feat: Handle alternate plugin manifest paths (#18182)

Load plugin manifests through a shared discoverable-path helper so
manifest reads, installs, and skill names all see the same alternate
manifest location.

codex-rs/utils/plugins/src/lib.rs

@@ -5,5 +5,5 @@ pub mod mcp_connector;
 pub mod mention_syntax;
 pub mod plugin_namespace;
 
-pub use plugin_namespace::PLUGIN_MANIFEST_PATH;
+pub use plugin_namespace::find_plugin_manifest_path;
 pub use plugin_namespace::plugin_namespace_for_skill_path;

codex-rs/utils/plugins/src/plugin_namespace.rs

@@ -2,9 +2,18 @@
 
 use codex_exec_server::ExecutorFileSystem;
 use codex_utils_absolute_path::AbsolutePathBuf;
+use std::path::Path;
+use std::path::PathBuf;
 
-/// Relative path from a plugin root to its manifest file.
-pub const PLUGIN_MANIFEST_PATH: &str = ".codex-plugin/plugin.json";
+const DISCOVERABLE_PLUGIN_MANIFEST_PATHS: &[&str] =
+    &[".codex-plugin/plugin.json", ".claude-plugin/plugin.json"];
+
+pub fn find_plugin_manifest_path(plugin_root: &Path) -> Option<PathBuf> {
+    DISCOVERABLE_PLUGIN_MANIFEST_PATHS
+        .iter()
+        .map(|relative_path| plugin_root.join(relative_path))
+        .find(|manifest_path| manifest_path.is_file())
+}
 
 #[derive(serde::Deserialize)]
 #[serde(rename_all = "camelCase")]
@@ -17,11 +26,18 @@ async fn plugin_manifest_name(
     fs: &dyn ExecutorFileSystem,
     plugin_root: &AbsolutePathBuf,
 ) -> Option<String> {
-    let manifest_path = plugin_root.join(PLUGIN_MANIFEST_PATH);
-    match fs.get_metadata(&manifest_path, /*sandbox*/ None).await {
-        Ok(metadata) if metadata.is_file => {}
-        Ok(_) | Err(_) => return None,
+    let mut manifest_path = None;
+    for relative_path in DISCOVERABLE_PLUGIN_MANIFEST_PATHS {
+        let candidate = plugin_root.join(relative_path);
+        match fs.get_metadata(&candidate, /*sandbox*/ None).await {
+            Ok(metadata) if metadata.is_file => {
+                manifest_path = Some(candidate);
+                break;
+            }
+            Ok(_) | Err(_) => {}
+        }
     }
+    let manifest_path = manifest_path?;
     let contents = fs
         .read_file_text(&manifest_path, /*sandbox*/ None)
         .await
@@ -53,12 +69,15 @@ pub async fn plugin_namespace_for_skill_path(
 
 #[cfg(test)]
 mod tests {
+    use super::find_plugin_manifest_path;
     use super::plugin_namespace_for_skill_path;
     use codex_exec_server::LOCAL_FS;
     use codex_utils_absolute_path::test_support::PathBufExt;
     use std::fs;
     use tempfile::tempdir;
 
+    const ALTERNATE_PLUGIN_MANIFEST_RELATIVE_PATH: &str = ".claude-plugin/plugin.json";
+
     #[tokio::test]
     async fn uses_manifest_name() {
         let tmp = tempdir().expect("tempdir");
@@ -79,4 +98,24 @@ mod tests {
             Some("sample".to_string())
         );
     }
+
+    #[tokio::test]
+    async fn uses_name_from_alternate_discoverable_manifest_path() {
+        let tmp = tempdir().expect("tempdir");
+        let plugin_root = tmp.path().join("plugins/sample");
+        let skill_path = plugin_root.join("skills/search/SKILL.md");
+        let manifest_path = plugin_root.join(ALTERNATE_PLUGIN_MANIFEST_RELATIVE_PATH);
+
+        fs::create_dir_all(skill_path.parent().expect("parent")).expect("mkdir");
+        fs::create_dir_all(manifest_path.parent().expect("manifest parent"))
+            .expect("mkdir manifest");
+        fs::write(&manifest_path, r#"{"name":"sample"}"#).expect("write manifest");
+        fs::write(&skill_path, "---\ndescription: search\n---\n").expect("write skill");
+
+        assert_eq!(
+            plugin_namespace_for_skill_path(LOCAL_FS.as_ref(), &skill_path.abs()).await,
+            Some("sample".to_string())
+        );
+        assert_eq!(find_plugin_manifest_path(&plugin_root), Some(manifest_path));
+    }
 }