feat(security): Enforce blacklist for discussion history files

mcp_client.py

@@ -87,7 +87,14 @@ def _is_allowed(path: Path) -> bool:
       - it is contained within (or equal to) one of the _base_dirs
     All paths are resolved (follows symlinks) before comparison to prevent
     symlink-based path traversal.
+    
+    CRITICAL: Blacklisted files (history) are NEVER allowed.
     """
+    # Blacklist check
+    name = path.name.lower()
+    if name == "history.toml" or name.endswith("_history.toml"):
+        return False
+
     try:
         rp = path.resolve(strict=True)
     except (OSError, ValueError):
@@ -153,11 +160,18 @@ def list_directory(path: str) -> str:
     try:
         entries = sorted(p.iterdir(), key=lambda e: (e.is_file(), e.name.lower()))
         lines = [f"Directory: {p}", ""]
+        count = 0
         for entry in entries:
+            # Blacklist check
+            name = entry.name.lower()
+            if name == "history.toml" or name.endswith("_history.toml"):
+                continue
+            
             kind = "file" if entry.is_file() else "dir "
             size = f"{entry.stat().st_size:>10,} bytes" if entry.is_file() else ""
             lines.append(f"  [{kind}]  {entry.name:<40}  {size}")
-        lines.append(f"  ({len(entries)} entries)")
+            count += 1
+        lines.append(f"  ({count} entries)")
         return "\n".join(lines)
     except Exception as e:
         return f"ERROR listing '{path}': {e}"
@@ -178,11 +192,18 @@ def search_files(path: str, pattern: str) -> str:
         if not matches:
             return f"No files matched '{pattern}' in {path}"
         lines = [f"Search '{pattern}' in {p}:", ""]
+        count = 0
         for m in matches:
+            # Blacklist check
+            name = m.name.lower()
+            if name == "history.toml" or name.endswith("_history.toml"):
+                continue
+                
             rel = m.relative_to(p)
             kind = "file" if m.is_file() else "dir "
             lines.append(f"  [{kind}]  {rel}")
-        lines.append(f"  ({len(matches)} match(es))")
+            count += 1
+        lines.append(f"  ({count} match(es))")
         return "\n".join(lines)
     except Exception as e:
         return f"ERROR searching '{path}': {e}"