Respect --torch-backend in uv tool commands (#17117)

## Summary

Like `uv pip`, these don't require a universal resolution, so
`--torch-backend` is easy to support.

crates/uv-cli/src/lib.rs

@@ -5371,6 +5371,21 @@ pub struct ToolRunArgs {
     #[arg(long)]
     pub python_platform: Option<TargetTriple>,
 
+    /// The backend to use when fetching packages in the PyTorch ecosystem (e.g., `cpu`, `cu126`, or `auto`)
+    ///
+    /// When set, uv will ignore the configured index URLs for packages in the PyTorch ecosystem,
+    /// and will instead use the defined backend.
+    ///
+    /// For example, when set to `cpu`, uv will use the CPU-only PyTorch index; when set to `cu126`,
+    /// uv will use the PyTorch index for CUDA 12.6.
+    ///
+    /// The `auto` mode will attempt to detect the appropriate PyTorch index based on the currently
+    /// installed CUDA drivers.
+    ///
+    /// This option is in preview and may change in any future release.
+    #[arg(long, value_enum, env = EnvVars::UV_TORCH_BACKEND)]
+    pub torch_backend: Option<TorchMode>,
+
     #[arg(long, hide = true)]
     pub generate_shell_completion: Option<clap_complete_command::Shell>,
 }
@@ -5547,6 +5562,21 @@ pub struct ToolInstallArgs {
     /// `--python-platform` option is intended for advanced use cases.
     #[arg(long)]
     pub python_platform: Option<TargetTriple>,
+
+    /// The backend to use when fetching packages in the PyTorch ecosystem (e.g., `cpu`, `cu126`, or `auto`)
+    ///
+    /// When set, uv will ignore the configured index URLs for packages in the PyTorch ecosystem,
+    /// and will instead use the defined backend.
+    ///
+    /// For example, when set to `cpu`, uv will use the CPU-only PyTorch index; when set to `cu126`,
+    /// uv will use the PyTorch index for CUDA 12.6.
+    ///
+    /// The `auto` mode will attempt to detect the appropriate PyTorch index based on the currently
+    /// installed CUDA drivers.
+    ///
+    /// This option is in preview and may change in any future release.
+    #[arg(long, value_enum, env = EnvVars::UV_TORCH_BACKEND)]
+    pub torch_backend: Option<TorchMode>,
 }
 
 #[derive(Args)]

crates/uv-cli/src/options.rs

@@ -366,6 +366,7 @@ pub fn resolver_options(
             exclude_newer_package.unwrap_or_default(),
         ),
         link_mode,
+        torch_backend: None,
         no_build: flag(no_build, build, "build"),
         no_build_package: Some(no_build_package),
         no_binary: flag(no_binary, binary, "binary"),

crates/uv-settings/src/settings.rs

@@ -370,6 +370,7 @@ pub struct ResolverOptions {
     pub config_settings_package: Option<PackageConfigSettings>,
     pub exclude_newer: ExcludeNewer,
     pub link_mode: Option<LinkMode>,
+    pub torch_backend: Option<TorchMode>,
     pub upgrade: Option<Upgrade>,
     pub build_isolation: Option<BuildIsolation>,
     pub no_build: Option<bool>,
@@ -404,6 +405,7 @@ pub struct ResolverInstallerOptions {
     pub exclude_newer: Option<ExcludeNewerValue>,
     pub exclude_newer_package: Option<ExcludeNewerPackage>,
     pub link_mode: Option<LinkMode>,
+    pub torch_backend: Option<TorchMode>,
     pub compile_bytecode: Option<bool>,
     pub no_sources: Option<bool>,
     pub upgrade: Option<Upgrade>,
@@ -412,7 +414,6 @@ pub struct ResolverInstallerOptions {
     pub no_build_package: Option<Vec<PackageName>>,
     pub no_binary: Option<bool>,
     pub no_binary_package: Option<Vec<PackageName>>,
-    pub torch_backend: Option<TorchMode>,
 }
 
