project_path, &search_paths);
 
         if self.cache_key == Some(new_cache_key) {
             return;
@@ -56,7 +56,7 @@ impl WorkspaceWatcher {
         // ```text
         // - bar
         //   - baz.py
-        // - workspace
+        // - project
         //   - bar -> /bar
         //   - foo.py
         // ```
@@ -68,23 +68,23 @@ impl WorkspaceWatcher {
 
         self.has_errored_paths = false;
 
-        let workspace_path = db
+        let project_path = db
             .system()
-            .canonicalize_path(&workspace_path)
-            .unwrap_or(workspace_path);
+            .canonicalize_path(&project_path)
+            .unwrap_or(project_path);
 
-        // Find the non-overlapping module search paths and filter out paths that are already covered by the workspace.
+        // Find the non-overlapping module search paths and filter out paths that are already covered by the project.
         // Module search paths are already canonicalized.
         let unique_module_paths = ruff_db::system::deduplicate_nested_paths(
             search_paths
                 .into_iter()
-                .filter(|path| !path.starts_with(&workspace_path)),
+                .filter(|path| !path.starts_with(&project_path)),
         )
         .map(SystemPath::to_path_buf);
 
-        // Now add the new paths, first starting with the workspace path and then
+        // Now add the new paths, first starting with the project path and then
         // adding the library search paths.
-        for path in std::iter::once(workspace_path).chain(unique_module_paths) {
+        for path in std::iter::once(project_path).chain(unique_module_paths) {
             // Log a warning. It's not worth aborting if registering a single folder fails because
             // Ruff otherwise stills works as expected.
             if let Err(error) = self.watcher.watch(&path) {
@@ -106,10 +106,10 @@ impl WorkspaceWatcher {
         self.cache_key = Some(new_cache_key);
     }
 
-    fn compute_cache_key(workspace_root: &SystemPath, search_paths: &[&SystemPath]) -> u64 {
+    fn compute_cache_key(project_root: &SystemPath, search_paths: &[&SystemPath]) -> u64 {
         let mut cache_key_hasher = CacheKeyHasher::new();
         search_paths.cache_key(&mut cache_key_hasher);
-        workspace_root.cache_key(&mut cache_key_hasher);
+        project_root.cache_key(&mut cache_key_hasher);
 
