The Capability Enforcer

The enforcer is the on-chain component that makes ChainRender apps safe by construction. It walks a composition and either passes it (with an honest grade) or refuses it — so an unsafe app cannot be registered in the first place. Safety isn't a warning you might ignore; it's a gate you cannot pass.

What it refuses (the hard rails)

• R1 — no arbitrary code. An escape hatch to unanalyzable code refuses the whole composition. Unanalyzable = unsafe.
• R2 — no dishonest envelope. An app that under-declares what it actually does (hiding a capability it reaches) is refused. You cannot claim to be safer than you are.
• R3 — no out-of-envelope actions. An action requiring a capability the app never declared is blocked.
• R4 — no value smuggling. An action that moves value while the app never declared VALUE is blocked — even if it tries to hide the value from its own capability set.
• R5 — no arbitrary calls. An action whose {to, selector} isn't in the declared call set is blocked. A button can only do what it openly says it does.
• R6 — no off-envelope bindings. A data binding needing an undeclared capability is blocked.
• R7 — dependency honesty. Immutable deps grade A, attested B, unproven/mutable C — conservatively, never refused but always disclosed.

Why refusal, not just warning

A warning can be ignored, suppressed, or missed. For a UI that signs transactions, "safe unless you click through a warning" isn't safe. So the unsafe cases are refused at registration — they never become a live app. What remains is a system where every registered app is structurally incapable of the smuggling attacks above, and its grade honestly reflects whatever safe dependencies it does have.

Drift-locked with the SDK

The SDK's grade() computes the same result the on-chain enforcer does — a test asserts they never diverge. So the grade you see while building is exactly what the chain will enforce. No surprises at deploy time.

Related

• The Trust Grade — what passes gets graded.
• Actions & Signing — how declared actions satisfy R3–R5.