fix: deduplicate Windows Conda paths by disk casing

Preserve authoritative Windows path casing when well-known and configured Conda aliases refer to the same installation. Add a regression covering lowercase environment aliases.\n\nFixes #518\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: karthiknadig

Cargo.lock

@@ -21,5 +21,8 @@ env_logger = "0.10.2"
 yaml-rust2 = "0.8.1"
 rayon = "1.11.0"
 
+[dev-dependencies]
+tempfile = "3.13"
+
 [features]
 ci = []

crates/pet-conda/Cargo.toml

@@ -319,6 +319,25 @@ pub fn get_conda_envs_from_environment_txt(env_vars: &EnvVariables) -> Vec<PathB
     envs
 }
 
+#[cfg(windows)]
+fn restore_existing_leaf_case(path: PathBuf) -> PathBuf {
+    let Some(parent) = path.parent() else {
+        return path;
+    };
+    let Some(file_name) = path.file_name() else {
+        return path;
+    };
+    let Ok(entries) = fs::read_dir(parent) else {
+        return path;
+    };
+
+    entries
+        .filter_map(Result::ok)
+        .find(|entry| entry.file_name().eq_ignore_ascii_case(file_name))
+        .map(|entry| entry.path())
+        .unwrap_or(path)
+}
+
 #[cfg(windows)]
 pub fn get_known_conda_install_locations(
     env_vars: &EnvVariables,
@@ -416,15 +435,6 @@ pub fn get_known_conda_install_locations(
                 .join("conda"),
         );
     }
-    known_paths.sort();
-    known_paths.dedup();
-    // Ensure the casing of the paths are correct.
-    // Its possible the actual path is in a different case.
-    // E.g. instead of C:\username\miniconda it might bt C:\username\Miniconda
-    // We use lower cases above, but it could be in any case on disc.
-    // We do not want to have duplicates in different cases.
-    // & we'd like to preserve the case of the original path as on disc.
-    known_paths = known_paths.iter().map(norm_case).collect();
     if let Some(conda_dir) = get_conda_dir_from_exe(conda_executable) {
         known_paths.push(conda_dir);
     }
@@ -436,6 +446,13 @@ pub fn get_known_conda_install_locations(
     if let Some(mamba_dir) = get_conda_dir_from_exe(&find_mamba_binary(env_vars)) {
         known_paths.push(mamba_dir);
     }
+
+    known_paths = known_paths
+        .into_iter()
+        .filter(|path| path.exists())
+        .map(norm_case)
+        .map(restore_existing_leaf_case)
+        .collect();
     known_paths.sort();
     known_paths.dedup();
 

crates/pet-conda/src/environment_locations.rs

@@ -205,3 +205,44 @@ fn skips_path_lookup_when_conda_executable_provided() {
         locations
     );
 }
+
+#[cfg(windows)]
+#[test]
+fn deduplicates_windows_install_aliases_and_preserves_disk_casing() {
+    use common::create_env_variables;
+    use pet_conda::environment_locations::get_conda_environment_paths;
+    use std::fs;
+
+    let temp_dir = tempfile::tempdir().expect("failed to create temporary test directory");
+    let home = temp_dir.path();
+    let install = home.join("Miniconda3");
+    let child = install.join("envs").join("MyEnv");
+
+    fs::create_dir_all(install.join("conda-meta"))
+        .expect("failed to create base conda-meta directory");
+    fs::create_dir_all(install.join("condabin")).expect("failed to create base condabin directory");
+    fs::create_dir_all(child.join("conda-meta"))
+        .expect("failed to create child conda-meta directory");
+
+    let conda_state = home.join(".conda");
+    fs::create_dir_all(&conda_state).expect("failed to create .conda directory");
+    fs::write(
+        conda_state.join("environments.txt"),
+        format!("{}\n{}\n", install.display(), child.display()),
+    )
+    .expect("failed to write environments.txt");
+
+    let mut env = create_env_variables(home.to_path_buf(), home.to_path_buf());
+    env.userprofile = Some(home.to_string_lossy().into_owned());
+
+    let environments = get_conda_environment_paths(&env, &None);
+    let mut local_environments = environments
+        .into_iter()
+        .filter(|path| path.starts_with(home))
+        .collect::<Vec<_>>();
+    local_environments.sort();
+
+    let mut expected = vec![install, child];
+    expected.sort();
+    assert_eq!(local_environments, expected);
+}