uv-tool: ignore existing environment on interpreter mismatch

crates/uv-tool/src/lib.rs

@@ -204,7 +204,7 @@ impl InstalledTools {
         match PythonEnvironment::from_root(&environment_path, cache) {
             Ok(venv) => {
                 debug!(
-                    "Using existing environment for tool `{name}`: {}",
+                    "Found existing environment for tool `{name}`: {}",
                     environment_path.user_display()
                 );
                 Ok(Some(venv))

crates/uv/src/commands/tool/install.rs

@@ -276,19 +276,27 @@ pub(crate) async fn install(
         installed_tools
             .get_environment(&from.name, &cache)?
             .filter(|environment| {
-                python_request.as_ref().map_or(true, |python_request| {
-                    if python_request.satisfied(environment.interpreter(), &cache) {
-                        debug!("Found existing environment for `{from}`", from = from.name.cyan());
-                        true
-                    } else {
-                        let _ = writeln!(
-                            printer.stderr(),
-                            "Existing environment for `{from}` does not satisfy the requested Python interpreter",
-                            from = from.name.cyan(),
-                        );
-                        false
-                    }
-                })
+                // NOTE(lucab): this compares `base_prefix` paths as a proxy for
+                // detecting interpreters mismatches. Directly comparing interpreters
+                // (by paths or binaries on-disk) would result in several false
+                // positives on Windows due to file-copying and shims.
+                let old_base_prefix = environment.interpreter().sys_base_prefix();
+                let selected_base_prefix = interpreter.sys_base_prefix();
+                if old_base_prefix == selected_base_prefix {
+                    debug!(
+                        "Found existing interpreter for tool `{}`: {}",
+                        from.name,
+                        environment.interpreter().sys_executable().display()
+                    );
+                    true
+                } else {
+                    let _ = writeln!(
+                        printer.stderr(),
+                        "Ignored existing environment for `{from}` due to stale Python interpreter",
+                        from = from.name.cyan(),
+                    );
+                    false
+                }
             });
 
     // If the requested and receipt requirements are the same...

crates/uv/tests/tool_install.rs

@@ -2072,9 +2072,10 @@ fn tool_install_upgrade() {
     });
 }
 
-/// Test reinstalling tools with varying `--python` requests.
+/// Test reinstalling tools with varying `--python` and
+/// `--python-preference` parameters.
 #[test]
-fn tool_install_python_request() {
+fn tool_install_python_params() {
     let context = TestContext::new_with_versions(&["3.11", "3.12"])
         .with_filtered_counts()
         .with_filtered_exe_suffix();
@@ -2122,10 +2123,12 @@ fn tool_install_python_request() {
     `black` is already installed
     "###);
 
-    // Install with Python 3.11 (incompatible).
+    // Install with system Python 3.11 (different version, incompatible).
     uv_snapshot!(context.filters(), context.tool_install()
         .arg("-p")
         .arg("3.11")
+        .arg("--python-preference")
+        .arg("only-system")
         .arg("black")
         .env("UV_TOOL_DIR", tool_dir.as_os_str())
         .env("XDG_BIN_HOME", bin_dir.as_os_str())
@@ -2135,7 +2138,7 @@ fn tool_install_python_request() {
     ----- stdout -----
 
     ----- stderr -----
-    Existing environment for `black` does not satisfy the requested Python interpreter
+    Ignored existing environment for `black` due to stale Python interpreter
     Resolved [N] packages in [TIME]
     Prepared [N] packages in [TIME]
     Installed [N] packages in [TIME]
@@ -2147,6 +2150,69 @@ fn tool_install_python_request() {
      + platformdirs==4.2.0
     Installed 2 executables: black, blackd
     "###);
+
+    // Install with system Python 3.11 (compatible).
+    uv_snapshot!(context.filters(), context.tool_install()
+        .arg("-p")
+        .arg("3.11")
+        .arg("--python-preference")
+        .arg("only-system")
+        .arg("black")
+        .env("UV_TOOL_DIR", tool_dir.as_os_str())
+        .env("XDG_BIN_HOME", bin_dir.as_os_str())
+        .env("PATH", bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    `black` is already installed
+    "###);
+
+    // Install with managed Python 3.11 (different source, incompatible).
+    uv_snapshot!(context.filters(), context.tool_install()
+        .arg("-p")
+        .arg("3.11")
+        .arg("--python-preference")
+        .arg("only-managed")
+        .arg("black")
+        .env("UV_TOOL_DIR", tool_dir.as_os_str())
+        .env("XDG_BIN_HOME", bin_dir.as_os_str())
+        .env("PATH", bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Ignored existing environment for `black` due to stale Python interpreter
+    Resolved [N] packages in [TIME]
+    Installed [N] packages in [TIME]
+     + black==24.3.0
+     + click==8.1.7
+     + mypy-extensions==1.0.0
+     + packaging==24.0
+     + pathspec==0.12.1
+     + platformdirs==4.2.0
+    Installed 2 executables: black, blackd
+    "###);
+
+    // Install with managed Python 3.11 (compatible).
+    uv_snapshot!(context.filters(), context.tool_install()
+        .arg("-p")
+        .arg("3.11")
+        .arg("--python-preference")
+        .arg("only-managed")
+        .arg("black")
+        .env("UV_TOOL_DIR", tool_dir.as_os_str())
+        .env("XDG_BIN_HOME", bin_dir.as_os_str())
+        .env("PATH", bin_dir.as_os_str()), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    `black` is already installed
+    "###);
 }
 
 /// Test preserving a tool environment when new but incompatible requirements are requested.