diff --git a/backend/main.py b/backend/main.py
index 52a7695..0e83661 100644
--- a/backend/main.py
+++ b/backend/main.py
@@ -1,4 +1,5 @@
 import asyncio
+import zipfile
 import json
 import os
 import tempfile
@@ -205,17 +206,24 @@ async def upload_files(files: List[UploadFile] = File(...)):
             tmp_path = tmp.name
         try:
             if suffix == ".zip":
-                remote_tmp = f"/tmp/{file.filename}"
-                ssh_manager.upload_file(tmp_path, remote_tmp)
-                input_dir = STAGE_DIRS["input"]
-                out, err, code = ssh_manager.execute(
-                    f"unzip -o '{remote_tmp}' -d '{input_dir}' "
-                    f"&& rm '{remote_tmp}'",
-                    use_conda=False,
-                )
-                if code != 0:
-                    raise HTTPException(status_code=500, detail=f"Unzip failed for {file.filename}: {err}")
-                results.append({"file": file.filename, "action": "extracted"})
+                extracted = []
+                with zipfile.ZipFile(tmp_path) as zf:
+                    for member in zf.infolist():
+                        if member.is_dir():
+                            continue
+                        name = Path(member.filename).name
+                        if not name or name.startswith("."):
+                            continue
+                        with zf.open(member) as src, tempfile.NamedTemporaryFile(delete=False, suffix=Path(name).suffix) as out_tmp:
+                            out_tmp.write(src.read())
+                            out_tmp_path = out_tmp.name
+                        try:
+                            remote_path = f"{STAGE_DIRS['input']}/{name}"
+                            ssh_manager.upload_file(out_tmp_path, remote_path)
+                            extracted.append(name)
+                        finally:
+                            os.unlink(out_tmp_path)
+                results.append({"file": file.filename, "action": "extracted", "files": extracted})
             else:
                 remote_path = f"{STAGE_DIRS['input']}/{file.filename}"
                 ssh_manager.upload_file(tmp_path, remote_path)