Cloak — Agent Security Skill

This file instructs AI coding agents to protect .env secrets using Cloak. Add it to your project root or append its contents to your CLAUDE.md / .cursorrules / .windsurfrules.

What is Cloak

Cloak encrypts real .env values into a vault and replaces them on disk with structurally valid sandbox values. The developer sees real values in their editor (the extension decrypts them). You (the agent) see sandbox values — that is by design.

Detection

On first interaction with a project, check for a .cloak file in the project root.

• .cloak exists → Cloak is active. Follow the rules below.
• .cloak does NOT exist but .env exists → suggest cloak init (always ask first, never run without consent).
• Neither exists → no action needed.

Rules

Reading .env files

You CAN read .env files. The values on disk are sandbox values (fakes) — they are safe to read, display, and use in code examples. They are structurally valid (e.g. sk_test_cloak_sandbox_000 for Stripe, postgres://dev:dev@localhost:5432/devdb for databases).

Do NOT attempt to access real secret values. Do NOT read vault files, recovery files, or any file under the cloak config directory (~/.config/cloak/, ~/Library/Application Support/cloak/, or %APPDATA%\cloak\).

Running commands that need real env vars

Use cloak run to inject real environment variables into any process:

cloak run npm start
cloak run python app.py
cloak run go run main.go
cloak run docker compose up

Do NOT try to read secrets from the vault and inject them manually. cloak run handles authentication (Touch ID on macOS, password on other platforms) — the developer will be prompted, and that is expected.

Adding or updating secrets

Use cloak set with the key and value as separate arguments:

cloak set STRIPE_KEY sk_test_EXAMPLE000000000000000000
cloak set DATABASE_URL "postgres://admin:s3cret@db.example.com:5432/myapp"

Do NOT write secrets directly to .env files. The .env file on disk is managed by Cloak — direct edits will be overwritten.

Modifying .env structure

To add/remove keys, change comments, or restructure the file, use:

cloak edit          # opens real values in $EDITOR, re-encrypts on save
cloak set KEY VALUE # add or update a single key

Do NOT directly edit .env when .cloak is present.

Checking status

cloak status    # shows protection state — no auth required

Error recovery

If you see a keychain or decryption error, suggest:

cloak recover
# The developer will need the recovery key shown during `cloak init`

If Cloak is not installed

If the developer wants to use Cloak but it's not installed:

# macOS / Linux
curl -fsSL https://getcloak.dev/install.sh | sh

# Windows (PowerShell)
irm https://getcloak.dev/install.ps1 | iex

The VS Code / Cursor extension is available as "Cloak" in the marketplace.

Command Reference

"Auth required" means the developer will be prompted for Touch ID (macOS) or their CLI password. This is expected — it prevents agents from accessing secrets programmatically.

For CLAUDE.md

## Secrets

This project uses Cloak to protect .env secrets.
- The .env file on disk contains sandbox values (safe to read).
- Use `cloak run <command>` to run processes that need real env vars.
- Use `cloak set KEY VALUE` to add or update secrets.
- Do not write to .env directly — use `cloak set` or `cloak edit`.
- If .cloak marker is missing and .env exists, ask before running `cloak init`.

For .cursorrules / .windsurfrules

This project uses Cloak for .env secret protection. The .env on disk has sandbox values (safe to read).
Use `cloak run <command>` for real env vars. Use `cloak set KEY VALUE` to add secrets.
Do not modify .env directly. If .cloak is missing and .env exists, suggest `cloak init` (ask first).