When Hermes Agent proposes a change to a file in your workspace, you don’t have to accept it blindly. The diff viewer shows you exactly what would change — original content on the left, proposed content on the right — before anything is written to disk. You stay in control of every edit.
The diff workflow
The typical flow for reviewing a Hermes-proposed change looks like this:
- Hermes proposes a change. During a chat session, the agent calls the
propose_diff tool with the file path and new content. The file opens in the editor with inline decorations — red for removed lines, green for added lines — while the original content remains on disk.
- The diff viewer opens. VS Code’s native diff panel shows the original file alongside the proposed version, giving you a side-by-side or inline view of every change.
- You review the changes. Scroll through the diff at your own pace. You can make additional edits in the proposed-content pane if needed.
- Accept or discard. Run Hermes: Apply Hermes Changes to write the proposed content to disk, or simply close the diff panel to discard without touching the file.
Commands
Use any of the following commands from the Command Palette (Ctrl+Shift+P / Cmd+Shift+P) or from the chat interface:
| Command | Command ID | What it does |
|---|
| Hermes: Show Diff | hermes.showDiff | Opens a visual diff panel comparing the original file with the proposed content |
| Hermes: Preview Hermes Changes | hermes.previewDiff | Previews the proposed changes in a labeled diff panel (Hermes: <filename>) |
| Hermes: Apply Hermes Changes | hermes.applyDiff | Writes the proposed changes to disk and saves the file immediately |
propose_diff is pending.
If you are unsure about a change, simply close the diff panel without running Apply — the original file is untouched until you explicitly accept. If you do apply a change and then change your mind, use Ctrl+Z (or Cmd+Z) in the editor to undo. Note that undoing after a save is reversible only while the file buffer is still open with undo history; once you close the file, the undo stack is lost.