{"slug": "claude-code-stop-it-from-touching-your-env-files", "title": "Claude Code: Stop it from touching your .env files", "summary": "A developer has created a PreToolUse hook for Claude Code that blocks the AI agent from modifying .env files, preventing accidental overwrites of database passwords and API keys. The 60-line hook intercepts write_file and edit_file tool calls, checks if the target path ends with .env, .env.local, or .env.production, and blocks the action with a security message. The safeguard turns destructive edits into controlled prompt engineering tasks, and the pattern can be extended to protect .gitignore or package-lock.json.", "body_md": "# Claude Code: Stop it from touching your .env files\n\n[Claude](/en/tags/claude/)Code is incredibly powerful, but giving an LLM agent full permission to rewrite your environment variables is a recipe for a production disaster. I wanted a way to lock down my\n\n`.env`\n\nfiles without manually babysitting every single tool call, so I implemented a `PreToolUse`\n\nhook to act as a safety guard.The logic is simple: the hook intercepts the tool call, checks if the target file is a `.env`\n\nfile, and kills the process if it detects an unauthorized edit attempt. It's about 60 lines of code, but it saves a massive amount of anxiety.\n\nHere is how to set up this safeguard in your AI workflow:\n\n## Implementation Steps\n\n1. Create a hook file in your project directory (e.g., `.claude/hooks/protect-env.ts`\n\n).\n\n2. Implement the logic to intercept `write_file`\n\nor `edit_file`\n\ntool calls.\n\n3. Configure your Claude Code environment to execute this hook before tool execution.\n\nHere is the core logic for the hook:\n\n```\nexport async function PreToolUse(toolCall: ToolCall): Promise<HookResult> {\n  const { toolName, arguments: args } = toolCall;\n  \n  // Define protected files\n  const protectedFiles = ['.env', '.env.local', '.env.production'];\n  \n  if (toolName === 'write_file' || toolName === 'edit_file') {\n    const path = args.path;\n    if (protectedFiles.some(file => path.endsWith(file))) {\n      return {\n        result: 'block',\n        message: `Security Block: Claude is not allowed to modify ${path} directly. Please provide the values manually.`\n      };\n    }\n  }\n  \n  return { result: 'allow' };\n}\n```\n\n## Productivity Gains\n\nSince adding this, my deployment process is much safer. Instead of the agent accidentally overwriting a DB password or an API key during a refactor, it now stops and asks me for the specific value. This turns a potentially destructive action into a controlled prompt engineering task.\n\nFor anyone building a real-world LLM agent integration, these kinds of \"guardrail\" hooks are essential. You can easily extend this pattern to protect your `.gitignore`\n\nor your `package-lock.json`\n\nto prevent the agent from messing up your dependency versions.\n\n[Next World-Model-Optimizer: Distilling Frontier LLMs for Agents →](/en/threads/3931/)", "url": "https://wpnews.pro/news/claude-code-stop-it-from-touching-your-env-files", "canonical_source": "https://promptcube3.com/en/threads/3985/", "published_at": "2026-07-27 16:13:47+00:00", "updated_at": "2026-07-27 16:40:32.951460+00:00", "lang": "en", "topics": ["ai-agents", "ai-safety", "developer-tools"], "entities": ["Claude Code", "Claude"], "alternates": {"html": "https://wpnews.pro/news/claude-code-stop-it-from-touching-your-env-files", "markdown": "https://wpnews.pro/news/claude-code-stop-it-from-touching-your-env-files.md", "text": "https://wpnews.pro/news/claude-code-stop-it-from-touching-your-env-files.txt", "jsonld": "https://wpnews.pro/news/claude-code-stop-it-from-touching-your-env-files.jsonld"}}