 impl From<ResolverInstallerSchema> for ResolverInstallerOptions {
@@ -438,6 +439,7 @@ impl From<ResolverInstallerSchema> for ResolverInstallerOptions {
             exclude_newer,
             exclude_newer_package,
             link_mode,
+            torch_backend,
             compile_bytecode,
             no_sources,
             upgrade,
@@ -448,7 +450,6 @@ impl From<ResolverInstallerSchema> for ResolverInstallerOptions {
             no_build_package,
             no_binary,
             no_binary_package,
-            torch_backend,
         } = value;
         Self {
             index,
@@ -473,6 +474,7 @@ impl From<ResolverInstallerSchema> for ResolverInstallerOptions {
             exclude_newer,
             exclude_newer_package,
             link_mode,
+            torch_backend,
             compile_bytecode,
             no_sources,
             upgrade: Upgrade::from_args(
@@ -488,7 +490,6 @@ impl From<ResolverInstallerSchema> for ResolverInstallerOptions {
             no_build_package,
             no_binary,
             no_binary_package,
-            torch_backend,
         }
     }
 }
@@ -1925,6 +1926,7 @@ impl From<ResolverInstallerSchema> for ResolverOptions {
             extra_build_dependencies: value.extra_build_dependencies,
             extra_build_variables: value.extra_build_variables,
             no_sources: value.no_sources,
+            torch_backend: value.torch_backend,
         }
     }
 }
@@ -2004,6 +2006,7 @@ pub struct ToolOptions {
     pub no_build_package: Option<Vec<PackageName>>,
     pub no_binary: Option<bool>,
     pub no_binary_package: Option<Vec<PackageName>>,
+    pub torch_backend: Option<TorchMode>,
 }
 
 impl From<ResolverInstallerOptions> for ToolOptions {
@@ -2034,6 +2037,7 @@ impl From<ResolverInstallerOptions> for ToolOptions {
             no_build_package: value.no_build_package,
             no_binary: value.no_binary,
             no_binary_package: value.no_binary_package,
+            torch_backend: value.torch_backend,
         }
     }
 }
@@ -2068,7 +2072,7 @@ impl From<ToolOptions> for ResolverInstallerOptions {
             no_build_package: value.no_build_package,
             no_binary: value.no_binary,
             no_binary_package: value.no_binary_package,
-            torch_backend: None,
+            torch_backend: value.torch_backend,
         }
     }
 }
@@ -2150,7 +2154,7 @@ pub struct OptionsWire {
     // `crates/uv-workspace/src/pyproject.rs`. The documentation lives on that struct.
     // They're respected in both `pyproject.toml` and `uv.toml` files.
     override_dependencies: Option<Vec<Requirement<VerbatimParsedUrl>>>,
-    exclude_dependencies: Option<Vec<uv_normalize::PackageName>>,
+    exclude_dependencies: Option<Vec<PackageName>>,
     constraint_dependencies: Option<Vec<Requirement<VerbatimParsedUrl>>>,
     build_constraint_dependencies: Option<Vec<Requirement<VerbatimParsedUrl>>>,
     environments: Option<SupportedEnvironments>,

crates/uv/src/commands/build_frontend.rs

@@ -216,6 +216,7 @@ async fn build_impl(
         upgrade: _,
         build_options,
         sources,
+        torch_backend: _,
     } = settings;
 
     // Determine the source to build.

crates/uv/src/commands/project/lock.rs

@@ -470,6 +470,7 @@ async fn do_lock(
         upgrade,
         build_options,
         sources,
+        torch_backend: _,
     } = settings;
 
     if !preview.is_enabled(PreviewFeatures::EXTRA_BUILD_DEPENDENCIES)

crates/uv/src/commands/project/mod.rs

@@ -43,6 +43,7 @@ use uv_resolver::{
 use uv_scripts::Pep723ItemRef;
 use uv_settings::PythonInstallMirrors;
 use uv_static::EnvVars;
+use uv_torch::{TorchSource, TorchStrategy};
 use uv_types::{BuildIsolation, EmptyInstalledPackages, HashStrategy};
 use uv_virtualenv::remove_virtualenv;
 use uv_warnings::{warn_user, warn_user_once};
@@ -278,6 +279,9 @@ pub(crate) enum ProjectError {
     #[error(transparent)]
     RetryParsing(#[from] uv_client::RetryParsingError),
 
