Reimplement skills loading using SkillsManager + skills/list op. (#7914)

refactor the way we load and manage skills:
1. Move skill discovery/caching into SkillsManager and reuse it across
sessions.
2. Add the skills/list API (Op::ListSkills/SkillsListResponse) to fetch
skills for one or more cwds. Also update app-server for VSCE/App;
3. Trigger skills/list during session startup so UIs preload skills and
handle errors immediately.

codex-rs/tui2/src/chatwidget.rs

@@ -33,6 +33,7 @@ use codex_core::protocol::ExecCommandEndEvent;
 use codex_core::protocol::ExecCommandSource;
 use codex_core::protocol::ExitedReviewModeEvent;
 use codex_core::protocol::ListCustomPromptsResponseEvent;
+use codex_core::protocol::ListSkillsResponseEvent;
 use codex_core::protocol::McpListToolsResponseEvent;
 use codex_core::protocol::McpStartupCompleteEvent;
 use codex_core::protocol::McpStartupStatus;
@@ -44,7 +45,7 @@ use codex_core::protocol::PatchApplyBeginEvent;
 use codex_core::protocol::RateLimitSnapshot;
 use codex_core::protocol::ReviewRequest;
 use codex_core::protocol::ReviewTarget;
-use codex_core::protocol::SkillLoadOutcomeInfo;
+use codex_core::protocol::SkillsListEntry;
 use codex_core::protocol::StreamErrorEvent;
 use codex_core::protocol::TaskCompleteEvent;
 use codex_core::protocol::TerminalInteractionEvent;
@@ -392,7 +393,7 @@ impl ChatWidget {
     fn on_session_configured(&mut self, event: codex_core::protocol::SessionConfiguredEvent) {
         self.bottom_pane
             .set_history_metadata(event.history_log_id, event.history_entry_count);
-        self.set_skills_from_outcome(event.skill_load_outcome.as_ref());
+        self.set_skills(None);
         self.conversation_id = Some(event.session_id);
         self.current_rollout_path = Some(event.rollout_path.clone());
         let initial_messages = event.initial_messages.clone();
@@ -409,6 +410,7 @@ impl ChatWidget {
         }
         // Ask codex-core to enumerate custom prompts for this session.
         self.submit_op(Op::ListCustomPrompts);
+        self.submit_op(Op::ListSkills { cwds: Vec::new() });
         if let Some(user_message) = self.initial_user_message.take() {
             self.submit_user_message(user_message);
         }
@@ -417,11 +419,15 @@ impl ChatWidget {
         }
     }
 
-    fn set_skills_from_outcome(&mut self, outcome: Option<&SkillLoadOutcomeInfo>) {
-        let skills = outcome.map(skills_from_outcome);
+    fn set_skills(&mut self, skills: Option<Vec<SkillMetadata>>) {
         self.bottom_pane.set_skills(skills);
     }
 
+    fn set_skills_from_response(&mut self, response: &ListSkillsResponseEvent) {
+        let skills = skills_for_cwd(&self.config.cwd, &response.skills);
+        self.set_skills(Some(skills));
+    }
+
     pub(crate) fn open_feedback_note(
         &mut self,
         category: crate::app_event::FeedbackCategory,
@@ -1879,6 +1885,7 @@ impl ChatWidget {
             EventMsg::GetHistoryEntryResponse(ev) => self.on_get_history_entry_response(ev),
             EventMsg::McpListToolsResponse(ev) => self.on_list_mcp_tools(ev),
             EventMsg::ListCustomPromptsResponse(ev) => self.on_list_custom_prompts(ev),
+            EventMsg::ListSkillsResponse(ev) => self.on_list_skills(ev),
             EventMsg::ShutdownComplete => self.on_shutdown_complete(),
             EventMsg::TurnDiff(TurnDiffEvent { unified_diff }) => self.on_turn_diff(unified_diff),
             EventMsg::DeprecationNotice(ev) => self.on_deprecation_notice(ev),
@@ -3092,6 +3099,10 @@ impl ChatWidget {
         self.bottom_pane.set_custom_prompts(ev.custom_prompts);
     }
 
+    fn on_list_skills(&mut self, ev: ListSkillsResponseEvent) {
+        self.set_skills_from_response(&ev);
+    }
+
     pub(crate) fn open_review_popup(&mut self) {
         let mut items: Vec<SelectionItem> = Vec::new();
 
@@ -3476,18 +3487,6 @@ pub(crate) fn show_review_commit_picker_with_entries(
     });
 }
 
-fn skills_from_outcome(outcome: &SkillLoadOutcomeInfo) -> Vec<SkillMetadata> {
-    outcome
-        .skills
-        .iter()
-        .map(|skill| SkillMetadata {
-            name: skill.name.clone(),
-            description: skill.description.clone(),
-            path: skill.path.clone(),
-        })
-        .collect()
-}
-
 fn find_skill_mentions(text: &str, skills: &[SkillMetadata]) -> Vec<SkillMetadata> {
     let mut seen: HashSet<String> = HashSet::new();
     let mut matches: Vec<SkillMetadata> = Vec::new();
@@ -3504,5 +3503,24 @@ fn find_skill_mentions(text: &str, skills: &[SkillMetadata]) -> Vec<SkillMetadat
     matches
 }
 
+fn skills_for_cwd(cwd: &Path, skills_entries: &[SkillsListEntry]) -> Vec<SkillMetadata> {
+    skills_entries
+        .iter()
+        .find(|entry| entry.cwd.as_path() == cwd)
+        .map(|entry| {
+            entry
+                .skills
+                .iter()
+                .map(|skill| SkillMetadata {
+                    name: skill.name.clone(),
+                    description: skill.description.clone(),
+                    path: skill.path.clone(),
+                    scope: skill.scope,
+                })
+                .collect()
+        })
+        .unwrap_or_default()
+}
+
 #[cfg(test)]
 pub(crate) mod tests;