Use the root project name for the project virtual environment prompt (#7021)

Closes https://github.com/astral-sh/uv/issues/7001

Tested with a legacy virtual workspace and a project with a `[project]`
table.

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

@@ -410,10 +410,29 @@ pub(crate) async fn get_or_init_environment(
                 venv.user_display().cyan()
             )?;
 
+            // Determine a prompt for the environment, in order of preference:
+            //
+            // 1) The name of the project
+            // 2) The name of the directory at the root of the workspace
+            // 3) No prompt
+            let prompt = workspace
+                .pyproject_toml()
+                .project
+                .as_ref()
+                .map(|p| p.name.to_string())
+                .or_else(|| {
+                    workspace
+                        .install_path()
+                        .file_name()
+                        .map(|f| f.to_string_lossy().to_string())
+                })
+                .map(uv_virtualenv::Prompt::Static)
+                .unwrap_or(uv_virtualenv::Prompt::None);
+
             Ok(uv_virtualenv::create_venv(
                 &venv,
                 interpreter,
-                uv_virtualenv::Prompt::None,
+                prompt,
                 false,
                 false,
                 false,

crates/uv/tests/sync.rs

@@ -1891,3 +1891,42 @@ fn sync_virtual_env_warning() -> Result<()> {
 
     Ok(())
 }
+
+#[test]
+fn sync_environment_prompt() -> Result<()> {
+    let context = TestContext::new_with_versions(&["3.12"]);
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "my-project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["iniconfig"]
+        "#,
+    )?;
+
+    // Running `uv sync` should create `.venv`
+    uv_snapshot!(context.filters(), context.sync(), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using Python 3.12.[X] interpreter at: [PYTHON-3.12]
+    Creating virtualenv at: .venv
+    Resolved 2 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Installed 1 package in [TIME]
+     + iniconfig==2.0.0
+    "###);
+
+    // The `pyvenv.cfg` should contain the prompt matching the project name
+    let pyvenv_cfg =
+        fs_err::read_to_string(context.temp_dir.join(".venv").join("pyvenv.cfg")).unwrap();
+
+    assert!(pyvenv_cfg.contains("prompt = my-project"));
+
+    Ok(())
+}