Timeline

A name can reach the same check-in through two index entries, so one selection offers the same rid twice. MtimeMaxPick.offer keeps the first as `best` and appends the second to `tied`; winner then appends `best` back, so `tied` holds that rid twice.

Ancestor sets are self-inclusive, so each copy found itself in the other's set. Dominance skipped only the same INDEX, so both copies were dominated, every candidate was eliminated, and the maximal element a finite DAG must have came up null - a panic on `best.?`, reached through resolveName.

Dominance is about being a different check-in, not sitting at a different offset. The new test drives offer/winner directly, and also pins that a duplicate cannot shadow a real descendant. check-in: d3f58d2875 user: dmestas tags: sub-manifest

openReadOnly is what every CLI verb opens through, and until now it still checksummed every payload byte on every invocation -- so nothing users ran had gotten faster. It scans header-only now:

10k frames 42 MB 42.2ms -> 10.3ms 10k frames 410 MB 298.0ms -> 12.3ms 100k frames 416 MB 511.9ms -> 115.4ms 100 frames 419 MB 321.4ms -> 0.10ms

Open cost is a function of frame count rather than repository size. On a store of a few large artifacts it is effectively free.

This completes the sequence: vendor a faster crc, measure the path production actually takes, scan header-only on the append path, ship the fsck verb, then delete the eager check. Each step was gated on the one before it, and the deletion was deliberately last because it is the only one that gives something up.

What is given up: opening a repository no longer detects payload corruption. It surfaces on the read instead -- readFrameAt crc-checks every frame unconditionally now -- or on demand through "zit verify". That is the split git draws between ordinary operation and fsck, and it was signed off knowing the tradeoff. A damaged store also stays usable for everything that does not touch the damaged bytes, which the old eager check made impossible.

Slices 0 and 4 are closed too: the 4 KiB chunk widening landed inside verify, the only place that loop still runs, and the sidecar index is dead on its own gate -- the 100k-frame shape was to justify it by exceeding 150ms and came in at 119ms. mmap is dead alongside it, separately, because a mapping would keep shunned bytes resident and readable until every mapping dropped, which defeats reclamation rather than merely slowing it. Neither rejection is recorded at the logstore extension comment yet; that is the one piece of follow-up this leaves behind.

Verified on the merged tree: fmt clean, test 2327/2327, gate 19/19. On the branch tip, additionally e2e 671/671 and dst 6 seeds x 1000 steps. check-in: 6d9172d488 user: dmestas tags: trunk

zit now imports sqlite at defaults: 36,416 commits, 2,109 refs, 44m35s, no flags. Two independent walls stood in front of that.

Refs (issue 21). One file per ref made a ref's name a path, so the filesystem got a vote on which repositories are representable. sqlite has refs/remotes/origin/EQP-improvements and .../eqp-improvements at different commits -- legal, distinct git refs -- and on APFS the second landed on the first as a bare PathAlreadyExists, raised during publication after the whole import had run. Case was only the reachable instance; path length, reserved device names and each platform's own Unicode fold table are the same bug in other clothes.

They are one sorted file now, "refs", whose lines pair a canonical name with its target. Nothing reads it back -- "refs" is a reserved root the working-tree scan skips, and branches resolve through repostate's sym- tags -- so it is interop output and its job is to be legible. Sorting makes it byte-identical for a given ref set, so two imports of one repository can be compared.

This supersedes the ASCII-fold refusal from the previous commit. That was the right interim while a ref was a filename; with one file the collision is representable, so refusing it would be gratuitous. What survives is the genuine collision -- distinct sources normalizing to a byte-identical canonical name, refs/heads/./release against refs/heads/release -- which no layout can hold, and which now names both sources instead of only failing.

Budget (issue 20). The 4 GiB payload default refused sqlite's 12.2 GiB stream, and could not simply be raised: fileCommandCeiling divided the same number, so a larger allowance for a whole history was also a larger allowance for one commit's retained command list. Those bound different things and only one is memory -- payload streams and is released per event (sqlite's import held 21 MiB), while a commit's command list is held whole. The arena has max_command_arena_bytes of its own now and keeps the old 4 GiB; the cumulative total goes to 1 TiB.

The file-command ceiling is therefore structural: about 104 million commands in one commit, and no flag raises it. Its diagnostic says so rather than pointing at a knob that no longer moves it. The help text claimed the payload flag fixed both; it only ever fixed one. check-in: 8ae7041c2c user: dmestas tags: sub-manifest