How Claude Code Sandboxing Works: Sandboxed Bash, Network Allowlists, and the Threat Model of Six Isolation Approaches
Claude Code's built-in sandboxed Bash restricts every command at the OS level: writes are limited to the working directory plus session temp, while reads default to the entire machine; network traffic goes through a proxy allowlist that starts with zero domains. The switches live in the /sandbox panel and sandbox.enabled — there is no --sandbox flag. This post also compares sandbox runtime, dev containers, Docker, VMs, and Claude Code on the web to show when each heavier isolation tier earns its setup cost.