FAQ
AI Agent Security —
Frequently Asked Questions
Everything you need to know about protecting your files from AI coding agents like Claude Code, Cursor, and Copilot.
Getting Started
How do I stop Claude Code from reading my .env files?
Install Phylax and add .env to the [deny] bucket in your phylax.toml file. Phylax applies real Windows ACLs (DENY ACEs) at the OS level. The Windows kernel returns ACCESS_DENIED before Claude Code reads a single byte. No prompt rules, no workarounds — the kernel enforces it.
How do I prevent AI agents from deleting files?
Add your critical directories to the [deny] bucket in phylax.toml using glob patterns like "migrations/**" or "config/**". Phylax applies DENY ACEs that block delete operations at the kernel level. Additionally, use the [write] bucket for files you want agents to edit but not delete.
Does Phylax work with Cursor, Windsurf, and other AI tools?
Yes. Phylax operates at the operating system level, not the application level. It detects and blocks Claude Code, Cursor, Windsurf, OpenCode, GitHub Copilot, Aider, Goose, Cline, Gemini CLI, and any other tool that accesses the Windows filesystem. No per-tool integration needed.
Security & Protection
Can AI agents bypass file permissions?
Phylax uses three independent layers of protection. Layer 1: DENY ACEs block all access. Layer 2: WRITE_DAC protection prevents ACL modification and ownership changes. Layer 3: Mandatory Integrity Control labels at High Integrity with NO_WRITE_UP block privilege bypass. Even if an agent runs icacls /remove:d, the MIC label blocks it — agents run at Medium integrity and cannot write to High integrity files.
What's the difference between prompt rules and Phylax?
Prompt rules like CLAUDE.md or .cursorrules are text instructions that AI agents can acknowledge but still ignore. Phylax enforces at the OS level — if the Windows kernel returns ACCESS_DENIED, no amount of prompting or agent reasoning can override it. Real security requires OS-level enforcement, not text instructions.
How does Phylax detect which process is an AI agent?
Phylax uses five detection signals in priority order: (1) environment variables specific to AI tools, (2) executable image names, (3) Node.js processes with agent-specific command-line arguments, (4) Session 0 background processes without windows, and (5) parent process chain tracing. This multi-signal approach ensures reliable agent identification.
What happens when protection is on and I need to edit a protected file?
In Phase 1 (current), run phylax stop to temporarily disable protection, edit your files, then run phylax daemon start to re-enable. In Phase 2 (kernel minifilter driver, in development), the driver distinguishes between human and agent processes — you'll be able to edit denied files without stopping the daemon.
Pricing & Privacy
Is Phylax free?
Yes. Phylax is completely free and open source under the Apache 2.0 license. No paid tiers, no accounts, no cloud dependency. Everything runs 100% locally on your machine. Audit logs are stored in local SQLite at %APPDATA%\Phylax\phylax.db.
Does Phylax send my data anywhere?
No. Phylax is 100% local — no cloud, no accounts, no telemetry. Audit logs never leave your machine. The daemon makes zero outbound network requests. Your files, your rules, your machine — period.
Does Phylax require an internet connection?
No. Phylax works fully offline after installation. There are no cloud dependencies, no API calls, and no data leaves your machine. Perfect for air-gapped environments and offline development.
Compatibility & Setup
What Windows versions does Phylax support?
Phylax supports Windows 10 and Windows 11. It uses native Windows ACL APIs (SetNamedSecurityInfoW) and Mandatory Integrity Control labels, which are built into all modern Windows versions.
Will Phylax be available for macOS or Linux?
Yes — Phase 2.5 targets cross-platform support. Linux will use fanotify + eBPF with Landlock/SELinux enforcement. macOS will use the Endpoint Security (ES) framework. Same phylax.toml, same permission model, same audit trail — different kernel.
How long does it take to set up Phylax?
About 10 seconds. Run the install command, then phylax init creates your config file and starts the daemon. That's it. Your project is protected.