How to Review Your Agent's Code Changes from Your Phone

Your Claude Code agent just finished a multi-file refactor. Before you merge anything, you want to see what it actually changed. Grass lets you do that from your phone: open the diff viewer in the app, and you get a color-coded git diff HEAD with per-file stats and line numbers — no laptop, no IDE, no SSH session required. If something looks wrong, you can send a follow-up prompt from the same screen and the agent corrects course.

TL;DR

• Grass includes a built-in diff viewer showing git diff HEAD output — color-coded, with per-file stats and line numbers
• Accessible via a button in the chat header while you're in any active session
• Works for any file the agent has modified in the current working directory
• You can send follow-up instructions directly from the chat screen if you spot something to fix
• No IDE or SSH required — works entirely from the Grass mobile app

Why reviewing agent changes from mobile matters

An AI coding agent working on a feature build doesn't just touch one file. It might modify a dozen — route handlers, test files, type definitions, config — across multiple directories. When the agent reports it's done, you need to verify the output before you trust it.

The traditional path is: open your laptop, cd into the project, run git diff, scan through the output in a terminal. That's fine when you're at your desk. It's not fine when it's 11pm and the agent just finished, or when you're away from your machine and want a quick sanity check before letting the agent continue.

Grass gives you that sanity check from your phone. The diff viewer surfaces the same information as git diff HEAD — formatted for a mobile screen rather than a terminal window.

What the Grass diff viewer shows you

The diff viewer in Grass renders git diff HEAD for the active repository. For each modified file, you see:

• File path and change summary — how many lines were added and removed, displayed as per-file stats at the top of each section
• Color-coded line diffs — additions in green, deletions in red, matching the convention you'd see in GitHub or any standard diff tool
• Line numbers — so you can orient yourself in the file and follow the context of each change
• Syntax highlighting — code is rendered with language-appropriate highlighting, not as plain text

The viewer covers every file the agent has modified since the last commit in the current working directory. If the agent has made 15 file changes, all 15 are in the diff viewer, scrollable in one place.

Step-by-step: reviewing code changes from your phone

1. Open the Grass app and connect to your session. If you're not already connected, scan the QR code from grass start output or tap an existing server connection.
2. Select the repository and open the active session. Tap the server, pick your repo, choose your agent, and open the session where the agent has been working.
3. Tap the Diffs button in the chat header. It's in the top-right area of the chat screen. Tapping it opens the diff viewer as a modal overlay.
4. Scroll through the changed files. Each file is listed with its change stats. Scroll down to read through the diffs for each file in sequence.
5. Check for anything unexpected. Look for changes outside the scope of what you asked the agent to do, or modifications to files you didn't expect it to touch.
6. Return to chat and send a follow-up if needed. Close the diff viewer with a swipe, type a correction or clarification in the chat input, and the agent continues from there.

What you can and can't do in the diff viewer

The diff viewer is a read-only view of git diff HEAD. It shows you what the agent changed — it doesn't let you edit files directly from the mobile app. If you spot something that needs fixing, your options are:

• Send a follow-up prompt in chat — describe what needs to change and let the agent fix it. This is the fastest path for most corrections.
• Open your laptop — for surgical inline edits or anything that requires direct file manipulation, the standard workflow is: review on phone, fix on laptop.

For the majority of review scenarios — checking that the agent stayed in scope, verifying that test files were updated, confirming the right functions were modified — the diff viewer gives you everything you need without touching a keyboard.

What you need

• Grass CLI — npm install -g @grass-ai/ide (Node.js 18+ required)
• Grass mobile app — iOS App Store (native) or Android PWA
• An active session — the diff viewer shows changes in the current working directory; the agent needs to have made at least one file modification
• Claude Code or OpenCode — both agents work with the diff viewer
• Git — the repository must be a git repo; the diff is generated from git diff HEAD

Frequently asked questions

Does the Grass diff viewer show staged changes or unstaged changes?

The diff viewer shows the output of git diff HEAD, which includes all changes in the working directory relative to the last commit — both staged and unstaged. It doesn't distinguish between the two. If you want to see only staged changes, you'd need to run git diff --cached in a terminal.

Can I view changes to a specific file only?

Not in the current diff viewer — it shows all modified files in one scrollable view. To focus on a specific file, use the file explorer in the chat screen: navigate to the file and read its current contents. For diff output scoped to one file, you'd need a terminal session.

What if the agent hasn't committed anything yet — will I still see its changes?

Yes. git diff HEAD captures all working directory changes since the last commit, regardless of whether anything has been staged or committed. As long as the agent has modified files, the diff viewer will show them.

Can I review changes across multiple repositories at once?

Not in a single view. Each Grass session is scoped to one repository. If you're running agents on multiple repos simultaneously, you'd switch between sessions in the app to view the diffs for each one. Grass supports multiple server connections, so switching is quick — tap the server list and select a different connection.

How is this different from reviewing a pull request on GitHub?

The Grass diff viewer shows working directory changes before they're committed or pushed — it's a local git diff HEAD, not a PR diff. You'd use Grass to check the agent's work in progress, then push and open a PR for the standard team review flow. The two are complementary, not alternatives.

Can I use the diff viewer while the agent is still running?

Yes. You can open the diff viewer at any point during an active session to see changes the agent has made so far. The diff updates each time you open it. If the agent is mid-task, you'll see a partial diff of whatever files it has touched up to that moment.

Related use cases

Monitor a long-running coding agent overnight — How to stay connected to an agent session while you sleep: live output streaming, permission modals on your phone, and session recovery after a disconnect.

Approve or deny a coding agent action from your phone — When the agent wants to write a file or run a command, a native modal gives you one tap to approve or deny. How the permission flow works and when it triggers.

Kick off a coding task during your commute — Start a new agent session from your phone, describe the task, and let the agent work while you're in transit. The diff viewer is how you check the results when you arrive.