         cache_key_hasher.finish()
     }
diff --git a/crates/red_knot_workspace/src/workspace.rs b/crates/red_knot_workspace/src/workspace.rs
deleted file mode 100644
index 671a2a85ef..0000000000
--- a/crates/red_knot_workspace/src/workspace.rs
+++ /dev/null
@@ -1,665 +0,0 @@
-#![allow(clippy::ref_option)]
-
-use crate::db::Db;
-use crate::db::RootDatabase;
-use crate::workspace::files::{Index, Indexed, IndexedIter, PackageFiles};
-pub use metadata::{PackageMetadata, WorkspaceDiscoveryError, WorkspaceMetadata};
-use red_knot_python_semantic::types::check_types;
-use red_knot_python_semantic::SearchPathSettings;
-use ruff_db::diagnostic::{Diagnostic, DiagnosticId, ParseDiagnostic, Severity};
-use ruff_db::parsed::parsed_module;
-use ruff_db::source::{source_text, SourceTextError};
-use ruff_db::system::FileType;
-use ruff_db::{
-    files::{system_path_to_file, File},
-    system::{walk_directory::WalkState, SystemPath, SystemPathBuf},
-};
-use ruff_python_ast::{name::Name, PySourceType};
-use ruff_text_size::TextRange;
-use rustc_hash::{FxBuildHasher, FxHashSet};
-use salsa::{Durability, Setter as _};
-use std::borrow::Cow;
-use std::iter::FusedIterator;
-use std::{collections::BTreeMap, sync::Arc};
-
-mod files;
-mod metadata;
-mod pyproject;
-pub mod settings;
-
-/// The project workspace as a Salsa ingredient.
-///
-/// A workspace consists of one or multiple packages. Packages can be nested. A file in a workspace
-/// belongs to no or exactly one package (files can't belong to multiple packages).
-///
-/// How workspaces and packages are discovered is TBD. For now, a workspace can be any directory,
-/// and it always contains a single package which has the same root as the workspace.
-///
-/// ## Examples
-///
-/// ```text
-/// app-1/
-///     pyproject.toml
-///     src/
-///         ... python files
-///
-/// app-2/
-///     pyproject.toml
-///     src/
-///         ... python files
-///
-/// shared/
-///     pyproject.toml
-///     src/
-///         ... python files
-///
-/// pyproject.toml
-/// ```
-///
-/// The above project structure has three packages: `app-1`, `app-2`, and `shared`.
-/// Each of the packages can define their own settings in their `pyproject.toml` file, but
-/// they must be compatible. For example, each package can define a different `requires-python` range,
-/// but the ranges must overlap.
-///
-/// ## How is a workspace different from a program?
-/// There are two (related) motivations:
-///
-/// 1. Program is defined in `ruff_db` and it can't reference the settings types for the linter and formatter
-///    without introducing a cyclic dependency. The workspace is defined in a higher level crate
-///    where it can reference these setting types.
-/// 2. Running `ruff check` with different target versions results in different programs (settings) but
-///    it remains the same workspace. That's why program is a narrowed view of the workspace only
-///    holding on to the most fundamental settings required for checking.
-#[salsa::input]
-pub struct Workspace {
-    #[return_ref]
-    root_buf: SystemPathBuf,
-
-    /// The files that are open in the workspace.
-    ///
-    /// Setting the open files to a non-`None` value changes `check` to only check the
-    /// open files rather than all files in the workspace.
-    #[return_ref]
-    #[default]
-    open_fileset: Option<Arc<FxHashSet<File>>>,
-
-    /// The (first-party) packages in this workspace.
-    #[return_ref]
-    package_tree: PackageTree,
-
-    /// The unresolved search path configuration.
-    #[return_ref]
-    pub search_path_settings: SearchPathSettings,
-}
-
-/// A first-party package in a workspace.
-#[salsa::input]
-pub struct Package {
-    #[return_ref]
-    pub name: Name,
-
-    /// The path to the root directory of the package.
-    #[return_ref]
-    root_buf: SystemPathBuf,
-
-    /// The files that are part of this package.
-    #[default]
-    #[return_ref]
-    file_set: PackageFiles,
-    // TODO: Add the loaded settings.
-}
-
-impl Workspace {
-    pub fn from_metadata(db: &dyn Db, metadata: WorkspaceMetadata) -> Self {
-        let mut packages = BTreeMap::new();
-
-        for package in metadata.packages {
-            packages.insert(package.root.clone(), Package::from_metadata(db, package));
-        }
-
-        let program_settings = metadata.settings.program;
-
-        Workspace::builder(
-            metadata.root,
-            PackageTree(packages),
-            program_settings.search_paths,
-        )
-        .durability(Durability::MEDIUM)
-        .open_fileset_durability(Durability::LOW)
-        .new(db)
-    }
-
-    pub fn root(self, db: &dyn Db) -> &SystemPath {
-        self.root_buf(db)
-    }
-
-    pub fn reload(self, db: &mut dyn Db, metadata: WorkspaceMetadata) {
-        tracing::debug!("Reloading workspace");
-        assert_eq!(self.root(db), metadata.root());
-
-        let mut old_packages = self.package_tree(db).0.clone();
-        let mut new_packages = BTreeMap::new();
-
-        for package_metadata in metadata.packages {
-            let path = package_metadata.root().to_path_buf();
-
-            let package = if let Some(old_package) = old_packages.remove(&path) {
-                old_package.update(db, package_metadata);
-                old_package
-            } else {
-                Package::from_metadata(db, package_metadata)
-            };
-
-            new_packages.insert(path, package);
-        }
-
-        if &metadata.settings.program.search_paths != self.search_path_settings(db) {
-            self.set_search_path_settings(db)
-                .to(metadata.settings.program.search_paths);
-        }
-
-        self.set_package_tree(db).to(PackageTree(new_packages));
-    }
-
-    pub fn update_package(self, db: &mut dyn Db, metadata: PackageMetadata) -> anyhow::Result<()> {
-        let path = metadata.root().to_path_buf();
-
-        if let Some(package) = self.package_tree(db).get(&path) {
-            package.update(db, metadata);
-            Ok(())
-        } else {
-            Err(anyhow::anyhow!("Package {path} not found"))
-        }
-    }
-
-    pub fn packages(self, db: &dyn Db) -> &PackageTree {
-        self.package_tree(db)
-    }
-
-    /// Returns the closest package to which the first-party `path` belongs.
-    ///
-    /// Returns `None` if the `path` is outside of any package or if `file` isn't a first-party file
-    /// (e.g. third-party dependencies or `excluded`).
-    pub fn package(self, db: &dyn Db, path: impl AsRef<SystemPath>) -> Option<Package> {
-        let packages = self.package_tree(db);
-        packages.get(path.as_ref())
-    }
-
-    /// Checks all open files in the workspace and its dependencies.
-    pub fn check(self, db: &RootDatabase) -> Vec<Box<dyn Diagnostic>> {
-        let workspace_span = tracing::debug_span!("check_workspace");
-        let _span = workspace_span.enter();
-
-        tracing::debug!("Checking workspace");
-        let files = WorkspaceFiles::new(db, self);
-        let result = Arc::new(std::sync::Mutex::new(Vec::new()));
-        let inner_result = Arc::clone(&result);
-
-        let db = db.clone();
-        let workspace_span = workspace_span.clone();
-
-        rayon::scope(move |scope| {
-            for file in &files {
-                let result = inner_result.clone();
-                let db = db.clone();
-                let workspace_span = workspace_span.clone();
-
-                scope.spawn(move |_| {
-                    let check_file_span = tracing::debug_span!(parent: &workspace_span, "check_file", file=%file.path(&db));
-                    let _entered = check_file_span.entered();
-
-                    let file_diagnostics = check_file(&db, file);
-                    result.lock().unwrap().extend(file_diagnostics);
-                });
-            }
-        });
-
-        Arc::into_inner(result).unwrap().into_inner().unwrap()
-    }
-
-    /// Opens a file in the workspace.
-    ///
-    /// This changes the behavior of `check` to only check the open files rather than all files in the workspace.
-    pub fn open_file(self, db: &mut dyn Db, file: File) {
-        tracing::debug!("Opening file `{}`", file.path(db));
-
-        let mut open_files = self.take_open_files(db);
-        open_files.insert(file);
-        self.set_open_files(db, open_files);
-    }
-
-    /// Closes a file in the workspace.
-    pub fn close_file(self, db: &mut dyn Db, file: File) -> bool {
-        tracing::debug!("Closing file `{}`", file.path(db));
-
-        let mut open_files = self.take_open_files(db);
-        let removed = open_files.remove(&file);
-
-        if removed {
-            self.set_open_files(db, open_files);
-        }
-
-        removed
-    }
-
-    /// Returns the open files in the workspace or `None` if the entire workspace should be checked.
-    pub fn open_files(self, db: &dyn Db) -> Option<&FxHashSet<File>> {
-        self.open_fileset(db).as_deref()
-    }
-
-    /// Sets the open files in the workspace.
-    ///
-    /// This changes the behavior of `check` to only check the open files rather than all files in the workspace.
-    #[tracing::instrument(level = "debug", skip(self, db))]
-    pub fn set_open_files(self, db: &mut dyn Db, open_files: FxHashSet<File>) {
-        tracing::debug!("Set open workspace files (count: {})", open_files.len());
-
-        self.set_open_fileset(db).to(Some(Arc::new(open_files)));
-    }
-
-    /// This takes the open files from the workspace and returns them.
-    ///
-    /// This changes the behavior of `check` to check all files in the workspace instead of just the open files.
-    pub fn take_open_files(self, db: &mut dyn Db) -> FxHashSet<File> {
-        tracing::debug!("Take open workspace files");
-
-        // Salsa will cancel any pending queries and remove its own reference to `open_files`
-        // so that the reference counter to `open_files` now drops to 1.
-        let open_files = self.set_open_fileset(db).to(None);
-
-        if let Some(open_files) = open_files {
-            Arc::try_unwrap(open_files).unwrap()
-        } else {
-            FxHashSet::default()
-        }
-    }
-
-    /// Returns `true` if the file is open in the workspace.
-    ///
-    /// A file is considered open when:
-    /// * explicitly set as an open file using [`open_file`](Self::open_file)
-    /// * It has a [`SystemPath`] and belongs to a package's `src` files
-    /// * It has a [`SystemVirtualPath`](ruff_db::system::SystemVirtualPath)
-    pub fn is_file_open(self, db: &dyn Db, file: File) -> bool {
-        if let Some(open_files) = self.open_files(db) {
-            open_files.contains(&file)
-        } else if let Some(system_path) = file.path(db).as_system_path() {
-            self.package(db, system_path)
-                .is_some_and(|package| package.contains_file(db, file))
-        } else {
-            file.path(db).is_system_virtual_path()
-        }
-    }
-}
-
-impl Package {
-    pub fn root(self, db: &dyn Db) -> &SystemPath {
-        self.root_buf(db)
-    }
-
-    /// Returns `true` if `file` is a first-party file part of this package.
-    pub fn contains_file(self, db: &dyn Db, file: File) -> bool {
-        self.files(db).contains(&file)
-    }
-
-    #[tracing::instrument(level = "debug", skip(db))]
-    pub fn remove_file(self, db: &mut dyn Db, file: File) {
-        tracing::debug!(
-            "Removing file `{}` from package `{}`",
-            file.path(db),
-            self.name(db)
-        );
-
-        let Some(mut index) = PackageFiles::indexed_mut(db, self) else {
-            return;
-        };
-
-        index.remove(file);
-    }
-
-    pub fn add_file(self, db: &mut dyn Db, file: File) {
-        tracing::debug!(
-            "Adding file `{}` to package `{}`",
-            file.path(db),
-            self.name(db)
-        );
-
-        let Some(mut index) = PackageFiles::indexed_mut(db, self) else {
-            return;
-        };
-
-        index.insert(file);
-    }
-
-    /// Returns the files belonging to this package.
-    pub fn files(self, db: &dyn Db) -> Indexed<'_> {
-        let files = self.file_set(db);
-
-        let indexed = match files.get() {
-            Index::Lazy(vacant) => {
-                let _entered =
-                    tracing::debug_span!("index_package_files", package = %self.name(db)).entered();
-
-                let files = discover_package_files(db, self);
-                tracing::info!("Found {} files in package `{}`", files.len(), self.name(db));
-                vacant.set(files)
-            }
-            Index::Indexed(indexed) => indexed,
-        };
-
-        indexed
-    }
-
-    fn from_metadata(db: &dyn Db, metadata: PackageMetadata) -> Self {
-        Self::builder(metadata.name, metadata.root)
-            .durability(Durability::MEDIUM)
-            .file_set_durability(Durability::LOW)
