diff --git a/codex-rs/analytics/src/analytics_client_tests.rs b/codex-rs/analytics/src/analytics_client_tests.rs
index 54283cfcaf..49b07adcd0 100644
--- a/codex-rs/analytics/src/analytics_client_tests.rs
+++ b/codex-rs/analytics/src/analytics_client_tests.rs
@@ -234,7 +234,7 @@ fn sample_thread_start_response(
         model_provider: "openai".to_string(),
         service_tier: None,
         cwd: test_path_buf("/tmp").abs(),
-        mcp_server_names: Vec::new(),
+        mcp_server_names: None,
         runtime_workspace_roots: Vec::new(),
         instruction_sources: Vec::new(),
         approval_policy: AppServerAskForApproval::OnRequest,
diff --git a/codex-rs/analytics/src/client_tests.rs b/codex-rs/analytics/src/client_tests.rs
index 2c322c2bd8..cb95665b63 100644
--- a/codex-rs/analytics/src/client_tests.rs
+++ b/codex-rs/analytics/src/client_tests.rs
@@ -309,7 +309,7 @@ fn sample_thread_start_response() -> ClientResponsePayload {
         model_provider: "openai".to_string(),
         service_tier: None,
         cwd: test_path_buf("/tmp").abs(),
-        mcp_server_names: Vec::new(),
+        mcp_server_names: None,
         runtime_workspace_roots: Vec::new(),
         instruction_sources: Vec::new(),
         approval_policy: AppServerAskForApproval::OnRequest,
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
index 1b46445022..0dc90a266b 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
@@ -19532,12 +19532,15 @@
             "type": "array"
           },
           "mcpServerNames": {
-            "default": [],
+            "default": null,
             "description": "Names of the effective MCP servers in the thread's initial runtime.",
             "items": {
               "type": "string"
             },
-            "type": "array"
+            "type": [
+              "array",
+              "null"
+            ]
           },
           "model": {
             "type": "string"
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
index 7c3017abc1..0239e63bdf 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
@@ -17311,12 +17311,15 @@
           "type": "array"
         },
         "mcpServerNames": {
-          "default": [],
+          "default": null,
           "description": "Names of the effective MCP servers in the thread's initial runtime.",
           "items": {
             "type": "string"
           },
-          "type": "array"
+          "type": [
+            "array",
+            "null"
+          ]
         },
         "model": {
           "type": "string"
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
index b75556f47e..319d665607 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
@@ -2431,12 +2431,15 @@
       "type": "array"
     },
     "mcpServerNames": {
-      "default": [],
+      "default": null,
       "description": "Names of the effective MCP servers in the thread's initial runtime.",
       "items": {
         "type": "string"
       },
-      "type": "array"
+      "type": [
+        "array",
+        "null"
+      ]
     },
     "model": {
       "type": "string"
diff --git a/codex-rs/app-server-protocol/schema/typescript/v2/ThreadStartResponse.ts b/codex-rs/app-server-protocol/schema/typescript/v2/ThreadStartResponse.ts
index e934aeac49..b27f7502f8 100644
--- a/codex-rs/app-server-protocol/schema/typescript/v2/ThreadStartResponse.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/v2/ThreadStartResponse.ts
@@ -12,7 +12,7 @@ import type { Thread } from "./Thread";
 export type ThreadStartResponse = {thread: Thread, model: string, modelProvider: string, serviceTier: string | null, cwd: AbsolutePathBuf, /**
  * Names of the effective MCP servers in the thread's initial runtime.
  */
-mcpServerNames: Array<string>, /**
+mcpServerNames: Array<string> | null, /**
  * Environment-native paths to instruction source files currently loaded for this thread.