+    #[error(transparent)]
+    Accelerator(#[from] uv_torch::AcceleratorError),
+
     #[error(transparent)]
     Anyhow(#[from] anyhow::Error),
 }
@@ -1723,6 +1727,7 @@ pub(crate) async fn resolve_names(
                 prerelease: _,
                 resolution: _,
                 sources,
+                torch_backend,
                 upgrade: _,
             },
         compile_bytecode: _,
@@ -1731,10 +1736,27 @@ pub(crate) async fn resolve_names(
 
     let client_builder = client_builder.clone().keyring(*keyring_provider);
 
+    // Determine the PyTorch backend.
+    let torch_backend = torch_backend
+        .map(|mode| {
+            let source = if uv_auth::PyxTokenStore::from_settings()
+                .is_ok_and(|store| store.has_credentials())
+            {
+                TorchSource::Pyx
+            } else {
+                TorchSource::default()
+            };
+            TorchStrategy::from_mode(mode, source, interpreter.platform().os())
+        })
+        .transpose()
+        .ok()
+        .flatten();
+
     // Initialize the registry client.
     let client = RegistryClientBuilder::new(client_builder, cache.clone())
         .index_locations(index_locations.clone())
         .index_strategy(*index_strategy)
+        .torch_backend(torch_backend.clone())
         .markers(interpreter.markers())
         .platform(interpreter.platform())
         .build();
@@ -1880,6 +1902,7 @@ pub(crate) async fn resolve_environment(
         upgrade: _,
         build_options,
         sources,
+        torch_backend,
     } = settings;
 
     // Respect all requirements from the provided sources.
@@ -1900,10 +1923,33 @@ pub(crate) async fn resolve_environment(
     let marker_env = pip::resolution_markers(None, python_platform, interpreter);
     let python_requirement = PythonRequirement::from_interpreter(interpreter);
 
+    // Determine the PyTorch backend.
+    let torch_backend = torch_backend
+        .map(|mode| {
+            let source = if uv_auth::PyxTokenStore::from_settings()
+                .is_ok_and(|store| store.has_credentials())
+            {
+                TorchSource::Pyx
+            } else {
+                TorchSource::default()
+            };
+            TorchStrategy::from_mode(
+                mode,
+                source,
+                python_platform
+                    .map(|t| t.platform())
+                    .as_ref()
+                    .unwrap_or(interpreter.platform())
+                    .os(),
+            )
+        })
+        .transpose()?;
+
     // Initialize the registry client.
     let client = RegistryClientBuilder::new(client_builder, cache.clone())
         .index_locations(index_locations.clone())
         .index_strategy(*index_strategy)
+        .torch_backend(torch_backend.clone())
         .markers(interpreter.markers())
         .platform(interpreter.platform())
         .build();
@@ -2232,6 +2278,7 @@ pub(crate) async fn update_environment(
                 prerelease,
                 resolution,
                 sources,
+                torch_backend,
                 upgrade,
             },
         compile_bytecode,
@@ -2302,10 +2349,33 @@ pub(crate) async fn update_environment(
         }
     }
 
+    // Determine the PyTorch backend.
+    let torch_backend = torch_backend
+        .map(|mode| {
+            let source = if uv_auth::PyxTokenStore::from_settings()
+                .is_ok_and(|store| store.has_credentials())
+            {
+                TorchSource::Pyx
+            } else {
+                TorchSource::default()
+            };
+            TorchStrategy::from_mode(
+                mode,
+                source,
+                python_platform
+                    .map(|t| t.platform())
+                    .as_ref()
+                    .unwrap_or(interpreter.platform())
+                    .os(),
+            )
+        })
+        .transpose()?;
+
     // Initialize the registry client.
     let client = RegistryClientBuilder::new(client_builder, cache.clone())
         .index_locations(index_locations.clone())
         .index_strategy(*index_strategy)
+        .torch_backend(torch_backend.clone())
         .markers(interpreter.markers())
         .platform(interpreter.platform())
         .build();

