feat(frontend): auto login for HF Spaces

frontend.py

@@ -3,6 +3,8 @@
 from __future__ import annotations
 
 import asyncio
+import os
+from pathlib import Path
 from typing import Iterator, List, Optional
 import typing
 
@@ -25,6 +27,19 @@ def hf_login(token: str) -> str:
     return info.get("name") or info.get("email")
 
 
+def get_env_token() -> str | None:
+    """Return an available HuggingFace token from environment variables."""
+    for name in (
+        "HF_TOKEN",
+        "HF_SPACE_TOKEN",
+        "HF_API_TOKEN",
+        "HF_ACCESS_TOKEN",
+    ):
+        if token := os.getenv(name):
+            return token
+    return None
+
+
 # ---------------------------------------------------------------------------
 # File helpers
 # ---------------------------------------------------------------------------
@@ -117,20 +132,35 @@ def remove_session(user: str, session: str) -> None:
 # ---------------------------------------------------------------------------
 
 def build_ui() -> gr.Blocks:
+    token = get_env_token()
+    auto_user: str | None = None
+    auto_sessions: list[str] = []
+    if token:
+        try:
+            auto_user = hf_login(token)
+            auto_sessions = load_sessions(auto_user)
+        except Exception as exc:  # pragma: no cover - best effort
+            print(f"Automatic login failed: {exc}")
+
     with gr.Blocks(theme=gr.themes.Soft()) as demo:
-        user_state = gr.State(str)
+        user_state = gr.State(auto_user or str)
         session_state = gr.State("default")
         history_state = gr.State([])
 
-        with gr.Column() as login_col:
+        with gr.Column(visible=auto_user is None) as login_col:
             gr.Markdown("## HuggingFace Login")
             token_box = gr.Textbox(type="password", label="HuggingFace token")
             login_btn = gr.Button("Login")
             login_status = gr.Markdown()
 
-        with gr.Row(visible=False) as main_row:
+        with gr.Row(visible=auto_user is not None) as main_row:
             with gr.Column(scale=3):
-                session_drop = gr.Dropdown(label="Session", interactive=True)
+                session_drop = gr.Dropdown(
+                    label="Session",
+                    interactive=True,
+                    choices=auto_sessions,
+                    value=auto_sessions[0] if auto_sessions else None,
+                )
                 new_session = gr.Textbox(label="New Session Name")
                 create_btn = gr.Button("Create Session")
                 chatbox = gr.Chatbot(type="messages")
@@ -151,23 +181,28 @@ def build_ui() -> gr.Blocks:
         def do_login(token: str):
             user = hf_login(token)
             sessions = load_sessions(user)
-            return {user_state: user, session_drop: gr.Dropdown.update(choices=sessions), login_col: gr.Column.update(visible=False), main_row: gr.Row.update(visible=True)}
+            return {
+                user_state: user,
+                session_drop: gr.update(choices=sessions),
+                login_col: gr.update(visible=False),
+                main_row: gr.update(visible=True),
+            }
 
         login_btn.click(do_login, inputs=token_box, outputs=[user_state, session_drop, login_col, main_row])
 
         def create_session(user: str, name: str):
             if not name:
-                return gr.Dropdown.update()
+                return gr.update()
             reset_history(user, name)
             sessions = load_sessions(user)
-            return gr.Dropdown.update(value=name, choices=sessions)
+            return gr.update(value=name, choices=sessions)
 
         create_btn.click(create_session, inputs=[user_state, new_session], outputs=session_drop)
 
         def refresh_files(user: str, path: str):
             entries = list_directory(user, path)
             data = [[e["name"], e["is_dir"]] for e in entries]
-            return {file_list: gr.Dataframe.update(value=data), dir_path: path}
+            return {file_list: gr.update(value=data), dir_path: path}
 
         refresh_btn.click(refresh_files, inputs=[user_state, dir_path], outputs=[file_list, dir_path])
 
@@ -179,13 +214,13 @@ def build_ui() -> gr.Blocks:
 
         def save_file(user: str, path: str, content: str):
             write_file(user, path, content)
-            return gr.Textbox.update()
+            return gr.update()
 
         save_btn.click(save_file, inputs=[user_state, open_path, file_editor], outputs=file_editor)
 
         def delete_file(user: str, path: str):
             delete_path(user, path)
-            return gr.Textbox.update(value="")
+            return gr.update(value="")
 
         delete_btn.click(delete_file, inputs=[user_state, open_path], outputs=open_path)