  */
 instructionSources: Array<LegacyAppPathString>, approvalPolicy: AskForApproval, /**
diff --git a/codex-rs/app-server-protocol/src/protocol/common.rs b/codex-rs/app-server-protocol/src/protocol/common.rs
index 60f3e8d03e..7d53b19e9f 100644
--- a/codex-rs/app-server-protocol/src/protocol/common.rs
+++ b/codex-rs/app-server-protocol/src/protocol/common.rs
@@ -2608,7 +2608,7 @@ mod tests {
                 model_provider: "openai".to_string(),
                 service_tier: None,
                 cwd,
-                mcp_server_names: vec!["example".to_string()],
+                mcp_server_names: Some(vec!["example".to_string()]),
                 runtime_workspace_roots: Vec::new(),
                 instruction_sources: vec![
                     codex_utils_path_uri::LegacyAppPathString::from_abs_path(&absolute_path(
diff --git a/codex-rs/app-server-protocol/src/protocol/v2/tests.rs b/codex-rs/app-server-protocol/src/protocol/v2/tests.rs
index 77d8a1439b..4ed2a0dac0 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2/tests.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2/tests.rs
@@ -3978,6 +3978,7 @@ fn thread_lifecycle_responses_default_missing_optional_fields() {
         serde_json::from_value(response.clone()).expect("thread/fork response");
 
     assert_eq!(start.instruction_sources, Vec::<LegacyAppPathString>::new());
+    assert_eq!(start.mcp_server_names, None);
     assert_eq!(start.thread.parent_thread_id, None);
     assert_eq!(start.thread.recency_at, None);
     assert_eq!(
diff --git a/codex-rs/app-server-protocol/src/protocol/v2/thread.rs b/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
index cd751461ee..44669829ba 100644
--- a/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
+++ b/codex-rs/app-server-protocol/src/protocol/v2/thread.rs
@@ -175,7 +175,7 @@ pub struct ThreadStartResponse {
     pub cwd: AbsolutePathBuf,
     /// Names of the effective MCP servers in the thread's initial runtime.
     #[serde(default)]
-    pub mcp_server_names: Vec<String>,
+    pub mcp_server_names: Option<Vec<String>>,
     /// Thread-scoped runtime workspace roots used to materialize
     /// `:workspace_roots`.
     #[experimental("thread/start.runtimeWorkspaceRoots")]
diff --git a/codex-rs/app-server/src/request_processors/thread_processor.rs b/codex-rs/app-server/src/request_processors/thread_processor.rs
index be987b17b9..d91f040eba 100644
--- a/codex-rs/app-server/src/request_processors/thread_processor.rs
+++ b/codex-rs/app-server/src/request_processors/thread_processor.rs
@@ -1290,7 +1290,7 @@ impl ThreadRequestProcessor {
             model_provider: config_snapshot.model_provider_id,
             service_tier: config_snapshot.service_tier,
             cwd,
-            mcp_server_names,
+            mcp_server_names: Some(mcp_server_names),
             runtime_workspace_roots: config_snapshot.workspace_roots,
             instruction_sources,
             approval_policy: config_snapshot.approval_policy.into(),
diff --git a/codex-rs/app-server/tests/suite/v2/mcp_server_status.rs b/codex-rs/app-server/tests/suite/v2/mcp_server_status.rs
index 668e379313..36a15e6cce 100644
--- a/codex-rs/app-server/tests/suite/v2/mcp_server_status.rs
+++ b/codex-rs/app-server/tests/suite/v2/mcp_server_status.rs
@@ -81,7 +81,7 @@ url = "{mcp_server_url}/mcp"
     let thread_start_response: ThreadStartResponse = to_response(thread_start_response)?;
     assert_eq!(
         thread_start_response.mcp_server_names,
-        vec!["some-server".to_string()]
+        Some(vec!["some-server".to_string()])
     );
 
     let request_id = mcp
diff --git a/codex-rs/exec/src/lib_tests.rs b/codex-rs/exec/src/lib_tests.rs
index 93124c41eb..3c86aa6f39 100644
