@DanKornas highlighted Clampdown (github.com/89luca89/clampdown), a hardened container sandbox for coding agents: Landlock filesystem rules before the binary starts, deny-by-default egress with an allowlist, real API keys held in a separate auth proxy while the agent gets a dummy key, OCI hooks for nested containers, plus launch helpers for Claude Code, Codex, OpenCode, and pi (GPL-3.0-only).

Key Takeaways

  • ✓Landlock filesystem rules bind the agent to the project directory before start.
  • ✓Real keys stay in an auth proxy; the agent gets a dummy key and deny-by-default egress.
  • ✓Launch helpers for Claude Code, Codex, OpenCode, and pi; GPL-3.0-only.
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