-            .new(db)
-    }
-
-    fn update(self, db: &mut dyn Db, metadata: PackageMetadata) {
-        let root = self.root(db);
-        assert_eq!(root, metadata.root());
-
-        if self.name(db) != metadata.name() {
-            self.set_name(db).to(metadata.name);
-        }
-    }
-
-    pub fn reload_files(self, db: &mut dyn Db) {
-        tracing::debug!("Reloading files for package `{}`", self.name(db));
-
-        if !self.file_set(db).is_lazy() {
-            // Force a re-index of the files in the next revision.
-            self.set_file_set(db).to(PackageFiles::lazy());
-        }
-    }
-}
-
-pub(super) fn check_file(db: &dyn Db, file: File) -> Vec<Box<dyn Diagnostic>> {
-    let mut diagnostics: Vec<Box<dyn Diagnostic>> = Vec::new();
-    // Abort checking if there are IO errors.
-    let source = source_text(db.upcast(), file);
-
-    if let Some(read_error) = source.read_error() {
-        diagnostics.push(Box::new(IOErrorDiagnostic {
-            file,
-            error: read_error.clone(),
-        }));
-        return diagnostics;
-    }
-
-    let parsed = parsed_module(db.upcast(), file);
-    diagnostics.extend(parsed.errors().iter().map(|error| {
-        let diagnostic: Box<dyn Diagnostic> = Box::new(ParseDiagnostic::new(file, error.clone()));
-        diagnostic
-    }));
-
-    diagnostics.extend(check_types(db.upcast(), file).iter().map(|diagnostic| {
-        let boxed: Box<dyn Diagnostic> = Box::new(diagnostic.clone());
-        boxed
-    }));
-
-    diagnostics.sort_unstable_by_key(|diagnostic| diagnostic.range().unwrap_or_default().start());
-
-    diagnostics
-}
-
-fn discover_package_files(db: &dyn Db, package: Package) -> FxHashSet<File> {
-    let paths = std::sync::Mutex::new(Vec::new());
-    let packages = db.workspace().packages(db);
-
-    db.system().walk_directory(package.root(db)).run(|| {
-        Box::new(|entry| {
-            match entry {
-                Ok(entry) => {
-                    // Skip over any non python files to avoid creating too many entries in `Files`.
-                    match entry.file_type() {
-                        FileType::File => {
-                            if entry
-                                .path()
-                                .extension()
-                                .and_then(PySourceType::try_from_extension)
-                                .is_some()
-                            {
-                                let mut paths = paths.lock().unwrap();
-                                paths.push(entry.into_path());
-                            }
-                        }
-                        FileType::Directory | FileType::Symlink => {
-                            // Don't traverse into nested packages (the workspace-package is an ancestor of all other packages)
-                            if packages.get(entry.path()) != Some(package) {
-                                return WalkState::Skip;
-                            }
-                        }
-                    }
-                }
-                Err(error) => {
-                    // TODO Handle error
-                    tracing::error!("Failed to walk path: {error}");
-                }
-            }
-
-            WalkState::Continue
-        })
-    });
-
-    let paths = paths.into_inner().unwrap();
-    let mut files = FxHashSet::with_capacity_and_hasher(paths.len(), FxBuildHasher);
-
-    for path in paths {
-        // If this returns `None`, then the file was deleted between the `walk_directory` call and now.
-        // We can ignore this.
-        if let Ok(file) = system_path_to_file(db.upcast(), &path) {
-            files.insert(file);
-        }
-    }
-
-    files
-}
-
-#[derive(Debug)]
-enum WorkspaceFiles<'a> {
-    OpenFiles(&'a FxHashSet<File>),
-    PackageFiles(Vec<Indexed<'a>>),
-}
-
-impl<'a> WorkspaceFiles<'a> {
-    fn new(db: &'a dyn Db, workspace: Workspace) -> Self {
-        if let Some(open_files) = workspace.open_files(db) {
-            WorkspaceFiles::OpenFiles(open_files)
-        } else {
-            WorkspaceFiles::PackageFiles(
-                workspace
-                    .packages(db)
-                    .iter()
-                    .map(|package| package.files(db))
-                    .collect(),
-            )
-        }
-    }
-}
-
-impl<'a> IntoIterator for &'a WorkspaceFiles<'a> {
-    type Item = File;
-    type IntoIter = WorkspaceFilesIter<'a>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        match self {
-            WorkspaceFiles::OpenFiles(files) => WorkspaceFilesIter::OpenFiles(files.iter()),
-            WorkspaceFiles::PackageFiles(package_files) => {
-                let mut package_files = package_files.iter();
-                WorkspaceFilesIter::PackageFiles {
-                    current: package_files.next().map(IntoIterator::into_iter),
-                    package_files,
-                }
-            }
-        }
-    }
-}
-
-enum WorkspaceFilesIter<'db> {
-    OpenFiles(std::collections::hash_set::Iter<'db, File>),
-    PackageFiles {
-        package_files: std::slice::Iter<'db, Indexed<'db>>,
-        current: Option<IndexedIter<'db>>,
-    },
-}
-
-impl Iterator for WorkspaceFilesIter<'_> {
-    type Item = File;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        match self {
-            WorkspaceFilesIter::OpenFiles(files) => files.next().copied(),
-            WorkspaceFilesIter::PackageFiles {
-                package_files,
-                current,
-            } => loop {
-                if let Some(file) = current.as_mut().and_then(Iterator::next) {
-                    return Some(file);
-                }
-
-                *current = Some(package_files.next()?.into_iter());
-            },
-        }
-    }
-}
-
-#[derive(Debug)]
-pub struct IOErrorDiagnostic {
-    file: File,
-    error: SourceTextError,
-}
-
-impl Diagnostic for IOErrorDiagnostic {
-    fn id(&self) -> DiagnosticId {
-        DiagnosticId::Io
-    }
-
-    fn message(&self) -> Cow<str> {
-        self.error.to_string().into()
-    }
-
-    fn file(&self) -> File {
-        self.file
-    }
-
-    fn range(&self) -> Option<TextRange> {
-        None
-    }
-
-    fn severity(&self) -> Severity {
-        Severity::Error
-    }
-}
-
-#[derive(Debug, Eq, PartialEq, Clone)]
-pub struct PackageTree(BTreeMap<SystemPathBuf, Package>);
-
-impl PackageTree {
-    pub fn get(&self, path: &SystemPath) -> Option<Package> {
-        let (package_path, package) = self.0.range(..=path.to_path_buf()).next_back()?;
-
-        if path.starts_with(package_path) {
-            Some(*package)
-        } else {
-            None
-        }
-    }
-
-    // The package table should never be empty, that's why `is_empty` makes little sense
-    #[allow(clippy::len_without_is_empty)]
-    pub fn len(&self) -> usize {
-        self.0.len()
-    }
-
-    pub fn iter(&self) -> PackageTreeIter {
-        PackageTreeIter(self.0.values())
-    }
-}
-
-impl<'a> IntoIterator for &'a PackageTree {
-    type Item = Package;
-    type IntoIter = PackageTreeIter<'a>;
-
-    fn into_iter(self) -> Self::IntoIter {
-        self.iter()
-    }
-}
-
-pub struct PackageTreeIter<'a>(std::collections::btree_map::Values<'a, SystemPathBuf, Package>);
-
-impl Iterator for PackageTreeIter<'_> {
-    type Item = Package;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        self.0.next().copied()
-    }
-
-    fn size_hint(&self) -> (usize, Option<usize>) {
-        self.0.size_hint()
-    }
-
-    fn last(mut self) -> Option<Self::Item> {
-        self.0.next_back().copied()
-    }
-}
-
-impl ExactSizeIterator for PackageTreeIter<'_> {}
-impl FusedIterator for PackageTreeIter<'_> {}
-
-#[cfg(test)]
-mod tests {
-    use crate::db::tests::TestDb;
-    use crate::workspace::{check_file, WorkspaceMetadata};
-    use red_knot_python_semantic::types::check_types;
-    use ruff_db::diagnostic::Diagnostic;
-    use ruff_db::files::system_path_to_file;
-    use ruff_db::source::source_text;
-    use ruff_db::system::{DbWithTestSystem, SystemPath, SystemPathBuf};
-    use ruff_db::testing::assert_function_query_was_not_run;
-    use ruff_python_ast::name::Name;
-
-    #[test]
-    fn check_file_skips_type_checking_when_file_cant_be_read() -> ruff_db::system::Result<()> {
-        let workspace =
-            WorkspaceMetadata::single_package(Name::new_static("test"), SystemPathBuf::from("/"));
-        let mut db = TestDb::new(workspace);
-        let path = SystemPath::new("test.py");
-
-        db.write_file(path, "x = 10")?;
-        let file = system_path_to_file(&db, path).unwrap();
-
-        // Now the file gets deleted before we had a chance to read its source text.
-        db.memory_file_system().remove_file(path)?;
-        file.sync(&mut db);
-
-        assert_eq!(source_text(&db, file).as_str(), "");
-        assert_eq!(
-            check_file(&db, file)
-                .into_iter()
-                .map(|diagnostic| diagnostic.message().into_owned())
-                .collect::<Vec<_>>(),
-            vec!["Failed to read file: No such file or directory".to_string()]
-        );
-
-        let events = db.take_salsa_events();
-        assert_function_query_was_not_run(&db, check_types, file, &events);
-
-        // The user now creates a new file with an empty text. The source text
-        // content returned by `source_text` remains unchanged, but the diagnostics should get updated.
-        db.write_file(path, "").unwrap();
-
-        assert_eq!(source_text(&db, file).as_str(), "");
-        assert_eq!(
-            check_file(&db, file)
-                .into_iter()
-                .map(|diagnostic| diagnostic.message().into_owned())
-                .collect::<Vec<_>>(),
-            vec![] as Vec<String>
-        );
-
-        Ok(())
-    }
-}
diff --git a/crates/red_knot_workspace/src/workspace/metadata.rs b/crates/red_knot_workspace/src/workspace/metadata.rs
deleted file mode 100644
index fff479a336..0000000000
--- a/crates/red_knot_workspace/src/workspace/metadata.rs
+++ /dev/null
@@ -1,812 +0,0 @@
-use ruff_db::system::{GlobError, System, SystemPath, SystemPathBuf};
-use ruff_python_ast::name::Name;
-use rustc_hash::{FxBuildHasher, FxHashMap, FxHashSet};
-use thiserror::Error;
-
-use crate::workspace::pyproject::{PyProject, PyProjectError, Workspace};
-use crate::workspace::settings::{Configuration, WorkspaceSettings};
-
-#[derive(Debug, PartialEq, Eq)]
-#[cfg_attr(test, derive(serde::Serialize))]
-pub struct WorkspaceMetadata {
-    pub(super) root: SystemPathBuf,
-
-    /// The (first-party) packages in this workspace.
-    pub(super) packages: Vec<PackageMetadata>,
-
-    /// The resolved settings for this workspace.
-    pub(super) settings: WorkspaceSettings,
-}
-
-/// A first-party package in a workspace.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[cfg_attr(test, derive(serde::Serialize))]
-pub struct PackageMetadata {
-    pub(super) name: Name,
-
-    /// The path to the root directory of the package.
-    pub(super) root: SystemPathBuf,
-
-    pub(super) configuration: Configuration,
-}
-
-impl WorkspaceMetadata {
-    /// Creates a workspace that consists of a single package located at `root`.
-    pub fn single_package(name: Name, root: SystemPathBuf) -> Self {
-        let package = PackageMetadata {
-            name,
-            root: root.clone(),
-            configuration: Configuration::default(),
-        };
-
-        let packages = vec![package];
-        let settings = packages[0]
-            .configuration
-            .to_workspace_settings(&root, &packages);
-
-        Self {
-            root,
-            packages,
-            settings,
-        }
-    }
-
-    /// Discovers the closest workspace at `path` and returns its metadata.
-    ///
-    /// 1. Traverse upwards in the `path`'s ancestor chain and find the first `pyproject.toml`.
-    /// 1. If the `pyproject.toml` contains no `knot.workspace` table, then keep traversing the `path`'s ancestor
-    ///    chain until we find one or reach the root.
-    /// 1. If we've found a workspace, then resolve the workspace's members and assert that the closest
-    ///    package (the first found package without a `knot.workspace` table is a member. If not, create
-    ///    a single package workspace for the closest package.
-    /// 1. If there's no `pyrpoject.toml` with a `knot.workspace` table, then create a single-package workspace.
-    /// 1. If no ancestor directory contains any `pyproject.toml`, create an ad-hoc workspace for `path`
-    ///    that consists of a single package and uses the default settings.
-    pub fn discover(
-        path: &SystemPath,
-        system: &dyn System,
-        base_configuration: Option<&Configuration>,
-    ) -> Result<WorkspaceMetadata, WorkspaceDiscoveryError> {
-        tracing::debug!("Searching for a workspace in '{path}'");
