Harness Engineering Practices P15. Design Permissions Around Revocability, Not Capability 🎯 Point The question isn't "can it do X" but "can X be undone?" Revocability is the right axis for cutting the autonomy-safety tradeoff. 📝 Overview Freely permit reversible actions (commits to branches, file edits — git can undo these). Gate only irreversible actions (force-push, production writes, external emails, payments). Revocability is the criterion for permission design. 🔍 Explanation Most permission designs rely on "does this feel dangerous" intuition, which is often wrong. File editing looks "dangerous" but is instantly reversible via git, making actual risk low. An external API request looks "trivial" but can't be unsent, making actual risk high. Using revocability as the criterion naturally yields optimal autonomy-safety balance. Requiring approval for reversible operations causes "Gate Fatigue" (AP8) — humans rubber-stamp reflexively, missing truly dangerous operations. 🛠 How to Practice - List all operations the agent can perform and classify each as "reversible," "irreversible," or "conditionally reversible" - Permit reversible operations (branch commits, file edits, sandbox execution, etc.) without approval - Require approval gates for irreversible operations (force-push, production writes, external API calls, email sends, etc.) - Consider effect chains (a commit that triggers CI that triggers auto-deploy creates indirect irreversibility) 💼 Use Cases - Issue-to-PR agents: commits to branches are free, force-push is forbidden - Incident response: diagnosis (reads) is autonomous, remediation (production writes) requires human approval - Prototyping: sandbox operations are free, only external network access is gated ⚠ Pitfalls Judging "reversible" isn't always simple. A branch commit is reversible, but if that branch auto-triggers CI which triggers deployment, it has indirectly irreversible effects. Consider the full chain of effects when judging revocability. Don't over-rely on "it can be undone" either — the cost of undoing matters too. #HarnessEngineering# #AIAgent#