gemini-prompt: add Change API key button and fix mobile submit layout

[simonw]

• Show a "Change API key" button when a key is already stored in localStorage, so users can update it without clearing storage
• Add responsive CSS: on screens ≤600px the controls row wraps and the Submit button stretches full-width

https://claude.ai/code/session_01XXTsotCW64yZXECFgWokoj

[claude]

Claude finished @simonw's task —— View job

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Code Review Complete ✅

Reviewed PR #231: gemini-prompt API key management and mobile layout improvements

Todo List

• Read and analyze the changed file (gemini-prompt.html)
• Review code quality and best practices
• Check for potential bugs or issues
• Assess performance considerations
• Evaluate security concerns
• Consider test coverage needs
• Provide comprehensive feedback

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Review Feedback

✅ Code Quality & Best Practices

The implementation follows good practices:

• Clean CSS architecture: Well-organized CSS with logical sections and consistent naming
• Semantic HTML: Proper use of HTML elements and accessibility attributes
• Modern CSS: Uses flexbox, CSS custom properties approach, and modern selectors
• Consistent styling: Follows established design patterns from the existing codebase

✅ Mobile Responsiveness Implementation

The mobile layout changes are well-implemented:

@media (max-width: 600px) {
  .controls-row {
    flex-wrap: wrap;
  }
  #submit-btn {
    width: 100%;
  }
}

• Appropriate breakpoint: 600px is a sensible choice for mobile/tablet boundary
• Clean wrapping behavior: flex-wrap: wrap handles the layout gracefully
• Full-width CTA: Submit button stretching to full width on mobile improves usability

✅ API Key Management Feature

The "Change API key" functionality is well-designed:

• Progressive disclosure: Shows button only when key exists (gemini-prompt.html:341)
• Clear UX flow: Simple prompt-based interaction for key updates (gemini-prompt.html:356-362)
• Proper state management: Updates UI immediately after key changes

⚠️ Security Considerations

Medium Priority:

• localStorage exposure: API keys stored in localStorage are accessible to any JavaScript on the domain and persist across sessions. Consider adding a warning or implementing session storage for sensitive keys.
• Plain text storage: Keys are stored without any obfuscation. While client-side encryption has limitations, consider at least basic encoding.

Code reference: gemini-prompt.html:349, 359

✅ Performance Considerations

• Minimal overhead: The changes add negligible performance impact
• Efficient DOM updates: UI updates are properly scoped and don't trigger unnecessary reflows
• Event handling: Event listeners are appropriately attached without memory leaks

⚠️ Potential Issues

Low Priority:

1. Input validation: The API key change function accepts any non-empty string (gemini-prompt.html:358). Consider basic format validation for Gemini API keys.

2. Error handling: No error handling if localStorage is unavailable (private browsing, storage full):

localStorage.setItem(STORAGE_KEY_API, key.trim());

Medium Priority:
3. Accessibility: The "Change API key" button lacks ARIA labels or descriptions that would help screen readers understand its purpose.

❌ Test Coverage

• No automated tests: This is a client-side HTML file with no test coverage
• Manual testing recommended: The responsive behavior and API key management should be manually tested across devices
• Consider: Adding basic integration tests for localStorage functionality and responsive behavior

📋 Recommendations

1. Security hardening: Add a disclaimer about API key storage or implement session-only storage option
2. Input validation: Add basic API key format validation (Gemini keys typically start with AIza)
3. Error handling: Wrap localStorage operations in try-catch blocks
4. Accessibility: Add aria-label to the change API key button
5. Testing: Consider adding Cypress or Playwright tests for the key user flows

Overall Assessment

This is a solid, well-implemented feature that enhances user experience with both functional improvements (API key management) and responsive design. The code is clean, follows established patterns, and addresses real user needs. The main areas for improvement are security considerations and test coverage.

Recommendation: ✅ Approved - Changes are production-ready with minor enhancement opportunities noted above.

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