-
-        if !system.is_directory(path) {
-            return Err(WorkspaceDiscoveryError::NotADirectory(path.to_path_buf()));
-        }
-
-        let mut closest_package: Option<PackageMetadata> = None;
-
-        for ancestor in path.ancestors() {
-            let pyproject_path = ancestor.join("pyproject.toml");
-            if let Ok(pyproject_str) = system.read_to_string(&pyproject_path) {
-                let pyproject = PyProject::from_str(&pyproject_str).map_err(|error| {
-                    WorkspaceDiscoveryError::InvalidPyProject {
-                        path: pyproject_path,
-                        source: Box::new(error),
-                    }
-                })?;
-
-                let workspace_table = pyproject.workspace().cloned();
-                let package = PackageMetadata::from_pyproject(
-                    pyproject,
-                    ancestor.to_path_buf(),
-                    base_configuration,
-                );
-
-                if let Some(workspace_table) = workspace_table {
-                    let workspace_root = ancestor;
-                    tracing::debug!("Found workspace at '{}'", workspace_root);
-
-                    match collect_packages(
-                        package,
-                        &workspace_table,
-                        closest_package,
-                        base_configuration,
-                        system,
-                    )? {
-                        CollectedPackagesOrStandalone::Packages(mut packages) => {
-                            let mut by_name =
-                                FxHashMap::with_capacity_and_hasher(packages.len(), FxBuildHasher);
-
-                            let mut workspace_package = None;
-
-                            for package in &packages {
-                                if let Some(conflicting) = by_name.insert(package.name(), package) {
-                                    return Err(WorkspaceDiscoveryError::DuplicatePackageNames {
-                                        name: package.name().clone(),
-                                        first: conflicting.root().to_path_buf(),
-                                        second: package.root().to_path_buf(),
-                                    });
-                                }
-
-                                if package.root() == workspace_root {
-                                    workspace_package = Some(package);
-                                } else if !package.root().starts_with(workspace_root) {
-                                    return Err(WorkspaceDiscoveryError::PackageOutsideWorkspace {
-                                        package_name: package.name().clone(),
-                                        package_root: package.root().to_path_buf(),
-                                        workspace_root: workspace_root.to_path_buf(),
-                                    });
-                                }
-                            }
-
-                            let workspace_package = workspace_package
-                                .expect("workspace package to be part of the workspace's packages");
-
-                            let settings = workspace_package
-                                .configuration
-                                .to_workspace_settings(workspace_root, &packages);
-
-                            packages.sort_unstable_by(|a, b| a.root().cmp(b.root()));
-
-                            return Ok(Self {
-                                root: workspace_root.to_path_buf(),
-                                packages,
-                                settings,
-                            });
-                        }
-                        CollectedPackagesOrStandalone::Standalone(package) => {
-                            closest_package = Some(package);
-                            break;
-                        }
-                    }
-                }
-
-                // Not a workspace itself, keep looking for an enclosing workspace.
-                if closest_package.is_none() {
-                    closest_package = Some(package);
-                }
-            }
-        }
-
-        // No workspace found, but maybe a pyproject.toml was found.
-        let package = if let Some(enclosing_package) = closest_package {
-            tracing::debug!("Single package workspace at '{}'", enclosing_package.root());
-
-            enclosing_package
-        } else {
-            tracing::debug!("The ancestor directories contain no `pyproject.toml`. Falling back to a virtual project.");
-
-            // Create a package with a default configuration
-            PackageMetadata {
-                name: path.file_name().unwrap_or("root").into(),
-                root: path.to_path_buf(),
-                // TODO create the configuration from the pyproject toml
-                configuration: base_configuration.cloned().unwrap_or_default(),
-            }
-        };
-
-        let root = package.root().to_path_buf();
-        let packages = vec![package];
-        let settings = packages[0]
-            .configuration
-            .to_workspace_settings(&root, &packages);
-
-        Ok(Self {
-            root,
-            packages,
-            settings,
-        })
-    }
-
-    pub fn root(&self) -> &SystemPath {
-        &self.root
-    }
-
-    pub fn packages(&self) -> &[PackageMetadata] {
-        &self.packages
-    }
-
-    pub fn settings(&self) -> &WorkspaceSettings {
-        &self.settings
-    }
-}
-
-impl PackageMetadata {
-    pub(crate) fn from_pyproject(
-        pyproject: PyProject,
-        root: SystemPathBuf,
-        base_configuration: Option<&Configuration>,
-    ) -> Self {
-        let name = pyproject.project.and_then(|project| project.name);
-        let name = name
-            .map(|name| Name::new(&*name))
-            .unwrap_or_else(|| Name::new(root.file_name().unwrap_or("root")));
-
-        // TODO: load configuration from pyrpoject.toml
-        let mut configuration = Configuration::default();
-
-        if let Some(base_configuration) = base_configuration {
-            configuration.extend(base_configuration.clone());
-        }
-
-        PackageMetadata {
-            name,
-            root,
-            configuration,
-        }
-    }
-
-    pub fn name(&self) -> &Name {
-        &self.name
-    }
-
-    pub fn root(&self) -> &SystemPath {
-        &self.root
-    }
-}
-
-fn collect_packages(
-    workspace_package: PackageMetadata,
-    workspace_table: &Workspace,
-    closest_package: Option<PackageMetadata>,
-    base_configuration: Option<&Configuration>,
-    system: &dyn System,
-) -> Result<CollectedPackagesOrStandalone, WorkspaceDiscoveryError> {
-    let workspace_root = workspace_package.root().to_path_buf();
-    let mut member_paths = FxHashSet::default();
-
-    for glob in workspace_table.members() {
-        let full_glob = workspace_package.root().join(glob);
-
-        let matches = system.glob(full_glob.as_str()).map_err(|error| {
-            WorkspaceDiscoveryError::InvalidMembersPattern {
-                raw_glob: glob.clone(),
-                source: error,
-            }
-        })?;
-
-        for result in matches {
-            let path = result?;
-            let normalized = SystemPath::absolute(path, &workspace_root);
-
-            // Skip over non-directory entry. E.g.finder might end up creating a `.DS_STORE` file
-            // that ends up matching `/projects/*`.
-            if system.is_directory(&normalized) {
-                member_paths.insert(normalized);
-            } else {
-                tracing::debug!("Ignoring non-directory workspace member '{normalized}'");
-            }
-        }
-    }
-
-    // The workspace root is always a member. Don't re-add it
-    let mut packages = vec![workspace_package];
-    member_paths.remove(&workspace_root);
-
-    // Add the package that is closest to the current working directory except
-    // if that package isn't a workspace member, then fallback to creating a single
-    // package workspace.
-    if let Some(closest_package) = closest_package {
-        // the closest `pyproject.toml` isn't a member of this workspace because it is
-        // explicitly included or simply not listed.
-        // Create a standalone workspace.
-        if !member_paths.remove(closest_package.root())
-            || workspace_table.is_excluded(closest_package.root(), &workspace_root)?
-        {
-            tracing::debug!(
-                "Ignoring workspace '{workspace_root}' because package '{package}' is not a member",
-                package = closest_package.name()
-            );
-            return Ok(CollectedPackagesOrStandalone::Standalone(closest_package));
-        }
-
-        tracing::debug!("adding package '{}'", closest_package.name());
-        packages.push(closest_package);
-    }
-
-    // Add all remaining member paths
-    for member_path in member_paths {
-        if workspace_table.is_excluded(&member_path, workspace_root.as_path())? {
-            tracing::debug!("Ignoring excluded member '{member_path}'");
-            continue;
-        }
-
-        let pyproject_path = member_path.join("pyproject.toml");
-
-        let pyproject_str = match system.read_to_string(&pyproject_path) {
-            Ok(pyproject_str) => pyproject_str,
-
-            Err(error) => {
-                if error.kind() == std::io::ErrorKind::NotFound
-                    && member_path
-                        .file_name()
-                        .is_some_and(|name| name.starts_with('.'))
-                {
-                    tracing::debug!(
-                        "Ignore member '{member_path}' because it has no pyproject.toml and is hidden",
-                    );
-                    continue;
-                }
-
-                return Err(WorkspaceDiscoveryError::MemberFailedToReadPyProject {
-                    package_root: member_path,
-                    source: error,
-                });
-            }
-        };
-
-        let pyproject = PyProject::from_str(&pyproject_str).map_err(|error| {
-            WorkspaceDiscoveryError::InvalidPyProject {
-                source: Box::new(error),
-                path: pyproject_path,
-            }
-        })?;
-
-        if pyproject.workspace().is_some() {
-            return Err(WorkspaceDiscoveryError::NestedWorkspaces {
-                package_root: member_path,
-            });
-        }
-
-        let package = PackageMetadata::from_pyproject(pyproject, member_path, base_configuration);
-
-        tracing::debug!(
-            "Adding package '{}' at '{}'",
-            package.name(),
-            package.root()
-        );
-
-        packages.push(package);
-    }
-
-    packages.sort_unstable_by(|a, b| a.root().cmp(b.root()));
-
-    Ok(CollectedPackagesOrStandalone::Packages(packages))
-}
-
-enum CollectedPackagesOrStandalone {
-    Packages(Vec<PackageMetadata>),
-    Standalone(PackageMetadata),
-}
-
-#[derive(Debug, Error)]
-pub enum WorkspaceDiscoveryError {
-    #[error("workspace path '{0}' is not a directory")]
-    NotADirectory(SystemPathBuf),
-
-    #[error("nested workspaces aren't supported but the package located at '{package_root}' defines a `knot.workspace` table")]
-    NestedWorkspaces { package_root: SystemPathBuf },
-
-    #[error("the workspace contains two packages named '{name}': '{first}' and '{second}'")]
-    DuplicatePackageNames {
-        name: Name,
-        first: SystemPathBuf,
-        second: SystemPathBuf,
-    },
-
-    #[error("the package '{package_name}' located at '{package_root}' is outside the workspace's root directory '{workspace_root}'")]
-    PackageOutsideWorkspace {
-        workspace_root: SystemPathBuf,
-        package_name: Name,
-        package_root: SystemPathBuf,
-    },
-
-    #[error(
-        "failed to read the `pyproject.toml` for the package located at '{package_root}': {source}"
-    )]
-    MemberFailedToReadPyProject {
-        package_root: SystemPathBuf,
-        source: std::io::Error,
-    },
-
-    #[error("{path} is not a valid `pyproject.toml`: {source}")]
-    InvalidPyProject {
-        source: Box<PyProjectError>,
-        path: SystemPathBuf,
-    },
-
-    #[error("invalid glob '{raw_glob}' in `tool.knot.workspace.members`: {source}")]
-    InvalidMembersPattern {
-        source: glob::PatternError,
-        raw_glob: String,
-    },
-
-    #[error("failed to match member glob: {error}")]
-    FailedToMatchGlob {
-        #[from]
-        error: GlobError,
-    },
-}
-
-#[cfg(test)]
-mod tests {
-    //! Integration tests for workspace discovery
-
-    use crate::snapshot_workspace;
-    use anyhow::Context;
-    use insta::assert_ron_snapshot;
-    use ruff_db::system::{SystemPathBuf, TestSystem};
-
-    use crate::workspace::{WorkspaceDiscoveryError, WorkspaceMetadata};
