feat: TUI undo op (#5629)

codex-rs/protocol/src/models.rs

@@ -9,6 +9,7 @@ use serde::ser::Serializer;
 use ts_rs::TS;
 
 use crate::user_input::UserInput;
+use codex_git_tooling::GhostCommit;
 use schemars::JsonSchema;
 
 #[derive(Debug, Clone, Serialize, Deserialize, PartialEq, JsonSchema, TS)]
@@ -118,9 +119,7 @@ pub enum ResponseItem {
     },
     // Generated by the harness but considered exactly as a model response.
     GhostSnapshot {
-        commit_id: String,
-        #[serde(default, skip_serializing_if = "Option::is_none")]
-        parent: Option<String>,
+        ghost_commit: GhostCommit,
     },
     #[serde(other)]
     Other,