umputun / revdiff / 24852165736

Pull #146

github

fix(diff): address code review findings for divider work

- git totalOldLines: check "..." before ".." in ref splitting so A...B
  takes left operand A (not "A" + ".B"). triple-dot ranges still show
  the left operand of the range rather than merge-base, which is
  approximate but matches hg/jj behavior.
- gate totalOldLines subprocess behind compact mode in all VCS impls;
  full-file mode always reaches EOF so the trailing-divider probe was
  a wasted subprocess (~2× process launches per FileDiff call).
- extract countLines helper (called from 3 VCS totalOldLines methods).
- update ChangeDivider constant + DiffLine.Content godoc with new
  "⋯ N line[s] ⋯" format and pattern-match warning.
- unify hg/jj totalOldLines godoc with git's bullet format.
- clean up stale contradictory comments in TestParseUnifiedDiff_TrailingDivider.
- add TestGit_TotalOldLines (8 ref-resolution cases, locks in triple-dot fix).
- 3 new TestParseUnifiedDiff_TrailingDivider cases: insertion-only last
  hunk, deleted file, exact boundary.
- CLAUDE.md: extend Compact mode gotcha with divider-position details and
  add gotcha warning against pattern-matching DiffLine.Content on dividers.

Related to #145

70 of 102 new or added lines in 3 files covered. (68.63%)

8246 of 9229 relevant lines covered (89.35%)

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