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OpenClaw uses @openclaw/fs-safe for security-sensitive local file operations: root-bounded reads/writes, atomic replacement, archive extraction, temp workspaces, JSON state, and secret-file handling. It is a library guardrail for trusted OpenClaw code that receives untrusted path names, not a sandbox. Host filesystem permissions, OS users, containers, and the agent/tool policy still define the real blast radius.

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Default: no Python helper

OpenClaw sets the fs-safe POSIX Python helper to off by default:
  • the gateway should not spawn a persistent Python sidecar unless an operator opts in;
  • most installs do not need the extra parent-directory mutation hardening;
  • disabling Python keeps runtime behavior predictable across desktop, Docker, CI, and bundled-app environments.
OpenClaw only changes the default. An explicit setting always wins: 
# Default OpenClaw behavior: Node-only fs-safe fallbacks.
OPENCLAW_FS_SAFE_PYTHON_MODE=off

# Opt into the helper when available, falling back if unavailable.
OPENCLAW_FS_SAFE_PYTHON_MODE=auto

# Fail closed if the helper cannot start.
OPENCLAW_FS_SAFE_PYTHON_MODE=require

# Optional explicit interpreter path.
OPENCLAW_FS_SAFE_PYTHON=/usr/bin/python3
The generic fs-safe env names also work: FS_SAFE_PYTHON_MODE and FS_SAFE_PYTHON. Use require (not auto) when the helper is part of your security posture; auto silently falls back to Node-only behavior if the helper cannot start.

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What stays protected without Python

With the helper off, OpenClaw still gets fs-safe’s Node-only guardrails:
  • rejects relative-path escapes (..), absolute paths, and path separators where only bare names are allowed;
  • resolves operations through a trusted root handle instead of ad-hoc path.resolve(...).startsWith(...) checks;
  • refuses symlink and hardlink patterns on APIs that require that policy;
  • opens files with identity checks where the API returns or consumes file contents;
  • writes state/config files via atomic sibling-temp + rename;
  • enforces byte limits for reads and archive extraction;
  • applies private file modes for secrets and state files where the API requires them.
This covers OpenClaw’s normal threat model: trusted gateway code handling untrusted model/plugin/channel path input inside a single trusted operator boundary.

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What Python adds

On POSIX, the optional helper keeps one persistent Python process and uses fd-relative filesystem operations for parent-directory mutations: rename, remove, mkdir, stat/list, and some write paths. That narrows same-UID race windows where another process swaps a parent directory between validation and mutation — defense in depth on hosts where untrusted local processes can modify the same directories OpenClaw operates in. If your deployment has that risk and Python is guaranteed to exist, set: 
OPENCLAW_FS_SAFE_PYTHON_MODE=require

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Plugin and core guidance

  • Plugin-facing file access should go through openclaw/plugin-sdk/* helpers, not raw fs, when a path comes from a message, model output, config, or plugin input.
  • Core code should use the fs-safe wrappers under src/infra/* so OpenClaw’s process policy applies consistently.
  • Archive extraction should use the fs-safe archive helpers with explicit size, entry-count, link, and destination limits.
  • Secrets should use OpenClaw secret helpers or fs-safe secret/private-state helpers; do not hand-roll mode checks around fs.writeFile.
  • For hostile local-user isolation, do not rely on fs-safe alone. Run separate gateways under separate OS users/hosts, or use sandboxing.
Related: Security, Sandboxing, Exec approvals, Secrets.