Avoid redundant members update in uv init (#5321)

## Summary

If the path is already covered by `members`, we don't need to update it.

Closes #5320.

crates/uv-workspace/src/workspace.rs

@@ -345,6 +345,13 @@ impl Workspace {
         }
     }
 
+    /// Returns `true` if the path is a workspace member.
+    pub fn includes(&self, project_path: &Path) -> bool {
+        self.packages
+            .values()
+            .any(|member| project_path == member.root())
+    }
+
     /// Collect the workspace member projects from the `members` and `excludes` entries.
     async fn collect_members(
         workspace_root: PathBuf,

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

@@ -123,6 +123,14 @@ pub(crate) async fn init(
                 name.cyan(),
                 workspace.install_path().simplified_display().cyan()
             )?;
+        } else if workspace.includes(&path) {
+            // If the member is already included in the workspace, skip the `members` addition.
+            writeln!(
+                printer.stderr(),
+                "Project `{}` is already a member of workspace `{}`",
+                name.cyan(),
+                workspace.install_path().simplified_display().cyan()
+            )?;
         } else {
             // Add the package to the workspace.
             let mut pyproject = PyProjectTomlMut::from_toml(workspace.pyproject_toml())?;

crates/uv/tests/init.rs

@@ -748,7 +748,7 @@ fn init_matches_members() -> Result<()> {
 
     ----- stderr -----
     warning: `uv init` is experimental and may change without warning
-    Adding `foo` as member of workspace `[TEMP_DIR]/`
+    Project `foo` is already a member of workspace `[TEMP_DIR]/`
     Initialized project `foo` at `[TEMP_DIR]/packages/foo`
     "###);
 
@@ -759,15 +759,15 @@ fn init_matches_members() -> Result<()> {
         assert_snapshot!(
             workspace, @r###"
         [tool.uv.workspace]
-        members = ['packages/*', "packages/foo"]
+        members = ['packages/*']
         "###
         );
     });
 
     Ok(())
 }
 
-/// Run `uv init` from within a workspace. The path is already included via `members`.
+/// Run `uv init` from within a workspace. The path is excluded via `exclude`.
 #[test]
 fn init_matches_exclude() -> Result<()> {
     let context = TestContext::new("3.12");