Enable using the markdown preview in the diff view #315174

Tracking issue for the work being done to let users see markdown diffs in a preview view instead of raw text. This may become the default for the agents UX and could be a useful option for users who care more about seeing the visual version of md doc's final state

Work

• Add better API for custom diff custom editors Add basic support for custom diff editors #313814

• Add api for using VS Code's diff algorithm Add document diff api proposal #314939

• Support rendering inner diffs (diffs within a line) Add inner highlighting support in md diff preview #315052

• Add scroll sync for side-by-side diffs

• 🏃 Make sure reopen with works properly in all cases

• 🏃 Make sure we open on the correct lines when switching between files

• 🏃 Fix Stylesheets and images for git: resources (left side)