Add install_mirrors to EnvironmentOptions (#15937)

## Summary

Add install_mirrors to EnvironmentOptions
Relates #14720

## Test Plan

Tests with existing tests

crates/uv-cli/src/lib.rs

@@ -28,6 +28,7 @@ use uv_resolver::{
     AnnotationStyle, ExcludeNewerPackageEntry, ExcludeNewerTimestamp, ForkStrategy, PrereleaseMode,
     ResolutionMode,
 };
+use uv_settings::PythonInstallMirrors;
 use uv_static::EnvVars;
 use uv_torch::TorchMode;
 use uv_workspace::pyproject_mut::AddBoundsKind;
@@ -5363,7 +5364,7 @@ pub struct PythonListArgs {
     /// URL pointing to JSON of custom Python installations.
     ///
     /// Note that currently, only local paths are supported.
-    #[arg(long, env = EnvVars::UV_PYTHON_DOWNLOADS_JSON_URL)]
+    #[arg(long)]
     pub python_downloads_json_url: Option<String>,
 }
 
@@ -5446,7 +5447,7 @@ pub struct PythonInstallArgs {
     /// `https://github.com/astral-sh/python-build-standalone/releases/download/20240713/cpython-3.12.4%2B20240713-aarch64-apple-darwin-install_only.tar.gz`.
     ///
     /// Distributions can be read from a local directory by using the `file://` URL scheme.
-    #[arg(long, env = EnvVars::UV_PYTHON_INSTALL_MIRROR)]
+    #[arg(long)]
     pub mirror: Option<String>,
 
     /// Set the URL to use as the source for downloading PyPy installations.
@@ -5455,13 +5456,13 @@ pub struct PythonInstallArgs {
     /// `https://downloads.python.org/pypy/pypy3.8-v7.3.7-osx64.tar.bz2`.
     ///
     /// Distributions can be read from a local directory by using the `file://` URL scheme.
-    #[arg(long, env = EnvVars::UV_PYPY_INSTALL_MIRROR)]
+    #[arg(long)]
     pub pypy_mirror: Option<String>,
 
     /// URL pointing to JSON of custom Python installations.
     ///
     /// Note that currently, only local paths are supported.
-    #[arg(long, env = EnvVars::UV_PYTHON_DOWNLOADS_JSON_URL)]
+    #[arg(long)]
     pub python_downloads_json_url: Option<String>,
 
     /// Reinstall the requested Python version, if it's already installed.
@@ -5494,6 +5495,17 @@ pub struct PythonInstallArgs {
     pub default: bool,
 }
 
+impl PythonInstallArgs {
+    #[must_use]
+    pub fn install_mirrors(&self) -> PythonInstallMirrors {
+        PythonInstallMirrors {
+            python_install_mirror: self.mirror.clone(),
+            pypy_install_mirror: self.pypy_mirror.clone(),
+            python_downloads_json_url: self.python_downloads_json_url.clone(),
+        }
+    }
+}
+
 #[derive(Args)]
 pub struct PythonUpgradeArgs {
     /// The directory Python installations are stored in.
@@ -5519,7 +5531,7 @@ pub struct PythonUpgradeArgs {
     /// `https://github.com/astral-sh/python-build-standalone/releases/download/20240713/cpython-3.12.4%2B20240713-aarch64-apple-darwin-install_only.tar.gz`.
     ///
     /// Distributions can be read from a local directory by using the `file://` URL scheme.
-    #[arg(long, env = EnvVars::UV_PYTHON_INSTALL_MIRROR)]
+    #[arg(long)]
     pub mirror: Option<String>,
 
     /// Set the URL to use as the source for downloading PyPy installations.
@@ -5528,7 +5540,7 @@ pub struct PythonUpgradeArgs {
     /// `https://downloads.python.org/pypy/pypy3.8-v7.3.7-osx64.tar.bz2`.
     ///
     /// Distributions can be read from a local directory by using the `file://` URL scheme.
-    #[arg(long, env = EnvVars::UV_PYPY_INSTALL_MIRROR)]
+    #[arg(long)]
     pub pypy_mirror: Option<String>,
 
     /// Reinstall the latest Python patch, if it's already installed.
@@ -5541,10 +5553,21 @@ pub struct PythonUpgradeArgs {
     /// URL pointing to JSON of custom Python installations.
     ///
     /// Note that currently, only local paths are supported.
-    #[arg(long, env = EnvVars::UV_PYTHON_DOWNLOADS_JSON_URL)]
+    #[arg(long)]
     pub python_downloads_json_url: Option<String>,
 }
 