--- a/codex-rs/exec/src/lib_tests.rs
+++ b/codex-rs/exec/src/lib_tests.rs
@@ -782,7 +782,7 @@ fn sample_thread_start_response() -> ThreadStartResponse {
         model_provider: "openai".to_string(),
         service_tier: None,
         cwd: test_path_buf("/tmp").abs(),
-        mcp_server_names: Vec::new(),
+        mcp_server_names: None,
         runtime_workspace_roots: Vec::new(),
         instruction_sources: Vec::new(),
         approval_policy: codex_app_server_protocol::AskForApproval::OnRequest,
diff --git a/codex-rs/tui/src/app/session_lifecycle.rs b/codex-rs/tui/src/app/session_lifecycle.rs
index e4f951a3d8..aa37a05a9a 100644
--- a/codex-rs/tui/src/app/session_lifecycle.rs
+++ b/codex-rs/tui/src/app/session_lifecycle.rs
@@ -517,6 +517,29 @@ impl App {
                 turns,
                 mcp_server_names,
             }) => {
+                let mcp_server_names = match mcp_server_names {
+                    Some(mcp_server_names) => mcp_server_names,
+                    None if self.chat_widget.startup_draft_needs_mcp_server_names() => {
+                        match super::background_requests::fetch_all_mcp_server_statuses(
+                            app_server.request_handle(),
+                            McpServerStatusDetail::ToolsAndAuthOnly,
+                            Some(session.thread_id),
+                        )
+                        .await
+                        {
+                            Ok(statuses) => {
+                                statuses.into_iter().map(|status| status.name).collect()
+                            }
+                            Err(err) => {
+                                tracing::warn!(
+                                    "failed to load startup MCP server names from an older app server: {err}"
+                                );
+                                Vec::new()
+                            }
+                        }
+                    }
+                    None => Vec::new(),
+                };
                 self.chat_widget
                     .set_startup_draft_expected_mcp_servers(mcp_server_names);
                 self.enqueue_primary_thread_session(session, turns).await?;
diff --git a/codex-rs/tui/src/app/tests.rs b/codex-rs/tui/src/app/tests.rs
index d5c4fae98e..2e7b14e048 100644
--- a/codex-rs/tui/src/app/tests.rs
+++ b/codex-rs/tui/src/app/tests.rs
@@ -3529,7 +3529,7 @@ async fn primary_thread_ignores_child_mcp_startup_notifications() {
         AppServerStartedThread {
             session: test_thread_session(child_thread_id, test_path_buf("/tmp/child")),
             turns: Vec::new(),
-            mcp_server_names: Vec::new(),
+            mcp_server_names: None,
         },
         &mut child_snapshot,
     )
@@ -5496,7 +5496,7 @@ async fn refreshed_snapshot_session_persists_resumed_turns() {
         AppServerStartedThread {
             session: resumed_session.clone(),
             turns: resumed_turns.clone(),
-            mcp_server_names: Vec::new(),
+            mcp_server_names: None,
         },
         &mut snapshot,
     )
diff --git a/codex-rs/tui/src/app/tests/startup.rs b/codex-rs/tui/src/app/tests/startup.rs
index e00115f287..45fcf63308 100644
--- a/codex-rs/tui/src/app/tests/startup.rs
+++ b/codex-rs/tui/src/app/tests/startup.rs
@@ -165,7 +165,7 @@ async fn restored_startup_draft_waits_for_effective_mcp_settlement() {
         Ok(AppServerStartedThread {
             session: test_thread_session(thread_id, test_path_buf("/tmp/project")),
             turns: Vec::new(),
-            mcp_server_names: vec!["test".to_string()],
+            mcp_server_names: Some(vec!["test".to_string()]),
         }),
     )
     .await
@@ -230,6 +230,44 @@ async fn restored_startup_draft_waits_for_effective_mcp_settlement() {
