Artifact Description [bc9e272bb3]

Artifact bc9e272bb3332b7b715fbcc254b63583aa294b769d423f4be48593152717dfb2:

• File src/sim/oracle.zig
  • 2026-07-20 05:33:57 — part of check-in [c52cc8cc76] on branch h10-ties — H10: fuzz equal-mtime ties in the repository-state DST

    sim/gen.zig emitted strictly-increasing unique mtimes, so the same-second selection tie -- once a real defect, the B1 regression cluster -- was only example-tested, blind to a class that already bit once.

    gen.zig gains a tie-permitting mode: a seeded roll reuses the previous mtime, bounded to short runs, and each reused-mtime check-in is shaped as a linear child of the previous one, so an equal-mtime run is a real descendant chain. oracle.zig now computes the documented tie-break in resolveName, tipSlot and openLeafOf -- descendant-before-ancestor over full ancestry, then least artifact hash (repostate.zig ancestryMaximal) -- so a resolution reverting to hash order is caught, not mirrored.

    dst.zig runs the tie sweep as additional coverage; the unique sweep is unchanged. Order-independence keeps its total-rule dimensions (leaf set, name resolution) under ties and skips the open-leaf set, whose equal-mtime supersede is implementation-defined (Section 5.3); the Section 6.3 branch representative is first-seen under a tie, checked in the unique sweep only.

    Reverting the tie-break to hash order trips the tie sweep at seed 1. (user: dmestas, size: 20001) [annotate] [blame] [check-ins using]

  • 2026-07-20 05:42:10 — part of check-in [b354fb5947] on branch trunk — Merge h10-ties: the simulator now generates the equal-mtime ties that hid B1

    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. (user: dmestas, size: 20001) [annotate] [blame] [check-ins using]