Make preview Python registration on Windows non-fatal (#14614)

Same as #14612 for registration with the Windows Registry.

crates/uv-cli/src/lib.rs

@@ -4954,6 +4954,17 @@ pub struct PythonInstallArgs {
     #[arg(long, overrides_with("bin"), conflicts_with("default"))]
     pub no_bin: bool,
 
+    /// Register the Python installation in the Windows registry.
+    ///
+    /// This is the default behavior on Windows. If this flag is provided explicitly, uv will error if the
+    /// registry entry cannot be created.
+    #[arg(long, overrides_with("no_registry"), hide = true)]
+    pub registry: bool,
+
+    /// Do not register the Python installation in the Windows registry.
+    #[arg(long, overrides_with("registry"))]
+    pub no_registry: bool,
+
     /// The Python version(s) to install.
     ///
     /// If not provided, the requested Python version(s) will be read from the `UV_PYTHON`

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

@@ -152,6 +152,7 @@ pub(crate) async fn install(
     reinstall: bool,
     upgrade: bool,
     bin: Option<bool>,
+    registry: Option<bool>,
     force: bool,
     python_install_mirror: Option<String>,
     pypy_install_mirror: Option<String>,
@@ -500,7 +501,7 @@ pub(crate) async fn install(
             );
         }
 
-        if preview.is_enabled() {
+        if preview.is_enabled() && !matches!(registry, Some(false)) {
             #[cfg(windows)]
             {
                 match uv_python::windows_registry::create_registry_entry(installation) {
@@ -670,11 +671,14 @@ pub(crate) async fn install(
     }
 
     if !errors.is_empty() {
-        // If there are only bin install errors and the user didn't opt-in, we're only going to warn
-        let fatal = errors
-            .iter()
-            .all(|(kind, _, _)| matches!(kind, InstallErrorKind::Bin))
-            && bin.is_none();
+        // If there are only side-effect install errors and the user didn't opt-in, we're only going
+        // to warn
+        let fatal = !errors.iter().all(|(kind, _, _)| match kind {
+            InstallErrorKind::Bin => bin.is_none(),
+            #[cfg(windows)]
+            InstallErrorKind::Registry => registry.is_none(),
+            InstallErrorKind::DownloadUnpack => false,
+        });
 
         for (kind, key, err) in errors
             .into_iter()
@@ -691,10 +695,14 @@ pub(crate) async fn install(
                     (level, "install executable for")
                 }
                 #[cfg(windows)]
-                InstallErrorKind::Registry => (
-                    "error".red().bold().to_string(),
-                    "install registry entry for",
-                ),
+                InstallErrorKind::Registry => {
+                    let level = match registry {
+                        None => "warning".yellow().bold().to_string(),
+                        Some(false) => continue,
+                        Some(true) => "error".red().bold().to_string(),
+                    };
+                    (level, "install registry entry for")
+                }
             };
 
             writeln!(
@@ -714,10 +722,8 @@ pub(crate) async fn install(
         }
 
         if fatal {
-            return Ok(ExitStatus::Success);
+            return Ok(ExitStatus::Failure);
         }
-
-        return Ok(ExitStatus::Failure);
     }
 
     Ok(ExitStatus::Success)

crates/uv/src/lib.rs

@@ -1403,6 +1403,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 args.reinstall,
                 upgrade,
                 args.bin,
+                args.registry,
                 args.force,
                 args.python_install_mirror,
                 args.pypy_install_mirror,
@@ -1432,6 +1433,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
                 reinstall,
                 upgrade,
                 args.bin,
+                args.registry,
                 args.force,
                 args.python_install_mirror,
                 args.pypy_install_mirror,

crates/uv/src/settings.rs

@@ -934,6 +934,7 @@ pub(crate) struct PythonInstallSettings {
     pub(crate) reinstall: bool,
     pub(crate) force: bool,
     pub(crate) bin: Option<bool>,
+    pub(crate) registry: Option<bool>,
     pub(crate) python_install_mirror: Option<String>,
     pub(crate) pypy_install_mirror: Option<String>,
     pub(crate) python_downloads_json_url: Option<String>,
@@ -964,6 +965,8 @@ impl PythonInstallSettings {
             reinstall,
             bin,
             no_bin,
+            registry,
+            no_registry,
             force,
             mirror: _,
             pypy_mirror: _,
@@ -977,6 +980,7 @@ impl PythonInstallSettings {
             reinstall,
             force,
             bin: flag(bin, no_bin, "bin"),
+            registry: flag(registry, no_registry, "registry"),
             python_install_mirror: python_mirror,
             pypy_install_mirror: pypy_mirror,
             python_downloads_json_url,
@@ -992,6 +996,7 @@ pub(crate) struct PythonUpgradeSettings {
     pub(crate) install_dir: Option<PathBuf>,
     pub(crate) targets: Vec<String>,
     pub(crate) force: bool,
+    pub(crate) registry: Option<bool>,
     pub(crate) python_install_mirror: Option<String>,
     pub(crate) pypy_install_mirror: Option<String>,
     pub(crate) python_downloads_json_url: Option<String>,
@@ -1019,6 +1024,7 @@ impl PythonUpgradeSettings {
         let force = false;
         let default = false;
         let bin = None;
+        let registry = None;
 
         let PythonUpgradeArgs {
             install_dir,
@@ -1032,6 +1038,7 @@ impl PythonUpgradeSettings {
             install_dir,
             targets,
             force,
+            registry,
             python_install_mirror: python_mirror,
             pypy_install_mirror: pypy_mirror,
             python_downloads_json_url,

crates/uv/tests/it/help.rs

@@ -507,6 +507,9 @@ fn help_subsubcommand() {
           --no-bin
               Do not install a Python executable into the `bin` directory
 
+          --no-registry
+              Do not register the Python installation in the Windows registry
+
           --mirror <MIRROR>
               Set the URL to use as the source for downloading Python installations.
               
@@ -795,6 +798,8 @@ fn help_flag_subsubcommand() {
               The directory to store the Python installation in [env: UV_PYTHON_INSTALL_DIR=]
           --no-bin
               Do not install a Python executable into the `bin` directory
+          --no-registry
+              Do not register the Python installation in the Windows registry
           --mirror <MIRROR>
               Set the URL to use as the source for downloading Python installations [env:
               UV_PYTHON_INSTALL_MIRROR=]