[skills] Auto install MCP dependencies when running skils with dependency specs. (#9982)

Auto install MCP dependencies when running skils with dependency specs.

codex-rs/core/src/state/session.rs

@@ -1,6 +1,7 @@
 //! Session-wide mutable state.
 
 use codex_protocol::models::ResponseItem;
+use std::collections::HashSet;
 
 use crate::codex::SessionConfiguration;
 use crate::context_manager::ContextManager;
@@ -15,6 +16,7 @@ pub(crate) struct SessionState {
     pub(crate) history: ContextManager,
     pub(crate) latest_rate_limits: Option<RateLimitSnapshot>,
     pub(crate) server_reasoning_included: bool,
+    pub(crate) mcp_dependency_prompted: HashSet<String>,
     /// Whether the session's initial context has been seeded into history.
     ///
     /// TODO(owen): This is a temporary solution to avoid updating a thread's updated_at
@@ -31,6 +33,7 @@ impl SessionState {
             history,
             latest_rate_limits: None,
             server_reasoning_included: false,
+            mcp_dependency_prompted: HashSet::new(),
             initial_context_seeded: false,
         }
     }
@@ -98,6 +101,17 @@ impl SessionState {
     pub(crate) fn server_reasoning_included(&self) -> bool {
         self.server_reasoning_included
     }
+
+    pub(crate) fn record_mcp_dependency_prompted<I>(&mut self, names: I)
+    where
+        I: IntoIterator<Item = String>,
+    {
+        self.mcp_dependency_prompted.extend(names);
+    }
+
+    pub(crate) fn mcp_dependency_prompted(&self) -> HashSet<String> {
+        self.mcp_dependency_prompted.clone()
+    }
 }
 
 // Sometimes new snapshots don't include credits or plan information.