feat: Implement core application structure with frontend styling, JavaScript, and Python backend services.

backend/history.py

@@ -0,0 +1,70 @@
+# backend/history.py
+import json
+import os
+import time
+import logging
+import shutil
+from pathlib import Path
+from typing import List, Dict, Any, Optional
+
+logger = logging.getLogger("obsigate.history")
+
+HISTORY_DIR = Path("data/history")
+
+def _get_history_file(username: str) -> Path:
+    HISTORY_DIR.mkdir(parents=True, exist_ok=True)
+    return HISTORY_DIR / f"{username}.json"
+
+def _read_history(username: str) -> List[Dict[str, Any]]:
+    h_file = _get_history_file(username)
+    if not h_file.exists():
+        return []
+    try:
+        return json.loads(h_file.read_text(encoding="utf-8"))
+    except Exception as e:
+        logger.error(f"Failed to read history for {username}: {e}")
+        return []
+
+def _write_history(username: str, history: List[Dict[str, Any]]):
+    h_file = _get_history_file(username)
+    try:
+        tmp = h_file.with_suffix(".tmp")
+        tmp.write_text(json.dumps(history, indent=2, ensure_ascii=False), encoding="utf-8")
+        shutil.move(str(tmp), str(h_file))
+    except Exception as e:
+        logger.error(f"Failed to write history for {username}: {e}")
+
+def record_open(username: str, vault: str, path: str, title: str = ""):
+    """Record that a file was opened by a user."""
+    if not username:
+        return
+    
+    history = _read_history(username)
+    
+    # Remove existing entry for the same file if any
+    history = [item for item in history if not (item["vault"] == vault and item["path"] == path)]
+    
+    # Add new entry at the beginning
+    history.insert(0, {
+        "vault": vault,
+        "path": path,
+        "title": title,
+        "opened_at": time.time()
+    })
+    
+    # Limit history size (e.g., 100 entries)
+    history = history[:100]
+    
+    _write_history(username, history)
+
+def get_recent_opened(username: str, vault_filter: Optional[str] = None, limit: int = 20) -> List[Dict[str, Any]]:
+    """Get the most recently opened files for a user."""
+    if not username:
+        return []
+        
+    history = _read_history(username)
+    
+    if vault_filter:
+        history = [item for item in history if item["vault"] == vault_filter]
+        
+    return history[:limit]