feat: persist and inherit per-thread multi-agent runtime

codex-rs/app-server/tests/common/models_cache.rs

@@ -54,6 +54,7 @@ fn preset_to_info(preset: &ModelPreset, priority: i32) -> ModelInfo {
         supports_search_tool: false,
         auto_review_model_override: None,
         tool_mode: None,
+        multi_agent_version: None,
     }
 }
 

codex-rs/app-server/tests/common/rollout.rs

@@ -194,6 +194,7 @@ fn create_fake_rollout_with_source_and_parent_thread_id(
         base_instructions: None,
         dynamic_tools: None,
         memory_mode: None,
+        multi_agent_version: None,
     };
     let payload = serde_json::to_value(SessionMetaLine {
         meta,
@@ -279,6 +280,7 @@ pub fn create_fake_rollout_with_text_elements(
         base_instructions: None,
         dynamic_tools: None,
         memory_mode: None,
+        multi_agent_version: None,
     };
     let payload = serde_json::to_value(SessionMetaLine {
         meta,

codex-rs/app-server/tests/suite/conversation_summary.rs

@@ -129,6 +129,7 @@ async fn get_conversation_summary_by_thread_id_reads_pathless_store_thread() ->
             thread_source: None,
             base_instructions: BaseInstructions::default(),
             dynamic_tools: Vec::new(),
+            multi_agent_version: None,
             metadata: ThreadPersistenceMetadata {
                 cwd: None,
                 model_provider: "test-provider".to_string(),

codex-rs/app-server/tests/suite/v2/thread_fork.rs

@@ -29,6 +29,10 @@ use codex_app_server_protocol::TurnStatus;
 use codex_app_server_protocol::UserInput;
 use codex_config::types::AuthCredentialsStoreMode;
 use codex_login::REFRESH_TOKEN_URL_OVERRIDE_ENV_VAR;
+use codex_protocol::protocol::MultiAgentVersion;
+use codex_protocol::protocol::RolloutItem;
+use codex_rollout::append_rollout_item_to_path;
+use codex_rollout::read_session_meta_line;
 use pretty_assertions::assert_eq;
 use serde_json::Value;
 use serde_json::json;
@@ -81,6 +85,9 @@ async fn thread_fork_creates_new_thread_and_emits_started() -> Result<()> {
         "expected original rollout to exist at {}",
         original_path.display()
     );
+    let mut session_meta = read_session_meta_line(&original_path).await?;
+    session_meta.meta.multi_agent_version = Some(MultiAgentVersion::V1);
+    append_rollout_item_to_path(&original_path, &RolloutItem::SessionMeta(session_meta)).await?;
     let original_contents = std::fs::read_to_string(&original_path)?;
 
     let mut mcp = McpProcess::new(codex_home.path()).await?;

codex-rs/app-server/tests/suite/v2/thread_read.rs

@@ -1363,6 +1363,7 @@ async fn seed_pathless_store_thread(
             thread_source: None,
             base_instructions: BaseInstructions::default(),
             dynamic_tools: Vec::new(),
+            multi_agent_version: None,
             metadata: ThreadPersistenceMetadata {
                 cwd: None,
                 model_provider: "test-provider".to_string(),

