9087/dsh-diff-approval

Pending-change review for DeepSeek Harness: every `edit`, `write` and `str_replace_editor` change is collected automatically into the file list, where a single change block, the blocks within a selection, or the whole file can be kept or reverted, and undo/redo is supported. It imports the workspace's version-control changes, shows the diff in a single-column or side-by-side view, and provides a Markdown preview in which changes can also be kept or reverted, in-file search, block jumping and copyable line references; the diff data is stored persistently, so the review continues after a restart.