Attach subcommand to User-Agent string

crates/uv-client/src/base_client.rs

@@ -89,6 +89,8 @@ pub struct BaseClientBuilder<'a> {
     cross_origin_credential_policy: CrossOriginCredentialsPolicy,
     /// Optional custom reqwest client to use instead of creating a new one.
     custom_client: Option<Client>,
+    /// uv subcommand in which this client is being used
+    subcommand: Option<Vec<String>>,
 }
 
 /// The policy for handling HTTP redirects.
@@ -143,6 +145,7 @@ impl Default for BaseClientBuilder<'_> {
             redirect_policy: RedirectPolicy::default(),
             cross_origin_credential_policy: CrossOriginCredentialsPolicy::Secure,
             custom_client: None,
+            subcommand: None,
         }
     }
 }
@@ -276,6 +279,12 @@ impl<'a> BaseClientBuilder<'a> {
         self
     }
 
+    #[must_use]
+    pub fn subcommand(mut self, subcommand: Vec<String>) -> Self {
+        self.subcommand = Some(subcommand);
+        self
+    }
+
     pub fn is_native_tls(&self) -> bool {
         self.native_tls
     }
@@ -358,7 +367,7 @@ impl<'a> BaseClientBuilder<'a> {
         let mut user_agent_string = format!("uv/{}", version());
 
         // Add linehaul metadata.
-        let linehaul = LineHaul::new(self.markers, self.platform);
+        let linehaul = LineHaul::new(self.markers, self.platform, self.subcommand.clone());
         if let Ok(output) = serde_json::to_string(&linehaul) {
             let _ = write!(user_agent_string, " {output}");
         }

crates/uv-client/src/linehaul.rs

@@ -12,6 +12,7 @@ use uv_version::version;
 pub struct Installer {
     pub name: Option<String>,
     pub version: Option<String>,
+    pub subcommand: Option<Vec<String>>,
 }
 
 #[derive(Debug, Clone, PartialEq, Deserialize, Serialize)]
@@ -63,7 +64,11 @@ pub struct LineHaul {
 impl LineHaul {
     /// Initializes Linehaul information based on PEP 508 markers.
     #[instrument(name = "linehaul", skip_all)]
-    pub fn new(markers: Option<&MarkerEnvironment>, platform: Option<&Platform>) -> Self {
+    pub fn new(
+        markers: Option<&MarkerEnvironment>,
+        platform: Option<&Platform>,
+        subcommand: Option<Vec<String>>,
+    ) -> Self {
         // https://github.com/pypa/pip/blob/24.0/src/pip/_internal/network/session.py#L87
         let looks_like_ci = [
             EnvVars::BUILD_BUILDID,
@@ -123,6 +128,7 @@ impl LineHaul {
             installer: Option::from(Installer {
                 name: Some("uv".to_string()),
                 version: Some(version().to_string()),
+                subcommand,
             }),
             python: markers.map(|markers| markers.python_full_version().version.to_string()),
             implementation: Option::from(Implementation {

crates/uv-client/tests/it/user_agent_version.rs

@@ -57,7 +57,70 @@ async fn test_user_agent_has_version() -> Result<()> {
         assert_json_snapshot!(&linehaul.installer, @r#"
         {
           "name": "uv",
-          "version": "[VERSION]"
+          "version": "[VERSION]",
+          "subcommand": null
+        }
+        "#);
+    });
+
+    // Wait for the server task to complete, to be a good citizen.
+    let _ = server_task.await?;
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn test_user_agent_has_subcommand() -> Result<()> {
+    // Initialize dummy http server
+    let (server_task, addr) = start_http_user_agent_server().await?;
+
+    // Initialize uv-client
+    let cache = Cache::temp()?.init()?;
+    let client = RegistryClientBuilder::new(
+        BaseClientBuilder::default().subcommand(vec!["foo".to_owned(), "bar".to_owned()]),
+        cache,
+    )
+    .build();
+
+    // Send request to our dummy server
+    let url = DisplaySafeUrl::from_str(&format!("http://{addr}"))?;
+    let res = client
+        .cached_client()
+        .uncached()
+        .for_host(&url)
+        .get(Url::from(url))
+        .send()
+        .await?;
+
+    // Check the HTTP status
+    assert!(res.status().is_success());
+
+    // Check User Agent
+    let body = res.text().await?;
+
+    let (uv_version, uv_linehaul) = body
+        .split_once(' ')
+        .expect("Failed to split User-Agent header");
+
+    // Deserializing Linehaul
+    let linehaul: LineHaul = serde_json::from_str(uv_linehaul)?;
+
+    // Assert linehaul user agent
+    let filters = vec![(version(), "[VERSION]")];
+    with_settings!({
+        filters => filters
+    }, {
+        // Assert uv version
+        assert_snapshot!(uv_version, @"uv/[VERSION]");
+        // Assert linehaul json
+        assert_json_snapshot!(&linehaul.installer, @r#"
+        {
+          "name": "uv",
+          "version": "[VERSION]",
+          "subcommand": [
+            "foo",
+            "bar"
+          ]
         }
         "#);
     });
@@ -152,11 +215,12 @@ async fn test_user_agent_has_linehaul() -> Result<()> {
         assert_json_snapshot!(&linehaul, {
             ".distro" => "[distro]",
             ".ci" => "[ci]"
-        }, @r###"
+        }, @r#"
         {
           "installer": {
             "name": "uv",
-            "version": "[VERSION]"
+            "version": "[VERSION]",
+            "subcommand": null
           },
           "python": "3.12.2",
           "implementation": {
@@ -174,7 +238,7 @@ async fn test_user_agent_has_linehaul() -> Result<()> {
           "rustc_version": null,
           "ci": "[ci]"
         }
-        "###);
+        "#);
     });
 
     // Assert distro