fix(python): name the project interpreter in the status bar wherever it lives (#1461)

An interpreter that detection doesn't look for (a virtualenv in a subfolder such as backend/.venv, or one set by path) was missing from sdk_detect, so the status bar and interpreter menu showed its raw path. sdk_detect for Python now adds the project's interpreter when detection didn't find it, named by the same rules, and a project-local .venv in a subfolder is named after that folder.

Fixes #1428

crates/ide-sdk/src/discover.rs

@@ -184,6 +184,12 @@ fn python(root: Option<&Path>) -> Vec<Sdk> {
     par_map(&candidates, |(path, source)| python_sdk(path, source, root))
 }
 
+/// Interpreter `path` (one the project is set to, wherever it lives) as an SDK, named
+/// like the detected ones.
+pub fn python_interpreter_sdk(path: &Path, root: Option<&Path>) -> Option<Sdk> {
+    python_sdk(path, if venv_of(path).is_some() { "venv" } else { "system" }, root)
+}
+
 pub(crate) fn python_sdk(path: &Path, source: &str, root: Option<&Path>) -> Option<Sdk> {
     let version = query(path, &["--version"], VERSION_TIMEOUT)
         .and_then(|v| v.strip_prefix("Python ").map(str::to_owned))
@@ -193,10 +199,11 @@ pub(crate) fn python_sdk(path: &Path, source: &str, root: Option<&Path>) -> Opti
     let label = match (&venv, source) {
         (Some(home), _) => {
             let dir = home.file_name().map(|n| n.to_string_lossy().into_owned()).unwrap_or_default();
-            // `.venv` inside a project reads better as the project name, like PyCharm.
+            // `.venv` inside a project reads better as the folder that holds it (the project,
+            // or a member such as `backend`), like PyCharm.
             let owner = home.parent().and_then(|p| p.file_name()).map(|n| n.to_string_lossy().into_owned());
             match (dir.starts_with('.') || dir == "venv" || dir == "env", owner, root) {
-                (true, Some(owner), Some(root)) if home.parent() == Some(root) => format!("Python {short} ({owner})"),
+                (true, Some(owner), Some(root)) if home.starts_with(root) => format!("Python {short} ({owner})"),
                 _ => format!("Python {short} ({dir})"),
             }
         }

crates/ide-sdk/src/lib.rs

@@ -28,7 +28,7 @@ use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::path::{Path, PathBuf};
 
-pub use discover::{detect, jdk_sdk};
+pub use discover::{detect, jdk_sdk, python_interpreter_sdk};
 
 /// What [`detect`] looks for.
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Type)]

crates/ide-sdk/src/tests.rs

@@ -76,6 +76,23 @@ fn project_venv_is_the_default_interpreter() {
     assert_eq!(python_interpreter(tmp.path(), &s).unwrap(), Path::new("/opt/py/bin/python3"));
 }
 
+#[test]
+fn an_interpreter_outside_detection_is_named_like_a_detected_one() {
+    let tmp = tempfile::tempdir().unwrap();
+    let root = tmp.path().join("shop");
+    let member = fake_venv(&root.join("backend"), ".venv");
+    let sdk = crate::python_interpreter_sdk(&member, Some(&root)).unwrap();
+    assert_eq!(
+        (sdk.name.as_str(), sdk.version.as_deref(), sdk.source.as_str()),
+        ("Python 3.12 (backend)", Some("3.12.1"), "venv")
+    );
+    let own = fake_venv(&root, ".venv");
+    assert_eq!(crate::python_interpreter_sdk(&own, Some(&root)).unwrap().name, "Python 3.12 (shop)");
+    // Outside the project the folder name says which one it is.
+    let elsewhere = fake_venv(&tmp.path().join("other"), ".venv");
+    assert_eq!(crate::python_interpreter_sdk(&elsewhere, Some(&root)).unwrap().name, "Python 3.12 (.venv)");
+}
+
 #[test]
 fn pyright_gets_python_path_and_venv_env() {
     let tmp = tempfile::tempdir().unwrap();