codex-rs/app-server/tests/suite/v2/thread_resume.rs

@@ -63,6 +63,8 @@ use codex_protocol::protocol::EventMsg;
 use codex_protocol::protocol::ImageGenerationEndEvent;
 use codex_protocol::protocol::McpInvocation;
 use codex_protocol::protocol::McpToolCallEndEvent;
+use codex_protocol::protocol::MultiAgentVersion;
+use codex_protocol::protocol::RolloutItem;
 use codex_protocol::protocol::SessionMeta;
 use codex_protocol::protocol::SessionMetaLine;
 use codex_protocol::protocol::SessionSource as RolloutSessionSource;
@@ -74,6 +76,8 @@ use codex_protocol::protocol::TurnAbortedEvent;
 use codex_protocol::protocol::TurnStartedEvent;
 use codex_protocol::user_input::ByteRange;
 use codex_protocol::user_input::TextElement;
+use codex_rollout::append_rollout_item_to_path;
+use codex_rollout::read_session_meta_line;
 use codex_state::StateRuntime;
 use codex_utils_absolute_path::AbsolutePathBuf;
 use core_test_support::responses;
@@ -1805,6 +1809,7 @@ stream_max_retries = 0
         base_instructions: None,
         dynamic_tools: None,
         memory_mode: None,
+        multi_agent_version: None,
     };
     std::fs::write(
         &rollout_path,
@@ -2013,7 +2018,7 @@ async fn thread_resume_and_read_interrupt_incomplete_rollout_turn_when_thread_is
 async fn thread_resume_defers_updated_at_until_turn_start() -> Result<()> {
     let server = create_mock_responses_server_repeating_assistant("Done").await;
     let codex_home = TempDir::new()?;
-    let rollout = setup_rollout_fixture(codex_home.path(), &server.uri())?;
+    let rollout = setup_rollout_fixture(codex_home.path(), &server.uri()).await?;
     let thread_id = rollout.conversation_id.clone();
 
     let mut mcp = McpProcess::new(codex_home.path()).await?;
@@ -3051,7 +3056,7 @@ async fn thread_resume_with_overrides_defers_updated_at_until_turn_start() -> Re
 async fn thread_resume_fails_when_required_mcp_server_fails_to_initialize() -> Result<()> {
     let server = create_mock_responses_server_repeating_assistant("Done").await;
     let codex_home = TempDir::new()?;
-    let rollout = setup_rollout_fixture(codex_home.path(), &server.uri())?;
+    let rollout = setup_rollout_fixture(codex_home.path(), &server.uri()).await?;
     create_config_toml_with_required_broken_mcp(codex_home.path(), &server.uri())?;
 
     let mut mcp = McpProcess::new(codex_home.path()).await?;
@@ -3614,7 +3619,7 @@ struct RolloutFixture {
     before_modified: std::time::SystemTime,
 }
 
-fn setup_rollout_fixture(codex_home: &Path, server_uri: &str) -> Result<RolloutFixture> {
+async fn setup_rollout_fixture(codex_home: &Path, server_uri: &str) -> Result<RolloutFixture> {
     create_config_toml(codex_home, server_uri)?;
 
     let preview = "Saved user message";
@@ -3631,6 +3636,10 @@ fn setup_rollout_fixture(codex_home: &Path, server_uri: &str) -> Result<RolloutF
         /*git_info*/ None,
     )?;
     let rollout_file_path = rollout_path(codex_home, filename_ts, &conversation_id);
+    let mut session_meta = read_session_meta_line(&rollout_file_path).await?;
+    session_meta.meta.multi_agent_version = Some(MultiAgentVersion::V1);
+    append_rollout_item_to_path(&rollout_file_path, &RolloutItem::SessionMeta(session_meta))
+        .await?;
     set_rollout_mtime(rollout_file_path.as_path(), expected_updated_at_rfc3339)?;
     let before_modified = std::fs::metadata(&rollout_file_path)?.modified()?;
     Ok(RolloutFixture {

codex-rs/app-server/tests/suite/v2/thread_unarchive.rs

@@ -216,6 +216,7 @@ async fn thread_unarchive_preserves_pathless_store_metadata() -> Result<()> {
             thread_source: None,
             base_instructions: BaseInstructions::default(),
             dynamic_tools: Vec::new(),
+            multi_agent_version: None,
             metadata: ThreadPersistenceMetadata {
                 cwd: None,
                 model_provider: "test-provider".to_string(),

codex-rs/codex-api/tests/models_integration.rs

@@ -100,6 +100,7 @@ async fn models_client_hits_models_endpoint() {
             supports_search_tool: false,
             auto_review_model_override: None,
             tool_mode: None,
+            multi_agent_version: None,
         }],
     };