Make uv add --workspace the default for packages in the same source tree

crates/uv-cli/src/lib.rs

@@ -3633,7 +3633,8 @@ pub struct AddArgs {
         conflicts_with = "dev",
         conflicts_with = "optional",
         conflicts_with = "package",
-        conflicts_with = "workspace"
+        conflicts_with = "workspace",
+        conflicts_with = "no_workspace"
     )]
     pub script: Option<PathBuf>,
 
@@ -3654,8 +3655,15 @@ pub struct AddArgs {
     ///
     /// When used with a path dependency, the package will be added to the workspace's `members`
     /// list in the root `pyproject.toml` file.
-    #[arg(long)]
+    #[arg(long, conflicts_with = "no_workspace")]
     pub workspace: bool,
+
+    /// Prevent adding the dependency as a workspace member.
+    ///
+    /// By default, uv will add path dependencies within the same source tree as workspace members.
+    /// Use this flag to add the dependency as a regular path dependency instead.
+    #[arg(long, conflicts_with = "workspace")]
+    pub no_workspace: bool,
 }
 
 #[derive(Args)]

crates/uv/src/commands/project/add.rs

@@ -84,6 +84,7 @@ pub(crate) async fn add(
     package: Option<PackageName>,
     python: Option<String>,
     workspace: bool,
+    no_workspace: bool,
     install_mirrors: PythonInstallMirrors,
     settings: ResolverInstallerSettings,
     network_settings: NetworkSettings,
@@ -495,16 +496,28 @@ pub(crate) async fn add(
     // Track modification status, for reverts.
     let mut modified = false;
 
-    // If `--workspace` is provided, add any members to the `workspace` section of the
-    // `pyproject.toml` file.
-    if workspace {
+    // Determine if we should add path dependencies as workspace members.
+    // This is the default behavior for path dependencies within the same source tree,
+    // unless explicitly disabled with `--no-workspace`.
+    let should_add_workspace_members = if workspace {
+        true
+    } else if no_workspace {
+        false
+    } else {
+        // Default: add as workspace members if the path is within the workspace root
+        true
+    };
+
+    // If we should add workspace members, add any path dependencies to the `workspace` section
+    // of the `pyproject.toml` file.
+    if should_add_workspace_members {
         let AddTarget::Project(project, python_target) = target else {
             unreachable!("`--workspace` and `--script` are conflicting options");
         };
 
-        let workspace = project.workspace();
+        let workspace_obj = project.workspace();
         let mut toml = PyProjectTomlMut::from_toml(
-            &workspace.pyproject_toml().raw,
+            &workspace_obj.pyproject_toml().raw,
             DependencyTarget::PyProjectToml,
         )?;
 
@@ -517,20 +530,32 @@ pub(crate) async fn add(
                     project.root().join(install_path)
                 };
 
-                // Check if the path is not already included in the workspace.
-                if !workspace.includes(&absolute_path)? {
-                    let relative_path = absolute_path
-                        .strip_prefix(workspace.install_path())
-                        .unwrap_or(&absolute_path);
-
-                    toml.add_workspace(relative_path)?;
-                    modified |= true;
-
-                    writeln!(
-                        printer.stderr(),
-                        "Added `{}` to workspace members",
-                        relative_path.user_display().cyan()
-                    )?;
+                // Check if the path is within the workspace root (same source tree)
+                let is_within_workspace = absolute_path
+                    .strip_prefix(workspace_obj.install_path())
+                    .is_ok();
+
+                // Only add to workspace if:
+                // 1. The path is within the workspace root (same source tree), OR
+                // 2. --workspace was explicitly provided
+                let should_add_to_workspace = is_within_workspace || workspace;
+
+                if should_add_to_workspace {
+                    // Check if the path is not already included in the workspace.
+                    if !workspace_obj.includes(&absolute_path)? {
+                        let relative_path = absolute_path
+                            .strip_prefix(workspace_obj.install_path())
+                            .unwrap_or(&absolute_path);
+
+                        toml.add_workspace(relative_path)?;
+                        modified |= true;
+
+                        writeln!(
+                            printer.stderr(),
+                            "Added `{}` to workspace members",
+                            relative_path.user_display().cyan()
+                        )?;
+                    }
                 }
             }
         }
@@ -540,7 +565,7 @@ pub(crate) async fn add(
         target = if modified {
             let workspace_content = toml.to_string();
             fs_err::write(
-                workspace.install_path().join("pyproject.toml"),
+                workspace_obj.install_path().join("pyproject.toml"),
                 &workspace_content,
             )?;
 

