fix(python): exclude virtual environments from detected roots whatever their name

Root detection only skipped environments named `venv` / `.venv`. A venv with another
name in the project (e.g. `code10`) was walked into, and any package in its
site-packages that ships `pyproject.toml`, `setup.py` or `requirements.txt` became a
source root. Source roots go on PYTHONPATH for runs, so a package directory with an
`io` package shadowed the standard library and Python 3.10 failed at startup with
`init_sys_streams: module 'io' has no attribute 'open'`.

A directory with `pyvenv.cfg` (venv, virtualenv, uv) or `conda-meta` (conda) is now
an excluded root and not searched for modules; creating one re-runs detection.
Project discovery in the workspace folder picker skips such directories too, so
packages inside an environment are not offered as projects.

crates/ide-workspace/src/project_discovery.rs

@@ -108,7 +108,9 @@ fn discover_with_limit(
                 if name.starts_with('.') || SKIP_DIRS.contains(&name.as_ref()) {
                     continue;
                 }
-                if entry.file_type().is_ok_and(|kind| kind.is_dir()) {
+                if entry.file_type().is_ok_and(|kind| kind.is_dir())
+                    && crate::roots::virtual_env_marker(&entry.path()).is_none()
+                {
                     children.push(entry.path());
                 }
             }
@@ -170,6 +172,19 @@ mod tests {
         assert_eq!(result.direct[0], root);
     }
 
+    #[test]
+    fn skips_virtual_environments_whatever_their_name() {
+        let tmp = tempfile::tempdir().unwrap();
+        let root = tmp.path();
+        project(root, "code10", "pyvenv.cfg");
+        project(root, "code10/Lib/site-packages/pkg", "pyproject.toml");
+        fs::create_dir_all(root.join("conda/conda-meta")).unwrap();
+        project(root, "conda/pkgs/dep", "setup.py");
+        let app = project(root, "app", "pyproject.toml");
+        let result = discover(vec![root.into()], &CancellationToken::new()).unwrap();
+        assert_eq!(result.projects.iter().map(|p| p.path.to_path_buf()).collect::<Vec<_>>(), [app]);
+    }
+
     #[test]
     fn finds_depth_four_but_not_five_and_retains_empty_folders() {
         let tmp = tempfile::tempdir().unwrap();

crates/ide-workspace/src/roots/detect.rs

@@ -17,6 +17,19 @@ const PYTHON_FILES: &[&str] = &["pyproject.toml", "setup.py", "setup.cfg", "Pipf
 const SKIP_DIRS: &[&str] =
     &["node_modules", "target", "build", "dist", "out", "venv", "__pycache__", "vendor", "bower_components"];
 
+/// A Python virtual environment (`python -m venv`, virtualenv, uv) or conda environment,
+/// whatever it is named: its packages are dependencies, not modules of the project.
+/// Returns the file that marks it.
+pub(crate) fn virtual_env_marker(dir: &Path) -> Option<&'static str> {
+    if dir.join("pyvenv.cfg").is_file() {
+        Some("pyvenv.cfg")
+    } else if dir.join("conda-meta").is_dir() {
+        Some("conda-meta")
+    } else {
+        None
+    }
+}
+
 /// Build files whose changes can change the detected roots.
 pub(crate) const BUILD_FILES: &[&str] = &[
     "pom.xml",
@@ -65,7 +78,10 @@ pub fn affects_roots(rel: &Path) -> bool {
     let Some(name) = names.next() else { return false };
     BUILD_FILES.contains(&name)
         || ROOT_NAMES.contains(&name)
-        || matches!(name, "Assets" | "Packages" | "ProjectSettings" | "ProjectVersion.txt")
+        || matches!(
+            name,
+            "Assets" | "Packages" | "ProjectSettings" | "ProjectVersion.txt" | "pyvenv.cfg" | "conda-meta"
+        )
         || names.next() == Some("src")
 }
 
@@ -131,6 +147,13 @@ pub fn detect(root: &Path) -> Vec<SourceFolder> {
             if found.iter().any(|f| *f == child || f.is_empty() && name == "src") {
                 continue;
             }
+            if let Some(marker) = virtual_env_marker(&root.join(&child)) {
+                if !out.iter().any(|r| r.path == child) {
+                    let from = join(&child, marker);
+                    out.push(SourceFolder { path: child, kind: RootKind::Excluded, detected_from: Some(from) });
+                }
+                continue;
+            }
             queue.push_back((child, depth + 1));
         }
     }
@@ -505,6 +528,35 @@ mod tests {
         );
     }
 
+    #[test]
+    fn virtual_environments_are_excluded_whatever_their_name() {
+        // A package in the environment's site-packages has build files of its own; as a
+        // source root it would be put on PYTHONPATH and shadow the standard library.
+        let dir = tree(&[
+            "requirements.txt",
+            "app.py",
+            "code10/pyvenv.cfg",
+            "code10/Lib/site-packages/pkg/pyproject.toml",
+            "code10/Lib/site-packages/pkg/io/__init__.py",
+            "envs/conda/conda-meta/",
+            "envs/conda/lib/pkg/setup.py",
+            "svc/pyproject.toml",
+            "svc/env/pyvenv.cfg",
+            "svc/env/lib/python3.12/site-packages/dep/setup.py",
+        ]);
+        assert_eq!(
+            summary(&detect(dir.path())),
+            vec![
+                "[email protected]",
+                "code10=Excluded@code10/pyvenv.cfg",
+                "envs/conda=Excluded@envs/conda/conda-meta",
+                "svc=Source@svc/pyproject.toml",
+                "svc/env=Excluded@svc/env/pyvenv.cfg",
+            ]
+        );
+        assert!(affects_roots(Path::new("code10/pyvenv.cfg")));
+    }
+
     #[test]
     fn first_ecosystem_wins_for_a_shared_folder() {
         // A Gradle build with a frontend: `build` stays Gradle's, `src` is not a Node root.

crates/ide-workspace/src/roots/mod.rs

@@ -6,7 +6,7 @@
 //! project-relative and `/`-separated; `""` is the project root itself.
 
 mod detect;
-pub(crate) use detect::BUILD_FILES;
+pub(crate) use detect::{BUILD_FILES, virtual_env_marker};
 mod gradle;
 mod java;
 mod maven;