Route skill discovery and loading through EnvironmentAccess (#46293)

## What changed

Use `EnvironmentAccess` for skill discovery, environment skill loading, and plugin namespace resolution, replacing direct `ExecutorFileSystem` calls with explicit `None` sandbox arguments.

Wrap existing host and executor filesystems with `FileSystemEnvironmentAccessor::unrestricted` to preserve their current access behavior. Update discovery, loading, and namespace tests to use the same adapter.

GitOrigin-RevId: d68168cc0ee19dc303ef4ee726cf1de1a8db81e0

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

@@ -1,6 +1,7 @@
 //! Resolve plugin namespace from skill file paths by walking ancestors for `plugin.json`.
 
-use codex_exec_server::ExecutorFileSystem;
+use codex_exec_server::EnvironmentAccess;
+use codex_exec_server::EnvironmentAccessExt;
 use codex_exec_server::GetMetadataOptions;
 use codex_exec_server::ReadFileOptions;
 use codex_exec_server_protocol::DISCOVERABLE_PLUGIN_MANIFEST_PATHS;
@@ -87,18 +88,14 @@ struct RawPluginManifestName {
 
 /// Returns the plugin manifest `name` defined directly below `plugin_root`.
 pub async fn plugin_namespace_for_root_uri(
-    fs: &dyn ExecutorFileSystem,
+    fs: &dyn EnvironmentAccess,
     plugin_root: &PathUri,
 ) -> Option<String> {
     let mut manifest_path = None;
     for relative_path in DISCOVERABLE_PLUGIN_MANIFEST_PATHS {
         let candidate = plugin_root.join(relative_path).ok()?;
         match fs
-            .get_metadata(
-                &candidate,
-                GetMetadataOptions::default(),
-                /*sandbox*/ None,
-            )
+            .get_metadata(&candidate, GetMetadataOptions::default())
             .await
         {
             Ok(metadata) if metadata.is_file => {
@@ -109,11 +106,7 @@ pub async fn plugin_namespace_for_root_uri(
         }
     }
     let contents = fs
-        .read_file_text(
-            &manifest_path?,
-            ReadFileOptions::default(),
-            /*sandbox*/ None,
-        )
+        .read_file_text(&manifest_path?, ReadFileOptions::default())
         .await
         .ok()?;
     let RawPluginManifestName { name: raw_name } = serde_json::from_str(&contents).ok()?;
@@ -131,6 +124,7 @@ mod tests {
     use super::AGENT_PLUGIN_SCHEMA_URI;
     use super::find_plugin_manifest_path;
     use super::plugin_namespace_for_root_uri;
+    use codex_exec_server::FileSystemEnvironmentAccessor;
     use codex_exec_server::LOCAL_FS;
     use codex_utils_absolute_path::test_support::PathBufExt;
     use codex_utils_path_uri::PathUri;
@@ -157,7 +151,7 @@ mod tests {
 
         assert_eq!(
             plugin_namespace_for_root_uri(
-                LOCAL_FS.as_ref(),
+                &FileSystemEnvironmentAccessor::unrestricted(&LOCAL_FS),
                 &PathUri::from_abs_path(&plugin_root.abs()),
             )
             .await,
@@ -180,7 +174,7 @@ mod tests {
 
         assert_eq!(
             plugin_namespace_for_root_uri(
-                LOCAL_FS.as_ref(),
+                &FileSystemEnvironmentAccessor::unrestricted(&LOCAL_FS),
                 &PathUri::from_abs_path(&plugin_root.abs()),
             )
             .await,
@@ -204,7 +198,7 @@ mod tests {
 
         assert_eq!(
             plugin_namespace_for_root_uri(
-                LOCAL_FS.as_ref(),
+                &FileSystemEnvironmentAccessor::unrestricted(&LOCAL_FS),
                 &PathUri::from_abs_path(&plugin_root.abs()),
             )
             .await,