diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index 21a72b00c5..63e459a918 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -801,6 +801,7 @@ impl Session {
             InitialHistory::Resumed(_) | InitialHistory::Forked(_) => {
                 let rollout_items = conversation_history.get_rollout_items();
                 let persist = matches!(conversation_history, InitialHistory::Forked(_));
+                let append_env_context = matches!(conversation_history, InitialHistory::Resumed(_));
 
                 // If resuming, warn when the last recorded model differs from the current one.
                 if let InitialHistory::Resumed(_) = conversation_history
@@ -845,6 +846,12 @@ impl Session {
                     state.set_token_info(Some(info));
                 }
 
+                if append_env_context {
+                    let env_item = self.build_environment_context_item(&turn_context);
+                    self.record_conversation_items(&turn_context, std::slice::from_ref(&env_item))
+                        .await;
+                }
+
                 // If persisting, persist all rollout items as-is (recorder filters)
                 if persist && !rollout_items.is_empty() {
                     self.persist_rollout_items(&rollout_items).await;
@@ -1333,9 +1340,18 @@ impl Session {
         }
     }
 
+    fn build_environment_context_item(&self, turn_context: &TurnContext) -> ResponseItem {
+        let shell = self.user_shell();
+        ResponseItem::from(EnvironmentContext::new(
+            Some(turn_context.cwd.clone()),
+            Some(turn_context.approval_policy),
+            Some(turn_context.sandbox_policy.clone()),
+            shell.as_ref().clone(),
+        ))
+    }
+
     pub(crate) fn build_initial_context(&self, turn_context: &TurnContext) -> Vec<ResponseItem> {
         let mut items = Vec::<ResponseItem>::with_capacity(3);
-        let shell = self.user_shell();
         if let Some(developer_instructions) = turn_context.developer_instructions.as_deref() {
             items.push(DeveloperInstructions::new(developer_instructions.to_string()).into());
         }
@@ -1348,12 +1364,7 @@ impl Session {
                 .into(),
             );
         }
-        items.push(ResponseItem::from(EnvironmentContext::new(
-            Some(turn_context.cwd.clone()),
-            Some(turn_context.approval_policy),
-            Some(turn_context.sandbox_policy.clone()),
-            shell.as_ref().clone(),
-        )));
+        items.push(self.build_environment_context_item(turn_context));
         items
     }
 
@@ -2925,6 +2936,8 @@ mod tests {
     async fn record_initial_history_reconstructs_resumed_transcript() {
         let (session, turn_context) = make_session_and_context().await;
         let (rollout_items, expected) = sample_rollout(&session, &turn_context);
+        let mut expected = expected;
+        expected.push(session.build_environment_context_item(&turn_context));
 
         session
             .record_initial_history(InitialHistory::Resumed(ResumedHistory {
diff --git a/codex-rs/core/tests/suite/resume.rs b/codex-rs/core/tests/suite/resume.rs
index 1fee3858e2..0b733c11a8 100644
--- a/codex-rs/core/tests/suite/resume.rs
+++ b/codex-rs/core/tests/suite/resume.rs
@@ -1,4 +1,7 @@
 use anyhow::Result;
+use codex_core::config::Constrained;
+use codex_core::protocol::AskForApproval;
+use codex_core::protocol::ENVIRONMENT_CONTEXT_OPEN_TAG;
 use codex_core::protocol::EventMsg;
 use codex_core::protocol::Op;
 use codex_protocol::user_input::UserInput;
@@ -12,6 +15,7 @@ use core_test_support::responses::start_mock_server;
 use core_test_support::skip_if_no_network;
 use core_test_support::test_codex::test_codex;
 use core_test_support::wait_for_event;
+use pretty_assertions::assert_eq;
 use std::sync::Arc;
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
@@ -120,3 +124,78 @@ async fn resume_includes_initial_messages_from_reasoning_events() -> Result<()>
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn resume_appends_environment_context_on_first_turn() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let server = start_mock_server().await;
+    let mut builder = test_codex();
+    let initial = builder.build(&server).await?;
+    let codex = Arc::clone(&initial.codex);
+    let home = initial.home.clone();
+    let rollout_path = initial.session_configured.rollout_path.clone();
+
+    let initial_sse = sse(vec![
+        ev_response_created("resp-initial"),
+        ev_assistant_message("msg-1", "Completed first turn"),
+        ev_completed("resp-initial"),
+    ]);
+    mount_sse_once(&server, initial_sse).await;
+
+    codex
+        .submit(Op::UserInput {
+            items: vec![UserInput::Text {
+                text: "Record some messages".into(),
+            }],
+            final_output_json_schema: None,
+        })
+        .await?;
+
+    wait_for_event(&codex, |event| matches!(event, EventMsg::TaskComplete(_))).await;
+
+    let mut resume_builder = test_codex().with_config(|config| {
+        config.approval_policy = Constrained::allow_any(AskForApproval::Never);
+    });
+    let resumed = resume_builder.resume(&server, home, rollout_path).await?;
+
+    let resumed_sse = sse(vec![
+        ev_response_created("resp-resume"),
+        ev_assistant_message("msg-2", "Completed after resume"),
+        ev_completed("resp-resume"),
+    ]);
+    let resumed_mock = mount_sse_once(&server, resumed_sse).await;
+
+    resumed
+        .codex
+        .submit(Op::UserInput {
+            items: vec![UserInput::Text {
+                text: "After resume".into(),
+            }],
+            final_output_json_schema: None,
+        })
+        .await?;
+    wait_for_event(&resumed.codex, |event| {
+        matches!(event, EventMsg::TaskComplete(_))
+    })
+    .await;
+
+    let body = resumed_mock.single_request().body_json();
+    let input = body["input"]
+        .as_array()
+        .expect("resume request input is an array");
+    let env_texts: Vec<&str> = input
+        .iter()
+        .filter_map(|item| item["content"][0]["text"].as_str())
+        .filter(|text| text.starts_with(ENVIRONMENT_CONTEXT_OPEN_TAG))
+        .collect();
+
+    assert_eq!(env_texts.is_empty(), false);
+    let last_env = env_texts.last().expect("environment context present");
+    assert_eq!(
+        last_env.contains("<approval_policy>never</approval_policy>"),
+        true,
+    );
+
+    Ok(())
+}