[Devin] fix: replace undefined viewCart() with working cart handler

[devin-ai-integration]

What

Clicking the "Cart (0)" button in the header throws a ReferenceError: viewCart is not defined because the onClick handler calls viewCart() which was never defined anywhere in the codebase. The button looks correct and is styled properly, making this bug easy to miss during visual testing.

Where

File: app/main.js
Line: 181 (onClick={() => viewCart()})

How I found it

• Browser interaction: Clicked the "Cart (0)" button in the header. Nothing visible happened, but the browser console showed a ReferenceError.
• Playwright verification: Captured the page error event:

PAGE ERROR: viewCart is not defined

Evidence

Playwright pageerror event captured:

PAGE ERROR: viewCart is not defined
PAGE ERROR: viewCart is not defined

Fix

Replaced the undefined viewCart() call with a handleViewCart function defined within the App component. Since there's no cart view page in this demo app, the handler shows a toast with the current cart item count.

Confidence

High — Reproducible on every click. The ReferenceError is unambiguous.

Summary

Fixes ReferenceError thrown when clicking the Cart button by replacing the undefined viewCart() with a working handler.

Review & Testing Checklist for Human

• Click the Cart button — verify no console errors appear
• Verify a toast notification appears showing the cart count
• Add an item to cart first, then click Cart — verify the count in the toast is correct

Notes

Found via browser interaction testing — the button is prominently placed but completely non-functional due to the undefined function reference.

Link to Devin session: https://app.devin.ai/sessions/3b3d59c7eee04cea9069529fd6fff39d
Requested by: @scoobycoder

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment and CI monitoring

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
devin-ai-kata	Ready	Preview, Comment	Apr 26, 2026 7:49pm