Idea Lab · Oct 15 2026 · AI idea demo

Stand-In

Stand-In is a broker that sits between an agent and its secrets. The agent only ever sees a handle such as {{secret:vps-a/ssh}}. The broker swaps in the real value inside the sandbox at the moment a command runs, checks the handle's host and time scope, strips the value back out of the output, and holds any outbound email, chat message or memory write that would carry secret material. Step through the scripted agent session below and compare the two panes: on the left is the model's context, on the right is what actually ran.

Example data · simulated session · no real keys or servers

Handle	Allowed hosts	Expires in	Real value (broker only)

Stand-In on

What the model sees 0 secrets in context

Press “Run next step” to start the session.

What actually ran sandbox and outbound gate

Commands and outbound messages appear here.

What to try

Run all six steps with Stand-In on. Step 4 asks to email the key to a teammate and is held; step 6 uses a handle on a host it is not scoped for and is refused.
Reset, switch Stand-In off and run again. Watch the left pane: the raw key enters the model's context at step 2 and leaves in an email at step 4.
Reset, press “Expire vps-a/ssh now”, then run the session. The deploy step fails closed instead of falling back to a pasted key.

This is a scripted illustration of the design. It does not measure detection rates; a real build would need tests against encoded, split and paraphrased secrets.