Diff View

Diff view compares the current file content against a baseline, showing changes inline.

Toggle diff view

Press Cmd+D or use View > Diff Mode.

Diff mode is per-tab — each tab can have its own diff state.

Baseline resolution

Mark resolves the baseline in this order:

1. .before file — if document.md.before exists alongside document.md, it is used as the baseline. This lets you create explicit comparison points.
2. Git HEAD — falls back to git show HEAD:{relative_path} for the last committed version.

If neither is available (e.g., the file is new and untracked), an error message is shown.

Creating a .before baseline

cp document.md document.md.before
# ... make edits to document.md ...
# Open in Mark, press Cmd+D to see the diff

This is useful for reviewing changes before committing, or for comparing against a specific snapshot.

Display

The diff view uses CodeMirror's MergeView with inline diff rendering. Identical sections are collapsed to focus on changes. The view is read-only — switch back to normal mode (Cmd+D again) to resume editing.