     assert_eq!(app.chat_widget.composer_text_with_pending(), "");
 }
 
+#[tokio::test]
+async fn restored_startup_draft_loads_mcp_names_from_older_app_servers() {
+    let (mut app, _app_event_rx, mut op_rx) = make_test_app_with_channels().await;
+    app.pending_startup_thread_start = true;
+    app.chat_widget
+        .set_queue_submissions_until_session_configured(/*queue*/ true);
+    app.chat_widget
+        .restore_startup_draft("captured during startup");
+
+    let mut app_server = Box::pin(crate::start_embedded_app_server_for_picker(
+        app.chat_widget.config_ref(),
+    ))
+    .await
+    .expect("embedded app server");
+    let mut started = app_server
+        .start_thread(app.chat_widget.config_ref())
+        .await
+        .expect("startup thread");
+    started.mcp_server_names = None;
+
+    app.handle_startup_thread_started(&mut app_server, Ok(started))
+        .await
+        .expect("older app-server startup should attach");
+    app.chat_widget
+        .handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
+
+    match next_user_turn_op(&mut op_rx) {
+        Op::UserTurn { items, .. } => assert_eq!(
+            items,
+            vec![UserInput::Text {
+                text: "captured during startup".to_string(),
+                text_elements: Vec::new(),
+            }]
+        ),
+        other => panic!("expected restored startup input submission, got {other:?}"),
+    }
+}
+
 #[tokio::test]
 async fn startup_without_restored_draft_uses_normal_queued_submission() {
     let (mut app, _app_event_rx, _op_rx) = make_test_app_with_channels().await;
@@ -306,7 +344,7 @@ fn stale_startup_thread_started_removes_local_routing_state() -> Result<()> {
                 Ok(AppServerStartedThread {
                     session: test_thread_session(stale_thread_id, test_path_buf("/tmp/project")),
                     turns: Vec::new(),
-                    mcp_server_names: Vec::new(),
+                    mcp_server_names: None,
                 }),
             )
             .await?;
diff --git a/codex-rs/tui/src/app_server_session.rs b/codex-rs/tui/src/app_server_session.rs
index d3261b3baf..5d7efa627a 100644
--- a/codex-rs/tui/src/app_server_session.rs
+++ b/codex-rs/tui/src/app_server_session.rs
@@ -203,7 +203,7 @@ impl ThreadParamsMode {
 pub(crate) struct AppServerStartedThread {
     pub(crate) session: ThreadSessionState,
     pub(crate) turns: Vec<Turn>,
-    pub(crate) mcp_server_names: Vec<String>,
+    pub(crate) mcp_server_names: Option<Vec<String>>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]
@@ -1548,7 +1548,7 @@ async fn started_thread_from_resume_response(
     Ok(AppServerStartedThread {
         session,
         turns: response.thread.turns,
-        mcp_server_names: Vec::new(),
+        mcp_server_names: None,
     })
 }
 
@@ -1564,7 +1564,7 @@ async fn started_thread_from_fork_response(
     Ok(AppServerStartedThread {
         session,
         turns: response.thread.turns,
-        mcp_server_names: Vec::new(),
+        mcp_server_names: None,
     })
 }
 
diff --git a/codex-rs/tui/src/chatwidget/input_flow.rs b/codex-rs/tui/src/chatwidget/input_flow.rs
index 85d79c02c3..1e385b3d0e 100644
--- a/codex-rs/tui/src/chatwidget/input_flow.rs
+++ b/codex-rs/tui/src/chatwidget/input_flow.rs
@@ -25,6 +25,10 @@ impl ChatWidget {
         self.finish_startup_draft_protection_if_ready();
     }
 
+    pub(crate) fn startup_draft_needs_mcp_server_names(&self) -> bool {
+        self.startup_draft_pending_mcp_servers.is_some()
+    }
+
     pub(super) fn finish_startup_draft_protection_if_ready(&mut self) {
         let startup_ready = self.is_session_configured()
             && self