Remove obsolete plugin skill discovery helpers (#37832)

## What changed

- Remove the path-only `effective_skill_roots` API and its type-erasing trait in favor of `effective_plugin_skill_roots`, which preserves plugin metadata.
- Remove skill-path ancestor lookup helpers and keep namespace resolution scoped to an explicit plugin root.
- Update plugin manager and namespace tests to exercise the retained APIs directly.

GitOrigin-RevId: 507bf43bc6147bb5ab2deba4fa176bea2535159c

codex-rs/core-plugins/src/manager_tests.rs

@@ -991,7 +991,11 @@ async fn load_plugins_loads_default_skills_and_mcp_servers() {
         }]
     );
     assert_eq!(
-        outcome.effective_skill_roots(),
+        outcome
+            .effective_plugin_skill_roots()
+            .into_iter()
+            .map(|root| root.path)
+            .collect::<Vec<_>>(),
         vec![plugin_root.join("skills").abs()]
     );
     assert_eq!(outcome.effective_mcp_servers().len(), 1);
@@ -2596,7 +2600,7 @@ async fn load_plugins_preserves_disabled_plugins_without_effective_contributions
             error: None,
         }]
     );
-    assert!(outcome.effective_skill_roots().is_empty());
+    assert!(outcome.effective_plugin_skill_roots().is_empty());
     assert!(outcome.effective_mcp_servers().is_empty());
 }
 
@@ -3086,7 +3090,7 @@ async fn load_plugins_rejects_invalid_plugin_keys() {
         outcome.plugins()[0].error.as_deref(),
         Some("invalid plugin key `sample`; expected <plugin>@<marketplace>")
     );
-    assert!(outcome.effective_skill_roots().is_empty());
+    assert!(outcome.effective_plugin_skill_roots().is_empty());
     assert!(outcome.effective_mcp_servers().is_empty());
 }
 

codex-rs/plugin/src/lib.rs

@@ -3,7 +3,6 @@
 use std::collections::HashSet;
 
 pub use codex_utils_plugins::mention_syntax;
-pub use codex_utils_plugins::plugin_namespace_for_skill_path;
 
 mod load_outcome;
 pub mod manifest;
@@ -12,7 +11,6 @@ mod provider;
 
 use codex_config::HookEventsToml;
 use codex_utils_absolute_path::AbsolutePathBuf;
-pub use load_outcome::EffectiveSkillRoots;
 pub use load_outcome::LoadedPlugin;
 pub use load_outcome::PluginLoadOutcome;
 pub use load_outcome::prompt_safe_plugin_description;

codex-rs/plugin/src/load_outcome.rs

@@ -120,18 +120,6 @@ impl<M: Clone> PluginLoadOutcome<M> {
         }
     }
 
-    pub fn effective_skill_roots(&self) -> Vec<AbsolutePathBuf> {
-        let mut skill_roots: Vec<AbsolutePathBuf> = self
-            .plugins
-            .iter()
-            .filter(|plugin| plugin.is_active())
-            .flat_map(|plugin| plugin.skill_roots.iter().cloned())
-            .collect();
-        skill_roots.sort_unstable();
-        skill_roots.dedup();
-        skill_roots
-    }
-
     pub fn effective_plugin_skill_roots(&self) -> Vec<PluginSkillRoot> {
         let mut skill_roots = Vec::new();
         let mut seen_paths = HashSet::new();
@@ -205,24 +193,6 @@ impl<M: Clone> PluginLoadOutcome<M> {
     }
 }
 
-/// Implemented by [`PluginLoadOutcome`] so callers (e.g. skills) can depend on `codex-plugin`
-/// without naming the MCP config type parameter.
-pub trait EffectiveSkillRoots {
-    fn effective_skill_roots(&self) -> Vec<AbsolutePathBuf>;
-
-    fn effective_plugin_skill_roots(&self) -> Vec<PluginSkillRoot>;
-}
-
-impl<M: Clone> EffectiveSkillRoots for PluginLoadOutcome<M> {
-    fn effective_skill_roots(&self) -> Vec<AbsolutePathBuf> {
-        PluginLoadOutcome::effective_skill_roots(self)
-    }
-
-    fn effective_plugin_skill_roots(&self) -> Vec<PluginSkillRoot> {
-        PluginLoadOutcome::effective_plugin_skill_roots(self)
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;