-
-    #[test]
-    fn package_without_pyproject() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([(root.join("foo.py"), ""), (root.join("bar.py"), "")])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)
-            .context("Failed to discover workspace")?;
-
-        assert_eq!(workspace.root(), &*root);
-
-        snapshot_workspace!(workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn single_package() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "backend"
-                    "#,
-                ),
-                (root.join("db/__init__.py"), ""),
-            ])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)
-            .context("Failed to discover workspace")?;
-
-        assert_eq!(workspace.root(), &*root);
-        snapshot_workspace!(workspace);
-
-        // Discovering the same package from a subdirectory should give the same result
-        let from_src = WorkspaceMetadata::discover(&root.join("db"), &system, None)
-            .context("Failed to discover workspace from src sub-directory")?;
-
-        assert_eq!(from_src, workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn workspace_members() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    exclude = ["packages/excluded"]
-                    "#,
-                ),
-                (
-                    root.join("packages/a/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "member-a"
-                    "#,
-                ),
-                (
-                    root.join("packages/x/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "member-x"
-                    "#,
-                ),
-            ])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)
-            .context("Failed to discover workspace")?;
-
-        assert_eq!(workspace.root(), &*root);
-
-        snapshot_workspace!(workspace);
-
-        // Discovering the same package from a member should give the same result
-        let from_src = WorkspaceMetadata::discover(&root.join("packages/a"), &system, None)
-            .context("Failed to discover workspace from src sub-directory")?;
-
-        assert_eq!(from_src, workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn workspace_excluded() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    exclude = ["packages/excluded"]
-                    "#,
-                ),
-                (
-                    root.join("packages/a/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "member-a"
-                    "#,
-                ),
-                (
-                    root.join("packages/excluded/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "member-x"
-                    "#,
-                ),
-            ])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)
-            .context("Failed to discover workspace")?;
-
-        assert_eq!(workspace.root(), &*root);
-        snapshot_workspace!(workspace);
-
-        // Discovering the `workspace` for `excluded` should discover a single-package workspace
-        let excluded_workspace =
-            WorkspaceMetadata::discover(&root.join("packages/excluded"), &system, None)
-                .context("Failed to discover workspace from src sub-directory")?;
-
-        assert_ne!(excluded_workspace, workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn workspace_non_unique_member_names() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-                (
-                    root.join("packages/a/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "a"
-                    "#,
-                ),
-                (
-                    root.join("packages/b/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "a"
-                    "#,
-                ),
-            ])
-            .context("Failed to write files")?;
-
-        let error = WorkspaceMetadata::discover(&root, &system, None).expect_err(
-            "Discovery should error because the workspace contains two packages with the same names.",
-        );
-
-        assert_error_eq(&error, "the workspace contains two packages named 'a': '/app/packages/a' and '/app/packages/b'");
-
-        Ok(())
-    }
-
-    #[test]
-    fn nested_workspaces() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-                (
-                    root.join("packages/a/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "nested-workspace"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-            ])
-            .context("Failed to write files")?;
-
-        let error = WorkspaceMetadata::discover(&root, &system, None).expect_err(
-            "Discovery should error because the workspace has a package that itself is a workspace",
-        );
-
-        assert_error_eq(&error, "nested workspaces aren't supported but the package located at '/app/packages/a' defines a `knot.workspace` table");
-
-        Ok(())
-    }
-
-    #[test]
-    fn member_missing_pyproject_toml() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-                (root.join("packages/a/test.py"), ""),
-            ])
-            .context("Failed to write files")?;
-
-        let error = WorkspaceMetadata::discover(&root, &system, None)
-            .expect_err("Discovery should error because member `a` has no `pypyroject.toml`");
-
-        assert_error_eq(&error, "failed to read the `pyproject.toml` for the package located at '/app/packages/a': No such file or directory");
-
-        Ok(())
-    }
-
-    /// Folders that match the members pattern but don't have a pyproject.toml
-    /// aren't valid members and discovery fails. However, don't fail
-    /// if the folder name indicates that it is a hidden folder that might
-    /// have been created by another tool
-    #[test]
-    fn member_pattern_matching_hidden_folder() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-                (root.join("packages/.hidden/a.py"), ""),
-            ])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)?;
-
-        snapshot_workspace!(workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn member_pattern_matching_file() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["packages/*"]
-                    "#,
-                ),
-                (root.join("packages/.DS_STORE"), ""),
-            ])
-            .context("Failed to write files")?;
-
-        let workspace = WorkspaceMetadata::discover(&root, &system, None)?;
-
-        snapshot_workspace!(&workspace);
-
-        Ok(())
-    }
-
-    #[test]
-    fn workspace_root_not_an_ancestor_of_member() -> anyhow::Result<()> {
-        let system = TestSystem::default();
-        let root = SystemPathBuf::from("/app");
-
-        system
-            .memory_file_system()
-            .write_files([
-                (
-                    root.join("pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "workspace-root"
-
-                    [tool.knot.workspace]
-                    members = ["../packages/*"]
-                    "#,
-                ),
-                (
-                    root.join("../packages/a/pyproject.toml"),
-                    r#"
-                    [project]
-                    name = "a"
-                    "#,
-                ),
-            ])
-            .context("Failed to write files")?;
-
-        let error = WorkspaceMetadata::discover(&root, &system, None).expect_err(
-            "Discovery should error because member `a` is outside the workspace's directory`",
-        );
-
-        assert_error_eq(&error, "the package 'a' located at '/packages/a' is outside the workspace's root directory '/app'");
-
-        Ok(())
-    }
-
-    #[track_caller]
-    fn assert_error_eq(error: &WorkspaceDiscoveryError, message: &str) {
-        assert_eq!(error.to_string().replace('\\', "/"), message);
-    }
-
-    /// Snapshots a workspace but with all paths using unix separators.
-    #[macro_export]
-    macro_rules! snapshot_workspace {
-    ($workspace:expr) => {{
-        assert_ron_snapshot!($workspace,{
-            ".root" => insta::dynamic_redaction(|content, _content_path| {
-                content.as_str().unwrap().replace("\\", "/")
-            }),
-            ".packages[].root" => insta::dynamic_redaction(|content, _content_path| {
-                content.as_str().unwrap().replace("\\", "/")
-            }),
-        });
-    }};
-}
-}
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_file.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_file.snap
deleted file mode 100644
index 804be9349a..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_file.snap
+++ /dev/null
@@ -1,34 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: "&workspace"
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("workspace-root"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_hidden_folder.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_hidden_folder.snap
deleted file mode 100644
index 3aabf1ceb2..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__member_pattern_matching_hidden_folder.snap
+++ /dev/null
@@ -1,34 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: workspace
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("workspace-root"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__package_without_pyproject.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__package_without_pyproject.snap
deleted file mode 100644
index 73329a8552..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__package_without_pyproject.snap
+++ /dev/null
@@ -1,34 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: workspace
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("app"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__single_package.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__single_package.snap
deleted file mode 100644
index 6255e40868..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__single_package.snap
+++ /dev/null
@@ -1,34 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: workspace
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("backend"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_excluded.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_excluded.snap
deleted file mode 100644
index 4c68fd8714..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_excluded.snap
+++ /dev/null
@@ -1,47 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: workspace
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("workspace-root"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-    PackageMetadata(
-      name: Name("member-a"),
-      root: "/app/packages/a",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_members.snap b/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_members.snap
deleted file mode 100644
index 4f3c74ba34..0000000000
--- a/crates/red_knot_workspace/src/workspace/snapshots/red_knot_workspace__workspace__metadata__tests__workspace_members.snap
+++ /dev/null
@@ -1,60 +0,0 @@
----
-source: crates/red_knot_workspace/src/workspace/metadata.rs
-expression: workspace
----
-WorkspaceMetadata(
-  root: "/app",
-  packages: [
-    PackageMetadata(
-      name: Name("workspace-root"),
-      root: "/app",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-    PackageMetadata(
-      name: Name("member-a"),
-      root: "/app/packages/a",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-    PackageMetadata(
-      name: Name("member-x"),
-      root: "/app/packages/x",
-      configuration: Configuration(
-        python_version: None,
-        search_paths: SearchPathConfiguration(
-          extra_paths: None,
-          src_root: None,
-          typeshed: None,
-          site_packages: None,
-        ),
-      ),
-    ),
-  ],
-  settings: WorkspaceSettings(
-    program: ProgramSettings(
-      python_version: "3.9",
-      python_platform: all,
-      search_paths: SearchPathSettings(
-        extra_paths: [],
-        src_root: "/app",
-        typeshed: None,
-        site_packages: Known([]),
-      ),
-    ),
-  ),
-)
diff --git a/crates/red_knot_workspace/tests/check.rs b/crates/red_knot_workspace/tests/check.rs
index 8b5aeb1b20..afbdbe3bd8 100644
--- a/crates/red_knot_workspace/tests/check.rs
+++ b/crates/red_knot_workspace/tests/check.rs
@@ -1,7 +1,7 @@
 use anyhow::{anyhow, Context};
 use red_knot_python_semantic::{HasTy, SemanticModel};
-use red_knot_workspace::db::RootDatabase;
-use red_knot_workspace::workspace::WorkspaceMetadata;
+use red_knot_workspace::db::ProjectDatabase;
+use red_knot_workspace::project::ProjectMetadata;
 use ruff_db::files::{system_path_to_file, File};
 use ruff_db::parsed::parsed_module;
 use ruff_db::system::{SystemPath, SystemPathBuf, TestSystem};
@@ -9,12 +9,12 @@ use ruff_python_ast::visitor::source_order;
 use ruff_python_ast::visitor::source_order::SourceOrderVisitor;
 use ruff_python_ast::{self as ast, Alias, Expr, Parameter, ParameterWithDefault, Stmt};
 