+impl PythonUpgradeArgs {
+    #[must_use]
+    pub fn install_mirrors(&self) -> PythonInstallMirrors {
+        PythonInstallMirrors {
+            python_install_mirror: self.mirror.clone(),
+            pypy_install_mirror: self.pypy_mirror.clone(),
+            python_downloads_json_url: self.python_downloads_json_url.clone(),
+        }
+    }
+}
+
 #[derive(Args)]
 pub struct PythonUninstallArgs {
     /// The directory where the Python was installed.

crates/uv-settings/src/lib.rs

@@ -570,6 +570,7 @@ pub enum Error {
 pub struct EnvironmentOptions {
     pub python_install_bin: Option<bool>,
     pub python_install_registry: Option<bool>,
+    pub install_mirrors: PythonInstallMirrors,
 }
 
 impl EnvironmentOptions {
@@ -580,6 +581,17 @@ impl EnvironmentOptions {
             python_install_registry: parse_boolish_environment_variable(
                 EnvVars::UV_PYTHON_INSTALL_REGISTRY,
             )?,
+            install_mirrors: PythonInstallMirrors {
+                python_install_mirror: parse_string_environment_variable(
+                    EnvVars::UV_PYTHON_INSTALL_MIRROR,
+                )?,
+                pypy_install_mirror: parse_string_environment_variable(
+                    EnvVars::UV_PYPY_INSTALL_MIRROR,
+                )?,
+                python_downloads_json_url: parse_string_environment_variable(
+                    EnvVars::UV_PYTHON_DOWNLOADS_JSON_URL,
+                )?,
+            },
         })
     }
 }
@@ -635,3 +647,24 @@ fn parse_boolish_environment_variable(name: &'static str) -> Result<Option<bool>
 
     Ok(Some(value))
 }
+
+/// Parse a string environment variable.
+fn parse_string_environment_variable(name: &'static str) -> Result<Option<String>, Error> {
+    match std::env::var(name) {
+        Ok(v) => {
+            if v.is_empty() {
+                Ok(None)
+            } else {
+                Ok(Some(v))
+            }
+        }
+        Err(e) => match e {
+            std::env::VarError::NotPresent => Ok(None),
+            std::env::VarError::NotUnicode(err) => Err(Error::InvalidEnvironmentVariable {
+                name: name.to_string(),
+                value: err.to_string_lossy().to_string(),
+                err: "expected a valid UTF-8 string".to_string(),
+            }),
+        },
+    }
+}

crates/uv-settings/src/settings.rs

@@ -22,7 +22,6 @@ use uv_resolver::{
     AnnotationStyle, ExcludeNewer, ExcludeNewerPackage, ExcludeNewerTimestamp, ForkStrategy,
     PrereleaseMode, ResolutionMode,
 };
-use uv_static::EnvVars;
 use uv_torch::TorchMode;
 use uv_workspace::pyproject::ExtraBuildDependencies;
 use uv_workspace::pyproject_mut::AddBoundsKind;
@@ -958,7 +957,7 @@ pub struct ResolverInstallerSchema {
 }
 
 /// Shared settings, relevant to all operations that might create managed python installations.
-#[derive(Debug, Clone, PartialEq, Eq, Deserialize, CombineOptions, OptionsMetadata)]
+#[derive(Debug, Clone, Default, PartialEq, Eq, Deserialize, CombineOptions, OptionsMetadata)]
 #[serde(rename_all = "kebab-case")]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 pub struct PythonInstallMirrors {
@@ -1007,26 +1006,15 @@ pub struct PythonInstallMirrors {
     pub python_downloads_json_url: Option<String>,
 }
 