crates/uv/src/commands/project/sync.rs

@@ -676,6 +676,7 @@ pub(super) async fn do_sync(
                 prerelease: PrereleaseMode::default(),
                 resolution: ResolutionMode::default(),
                 sources,
+                torch_backend: None,
                 upgrade: Upgrade::default(),
             };
             script_extra_build_requires(

crates/uv/src/commands/project/tree.rs

@@ -212,6 +212,7 @@ pub(crate) async fn tree(
                 upgrade: _,
                 build_options: _,
                 sources: _,
+                torch_backend: _,
             } = &settings;
 
             let capabilities = IndexCapabilities::default();

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

@@ -28,7 +28,7 @@ use uv_python::{
 use uv_requirements::{RequirementsSource, RequirementsSpecification};
 use uv_settings::{PythonInstallMirrors, ResolverInstallerOptions, ToolOptions};
 use uv_tool::InstalledTools;
-use uv_warnings::warn_user;
+use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::WorkspaceCache;
 
 use crate::commands::ExitStatus;
@@ -76,6 +76,12 @@ pub(crate) async fn install(
     printer: Printer,
     preview: Preview,
 ) -> Result<ExitStatus> {
+    if settings.resolver.torch_backend.is_some() {
+        warn_user_once!(
+            "The `--torch-backend` option is experimental and may change without warning."
+        );
+    }
+
     let reporter = PythonDownloadReporter::single(printer);
 
     let python_request = python.as_deref().map(PythonRequest::parse);

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

@@ -129,6 +129,12 @@ pub(crate) async fn run(
             .is_some_and(|ext| ext.eq_ignore_ascii_case("py") || ext.eq_ignore_ascii_case("pyw"))
     }
 
+    if settings.resolver.torch_backend.is_some() {
+        warn_user_once!(
+            "The `--torch-backend` option is experimental and may change without warning."
+        );
+    }
+
     // Read from the `.env` file, if necessary.
     if !no_env_file {
         for env_file_path in env_file.iter().rev().map(PathBuf::as_path) {

crates/uv/src/settings.rs

@@ -586,6 +586,7 @@ impl ToolRunSettings {
             lfs,
             python,
             python_platform,
+            torch_backend,
             generate_shell_completion: _,
         } = args;
 
@@ -615,21 +616,24 @@ impl ToolRunSettings {
             }
         }
 
+        let filesystem_options = filesystem.map(FilesystemOptions::into_options);
+
         let options =
             resolver_installer_options(installer, build).combine(ResolverInstallerOptions::from(
-                filesystem
-                    .clone()
-                    .map(FilesystemOptions::into_options)
-                    .map(|options| options.top_level)
+                filesystem_options
+                    .as_ref()
+                    .map(|options| options.top_level.clone())
                     .unwrap_or_default(),
             ));
 
-        let filesystem_install_mirrors = filesystem
-            .map(FilesystemOptions::into_options)
-            .map(|options| options.install_mirrors)
+        let filesystem_install_mirrors = filesystem_options
+            .map(|options| options.install_mirrors.clone())
             .unwrap_or_default();
 
-        let settings = ResolverInstallerSettings::from(options.clone());
+        let mut settings = ResolverInstallerSettings::from(options.clone());
+        if torch_backend.is_some() {
+            settings.resolver.torch_backend = torch_backend;
+        }
         let lfs = GitLfsSetting::new(lfs.then_some(true), environment.lfs);
 
         Self {
@@ -727,23 +731,27 @@ impl ToolInstallSettings {
             refresh,
             python,
             python_platform,
+            torch_backend,
         } = args;
 
