zit 0.13.0

zit 0.13.0 aligns its line diff and three-way merge with Fossil's, and makes the reads a forge pages through cheap on large stores: annotate, the history of one file, and the daemon's start and feed.

This release is from trunk. Stores and the wire are unchanged from 0.12.1. Two caches beside each store are rebuilt once; see Compatibility.

Diff and merge follow Fossil

• Line diff. Every line diff in zit, from diff and its line counts to annotate and merge, is a port of the line diff in Fossil's diff.c (D. Richard Hipp). It replaces the patience and Myers engines, so zit aligns repeated lines as Fossil does, and annotate credits a check-in only with the lines its diff adds.
• Three-way merge. merge walks the two edit scripts as Fossil's merge3.c does. An edit beside the other side's change now merges cleanly. Where both sides add lines at the same point, the merge now stops with a conflict, as Fossil's does, instead of taking both. Every merge decision and merged text matches fossil 3-way-merge, except where zit keeps a final newline or a byte-order mark on purpose.

annotate

• -n N is Fossil's version limit. annotate -n N walks at most N versions of the file, newest first. A line the oldest walked version already carried is printed with blank check-in and date columns, as fossil annotate prints it. Before, -n counted check-ins and credited older lines to the oldest check-in shown. A script that read those columns from every line must now allow blank ones, or pass -n none.
• Versions come from the file-history index, and the walk stops as soon as -n or the nearest cached version allows. annotate -n 50 of the most-edited file in a 644 MB store went from 38 s to 50 ms.
• A blame cache. annotate keeps the answers for a file's recently annotated versions in .zit-cache and starts from the nearest one, so annotating a tip after a new commit costs tens of milliseconds instead of seconds. An answer that depended on a missing parent, a gap, a limit or content removed by policy is never cached.

log for a path

• zit log PATH reads content only for the rows it prints and decides the rest from the file index. A 200-row page of a 2,000-version history costs tens of milliseconds.
• --offset N skips N rows, as Fossil's finfo spells it. --cursor C starts after the row a cursor names, and -F json returns the next cursor. A cursor page costs the same at any depth; an offset page still costs the rows it skips. Page by cursor where you can.

Daemon

• Start. zit daemon answers its first request in about 0.3 s on a 68,000-file store, where it took 8 to 10 s. It opens what a commit needs on the first commit, from the saved log index, and that commit costs about a second more than later ones.
• After a commit the daemon reads only the frames the commit added instead of reopening the store.
• Feed pages. A feed request may carry limit, the most check-ins to return; the reply's more says whether more follow. A page of 500 costs about 0.2 s. A request without limit is answered as before, and every feed reply now carries more. more can be true when only tag or other control artifacts follow, in which case the next page is empty. A daemon older than 0.13.0 refuses a request carrying limit.
• A session that reads the whole bootstrap feed peaks at 1.0 to 1.1 GB on a 68,000-file store, paged or not.

Compatibility

Stores, check-ins, the sync protocol and the daemon protocol version are unchanged.

Two caches in .zit-cache are rebuilt from the store, because the line diff behind them changed: the blame cache, by the first annotate of each file, and the line counts, by the first crosslink. Measured on a forge's stores, first command after upgrading from 0.12.1:

store	command	first call	later calls	peak memory
pkgsrc (644 MB, 68,000 files)	crosslink --lines	207 s	0.3 s	732 MB
pkgsrc	ls --long tip	5.2 s	0.7 s	211 MB
pkgsrc	annotate -n 50, most-edited file	0.3 s		146 MB
pkgsrc	info, ls, log, one-file diff	under 1.2 s		under 200 MB
a 119 MB forge store	each of the above but crosslink	under 0.8 s		under 30 MB

The line counts dominate: a consumer of crosslink --lines pays for them once per store. A server can build the new caches ahead of time on a copy of each store (crosslink --lines and ls --long tip), then move the copy's .zit-cache into place at the switch, as for 0.12.0. Do not let an older zit open a store whose caches are in the new format: it rebuilds its own over them.

Merges that both add lines at the same point now conflict where 0.12.1 took both sides; see above.

Qualification

The release manifest records native qualification against the exact tagged source archive on macOS ARM64, Linux x86-64 and Linux ARM64, using the pinned Zig 0.17.0 toolchain. Publication is gated on unit and end-to-end tests, Git differentials, deterministic simulation, seeded fuzzing, and Fossil interoperability checks on every distributed target.

For the basis of the conformance claim, see the 0.1.0 release notes.