-impl Default for PythonInstallMirrors {
-    fn default() -> Self {
-        Self::resolve(None, None, None)
-    }
-}
-
 impl PythonInstallMirrors {
-    pub fn resolve(
-        python_mirror: Option<String>,
-        pypy_mirror: Option<String>,
-        python_downloads_json_url: Option<String>,
-    ) -> Self {
-        let python_mirror_env = std::env::var(EnvVars::UV_PYTHON_INSTALL_MIRROR).ok();
-        let pypy_mirror_env = std::env::var(EnvVars::UV_PYPY_INSTALL_MIRROR).ok();
-        let python_downloads_json_url_env =
-            std::env::var(EnvVars::UV_PYTHON_DOWNLOADS_JSON_URL).ok();
+    #[must_use]
+    pub fn combine(self, other: Self) -> Self {
         Self {
-            python_install_mirror: python_mirror_env.or(python_mirror),
-            pypy_install_mirror: pypy_mirror_env.or(pypy_mirror),
-            python_downloads_json_url: python_downloads_json_url_env.or(python_downloads_json_url),
+            python_install_mirror: self.python_install_mirror.or(other.python_install_mirror),
+            pypy_install_mirror: self.pypy_install_mirror.or(other.pypy_install_mirror),
+            python_downloads_json_url: self
+                .python_downloads_json_url
+                .or(other.python_downloads_json_url),
         }
     }
 }
@@ -2270,11 +2258,11 @@ impl From<OptionsWire> for Options {
             build_constraint_dependencies,
             environments,
             required_environments,
-            install_mirrors: PythonInstallMirrors::resolve(
+            install_mirrors: PythonInstallMirrors {
                 python_install_mirror,
                 pypy_install_mirror,
                 python_downloads_json_url,
-            ),
+            },
             conflicts,
             publish: PublishOptions {
                 publish_url,

crates/uv/src/lib.rs

@@ -523,7 +523,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             args.compat_args.validate()?;
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipCompileSettings::resolve(args, filesystem);
+            let args = PipCompileSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -624,7 +624,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             args.compat_args.validate()?;
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipSyncSettings::resolve(args, filesystem);
+            let args = PipSyncSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -703,7 +703,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             args.compat_args.validate()?;
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let mut args = PipInstallSettings::resolve(args, filesystem);
+            let mut args = PipInstallSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             let mut requirements = Vec::with_capacity(
@@ -845,7 +845,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PipCommand::Uninstall(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipUninstallSettings::resolve(args, filesystem);
+            let args = PipUninstallSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -881,7 +881,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PipCommand::Freeze(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipFreezeSettings::resolve(args, filesystem);
+            let args = PipFreezeSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -904,7 +904,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             args.compat_args.validate()?;
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipListSettings::resolve(args, filesystem);
+            let args = PipListSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -935,7 +935,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PipCommand::Show(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipShowSettings::resolve(args, filesystem);
+            let args = PipShowSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -956,7 +956,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PipCommand::Tree(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipTreeSettings::resolve(args, filesystem);
+            let args = PipTreeSettings::resolve(args, filesystem, environment);
 
             // Initialize the cache.
             let cache = cache.init()?;
@@ -989,7 +989,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PipCommand::Check(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = PipCheckSettings::resolve(args, filesystem);
+            let args = PipCheckSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1026,7 +1026,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
         }
         Commands::Build(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::BuildSettings::resolve(args, filesystem);
+            let args = settings::BuildSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1085,7 +1085,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             }
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::VenvSettings::resolve(args, filesystem);
+            let args = settings::VenvSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1222,7 +1222,12 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             }
 
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::ToolRunSettings::resolve(args, filesystem, invocation_source);
+            let args = settings::ToolRunSettings::resolve(
+                args,
+                filesystem,
+                invocation_source,
+                environment,
+            );
             show_settings!(args);
 
             // Initialize the cache.
@@ -1299,7 +1304,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: ToolCommand::Install(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::ToolInstallSettings::resolve(args, filesystem);
+            let args = settings::ToolInstallSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1405,7 +1410,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: ToolCommand::Upgrade(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::ToolUpgradeSettings::resolve(args, filesystem);
+            let args = settings::ToolUpgradeSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1458,7 +1463,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PythonCommand::List(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::PythonListSettings::resolve(args, filesystem);
+            let args = settings::PythonListSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1515,7 +1520,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PythonCommand::Upgrade(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::PythonUpgradeSettings::resolve(args, filesystem);
+            let args = settings::PythonUpgradeSettings::resolve(args, filesystem, environment);
             show_settings!(args);
             let upgrade = true;
 
@@ -1598,7 +1603,7 @@ async fn run(mut cli: Cli) -> Result<ExitStatus> {
             command: PythonCommand::Pin(args),
         }) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::PythonPinSettings::resolve(args, filesystem);
+            let args = settings::PythonPinSettings::resolve(args, filesystem, environment);
 
             // Initialize the cache.
             let cache = cache.init()?;
@@ -1744,10 +1749,13 @@ async fn run_project(
         };
     }
 
