External diff & merge tools

Gitcito's diff viewer and three-pane resolver handle most days. Some days they do not: a 4,000-line generated file, a merge where you need to see four columns at once, or simply the tool you have used for a decade and read faster than any new one.

Settings → General → External diff & merge tools.

It is git's list, not ours

Gitcito keeps no table of its own. The dropdowns are git difftool --tool-help and git mergetool --tool-help, which is why:

• The tools git already found on your machine are listed first; the ones it knows but cannot find are listed after, marked not installed.

• A custom tool works with no extra support. If you have

  git config --global difftool.mine.cmd 'mycompare "$LOCAL" "$REMOTE"'
  

  then mine appears in the dropdown like any built-in.

• Your choices are written to diff.tool and merge.tool in your global git config — the same keys your terminal reads. Set it here and git difftool on the command line behaves the same way. Set it there and Gitcito picks it up.

Git knows roughly thirty tools out of the box, including Kaleidoscope, Beyond Compare, Meld, KDiff3, P4Merge, Araxis, DiffMerge, WinMerge, FileMerge, VS Code and the vim family.

Where the actions appear

Both entries only appear when a tool is actually configured; an unconfigured git difftool would just error, and an inert button is worse than no button.

What happens while the tool is open

Gitcito waits for it to close. That is deliberate — git mergetool only stages the resolved file after the tool exits, so there is a real result to report — and it is why the button shows a spinner rather than returning immediately.

The rest of the app stays responsive: these run outside the per-repository lock that serialises normal git operations, so a merge tool left open over lunch does not freeze the tab behind it.

When an external merge succeeds, git stages the file itself and Gitcito closes the resolver and refreshes. If you close the tool without saving, git says so and nothing changes.

The .orig file

git mergetool leaves a <file>.orig backup next to the resolved file by default — git's behaviour, not Gitcito's. The toggle in Settings writes mergetool.keepBackup; turn it off and a resolved file leaves nothing behind.

Limits

• Working-tree diffs only. The composer's entry compares what you have now against the index. Comparing two historical commits externally is not wired up — use the built-in diff viewer or the comparison for that.
• One file at a time. There is no "diff every changed file" sweep.
• Gitcito never installs anything. A tool marked not installed stays selectable, because git may still find it after you install it — but it will fail until you do.