diff --git a/codex-rs/core/src/codex_apps_file_download.rs b/codex-rs/core/src/codex_apps_file_download.rs
index b26ba072c2..eee08c4fe1 100644
--- a/codex-rs/core/src/codex_apps_file_download.rs
+++ b/codex-rs/core/src/codex_apps_file_download.rs
@@ -1,3 +1,4 @@
+use crate::mcp_openai_file::OPENAI_LIBRARY_CONNECTOR_ID;
 use crate::session::session::Session;
 use crate::session::turn_context::TurnContext;
 use codex_api::OPENAI_FILE_UPLOAD_LIMIT_BYTES;
@@ -36,12 +37,17 @@ fn codex_apps_download_base_url(turn_context: &TurnContext) -> &str {
 
 fn should_materialize_codex_apps_file_download(
     server: &str,
+    connector_id: Option<&str>,
     codex_apps_meta: Option<&JsonMap<String, JsonValue>>,
 ) -> bool {
     if server != codex_mcp::CODEX_APPS_MCP_SERVER_NAME {
         return false;
     }
 
+    if connector_id != Some(OPENAI_LIBRARY_CONNECTOR_ID) {
+        return false;
+    }
+
     let Some(codex_apps_meta) = codex_apps_meta else {
         return false;
     };
@@ -56,10 +62,11 @@ pub(crate) async fn maybe_materialize_codex_apps_file_download_result(
     sess: &Session,
     turn_context: &TurnContext,
     server: &str,
+    connector_id: Option<&str>,
     codex_apps_meta: Option<&JsonMap<String, JsonValue>>,
     mut result: CallToolResult,
 ) -> CallToolResult {
-    if !should_materialize_codex_apps_file_download(server, codex_apps_meta)
+    if !should_materialize_codex_apps_file_download(server, connector_id, codex_apps_meta)
         || result.is_error == Some(true)
     {
         return result;
@@ -512,4 +519,48 @@ mod tests {
                     })
         }));
     }
+
+    #[tokio::test]
+    async fn codex_apps_file_download_materialization_is_noop_for_non_library_connector() {
+        let (session, turn_context) = make_session_and_context().await;
+        let original = CallToolResult {
+            content: vec![serde_json::json!({
+                "type": "text",
+                "text": serde_json::json!({
+                    "file_id": "file_123",
+                    "file_name": "testing-file.txt",
+                    "file_uri": {
+                        "download_url": "https://attacker.example/download/file_123",
+                        "file_name": "testing-file.txt",
+                    }
+                })
+                .to_string(),
+            })],
+            structured_content: Some(serde_json::json!({
+                "file_id": "file_123",
+                "file_name": "testing-file.txt",
+                "file_uri": {
+                    "download_url": "https://attacker.example/download/file_123",
+                    "file_name": "testing-file.txt",
+                }
+            })),
+            is_error: Some(false),
+            meta: None,
+        };
+
+        let result = maybe_materialize_codex_apps_file_download_result(
+            &session,
+            &turn_context,
+            codex_mcp::CODEX_APPS_MCP_SERVER_NAME,
+            Some("connector_not_library"),
+            Some(&serde_json::Map::from_iter([(
+                CODEX_APPS_META_MATERIALIZE_FILE_DOWNLOAD_KEY.to_string(),
+                JsonValue::Bool(true),
+            )])),
+            original.clone(),
+        )
+        .await;
+
+        assert_eq!(result, original);
+    }
 }
diff --git a/codex-rs/core/src/mcp_openai_file.rs b/codex-rs/core/src/mcp_openai_file.rs
index bc415a6ab9..bbefef7755 100644
--- a/codex-rs/core/src/mcp_openai_file.rs
+++ b/codex-rs/core/src/mcp_openai_file.rs
@@ -20,6 +20,8 @@ use codex_protocol::mcp::CallToolResult;
 use serde_json::Map as JsonMap;
 use serde_json::Value as JsonValue;
 
+pub(crate) const OPENAI_LIBRARY_CONNECTOR_ID: &str = "connector_openai_library";
+
 pub(crate) async fn rewrite_mcp_tool_arguments_for_openai_files(
     sess: &Session,
     turn_context: &TurnContext,
@@ -69,6 +71,7 @@ pub(crate) async fn postprocess_mcp_tool_result_for_openai_files(
     sess: &Session,
     turn_context: &TurnContext,
     server: &str,
+    connector_id: Option<&str>,
     codex_apps_meta: Option<&JsonMap<String, JsonValue>>,
     result: CallToolResult,
 ) -> CallToolResult {
@@ -76,6 +79,7 @@ pub(crate) async fn postprocess_mcp_tool_result_for_openai_files(
         sess,
         turn_context,
         server,
+        connector_id,
         codex_apps_meta,
         result,
     )
diff --git a/codex-rs/core/src/mcp_tool_call.rs b/codex-rs/core/src/mcp_tool_call.rs
index db5cbb63a4..c27a9d29ef 100644
--- a/codex-rs/core/src/mcp_tool_call.rs
+++ b/codex-rs/core/src/mcp_tool_call.rs
@@ -26,6 +26,7 @@ use crate::guardian::new_guardian_review_id;
 use crate::guardian::review_approval_request;
 use crate::guardian::routes_approval_to_guardian;
 use crate::hook_runtime::run_permission_request_hooks;
+use crate::mcp_openai_file::OPENAI_LIBRARY_CONNECTOR_ID;
 use crate::mcp_openai_file::postprocess_mcp_tool_result_for_openai_files;
 use crate::mcp_openai_file::rewrite_mcp_tool_arguments_for_openai_files;
 use crate::mcp_tool_approval_templates::RenderedMcpToolApprovalParam;
@@ -343,6 +344,7 @@ async fn handle_approved_mcp_tool_call(
             sess,
             turn_context,
             &server,
+            metadata.and_then(|metadata| metadata.connector_id.as_deref()),
             metadata.and_then(|metadata| metadata.codex_apps_meta.as_ref()),
             result,
         )
@@ -730,7 +732,6 @@ pub(crate) struct McpToolApprovalMetadata {
 }
 
 const CODEX_APPS_META_KEY: &str = "_codex_apps";
-const OPENAI_LIBRARY_CONNECTOR_ID: &str = "connector_openai_library";
 const MCP_TOOL_OPENAI_OUTPUT_TEMPLATE_META_KEY: &str = "openai/outputTemplate";
 const MCP_TOOL_UI_RESOURCE_URI_META_KEY: &str = "ui/resourceUri";
 const MCP_TOOL_THREAD_ID_META_KEY: &str = "threadId";