+    // Load environment variables not handled by Clap
+    let environment = EnvironmentOptions::new()?;
+
     match *project_command {
         ProjectCommand::Init(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::InitSettings::resolve(args, filesystem);
+            let args = settings::InitSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1782,7 +1790,7 @@ async fn run_project(
         }
         ProjectCommand::Run(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::RunSettings::resolve(args, filesystem);
+            let args = settings::RunSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1846,7 +1854,7 @@ async fn run_project(
         }
         ProjectCommand::Sync(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::SyncSettings::resolve(args, filesystem);
+            let args = settings::SyncSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1896,7 +1904,7 @@ async fn run_project(
         }
         ProjectCommand::Lock(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::LockSettings::resolve(args, filesystem);
+            let args = settings::LockSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -1942,7 +1950,7 @@ async fn run_project(
         }
         ProjectCommand::Add(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let mut args = settings::AddSettings::resolve(args, filesystem);
+            let mut args = settings::AddSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // If the script already exists, use it; otherwise, propagate the file path and we'll
@@ -2065,7 +2073,7 @@ async fn run_project(
         }
         ProjectCommand::Remove(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::RemoveSettings::resolve(args, filesystem);
+            let args = settings::RemoveSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -2109,7 +2117,7 @@ async fn run_project(
         }
         ProjectCommand::Version(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::VersionSettings::resolve(args, filesystem);
+            let args = settings::VersionSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -2149,7 +2157,7 @@ async fn run_project(
         }
         ProjectCommand::Tree(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::TreeSettings::resolve(args, filesystem);
+            let args = settings::TreeSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.
@@ -2194,7 +2202,7 @@ async fn run_project(
         }
         ProjectCommand::Export(args) => {
             // Resolve the settings from the command-line arguments and workspace configuration.
-            let args = settings::ExportSettings::resolve(args, filesystem);
+            let args = settings::ExportSettings::resolve(args, filesystem, environment);
             show_settings!(args);
 
             // Initialize the cache.

crates/uv/src/settings.rs

@@ -254,7 +254,11 @@ pub(crate) struct InitSettings {
 impl InitSettings {
     /// Resolve the [`InitSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: InitArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: InitArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let InitArgs {
             path,
             name,
@@ -293,7 +297,7 @@ impl InitSettings {
         )
         .unwrap_or(kind.packaged_by_default());
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
 
@@ -314,7 +318,9 @@ impl InitSettings {
             pin_python: flag(pin_python, no_pin_python, "pin-python").unwrap_or(!bare),
             no_workspace,
             python: python.and_then(Maybe::into_option),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -356,7 +362,11 @@ impl RunSettings {
 
     /// Resolve the [`RunSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: RunArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: RunArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let RunArgs {
             extra,
             all_extras,
@@ -401,7 +411,7 @@ impl RunSettings {
             max_recursion_depth,
         } = args;
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -461,7 +471,9 @@ impl RunSettings {
                 filesystem,
             ),
             env_file: EnvFile::from_args(env_file, no_env_file),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
             max_recursion_depth: max_recursion_depth.unwrap_or(Self::DEFAULT_MAX_RECURSION_DEPTH),
         }
     }
@@ -497,6 +509,7 @@ impl ToolRunSettings {
         args: ToolRunArgs,
         filesystem: Option<FilesystemOptions>,
         invocation_source: ToolRunCommand,
+        environment: EnvironmentOptions,
     ) -> Self {
         let ToolRunArgs {
             command,
@@ -554,7 +567,7 @@ impl ToolRunSettings {
                     .unwrap_or_default(),
             ));
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .map(FilesystemOptions::into_options)
             .map(|options| options.install_mirrors)
             .unwrap_or_default();
@@ -595,7 +608,9 @@ impl ToolRunSettings {
             refresh: Refresh::from(refresh),
             settings,
             options,
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
             env_file,
             no_env_file,
         }
@@ -627,7 +642,11 @@ pub(crate) struct ToolInstallSettings {
 impl ToolInstallSettings {
     /// Resolve the [`ToolInstallSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: ToolInstallArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: ToolInstallArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let ToolInstallArgs {
             package,
             editable,
@@ -656,7 +675,7 @@ impl ToolInstallSettings {
                     .unwrap_or_default(),
             ));
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .map(FilesystemOptions::into_options)
             .map(|options| options.install_mirrors)
             .unwrap_or_default();
@@ -701,7 +720,9 @@ impl ToolInstallSettings {
             refresh: Refresh::from(refresh),
             options,
             settings,
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -719,7 +740,11 @@ pub(crate) struct ToolUpgradeSettings {
 impl ToolUpgradeSettings {
     /// Resolve the [`ToolUpgradeSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: ToolUpgradeArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: ToolUpgradeArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let ToolUpgradeArgs {
             name,
             python,
@@ -788,7 +813,7 @@ impl ToolUpgradeSettings {
 
