Fail Fast

Activate when an operation may swallow, normalize, retry, aggregate, suppress, or
reroute an error; ignore a child failure; publish stale/partial success; or leave owned
work running.

Read the failure-path procedure (skill file). The first exception is the result:
preserve its raw traceback and causal chain, stop immediately, and remove every
false-success or alternate path at the owner.

Do not activate from a keyword alone. A UI loading placeholder, typed optional business
result, or ordinary non-error routing is not failover when its contract is explicit and
tested. A deterministic calculated default resolved by the typed owner before any
failure is likewise normal behavior, not fallback.