ClawShell is an open-source runtime security layer for OpenClaw (a local AI agent platform) that addresses the fundamental vulnerability of AI agents holding sensitive credentials. Rather than relying on prompt-level guards, ClawShell runs as a separate privileged Unix process, keeping API tokens and PII entirely out of the agent's process space. When the agent needs to call an external API, it sends a structured request to ClawShell, which executes the call in its protected environment and returns only the result — the token never enters agent memory. Built with Rust and Tokio, it installs via npm or Cargo, auto-migrates existing API keys from environment variables, and requires no changes to existing workflows. The core argument is that security enforced by the model is insufficient; structural OS-level isolation is required because prompt injection is an inherent property of LLMs, not a patchable bug.