         let args = resolver_installer_options(installer, build);
         let filesystem = filesystem.map(FilesystemOptions::into_options);
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|options| options.install_mirrors)
             .unwrap_or_default();
@@ -804,7 +829,9 @@ impl ToolUpgradeSettings {
             python_platform,
             args,
             filesystem: top_level,
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -900,7 +927,11 @@ pub(crate) struct PythonListSettings {
 impl PythonListSettings {
     /// Resolve the [`PythonListSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: PythonListArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PythonListArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PythonListArgs {
             request,
             all_versions,
@@ -919,8 +950,9 @@ impl PythonListSettings {
             None => None,
         };
 
-        let python_downloads_json_url =
-            python_downloads_json_url_arg.or(python_downloads_json_url_option);
+        let python_downloads_json_url = python_downloads_json_url_arg
+            .or(environment.install_mirrors.python_downloads_json_url)
+            .or(python_downloads_json_url_option);
 
         let kinds = if only_installed {
             PythonListKinds::Installed
@@ -982,19 +1014,20 @@ impl PythonInstallSettings {
         filesystem: Option<FilesystemOptions>,
         environment: EnvironmentOptions,
     ) -> Self {
-        let options = filesystem.map(FilesystemOptions::into_options);
-        let (python_mirror, pypy_mirror, python_downloads_json_url) = match options {
-            Some(options) => (
-                options.install_mirrors.python_install_mirror,
-                options.install_mirrors.pypy_install_mirror,
-                options.install_mirrors.python_downloads_json_url,
-            ),
-            None => (None, None, None),
-        };
-        let python_mirror = args.mirror.or(python_mirror);
-        let pypy_mirror = args.pypy_mirror.or(pypy_mirror);
-        let python_downloads_json_url =
-            args.python_downloads_json_url.or(python_downloads_json_url);
+        let filesystem_install_mirrors = filesystem
+            .map(|fs| fs.install_mirrors.clone())
+            .unwrap_or_default();
+
+        let install_mirrors = args
+            .install_mirrors()
+            .combine(environment.install_mirrors)
+            .combine(filesystem_install_mirrors);
+
+        let PythonInstallMirrors {
+            python_install_mirror,
+            pypy_install_mirror,
+            python_downloads_json_url,
+        } = install_mirrors;
 
         let PythonInstallArgs {
             install_dir,
@@ -1019,8 +1052,8 @@ impl PythonInstallSettings {
             bin: flag(bin, no_bin, "bin").or(environment.python_install_bin),
             registry: flag(registry, no_registry, "registry")
                 .or(environment.python_install_registry),
-            python_install_mirror: python_mirror,
-            pypy_install_mirror: pypy_mirror,
+            python_install_mirror,
+            pypy_install_mirror,
             python_downloads_json_url,
             default,
         }
@@ -1046,20 +1079,26 @@ pub(crate) struct PythonUpgradeSettings {
 impl PythonUpgradeSettings {
     /// Resolve the [`PythonUpgradeSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: PythonUpgradeArgs, filesystem: Option<FilesystemOptions>) -> Self {
-        let options = filesystem.map(FilesystemOptions::into_options);
-        let (python_mirror, pypy_mirror, python_downloads_json_url) = match options {
-            Some(options) => (
-                options.install_mirrors.python_install_mirror,
-                options.install_mirrors.pypy_install_mirror,
-                options.install_mirrors.python_downloads_json_url,
-            ),
-            None => (None, None, None),
-        };
-        let python_mirror = args.mirror.or(python_mirror);
-        let pypy_mirror = args.pypy_mirror.or(pypy_mirror);
-        let python_downloads_json_url =
-            args.python_downloads_json_url.or(python_downloads_json_url);
+    pub(crate) fn resolve(
+        args: PythonUpgradeArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
+        let filesystem_install_mirrors = filesystem
+            .map(|fs| fs.install_mirrors.clone())
+            .unwrap_or_default();
+
+        let install_mirrors = args
+            .install_mirrors()
+            .combine(environment.install_mirrors)
+            .combine(filesystem_install_mirrors);
+
+        let PythonInstallMirrors {
+            python_install_mirror,
+            pypy_install_mirror,
+            python_downloads_json_url,
+        } = install_mirrors;
+
         let force = false;
         let default = false;
         let bin = None;
@@ -1079,8 +1118,8 @@ impl PythonUpgradeSettings {
             targets,
             force,
             registry,
-            python_install_mirror: python_mirror,
-            pypy_install_mirror: pypy_mirror,
+            python_install_mirror,
+            pypy_install_mirror,
             reinstall,
             python_downloads_json_url,
             default,
@@ -1163,7 +1202,11 @@ pub(crate) struct PythonPinSettings {
 impl PythonPinSettings {
     /// Resolve the [`PythonPinSettings`] from the CLI and workspace configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: PythonPinArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PythonPinArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PythonPinArgs {
             request,
             no_resolved,
@@ -1173,7 +1216,7 @@ impl PythonPinSettings {
             rm,
         } = args;
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
 
