Function checker_ceiling 

pub fn checker_ceiling() -> GrantSet

The widest authority any checker may hold.

Included	Why
fs:read:**, fs:list:**, fs:stat:**	A checker has to see what it is judging.
proc:exec:**	The useful checkers shell out — a compiler, a type checker, a test runner.

What is left out matters more than what is in:

• No net. A checker cannot reach an inference API, so it cannot ask a model what it thinks. This is the mechanism behind “model-free”, and it is why the claim survives a checker author who did not read the docs.
• No secret. No API key, so no credential to reach one with even if egress were somehow available.
• No time, no rand. The two ordinary sources of a verdict that differs between two runs over identical inputs.
• No fs:write. A checker that could edit the workspace could make its own verdict true.

proc:exec is the one wide grant, and it is wide honestly: a subprocess can do whatever the sandbox lets it. Confining the child is feature 09’s job, which is exactly the division ARCHITECTURE.md §3 draws — this crate decides what authority is legitimate, the sandbox decides what is actually possible.