Macro degrade 

macro_rules! degrade {
    ($counter:expr, $($arg:tt)*) => { ... };
}

The one way to record a degraded path (one that recovers via fallback): warn and counter increment done atomically (the syntactic form of “don’t go silent” — ADR-0018).

rg degrade! enumerates every degraded path. Batch paths (scan internals) return degradation via stats fields and the worker layer maps them to counters in one place (don’t scatter the macro across the hot path).