@@ -1183,7 +1226,9 @@ impl PythonPinSettings {
             no_project,
             global,
             rm,
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1215,7 +1260,11 @@ pub(crate) struct SyncSettings {
 impl SyncSettings {
     /// Resolve the [`SyncSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: SyncArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: SyncArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let SyncArgs {
             extra,
             all_extras,
@@ -1254,7 +1303,7 @@ impl SyncSettings {
             no_check,
             output_format,
         } = args;
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1315,7 +1364,9 @@ impl SyncSettings {
             python_platform,
             refresh: Refresh::from(refresh),
             settings,
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1337,7 +1388,11 @@ pub(crate) struct LockSettings {
 impl LockSettings {
     /// Resolve the [`LockSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: LockArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: LockArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let LockArgs {
             check,
             check_exists,
@@ -1349,7 +1404,7 @@ impl LockSettings {
             python,
         } = args;
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1362,7 +1417,9 @@ impl LockSettings {
             python: python.and_then(Maybe::into_option),
             refresh: Refresh::from(refresh),
             settings: ResolverSettings::combine(resolver_options(resolver, build), filesystem),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1403,7 +1460,11 @@ pub(crate) struct AddSettings {
 impl AddSettings {
     /// Resolve the [`AddSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: AddArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: AddArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let AddArgs {
             packages,
             requirements,
@@ -1508,7 +1569,7 @@ impl AddSettings {
             }
         }
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .as_ref()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1548,7 +1609,9 @@ impl AddSettings {
                 resolver_installer_options(installer, build),
                 filesystem,
             ),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1574,7 +1637,11 @@ pub(crate) struct RemoveSettings {
 impl RemoveSettings {
     /// Resolve the [`RemoveSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: RemoveArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: RemoveArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let RemoveArgs {
             dev,
             optional,
@@ -1603,7 +1670,7 @@ impl RemoveSettings {
             DependencyType::Production
         };
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1628,7 +1695,9 @@ impl RemoveSettings {
                 resolver_installer_options(installer, build),
                 filesystem,
             ),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1656,7 +1725,11 @@ pub(crate) struct VersionSettings {
 impl VersionSettings {
     /// Resolve the [`RemoveSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: VersionArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: VersionArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let VersionArgs {
             value,
             bump,
@@ -1675,7 +1748,7 @@ impl VersionSettings {
             python,
         } = args;
 
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1697,7 +1770,9 @@ impl VersionSettings {
                 resolver_installer_options(installer, build),
                 filesystem,
             ),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1727,7 +1802,11 @@ pub(crate) struct TreeSettings {
 
 impl TreeSettings {
     /// Resolve the [`TreeSettings`] from the CLI and workspace configuration.
-    pub(crate) fn resolve(args: TreeArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: TreeArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let TreeArgs {
             tree,
             universal,
@@ -1748,7 +1827,8 @@ impl TreeSettings {
             python_platform,
             python,
         } = args;
-        let install_mirrors = filesystem
+
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1779,7 +1859,9 @@ impl TreeSettings {
             python_platform,
             python: python.and_then(Maybe::into_option),
             resolver: ResolverSettings::combine(resolver_options(resolver, build), filesystem),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1812,7 +1894,11 @@ pub(crate) struct ExportSettings {
 impl ExportSettings {
     /// Resolve the [`ExportSettings`] from the CLI and filesystem configuration.
     #[allow(clippy::needless_pass_by_value)]
-    pub(crate) fn resolve(args: ExportArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: ExportArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let ExportArgs {
             format,
             all_packages,
@@ -1851,7 +1937,7 @@ impl ExportSettings {
             script,
             python,
         } = args;
-        let install_mirrors = filesystem
+        let filesystem_install_mirrors = filesystem
             .clone()
             .map(|fs| fs.install_mirrors.clone())
             .unwrap_or_default();
@@ -1897,7 +1983,9 @@ impl ExportSettings {
             python: python.and_then(Maybe::into_option),
             refresh: Refresh::from(refresh),
             settings: ResolverSettings::combine(resolver_options(resolver, build), filesystem),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -1951,7 +2039,11 @@ pub(crate) struct PipCompileSettings {
 
