diff --git a/codex-rs/core/src/mcp_openai_file.rs b/codex-rs/core/src/mcp_openai_file.rs
index 5044568cd6..56f83f9f08 100644
--- a/codex-rs/core/src/mcp_openai_file.rs
+++ b/codex-rs/core/src/mcp_openai_file.rs
@@ -16,7 +16,6 @@ use crate::session::turn_context::TurnContext;
 use codex_api::OPENAI_FILE_UPLOAD_LIMIT_BYTES;
 use codex_api::upload_openai_file;
 use codex_login::CodexAuth;
-use codex_utils_path_uri::PathUri;
 use serde_json::Value as JsonValue;
 
 pub(crate) async fn rewrite_mcp_tool_arguments_for_openai_files(
@@ -122,14 +121,11 @@ async fn build_uploaded_argument_value(
             "no primary turn environment is available".to_string(),
         ));
     };
-    // TODO(anp): Resolve app tool file arguments using the selected environment's native path
-    // convention so uploads can read relative paths from foreign environments.
-    let native_environment_cwd = turn_environment
+    let path_uri = turn_environment
         .cwd()
-        .to_abs_path()
+        .join(file_path)
         .map_err(|error| contextualize_error(error.to_string()))?;
-    let resolved_path = native_environment_cwd.join(file_path);
-    let path_uri = PathUri::from_abs_path(&resolved_path);
+    let display_path = path_uri.inferred_native_path_string();
     let fs = turn_environment.environment.get_filesystem();
     let metadata = fs
         .get_metadata(&path_uri, /*sandbox*/ None)
@@ -137,27 +133,20 @@ async fn build_uploaded_argument_value(
         .map_err(|error| contextualize_error(error.to_string()))?;
     if !metadata.is_file {
         return Err(contextualize_error(format!(
-            "path `{}` is not a file",
-            resolved_path.display()
+            "path `{display_path}` is not a file"
         )));
     }
     if metadata.size > OPENAI_FILE_UPLOAD_LIMIT_BYTES {
         return Err(contextualize_error(format!(
-            "file `{}` is too large: {} bytes exceeds the limit of {} bytes",
-            resolved_path.display(),
-            metadata.size,
-            OPENAI_FILE_UPLOAD_LIMIT_BYTES,
+            "file `{display_path}` is too large: {} bytes exceeds the limit of {} bytes",
+            metadata.size, OPENAI_FILE_UPLOAD_LIMIT_BYTES,
         )));
     }
     let contents = fs
         .read_file_stream(&path_uri, /*sandbox*/ None)
         .await
         .map_err(|error| contextualize_error(error.to_string()))?;
-    let file_name = resolved_path
-        .file_name()
-        .and_then(|value| value.to_str())
-        .unwrap_or("file")
-        .to_string();
+    let file_name = path_uri.basename().unwrap_or_else(|| "file".to_string());
     let upload_auth = codex_model_provider::auth_provider_from_auth(auth);
     let uploaded = upload_openai_file(
         turn_context.config.chatgpt_base_url.trim_end_matches('/'),
diff --git a/codex-rs/core/tests/suite/openai_file_mcp.rs b/codex-rs/core/tests/suite/openai_file_mcp.rs
index c6d7a1d437..3c9445a36f 100644
--- a/codex-rs/core/tests/suite/openai_file_mcp.rs
+++ b/codex-rs/core/tests/suite/openai_file_mcp.rs
@@ -185,9 +185,10 @@ async fn run_extract_turn(test: &TestCodex, server: &MockServer) -> Result<Respo
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn codex_apps_file_params_upload_environment_files_before_mcp_tool_call() -> Result<()> {
-    // TODO(anp): Remove after file-upload fixtures support target-native Windows paths.
-    skip_if_wine_exec!(Ok(()), "uses a host-native file-upload path");
-
+    skip_if_wine_exec!(
+        Ok(()),
+        "13 MiB fixture exceeds the Wine exec WebSocket frame limit after base64 encoding"
+    );
     let server = start_mock_server().await;
     let apps_server = AppsTestServer::mount(&server).await?;
     mount_file_upload_mocks(&server, STREAMED_FILE_SIZE as u64).await;
@@ -246,6 +247,33 @@ async fn codex_apps_file_params_upload_environment_files_before_mcp_tool_call()
     Ok(())
 }
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn codex_apps_file_params_upload_relative_path_from_selected_environment() -> Result<()> {
+    let server = start_mock_server().await;
+    let apps_server = AppsTestServer::mount(&server).await?;
+    mount_file_upload_mocks(&server, /*file_size_bytes*/ 11).await;
+
+    let mut builder = apps_enabled_builder(apps_server.chatgpt_base_url.clone())
+        .with_workspace_setup(|cwd, fs| async move {
+            let report_path = PathUri::from_abs_path(&cwd.join("report.txt"));
+            fs.write_file(&report_path, b"hello world".to_vec(), /*sandbox*/ None)
+                .await?;
+            Ok(())
+        });
+    let test = builder.build_with_auto_env(&server).await?;
+    let _responses = run_extract_turn(&test, &server).await?;
+
+    let apps_tool_call =
+        recorded_apps_tool_call_by_name(&server, CALENDAR_EXTRACT_TEXT_TOOL_NAME).await;
+    assert_eq!(
+        apps_tool_call.pointer("/params/arguments/file"),
+        Some(&uploaded_file(&server, /*file_size_bytes*/ 11))
+    );
+
+    server.verify().await;
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn codex_apps_file_params_pass_uploaded_file_to_post_tool_use_hook() -> Result<()> {
     let server = start_mock_server().await;