+        let filesystem_options = filesystem.map(FilesystemOptions::into_options);
+
         let options =
             resolver_installer_options(installer, build).combine(ResolverInstallerOptions::from(
-                filesystem
-                    .clone()
-                    .map(FilesystemOptions::into_options)
-                    .map(|options| options.top_level)
+                filesystem_options
+                    .as_ref()
+                    .map(|options| options.top_level.clone())
                     .unwrap_or_default(),
             ));
 
-        let filesystem_install_mirrors = filesystem
-            .map(FilesystemOptions::into_options)
-            .map(|options| options.install_mirrors)
+        let filesystem_install_mirrors = filesystem_options
+            .map(|options| options.install_mirrors.clone())
             .unwrap_or_default();
 
-        let settings = ResolverInstallerSettings::from(options.clone());
+        let mut settings = ResolverInstallerSettings::from(options.clone());
+        if torch_backend.is_some() {
+            settings.resolver.torch_backend = torch_backend;
+        }
         let lfs = GitLfsSetting::new(lfs.then_some(true), environment.lfs);
 
         Self {
@@ -3199,6 +3207,7 @@ pub(crate) struct ResolverSettings {
     pub(crate) prerelease: PrereleaseMode,
     pub(crate) resolution: ResolutionMode,
     pub(crate) sources: SourceStrategy,
+    pub(crate) torch_backend: Option<TorchMode>,
     pub(crate) upgrade: Upgrade,
 }
 
@@ -3253,6 +3262,7 @@ impl From<ResolverOptions> for ResolverSettings {
             extra_build_variables: value.extra_build_variables.unwrap_or_default(),
             exclude_newer: value.exclude_newer,
             link_mode: value.link_mode.unwrap_or_default(),
+            torch_backend: value.torch_backend,
             sources: SourceStrategy::from_args(value.no_sources.unwrap_or_default()),
             upgrade: value.upgrade.unwrap_or_default(),
             build_options: BuildOptions::new(
@@ -3344,6 +3354,7 @@ impl From<ResolverInstallerOptions> for ResolverInstallerSettings {
                 prerelease: value.prerelease.unwrap_or_default(),
                 resolution: value.resolution.unwrap_or_default(),
                 sources: SourceStrategy::from_args(value.no_sources.unwrap_or_default()),
+                torch_backend: value.torch_backend,
                 upgrade: value.upgrade.unwrap_or_default(),
             },
             compile_bytecode: value.compile_bytecode.unwrap_or_default(),

crates/uv/tests/it/show_settings.rs

@@ -3565,6 +3565,7 @@ fn resolve_tool() -> anyhow::Result<()> {
             link_mode: Some(
                 Clone,
             ),
+            torch_backend: None,
             compile_bytecode: None,
             no_sources: None,
             upgrade: None,
@@ -3573,7 +3574,6 @@ fn resolve_tool() -> anyhow::Result<()> {
             no_build_package: None,
             no_binary: None,
             no_binary_package: None,
-            torch_backend: None,
         },
         settings: ResolverInstallerSettings {
             resolver: ResolverSettings {
@@ -3615,6 +3615,7 @@ fn resolve_tool() -> anyhow::Result<()> {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: LowestDirect,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -7912,6 +7913,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -8026,6 +8028,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -8140,6 +8143,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -8254,6 +8258,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -8368,6 +8373,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -8484,6 +8490,7 @@ fn preview_features() {
                 prerelease: IfNecessaryOrExplicit,
                 resolution: Highest,
                 sources: Enabled,
+                torch_backend: None,
                 upgrade: None,
             },
             compile_bytecode: false,
@@ -9738,6 +9745,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: None,
         },
     }
@@ -9857,6 +9865,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: Packages(
                 {
                     PackageName(
@@ -9999,6 +10008,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: All,
         },
     }
@@ -10116,6 +10126,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: None,
         },
     }
@@ -10223,6 +10234,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: All,
         },
     }
@@ -10331,6 +10343,7 @@ fn upgrade_project_cli_config_interaction() -> anyhow::Result<()> {
             prerelease: IfNecessaryOrExplicit,
             resolution: Highest,
             sources: Enabled,
+            torch_backend: None,
             upgrade: Packages(
                 {
                     PackageName(