-fn setup_db(workspace_root: &SystemPath, system: TestSystem) -> anyhow::Result<RootDatabase> {
-    let workspace = WorkspaceMetadata::discover(workspace_root, &system, None)?;
-    RootDatabase::new(workspace, system)
+fn setup_db(workspace_root: &SystemPath, system: TestSystem) -> anyhow::Result<ProjectDatabase> {
+    let workspace = ProjectMetadata::discover(workspace_root, &system, None)?;
+    ProjectDatabase::new(workspace, system)
 }
 
-fn get_workspace_root() -> anyhow::Result<SystemPathBuf> {
+fn get_cargo_workspace_root() -> anyhow::Result<SystemPathBuf> {
     Ok(SystemPathBuf::from(String::from_utf8(
         std::process::Command::new("cargo")
             .args(["locate-project", "--workspace", "--message-format", "plain"])
@@ -35,7 +35,7 @@ fn corpus_no_panic() -> anyhow::Result<()> {
 
 #[test]
 fn parser_no_panic() -> anyhow::Result<()> {
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     run_corpus_tests(&format!(
         "{workspace_root}/crates/ruff_python_parser/resources/**/*.py"
     ))
@@ -43,7 +43,7 @@ fn parser_no_panic() -> anyhow::Result<()> {
 