 impl PipCompileSettings {
     /// Resolve the [`PipCompileSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipCompileArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipCompileArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipCompileArgs {
             src_file,
             constraints,
@@ -2117,6 +2209,7 @@ impl PipCompileSettings {
                     ..PipOptions::from(resolver)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2135,7 +2228,11 @@ pub(crate) struct PipSyncSettings {
 
 impl PipSyncSettings {
     /// Resolve the [`PipSyncSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: Box<PipSyncArgs>, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: Box<PipSyncArgs>,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipSyncArgs {
             src_file,
             constraints,
@@ -2215,6 +2312,7 @@ impl PipSyncSettings {
                     ..PipOptions::from(installer)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2240,7 +2338,11 @@ pub(crate) struct PipInstallSettings {
 
 impl PipInstallSettings {
     /// Resolve the [`PipInstallSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipInstallArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipInstallArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipInstallArgs {
             package,
             requirements,
@@ -2377,6 +2479,7 @@ impl PipInstallSettings {
                     ..PipOptions::from(installer)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2393,7 +2496,11 @@ pub(crate) struct PipUninstallSettings {
 
 impl PipUninstallSettings {
     /// Resolve the [`PipUninstallSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipUninstallArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipUninstallArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipUninstallArgs {
             package,
             requirements,
@@ -2428,6 +2535,7 @@ impl PipUninstallSettings {
                     ..PipOptions::default()
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2443,7 +2551,11 @@ pub(crate) struct PipFreezeSettings {
 
 impl PipFreezeSettings {
     /// Resolve the [`PipFreezeSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipFreezeArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipFreezeArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipFreezeArgs {
             exclude_editable,
             strict,
@@ -2466,6 +2578,7 @@ impl PipFreezeSettings {
                     ..PipOptions::default()
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2483,7 +2596,11 @@ pub(crate) struct PipListSettings {
 
 impl PipListSettings {
     /// Resolve the [`PipListSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipListArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipListArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipListArgs {
             editable,
             exclude_editable,
@@ -2513,6 +2630,7 @@ impl PipListSettings {
                     ..PipOptions::from(fetch)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2528,7 +2646,11 @@ pub(crate) struct PipShowSettings {
 
 impl PipShowSettings {
     /// Resolve the [`PipShowSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipShowArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipShowArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipShowArgs {
             package,
             strict,
@@ -2551,6 +2673,7 @@ impl PipShowSettings {
                     ..PipOptions::default()
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2571,7 +2694,11 @@ pub(crate) struct PipTreeSettings {
 
 impl PipTreeSettings {
     /// Resolve the [`PipTreeSettings`] from the CLI and workspace configuration.
-    pub(crate) fn resolve(args: PipTreeArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipTreeArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipTreeArgs {
             show_version_specifiers,
             tree,
@@ -2600,6 +2727,7 @@ impl PipTreeSettings {
                     ..PipOptions::from(fetch)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2613,7 +2741,11 @@ pub(crate) struct PipCheckSettings {
 
 impl PipCheckSettings {
     /// Resolve the [`PipCheckSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: PipCheckArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: PipCheckArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let PipCheckArgs {
             python,
             system,
@@ -2632,6 +2764,7 @@ impl PipCheckSettings {
                     ..PipOptions::default()
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -2659,7 +2792,11 @@ pub(crate) struct BuildSettings {
 
 impl BuildSettings {
     /// Resolve the [`BuildSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: BuildArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: BuildArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let BuildArgs {
             src,
             out_dir,
@@ -2681,8 +2818,7 @@ impl BuildSettings {
             refresh,
             resolver,
         } = args;
-
-        let install_mirrors = match &filesystem {
+        let filesystem_install_mirrors = match &filesystem {
             Some(fs) => fs.install_mirrors.clone(),
             None => PythonInstallMirrors::default(),
         };
@@ -2708,7 +2844,9 @@ impl BuildSettings {
             python: python.and_then(Maybe::into_option),
             refresh: Refresh::from(refresh),
             settings: ResolverSettings::combine(resolver_options(resolver, build), filesystem),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }
@@ -2731,7 +2869,11 @@ pub(crate) struct VenvSettings {
 