crates/uv/src/lib.rs

@@ -1966,6 +1966,7 @@ async fn run_project(
                 args.package,
                 args.python,
                 args.workspace,
+                args.no_workspace,
                 args.install_mirrors,
                 args.settings,
                 globals.network_settings,

crates/uv/src/settings.rs

@@ -1327,6 +1327,7 @@ pub(crate) struct AddSettings {
     pub(crate) script: Option<PathBuf>,
     pub(crate) python: Option<String>,
     pub(crate) workspace: bool,
+    pub(crate) no_workspace: bool,
     pub(crate) install_mirrors: PythonInstallMirrors,
     pub(crate) refresh: Refresh,
     pub(crate) indexes: Vec<Index>,
@@ -1365,6 +1366,7 @@ impl AddSettings {
             script,
             python,
             workspace,
+            no_workspace,
         } = args;
 
         let dependency_type = if let Some(extra) = optional {
@@ -1466,6 +1468,7 @@ impl AddSettings {
             script,
             python: python.and_then(Maybe::into_option),
             workspace,
+            no_workspace,
             editable: flag(editable, no_editable, "editable"),
             extras: extra.unwrap_or_default(),
             refresh: Refresh::from(refresh),

crates/uv/tests/it/edit.rs

@@ -13040,3 +13040,128 @@ fn add_path_with_workspace() -> Result<()> {
 
     Ok(())
 }
+
+/// Add a path dependency within the same source tree - should default to workspace member
+#[test]
+fn add_path_default_workspace_same_source_tree() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let workspace_toml = context.temp_dir.child("pyproject.toml");
+    workspace_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+    "#})?;
+
+    // Create a dependency package within the workspace (same source tree)
+    let dep_dir = context.temp_dir.child("dep");
+    dep_dir.create_dir_all()?;
+
+    let dep_toml = dep_dir.child("pyproject.toml");
+    dep_toml.write_str(indoc! {r#"
+        [project]
+        name = "dep"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+    "#})?;
+
+    // Add the dependency without any flags - should default to workspace member
+    uv_snapshot!(context.filters(), context
+        .add()
+        .arg("./dep"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Added `dep` to workspace members
+    Resolved 2 packages in [TIME]
+    Audited in [TIME]
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+    assert_snapshot!(
+        pyproject_toml, @r#"
+    [project]
+    name = "parent"
+    version = "0.1.0"
+    requires-python = ">=3.12"
+    dependencies = [
+        "dep",
+    ]
+
+    [tool.uv.workspace]
+    members = [
+        "dep",
+    ]
+
+    [tool.uv.sources]
+    dep = { workspace = true }
+    "#
+    );
+
+    Ok(())
+}
+
+/// Add a path dependency within the same source tree with --no-workspace - should not add to workspace
+#[test]
+fn add_path_no_workspace_same_source_tree() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let workspace_toml = context.temp_dir.child("pyproject.toml");
+    workspace_toml.write_str(indoc! {r#"
+        [project]
+        name = "parent"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+    "#})?;
+
+    // Create a dependency package within the workspace (same source tree)
+    let dep_dir = context.temp_dir.child("dep");
+    dep_dir.create_dir_all()?;
+
+    let dep_toml = dep_dir.child("pyproject.toml");
+    dep_toml.write_str(indoc! {r#"
+        [project]
+        name = "dep"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = []
+    "#})?;
+
+    // Add the dependency with --no-workspace flag - should not add to workspace
+    uv_snapshot!(context.filters(), context
+        .add()
+        .arg("./dep")
+        .arg("--no-workspace"), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 2 packages in [TIME]
+    Audited in [TIME]
+    ");
+
+    let pyproject_toml = context.read("pyproject.toml");
+    assert_snapshot!(
+        pyproject_toml, @r#"
+    [project]
+    name = "parent"
+    version = "0.1.0"
+    requires-python = ">=3.12"
+    dependencies = [
+        "dep",
+    ]
+
+    [tool.uv.sources]
+    dep = { path = "dep" }
+    "#
+    );
+
+    Ok(())
+}