 #[test]
 fn linter_af_no_panic() -> anyhow::Result<()> {
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     run_corpus_tests(&format!(
         "{workspace_root}/crates/ruff_linter/resources/test/fixtures/[a-f]*/**/*.py"
     ))
@@ -51,7 +51,7 @@ fn linter_af_no_panic() -> anyhow::Result<()> {
 
 #[test]
 fn linter_gz_no_panic() -> anyhow::Result<()> {
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     run_corpus_tests(&format!(
         "{workspace_root}/crates/ruff_linter/resources/test/fixtures/[g-z]*/**/*.py"
     ))
@@ -60,7 +60,7 @@ fn linter_gz_no_panic() -> anyhow::Result<()> {
 #[test]
 #[ignore = "Enable running once there are fewer failures"]
 fn linter_stubs_no_panic() -> anyhow::Result<()> {
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     run_corpus_tests(&format!(
         "{workspace_root}/crates/ruff_linter/resources/test/fixtures/**/*.pyi"
     ))
@@ -69,7 +69,7 @@ fn linter_stubs_no_panic() -> anyhow::Result<()> {
 #[test]
 #[ignore = "Enable running over typeshed stubs once there are fewer failures"]
 fn typeshed_no_panic() -> anyhow::Result<()> {
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     run_corpus_tests(&format!(
         "{workspace_root}/crates/red_knot_vendored/vendor/typeshed/**/*.pyi"
     ))
@@ -85,7 +85,7 @@ fn run_corpus_tests(pattern: &str) -> anyhow::Result<()> {
 
