feat: integrate MinIO-backed user filesystem

app-instance/backend/beaver/tools/builtins/filesystem.py

@@ -14,7 +14,7 @@ from __future__ import annotations
 
 from dataclasses import dataclass, field
 import json
-from pathlib import Path
+from pathlib import Path, PurePosixPath
 from typing import Any, Iterable
 
 
@@ -24,6 +24,7 @@ MAX_READ_CHARS = 120_000
 MAX_SEARCH_RESULTS = 200
 MAX_SEARCH_FILE_BYTES = 2_000_000
 MAX_SEARCH_FILES = 5_000
+USER_FILE_VIRTUAL_ROOTS = {"uploads", "outputs", "shared", "tasks"}
 SKIP_DIR_NAMES = {
     ".git",
     ".hg",
@@ -161,9 +162,28 @@ def _workspace_root(workspace: str | None) -> Path:
     return root
 
 
+def _virtual_user_file_error(user_path: str | None) -> str | None:
+    raw = str(user_path or ".").replace("\\", "/").strip()
+    if not raw or raw in {".", "./"}:
+        return None
+    try:
+        parts = [part for part in PurePosixPath(raw.strip("/")).parts if part not in ("", ".")]
+    except TypeError:
+        return None
+    if parts and parts[0] in USER_FILE_VIRTUAL_ROOTS:
+        return (
+            f"{user_path} is a personal agent file system path, not a workspace path. "
+            "Use user_files_read or user_files_copy_to_workspace for reads; use "
+            "user_files_write for shared/tasks files or user_files_publish_output for outputs."
+        )
+    return None
+
+
 def _resolve_existing_path(workspace: str | None, user_path: str | None) -> tuple[Path, Path]:
     """Resolve a user path and ensure the real target stays inside workspace."""
 
+    if error := _virtual_user_file_error(user_path):
+        raise WorkspacePathError(error)
     root = _workspace_root(workspace)
     raw_path = Path(user_path or ".").expanduser()
     candidate = raw_path if raw_path.is_absolute() else root / raw_path
@@ -178,6 +198,8 @@ def _resolve_existing_path(workspace: str | None, user_path: str | None) -> tupl
 
 
 def _resolve_writable_path(workspace: str | None, user_path: str | None) -> tuple[Path, Path]:
+    if error := _virtual_user_file_error(user_path):
+        raise WorkspacePathError(error)
     root = _workspace_root(workspace)
     if not user_path or not str(user_path).strip():
         raise WorkspacePathError("path is required")