diff --git a/backend/app/gateway/routers/uploads.py b/backend/app/gateway/routers/uploads.py
index c43c820..d808a34 100644
--- a/backend/app/gateway/routers/uploads.py
+++ b/backend/app/gateway/routers/uploads.py
@@ -187,7 +187,10 @@ async def delete_uploaded_file(thread_id: str, filename: str) -> dict:
         raise HTTPException(status_code=403, detail="Access denied")
 
     try:
-        file_path.unlink()
+        if file_path.suffix.lower() in CONVERTIBLE_EXTENSIONS:
+            companion_markdown = file_path.with_suffix(".md")
+            companion_markdown.unlink(missing_ok=True)
+        file_path.unlink(missing_ok=True)
         logger.info(f"Deleted file: {filename}")
         return {"success": True, "message": f"Deleted {filename}"}
     except Exception as e:
diff --git a/backend/tests/test_uploads_router.py b/backend/tests/test_uploads_router.py
index 1e43ce5..649d0d3 100644
--- a/backend/tests/test_uploads_router.py
+++ b/backend/tests/test_uploads_router.py
@@ -96,3 +96,17 @@ def test_upload_files_rejects_dotdot_and_dot_filenames(tmp_path):
 
     # Only the safely normalised file should exist
     assert [f.name for f in thread_uploads_dir.iterdir()] == ["passwd"]
+
+
+def test_delete_uploaded_file_removes_generated_markdown_companion(tmp_path):
+    thread_uploads_dir = tmp_path / "uploads"
+    thread_uploads_dir.mkdir(parents=True)
+    (thread_uploads_dir / "report.pdf").write_bytes(b"pdf-bytes")
+    (thread_uploads_dir / "report.md").write_text("converted", encoding="utf-8")
+
+    with patch.object(uploads, "get_uploads_dir", return_value=thread_uploads_dir):
+        result = asyncio.run(uploads.delete_uploaded_file("thread-aio", "report.pdf"))
+
+    assert result == {"success": True, "message": "Deleted report.pdf"}
+    assert not (thread_uploads_dir / "report.pdf").exists()
+    assert not (thread_uploads_dir / "report.md").exists()