diff --git a/codex-rs/core/src/prompt_debug.rs b/codex-rs/core/src/prompt_debug.rs
index 1f62c2b08..b6c66410a 100644
--- a/codex-rs/core/src/prompt_debug.rs
+++ b/codex-rs/core/src/prompt_debug.rs
@@ -98,62 +98,3 @@ pub(crate) async fn build_prompt_input_from_session(
 
     Ok(prompt.get_formatted_input())
 }
-
-#[cfg(test)]
-mod tests {
-    use codex_protocol::models::ContentItem;
-    use codex_protocol::models::ResponseItem;
-    use codex_protocol::user_input::UserInput;
-    use codex_utils_absolute_path::AbsolutePathBuf;
-    use pretty_assertions::assert_eq;
-
-    use crate::config::test_config;
-
-    use super::build_prompt_input;
-
-    #[tokio::test]
-    async fn build_prompt_input_includes_context_and_user_message() {
-        let codex_home = tempfile::tempdir().expect("create codex home");
-        let cwd = tempfile::tempdir().expect("create cwd");
-        let mut config = test_config().await;
-        config.codex_home =
-            AbsolutePathBuf::from_absolute_path(codex_home.path()).expect("codex home is absolute");
-        config.cwd = AbsolutePathBuf::try_from(cwd.path().to_path_buf()).expect("absolute cwd");
-        config.user_instructions = Some("Project-specific test instructions".to_string());
-
-        let input = build_prompt_input(
-            config,
-            vec![UserInput::Text {
-                text: "hello from debug prompt".to_string(),
-                text_elements: Vec::new(),
-            }],
-        )
-        .await
-        .expect("build prompt input");
-
-        let expected_user_message = ResponseItem::Message {
-            id: None,
-            role: "user".to_string(),
-            content: vec![ContentItem::InputText {
-                text: "hello from debug prompt".to_string(),
-            }],
-            end_turn: None,
-            phase: None,
-        };
-        assert_eq!(input.last(), Some(&expected_user_message));
-        assert!(input.iter().any(|item| {
-            let ResponseItem::Message { content, .. } = item else {
-                return false;
-            };
-
-            content.iter().any(|content_item| {
-                let (ContentItem::InputText { text } | ContentItem::OutputText { text }) =
-                    content_item
-                else {
-                    return false;
-                };
-                text.contains("Project-specific test instructions")
-            })
-        }));
-    }
-}
diff --git a/codex-rs/core/tests/suite/mod.rs b/codex-rs/core/tests/suite/mod.rs
index 9f8389c45..6c4cb1981 100644
--- a/codex-rs/core/tests/suite/mod.rs
+++ b/codex-rs/core/tests/suite/mod.rs
@@ -67,6 +67,7 @@ mod personality;
 mod personality_migration;
 mod plugins;
 mod prompt_caching;
+mod prompt_debug_tests;
 mod quota_exceeded;
 mod realtime_conversation;
 mod remote_env;
diff --git a/codex-rs/core/tests/suite/prompt_debug_tests.rs b/codex-rs/core/tests/suite/prompt_debug_tests.rs
new file mode 100644
index 000000000..1221560bb
--- /dev/null
+++ b/codex-rs/core/tests/suite/prompt_debug_tests.rs
@@ -0,0 +1,60 @@
+use anyhow::Result;
+use codex_core::build_prompt_input;
+use codex_core::config::ConfigBuilder;
+use codex_core::config::ConfigOverrides;
+use codex_protocol::models::ContentItem;
+use codex_protocol::models::ResponseItem;
+use codex_protocol::user_input::UserInput;
+use pretty_assertions::assert_eq;
+use tempfile::TempDir;
+
+#[tokio::test]
+async fn build_prompt_input_includes_context_and_user_message() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    let cwd = TempDir::new()?;
+    let mut config = ConfigBuilder::default()
+        .codex_home(codex_home.path().to_path_buf())
+        .harness_overrides(ConfigOverrides {
+            cwd: Some(cwd.path().to_path_buf()),
+            codex_self_exe: Some(std::env::current_exe()?),
+            ..ConfigOverrides::default()
+        })
+        .build()
+        .await?;
+    config.user_instructions = Some("Project-specific test instructions".to_string());
+
+    let input = build_prompt_input(
+        config,
+        vec![UserInput::Text {
+            text: "hello from debug prompt".to_string(),
+            text_elements: Vec::new(),
+        }],
+    )
+    .await?;
+
+    let expected_user_message = ResponseItem::Message {
+        id: None,
+        role: "user".to_string(),
+        content: vec![ContentItem::InputText {
+            text: "hello from debug prompt".to_string(),
+        }],
+        end_turn: None,
+        phase: None,
+    };
+    assert_eq!(input.last(), Some(&expected_user_message));
+    assert!(input.iter().any(|item| {
+        let ResponseItem::Message { content, .. } = item else {
+            return false;
+        };
+
+        content.iter().any(|content_item| {
+            let (ContentItem::InputText { text } | ContentItem::OutputText { text }) = content_item
+            else {
+                return false;
+            };
+            text.contains("Project-specific test instructions")
+        })
+    }));
+
+    Ok(())
+}