diff --git a/codex-rs/app-server/src/codex_message_processor.rs b/codex-rs/app-server/src/codex_message_processor.rs
index b9513b259f..8fec01d029 100644
--- a/codex-rs/app-server/src/codex_message_processor.rs
+++ b/codex-rs/app-server/src/codex_message_processor.rs
@@ -2671,12 +2671,12 @@ impl CodexMessageProcessor {
         };
 
         let dependency_env = thread.dependency_env().await;
-        let contains = std::env::var(&key)
-            .ok()
-            .is_some_and(|value| !value.trim().is_empty())
-            || dependency_env
-                .get(&key)
-                .is_some_and(|value| !value.trim().is_empty());
+        let contains = match dependency_env.get(&key) {
+            Some(value) => !value.trim().is_empty(),
+            None => std::env::var(&key)
+                .ok()
+                .is_some_and(|value| !value.trim().is_empty()),
+        };
         self.outgoing
             .send_response(request_id, ThreadEnvContainsResponse { contains })
             .await;
diff --git a/codex-rs/app-server/tests/suite/v2/thread_shell_command.rs b/codex-rs/app-server/tests/suite/v2/thread_shell_command.rs
index 2dc552d8c5..02459fcb58 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_shell_command.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_shell_command.rs
@@ -81,7 +81,7 @@ async fn thread_env_contains_checks_process_env() -> Result<()> {
 
     let contains_id = mcp
         .send_thread_env_contains_request(ThreadEnvContainsParams {
-            thread_id: thread.id,
+            thread_id: thread.id.clone(),
             key: PROCESS_ENV_KEY.to_string(),
         })
         .await?;
@@ -93,6 +93,33 @@ async fn thread_env_contains_checks_process_env() -> Result<()> {
     let contains = to_response::<ThreadEnvContainsResponse>(contains_resp)?;
     assert_eq!(contains, ThreadEnvContainsResponse { contains: true });
 
+    let set_id = mcp
+        .send_thread_dependency_env_set_request(ThreadDependencyEnvSetParams {
+            thread_id: thread.id.clone(),
+            values: HashMap::from([(PROCESS_ENV_KEY.to_string(), String::new())]),
+        })
+        .await?;
+    let set_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(set_id)),
+    )
+    .await??;
+    let _: ThreadDependencyEnvSetResponse = to_response(set_resp)?;
+
+    let contains_id = mcp
+        .send_thread_env_contains_request(ThreadEnvContainsParams {
+            thread_id: thread.id,
+            key: PROCESS_ENV_KEY.to_string(),
+        })
+        .await?;
+    let contains_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(contains_id)),
+    )
+    .await??;
+    let contains = to_response::<ThreadEnvContainsResponse>(contains_resp)?;
+    assert_eq!(contains, ThreadEnvContainsResponse { contains: false });
+
     Ok(())
 }