feat: show forked from session id in /status (#9330)

Summary:
- Add forked_from to SessionMeta/SessionConfiguredEvent and persist it
for forked sessions.
- Surface forked_from in /status for tui + tui2 and add snapshots.

codex-rs/core/src/codex.rs

@@ -588,6 +588,8 @@ impl Session {
             ));
         }
 
+        let forked_from_id = initial_history.forked_from_id();
+
         let (conversation_id, rollout_params) = match &initial_history {
             InitialHistory::New | InitialHistory::Forked(_) => {
                 let conversation_id = ThreadId::default();
@@ -595,6 +597,7 @@ impl Session {
                     conversation_id,
                     RolloutRecorderParams::new(
                         conversation_id,
+                        forked_from_id,
                         session_configuration.user_instructions.clone(),
                         session_source,
                     ),
@@ -733,6 +736,7 @@ impl Session {
             id: INITIAL_SUBMIT_ID.to_owned(),
             msg: EventMsg::SessionConfigured(SessionConfiguredEvent {
                 session_id: conversation_id,
+                forked_from_id,
                 model: session_configuration.model.clone(),
                 model_provider_id: config.model_provider_id.clone(),
                 approval_policy: session_configuration.approval_policy.value(),

codex-rs/core/src/rollout/recorder.rs

@@ -57,6 +57,7 @@ pub struct RolloutRecorder {
 pub enum RolloutRecorderParams {
     Create {
         conversation_id: ThreadId,
+        forked_from_id: Option<ThreadId>,
         instructions: Option<String>,
         source: SessionSource,
     },
@@ -79,11 +80,13 @@ enum RolloutCmd {
 impl RolloutRecorderParams {
     pub fn new(
         conversation_id: ThreadId,
+        forked_from_id: Option<ThreadId>,
         instructions: Option<String>,
         source: SessionSource,
     ) -> Self {
         Self::Create {
             conversation_id,
+            forked_from_id,
             instructions,
             source,
         }
@@ -158,6 +161,7 @@ impl RolloutRecorder {
         let (file, rollout_path, meta) = match params {
             RolloutRecorderParams::Create {
                 conversation_id,
+                forked_from_id,
                 instructions,
                 source,
             } => {
@@ -181,6 +185,7 @@ impl RolloutRecorder {
                     path,
                     Some(SessionMeta {
                         id: session_id,
+                        forked_from_id,
                         timestamp,
                         cwd: config.cwd.clone(),
                         originator: originator().value,

codex-rs/core/src/rollout/tests.rs

@@ -641,6 +641,7 @@ async fn test_updated_at_uses_file_mtime() -> Result<()> {
         item: RolloutItem::SessionMeta(SessionMetaLine {
             meta: SessionMeta {
                 id: conversation_id,
+                forked_from_id: None,
                 timestamp: ts.to_string(),
                 instructions: None,
                 cwd: ".".into(),