diff --git a/CHANGELOG.md b/CHANGELOG.md
index a990d204..9fce67ca 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Duplicate chat uploads now report the actual stored filename in `/api/upload` responses, so suffixed files such as `photo-1.png` do not appear under the original basename in WebUI attachment metadata.
+
 ## [v0.51.152] — 2026-05-28 — Release DX (stage-batch34 — single-PR optional gateway-backed browser chat)
 
 ### Added
diff --git a/api/upload.py b/api/upload.py
index dc0aa0c1..b36cde46 100644
--- a/api/upload.py
+++ b/api/upload.py
@@ -125,7 +125,7 @@ def handle_upload(handler):
         dest.write_bytes(file_bytes)
         mime = mimetypes.guess_type(safe_name)[0] or 'application/octet-stream'
         return j(handler, {
-            'filename': safe_name,
+            'filename': dest.name,
             'path': str(dest),
             'size': dest.stat().st_size,
             'mime': mime,
diff --git a/tests/test_chat_upload_attachment_paths.py b/tests/test_chat_upload_attachment_paths.py
index 6e0fba38..08f7f2cc 100644
--- a/tests/test_chat_upload_attachment_paths.py
+++ b/tests/test_chat_upload_attachment_paths.py
@@ -4,6 +4,7 @@ from pathlib import Path
 
 ROOT = Path(__file__).resolve().parents[1]
 MESSAGES_JS = ROOT / "static" / "messages.js"
+UPLOAD_PY = ROOT / "api" / "upload.py"
 
 
 def test_image_uploads_use_server_path_in_attached_files_context():
@@ -19,3 +20,23 @@ def test_image_uploads_use_server_path_in_attached_files_context():
 
     assert "uploadedPaths=uploaded.map(u=>u&&u.is_image?" not in src
     assert "uploadedPaths=uploaded.map(u=>u&&u.path?u.path" in src
+
+
+def test_duplicate_upload_response_reports_actual_stored_filename(tmp_path, monkeypatch):
+    """Duplicate upload names should report the suffixed stored basename."""
+    monkeypatch.setenv("HERMES_WEBUI_ATTACHMENT_DIR", str(tmp_path))
+
+    from api.upload import _sanitize_upload_name, _upload_destination
+
+    safe_name = _sanitize_upload_name("photo.png")
+    first = _upload_destination("session-a", safe_name)
+    first.write_bytes(b"first")
+    second = _upload_destination("session-a", safe_name)
+
+    assert first.name == "photo.png"
+    assert second.name == "photo-1.png"
+
+    src = UPLOAD_PY.read_text(encoding="utf-8")
+    handle_body = src[src.index("def handle_upload"):src.index("def extract_archive", src.index("def handle_upload"))]
+    assert "'filename': dest.name" in handle_body
+    assert "'filename': safe_name" not in handle_body