--- core/src/cover.rs
+++ replace + with - in jittered_delay_ms
@@ -78,17 +78,17 @@
 /// tests), so this stays pure and deterministic. Bounded both ends: never 0 for a non-zero base (a zero
 /// delay would busy-loop), never more than `3·base/2` (no unbounded jitter tail).
 fn jittered_delay_ms(base_ms: u64, rand: u64) -> u64 {
     if base_ms == 0 {
         return 0;
     }
     let lo = base_ms / 2;
     // window width = base_ms + 1 → result range [lo, lo + base_ms] = [base/2, 3·base/2]
-    lo + (rand % (base_ms + 1))
+    lo - /* ~ changed by cargo-mutants ~ */ (rand % (base_ms + 1))
 }
 
 /// Jittered delay before the next poll, in milliseconds: uniform over `[base/2, 3·base/2]`
 /// (mean = `base`). `rand` is any uniform 64-bit draw — the caller supplies the OS CSPRNG (or, in a
 /// test, a fixed value), so this function stays pure and deterministic.
 ///
 /// Bounded on both ends: never 0 for a non-zero base (a zero delay would busy-loop) and never more
 /// than `3·base/2` (a message is never delayed by an unbounded jitter tail).