feat: add FUZZFORGE_USER_DIR env var to override user-global data dir

fuzzforge-cli/src/fuzzforge_cli/commands/mcp.py

@@ -177,7 +177,9 @@ def _generate_mcp_config(
     # User-global storage paths for FuzzForge containers.
     # Kept under ~/.fuzzforge so images are built once and shared across
     # all workspaces — regardless of where `fuzzforge mcp install` is run.
-    fuzzforge_home = Path.home() / ".fuzzforge"
+    # Override with FUZZFORGE_USER_DIR for isolated testing.
+    user_dir_env = os.environ.get("FUZZFORGE_USER_DIR")
+    fuzzforge_home = Path(user_dir_env).resolve() if user_dir_env else Path.home() / ".fuzzforge"
     graphroot = fuzzforge_home / "containers" / "storage"
     runroot = fuzzforge_home / "containers" / "run"
 

fuzzforge-cli/src/fuzzforge_cli/tui/helpers.py

@@ -9,6 +9,7 @@ and managing linked MCP hub repositories.
 from __future__ import annotations
 
 import json
+import os
 import subprocess
 from pathlib import Path
 from typing import Any
@@ -37,9 +38,16 @@ def get_fuzzforge_user_dir() -> Path:
     repositories, the hub registry, container storage (graphroot/runroot),
     and the hub workspace volume.
 
-    :return: ``Path.home() / ".fuzzforge"``
+    Override with the ``FUZZFORGE_USER_DIR`` environment variable to
+    redirect all user-global data to a custom path — useful for testing
+    a fresh install without touching the real ``~/.fuzzforge/``.
+
+    :return: ``Path.home() / ".fuzzforge"`` or ``$FUZZFORGE_USER_DIR``
 
     """
+    env_dir = os.environ.get("FUZZFORGE_USER_DIR")
+    if env_dir:
+        return Path(env_dir).resolve()
     return Path.home() / ".fuzzforge"