 impl VenvSettings {
     /// Resolve the [`VenvSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn resolve(args: VenvArgs, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn resolve(
+        args: VenvArgs,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let VenvArgs {
             python,
             system,
@@ -2779,6 +2921,7 @@ impl VenvSettings {
                     ..PipOptions::from(index_args)
                 },
                 filesystem,
+                environment,
             ),
         }
     }
@@ -3041,11 +3184,15 @@ pub(crate) struct PipSettings {
 
 impl PipSettings {
     /// Resolve the [`PipSettings`] from the CLI and filesystem configuration.
-    pub(crate) fn combine(args: PipOptions, filesystem: Option<FilesystemOptions>) -> Self {
+    pub(crate) fn combine(
+        args: PipOptions,
+        filesystem: Option<FilesystemOptions>,
+        environment: EnvironmentOptions,
+    ) -> Self {
         let Options {
             top_level,
             pip,
-            install_mirrors,
+            install_mirrors: filesystem_install_mirrors,
             ..
         } = filesystem
             .map(FilesystemOptions::into_options)
@@ -3386,7 +3533,9 @@ impl PipSettings {
                     top_level_no_build_package.unwrap_or_default(),
                 )),
             ),
-            install_mirrors,
+            install_mirrors: environment
+                .install_mirrors
+                .combine(filesystem_install_mirrors),
         }
     }
 }

crates/uv/tests/it/common/mod.rs

@@ -466,6 +466,15 @@ impl TestContext {
         self
     }
 
+    #[must_use]
+    pub fn with_empty_python_install_mirror(mut self) -> Self {
+        self.extra_env.push((
+            EnvVars::UV_PYTHON_INSTALL_MIRROR.into(),
+            String::new().into(),
+        ));
+        self
+    }
+
     /// Add extra directories and configuration for managed Python installations.
     #[must_use]
     pub fn with_managed_python_dirs(mut self) -> Self {

crates/uv/tests/it/help.rs

@@ -529,8 +529,6 @@ fn help_subsubcommand() {
               `https://github.com/astral-sh/python-build-standalone/releases/download/20240713/cpython-3.12.4%2B20240713-aarch64-apple-darwin-install_only.tar.gz`.
               
               Distributions can be read from a local directory by using the `file://` URL scheme.
-              
-              [env: UV_PYTHON_INSTALL_MIRROR=]
 
           --pypy-mirror <PYPY_MIRROR>
               Set the URL to use as the source for downloading PyPy installations.
@@ -539,15 +537,11 @@ fn help_subsubcommand() {
               `https://downloads.python.org/pypy/pypy3.8-v7.3.7-osx64.tar.bz2`.
               
               Distributions can be read from a local directory by using the `file://` URL scheme.
-              
-              [env: UV_PYPY_INSTALL_MIRROR=]
 
           --python-downloads-json-url <PYTHON_DOWNLOADS_JSON_URL>
               URL pointing to JSON of custom Python installations.
               
               Note that currently, only local paths are supported.
-              
-              [env: UV_PYTHON_DOWNLOADS_JSON_URL=]
 
       -r, --reinstall
               Reinstall the requested Python version, if it's already installed.
@@ -812,13 +806,11 @@ fn help_flag_subsubcommand() {
           --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=]
+              Set the URL to use as the source for downloading Python installations
           --pypy-mirror <PYPY_MIRROR>
-              Set the URL to use as the source for downloading PyPy installations [env:
-              UV_PYPY_INSTALL_MIRROR=]
+              Set the URL to use as the source for downloading PyPy installations
           --python-downloads-json-url <PYTHON_DOWNLOADS_JSON_URL>
-              URL pointing to JSON of custom Python installations [env: UV_PYTHON_DOWNLOADS_JSON_URL=]
+              URL pointing to JSON of custom Python installations
       -r, --reinstall
               Reinstall the requested Python version, if it's already installed
       -f, --force

crates/uv/tests/it/python_install.rs

@@ -22,6 +22,7 @@ fn python_install() {
         .with_filtered_python_keys()
         .with_filtered_exe_suffix()
         .with_managed_python_dirs()
+        .with_empty_python_install_mirror()
         .with_python_download_cache();
 
     // Install the latest version

crates/uv/tests/it/python_upgrade.rs

@@ -703,6 +703,7 @@ fn python_upgrade_force_install() -> Result<()> {
     let context = TestContext::new_with_versions(&["3.13"])
         .with_filtered_python_keys()
         .with_filtered_exe_suffix()
+        .with_empty_python_install_mirror()
         .with_managed_python_dirs();
 
     context