enject is a security-focused CLI tool that prevents AI agents and other processes from reading secrets out of `.env` files. It stores secrets in an encrypted local store (AES-256-GCM with Argon2id key derivation) and injects them into subprocess environments at runtime. The `.env` file on disk contains only `en://` symbolic references, never plaintext values. The tool provides commands to initialize a store, add/update/list/delete secrets, import a plaintext `.env` file (encrypting all values and rewriting it as a template), rotate the master password, and run a subprocess with resolved environment variables. The architecture is a single Rust binary with a clean `Store` trait abstraction separating the encryption backend from command logic. The codebase demonstrates strong security practices: secrets never touch disk as plaintext, nonces are freshly generated on every write, key material is zeroized immediately after use, and unresolved references cause hard errors. It includes comprehensive unit tests and a CI pipeline with linting, formatting, and security auditing.