Module fault 

Containing a failure the Studio did not expect.

The Studio runs the kernel, the English parser and the prover on the page’s own thread, so a bug in any of them — a panic, or the engine running out of stack on a deeply nested term — would take the whole page down with it. The web build aborts on panic, and an abort in wasm is a trap: it throws straight out of the module and leaves the page frozen mid-action.

contain runs work behind a boundary that turns such a failure into a Fault and leaves the page running. In the browser the boundary is a JavaScript try/catch around a call back into the module: a trap unwinds only the frames inside it. What the trap leaves behind is the module’s shadow-stack pointer, still set to the depth where the work died, so the boundary puts it back before any Rust runs again (build.rs exports __stack_pointer for this). A panic’s own message is taken on its way out by a panic hook, because the trap that ends it carries none. Natively a panic unwinds, and the boundary is catch_unwind.

What a trap cannot give back: the heap the abandoned frames owned stays allocated, and a RefCell they held borrowed stays borrowed — a later use of it faults again, and is contained again. And once a panic has been contained, std::thread::panicking() answers true for the rest of the page’s life, because the abort that ended the panic never let std count it done.

Structs

ActionFault

A Studio action that stopped on a fault: which action, and what stopped it.

Fault

A failure contain caught.

Enums

Cause

Why contained work stopped.

Functions

contain

Run work behind the fault boundary: its value, or the Fault that stopped it.