The generator only ever emitted strictly increasing, unique modification times, so the equal-second corner -- where two check-ins tie and the name must resolve by DAG ancestry, not hash order -- was covered only by hand-written regression tests. That corner was a real bug once. A new tie mode reuses the previous mtime on a seeded, bounded roll and shapes a reused-mtime check-in as a descendant chain, the exact shape the bug took; the oracle resolves a tie the way production does, by ancestry and then least hash, so a resolver that fell back to hash order is caught. Order comparison is done up to that tie-break, with the two genuinely implementation-defined dimensions skipped under ties and documented. Reverting the real tie-break in a scratch build makes the tie sweep fail where the unique sweep stays green -- proof the simulator now sees the class it was blind to. Default seeds draw no extra entropy, so the existing universe is unchanged. check-in: b354fb5947 user: dmestas tags: trunk