Before You Start
Make sure you've installed the Mouse extension and initialized your workspace by running Mouse: Initialize Workspace from the Command Palette (Ctrl+Shift+P / Cmd+Shift+P). If you haven't done this yet, see Installing Mouse.
To confirm Mouse is running, check the status bar; it should show Mouse: Trial or Mouse: Licensed.
Demo 1: Checklist Surgery
Ask your AI assistant:
"Please create a new file called
checklist-demo.mdwith a 20-item numbered checklist using Markdown checkboxes (all unchecked). Then mark items 1, 3, 5, 7, 9, 11, 13, 15, 17, and 19 as complete. Only insert anxin each checkbox. Do not copy or replace any of the item descriptions."
What happens: The agent creates the file, then uses a columnar edit to target the 10 specific lines and insert x at the checkbox column. Only the checkbox characters change; item descriptions are never read, echoed, or touched.
What just happened? Mouse surgically inserted x into each checkbox without reading or rewriting any of the item descriptions. That's why the diff shows exactly and only the 10 checkboxes. Nothing else changed. A baseline agent would have rewritten every line it touched, risking formatting errors and content drift.
Demo 2: Commenting Out Non-Contiguous Blocks
Ask your AI assistant:
"Please create a new file called
sample.jswith about 25-30 lines of JavaScript containing 3-4 distinct function blocks. Then comment out the first and third function blocks only, leaving the second and fourth blocks untouched. Use batch editing."
What happens: The agent creates the file, then uses batch editing with two columnar operations (one for each non-contiguous block), inserting // at the start of each targeted line. All operations are staged together. The agent reviews the proposed changes, then commits them to disk.
What just happened? Mouse staged two separate edits as a single atomic batch, let the agent review the result, and only then wrote to your file. The first and third blocks are commented out; the second and fourth are completely untouched. A baseline agent would have made multiple sequential replacements with no atomicity. If one failed, the file would be left partially edited.
Demo 3: Clean Deletion
Ask your AI assistant:
"Now delete the second function block entirely from
sample.js. Remove it cleanly with no leftover blank lines or formatting artifacts."
What happens: The agent removes the exact line range with a delete operation. It specifies only two numbers (start and end), regardless of the block's size.
What just happened? Mouse deleted the function cleanly with zero content echo. The agent didn't need to read all lines, copy them back, and replace them with nothing. The diff shows only the removed lines. Nothing else was touched. A baseline agent would have spent tokens proportional to the deletion size, and likely left formatting artifacts behind.
What You Just Saw
In under 10 minutes, your agent:
- Made surgical, column-level edits without rewriting surrounding content
- Batched multiple non-contiguous edits atomically with staging and review
- Deleted code cleanly with zero content echo and no artifacts
Your assistant used Mouse tools automatically. You do not need to change your system prompts, make special configurations, or master a steep learning curve. Mouse just works!
Next Steps
Now that you've seen Mouse in action, explore Best Practices to see what else Mouse can do.