Essential File Blocking for AI Coding Assistants: A Practical Security Checklist

AI coding assistants present a new security challenge: they read directly from your local filesystem, not just from your version-controlled repository. This means files protected by .gitignore from being pushed to GitHub remain accessible to the agent running on your machine.

Key Files to Block

Based on a Node/Firebase setup audit from the Reddit discussion, these are the critical files that should be blocked from AI coding assistants:

• AI Assistant Configs: ~/.claude/settings.json (contains MCP server API keys), ~/.cursor/mcp.json
• Service Credentials: ~/.npmrc (npm token for publishing packages), Firebase service account JSON files (with full project access), ~/.config/gcloud/application_default_credentials.json (GCP credentials), ~/.git-credentials and ~/.netrc (Git HTTPS tokens)
• Common Oversights: ~/.ssh/id_* (SSH private keys), ~/.bash_history (may contain pasted tokens), .env and .env.* files (gitignore doesn't protect from local agents), test files with hardcoded keys, .git/config (may contain HTTPS tokens), /proc/<pid>/environ (environment variables from running processes)
• CI/CD Secrets: GitHub Actions, Vercel, and other CI/CD secrets that may appear in logs if echoed

Server-Specific Concerns

The discussion notes that on servers, additional files become vulnerable:

• /etc/environment (global environment variables)
• /etc/ssl/private/* (TLS certificates)
• Database configuration files with connection strings containing passwords
• /var/log/* (logs that may accidentally contain tokens)
• Crontabs with inline secrets in scheduled commands

The core issue highlighted is that traditional Git-based security measures like .gitignore don't protect against AI agents reading local files. Developers need to implement explicit blocking for sensitive files that AI coding assistants might access during their operation.