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

@@ -16,8 +16,6 @@ pub use plugin_namespace::SUPPORTED_AGENT_PLUGIN_SCHEMA_URIS;
 pub use plugin_namespace::agent_plugin_schema_status;
 pub use plugin_namespace::find_plugin_manifest_path;
 pub use plugin_namespace::plugin_namespace_for_root_uri;
-pub use plugin_namespace::plugin_namespace_for_skill_path;
-pub use plugin_namespace::plugin_namespace_for_skill_uri;
 
 #[derive(Debug, Clone, Copy, Default, PartialEq, Eq, Hash)]
 pub enum SkillDiscoveryMode {

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

@@ -2,7 +2,6 @@
 
 use codex_exec_server::ExecutorFileSystem;
 use codex_exec_server_protocol::DISCOVERABLE_PLUGIN_MANIFEST_PATHS;
-use codex_utils_absolute_path::AbsolutePathBuf;
 use codex_utils_path_uri::PathUri;
 use std::path::Path;
 use std::path::PathBuf;
@@ -100,38 +99,15 @@ pub async fn plugin_namespace_for_root_uri(
     )
 }
 
-/// Returns the plugin manifest `name` for the nearest ancestor of `path` that contains a valid
-/// plugin manifest (same `name` rules as full manifest loading in codex-core).
-pub async fn plugin_namespace_for_skill_path(
-    fs: &dyn ExecutorFileSystem,
-    path: &AbsolutePathBuf,
-) -> Option<String> {
-    plugin_namespace_for_skill_uri(fs, &PathUri::from_abs_path(path)).await
-}
-
-/// Returns the plugin manifest `name` for the nearest URI ancestor of `path`.
-pub async fn plugin_namespace_for_skill_uri(
-    fs: &dyn ExecutorFileSystem,
-    path: &PathUri,
-) -> Option<String> {
-    let mut ancestor = Some(path.clone());
-    while let Some(path) = ancestor {
-        if let Some(name) = plugin_namespace_for_root_uri(fs, &path).await {
-            return Some(name);
-        }
-        ancestor = path.parent();
-    }
-    None
-}
-
 #[cfg(test)]
 mod tests {
     use super::AGENT_PLUGIN_MANIFEST_RELATIVE_PATH;
     use super::AGENT_PLUGIN_SCHEMA_URI;
     use super::find_plugin_manifest_path;
-    use super::plugin_namespace_for_skill_path;
+    use super::plugin_namespace_for_root_uri;
     use codex_exec_server::LOCAL_FS;
     use codex_utils_absolute_path::test_support::PathBufExt;
+    use codex_utils_path_uri::PathUri;
     use std::fs;
     use tempfile::tempdir;
 
@@ -154,7 +130,11 @@ mod tests {
         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,
+            plugin_namespace_for_root_uri(
+                LOCAL_FS.as_ref(),
+                &PathUri::from_abs_path(&plugin_root.abs()),
+            )
+            .await,
             Some("sample".to_string())
         );
     }
@@ -173,7 +153,11 @@ mod tests {
         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,
+            plugin_namespace_for_root_uri(
+                LOCAL_FS.as_ref(),
+                &PathUri::from_abs_path(&plugin_root.abs()),
+            )
+            .await,
             Some("sample".to_string())
         );
         assert_eq!(find_plugin_manifest_path(&plugin_root), Some(manifest_path));
@@ -193,7 +177,11 @@ mod tests {
         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,
+            plugin_namespace_for_root_uri(
+                LOCAL_FS.as_ref(),
+                &PathUri::from_abs_path(&plugin_root.abs()),
+            )
+            .await,
             Some("sample".to_string())
         );
         assert_eq!(find_plugin_manifest_path(&plugin_root), Some(manifest_path));