fuzz-target-every-parse: the §3.2 differential target — three parsers + skip_forward through the doc-hidden surfaces via shared invariants, 66 committed seeds + gitignore negation + README row; two real skip_forward findings fixed inline (division-by-zero/negative-interval wrap on sqlite+mem, i64 gap subtraction overflow on all three engines incl. pg) and registered as PROVENANCE D-38

alkstore-postgres/src/scheduler.rs

@@ -262,7 +262,7 @@ fn next_every_boundary(spec: &str, after: i64) -> Result<i64> {
 /// (the skipped boundaries never enqueue). 128-bit intermediates keep
 /// the arithmetic saturation-safe; the result clamps at `i64::MAX`.
 pub fn skip_forward(next_fire_at: i64, now: i64, interval: i64) -> i64 {
-    let gap = (now - next_fire_at) as i128;
+    let gap = now as i128 - next_fire_at as i128;
     let interval = interval.max(1) as i128;
     let next = (next_fire_at as i128) + (gap / interval + 1) * interval;
     if next > i64::MAX as i128 {