     let mut db = setup_db(&root, system.clone())?;
 
-    let workspace_root = get_workspace_root()?;
+    let workspace_root = get_cargo_workspace_root()?;
     let workspace_root = workspace_root.to_string();
 
     let corpus = glob::glob(pattern).context("Failed to compile pattern")?;
@@ -163,7 +163,7 @@ fn run_corpus_tests(pattern: &str) -> anyhow::Result<()> {
     Ok(())
 }
 
-fn pull_types(db: &RootDatabase, file: File) {
+fn pull_types(db: &ProjectDatabase, file: File) {
     let mut visitor = PullTypesVisitor::new(db, file);
 
     let ast = parsed_module(db, file);
@@ -176,7 +176,7 @@ struct PullTypesVisitor<'db> {
 }
 
 impl<'db> PullTypesVisitor<'db> {
-    fn new(db: &'db RootDatabase, file: File) -> Self {
+    fn new(db: &'db ProjectDatabase, file: File) -> Self {
         Self {
             model: SemanticModel::new(db, file),
         }
diff --git a/crates/ruff_benchmark/benches/red_knot.rs b/crates/ruff_benchmark/benches/red_knot.rs
index d7f59b623e..fbc0035afd 100644
--- a/crates/ruff_benchmark/benches/red_knot.rs
+++ b/crates/ruff_benchmark/benches/red_knot.rs
@@ -2,10 +2,10 @@
 
 use rayon::ThreadPoolBuilder;
 use red_knot_python_semantic::PythonVersion;
-use red_knot_workspace::db::{Db, RootDatabase};
+use red_knot_workspace::db::{Db, ProjectDatabase};
+use red_knot_workspace::project::settings::Configuration;
+use red_knot_workspace::project::ProjectMetadata;
 use red_knot_workspace::watch::{ChangeEvent, ChangedKind};
-use red_knot_workspace::workspace::settings::Configuration;
-use red_knot_workspace::workspace::WorkspaceMetadata;
 use ruff_benchmark::criterion::{criterion_group, criterion_main, BatchSize, Criterion};
 use ruff_benchmark::TestFile;
 use ruff_db::diagnostic::Diagnostic;
@@ -15,7 +15,7 @@ use ruff_db::system::{MemoryFileSystem, SystemPath, SystemPathBuf, TestSystem};
 use rustc_hash::FxHashSet;
 
 struct Case {
-    db: RootDatabase,
+    db: ProjectDatabase,
     fs: MemoryFileSystem,
     re: File,
     re_path: SystemPathBuf,
@@ -74,7 +74,7 @@ fn setup_case() -> Case {
     .unwrap();
 
     let src_root = SystemPath::new("/src");
-    let metadata = WorkspaceMetadata::discover(
+    let metadata = ProjectMetadata::discover(
         src_root,
         &system,
         Some(&Configuration {
@@ -84,13 +84,13 @@ fn setup_case() -> Case {
     )
     .unwrap();
 
-    let mut db = RootDatabase::new(metadata, system).unwrap();
+    let mut db = ProjectDatabase::new(metadata, system).unwrap();
 
     let tomllib_files: FxHashSet<File> = tomllib_filenames
         .iter()
         .map(|filename| system_path_to_file(&db, tomllib_path(filename)).unwrap())
         .collect();
-    db.workspace().set_open_files(&mut db, tomllib_files);
+    db.project().set_open_files(&mut db, tomllib_files);
 
     let re_path = tomllib_path("_re.py");
     let re = system_path_to_file(&db, &re_path).unwrap();
diff --git a/crates/ruff_db/src/files/file_root.rs b/crates/ruff_db/src/files/file_root.rs
index c12a9e0d0c..e4fe54102b 100644
--- a/crates/ruff_db/src/files/file_root.rs
+++ b/crates/ruff_db/src/files/file_root.rs
@@ -11,7 +11,7 @@ use crate::Db;
 ///
 /// We currently create roots for:
 /// * static module resolution paths
-/// * the workspace root
+/// * the project root
 ///
 /// The main usage of file roots is to determine a file's durability. But it can also be used
 /// to make a salsa query dependent on whether a file in a root has changed without writing any
@@ -43,17 +43,17 @@ impl FileRoot {
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum FileRootKind {
-    /// The root of a workspace.
-    Workspace,
+    /// The root of a project.
+    Project,
 
-    /// A non-workspace module resolution search path.
+    /// A non-project module resolution search path.
     LibrarySearchPath,
 }
 
 impl FileRootKind {
     const fn durability(self) -> Durability {
         match self {
-            FileRootKind::Workspace => Durability::LOW,
+            FileRootKind::Project => Durability::LOW,
             FileRootKind::LibrarySearchPath => Durability::HIGH,
         }
     }
diff --git a/crates/ruff_graph/src/db.rs b/crates/ruff_graph/src/db.rs
index a31b86e385..567cd33555 100644
--- a/crates/ruff_graph/src/db.rs
+++ b/crates/ruff_graph/src/db.rs
@@ -50,7 +50,7 @@ impl ModuleDb {
         let db = Self::default();
         Program::from_settings(
             &db,
-            &ProgramSettings {
+            ProgramSettings {
                 python_version,
                 python_platform: PythonPlatform::default(),
                 search_paths,
diff --git a/fuzz/fuzz_targets/red_knot_check_invalid_syntax.rs b/fuzz/fuzz_targets/red_knot_check_invalid_syntax.rs
index 953a19cbc7..549c0da233 100644
--- a/fuzz/fuzz_targets/red_knot_check_invalid_syntax.rs
+++ b/fuzz/fuzz_targets/red_knot_check_invalid_syntax.rs
@@ -115,7 +115,7 @@ fn setup_db() -> TestDb {
 
     Program::from_settings(
         &db,
-        &ProgramSettings {
+        ProgramSettings {
             python_version: PythonVersion::default(),
             python_platform: PythonPlatform::default(),
             search_paths: SearchPathSettings::new(src_root),