prefetch-npm-deps: extract package names from lockfile keys

The current approach parses tarball URLs to extract package names for
packument fetching. This is fragile as it only handles npmjs.org URLs
and requires special-casing other registries.

Use lockfile keys directly instead. The lockfile already contains the
canonical package names in the form "node_modules/@scope/name", so we
can simply strip the prefix rather than parsing URLs.

This handles all registries uniformly and eliminates the URL parsing
code along with its tests.

pkgs/build-support/node/prefetch-npm-deps/src/main.rs

@@ -23,28 +23,6 @@ fn cache_map_path() -> Option<PathBuf> {
     env::var_os("CACHE_MAP_PATH").map(PathBuf::from)
 }
 
-/// Extract the package name from an npm registry tarball URL.
-/// e.g., "https://registry.npmjs.org/@types/react-dom/-/react-dom-19.1.6.tgz"
-///    -> Some("@types/react-dom")
-fn extract_package_name_from_url(url: &Url) -> Option<String> {
-    // Only handle npm registry URLs
-    let host = url.host_str()?;
-    if !host.contains("npmjs.org") && !host.contains("npm.") {
-        return None;
-    }
-
-    let path = url.path();
-    // npm tarball URLs look like:
-    // /@scope/name/-/name-version.tgz
-    // /name/-/name-version.tgz
-
-    // Find the "/-/" separator which precedes the tarball filename
-    let separator_idx = path.find("/-/")?;
-    let package_path = &path[1..separator_idx]; // Skip leading /
-
-    Some(package_path.to_string())
-}
-
 /// Get the packument URL for a package name
 fn get_packument_url(registry: &str, package_name: &str) -> anyhow::Result<Url> {
     // URL-encode the package name for scoped packages
@@ -353,9 +331,10 @@ fn main() -> anyhow::Result<()> {
     cache.init()?;
 
     // Collect unique package names for packument fetching
+    // Extract from lockfile keys like "node_modules/@scope/name" -> "@scope/name"
     let package_names: HashSet<String> = packages
         .iter()
-        .filter_map(|p| extract_package_name_from_url(&p.url))
+        .filter_map(|p| p.name.rsplit_once("node_modules/").map(|(_, n)| n.to_string()))
         .collect();
 
     // Fetch and cache tarballs
@@ -553,34 +532,4 @@ mod tests {
         Ok(())
     }
 
-    #[test]
-    fn test_extract_package_name_from_url() {
-        use super::extract_package_name_from_url;
-        use url::Url;
-
-        // Regular package
-        assert_eq!(
-            extract_package_name_from_url(
-                &Url::parse("https://registry.npmjs.org/lodash/-/lodash-4.17.21.tgz").unwrap()
-            ),
-            Some("lodash".to_string())
-        );
-
-        // Scoped package
-        assert_eq!(
-            extract_package_name_from_url(
-                &Url::parse("https://registry.npmjs.org/@types/react-dom/-/react-dom-19.1.6.tgz")
-                    .unwrap()
-            ),
-            Some("@types/react-dom".to_string())
-        );
-
-        // Non-npm URL should return None
-        assert_eq!(
-            extract_package_name_from_url(
-                &Url::parse("https://github.com/foo/bar/archive/main.tar.gz").unwrap()
-            ),
-            None
-        );
-    }
 }