feat: Migrate Angular 9 Hacker News app to React with Vite + TypeScript

[devin-ai-integration]

feat: Migrate Angular 9 Hacker News app to React 18 + Vite

Summary

Complete rewrite of the Angular 9 Hacker News client to React 18 with Vite and TypeScript. All Angular constructs are replaced with React equivalents:

• Framework: Angular 9 → React 18 with functional components and hooks
• Build: Angular CLI → Vite with vite-plugin-pwa for service worker support
• Routing: Angular Router → React Router v6 with React.lazy() / Suspense for code-splitting (ItemDetails, UserProfile)
• Data fetching: RxJS Observables → async/await with fetch
• State: Angular Services + DI → React Context API (SettingsContext with useSettings hook)
• Styles: SCSS files preserved and migrated; theme system (default/night/amoledblack) kept intact
• Static assets: Moved from src/assets to public/ per Vite conventions

Deleted all Angular-specific files (angular.json, polyfills, e2e/protractor, zone.js, karma, tslint, ngsw-config, etc.) and replaced yarn.lock with package-lock.json.

Local Testing Screenshots

News Feed (/news/1) — numbered list, pagination, header with nav links and settings gear:

Item Details (/item/:id) — story metadata with nested, collapsible comment threads:

Review & Testing Checklist for Human

This is a full framework rewrite (113 files changed). Careful manual review is essential.

• Verify feed navigation — run npm install && npm run dev, open http://localhost:5173, and confirm all feed types (news, newest, show, ask, jobs) load with correct data, pagination, and scroll-to-top behavior
• Test theme switching — open the settings panel (gear icon), switch between default / night / amoledblack themes, and confirm styles apply correctly across all pages
• Test item details & comments — click into a story, verify nested comments render with collapse/expand ([-]/[+]) functionality and dangerouslySetInnerHTML renders content safely
• Test user profile page — click a username; note that during testing the external API (node-hnapi.herokuapp.com/user/:id) returned 404 for all users. Verify whether this is also broken on the original Angular app or a regression
• Verify PWA — run npm run build && npm run preview, check DevTools → Application for the service worker registration and manifest

Recommended test plan: npm install && npm run dev, navigate all feed types, click into a story with comments, toggle all 3 themes, adjust font size / list spacing in settings, then try the user profile link.

Notes

• Build passes TypeScript strict-mode compilation and Vite production bundling; CI (Snyk security + license) passes
• SCSS shows deprecation warnings for @import rules (Dart Sass 3.0 migration needed in future) — not errors
• dangerouslySetInnerHTML usage for comment/item content mirrors the original Angular [innerHTML] binding
• No automated tests are included (old Protractor e2e tests were removed with Angular)

Link to Devin run: https://app.devin.ai/sessions/4aa1f0dc3dde4fe1a714706107fa5861
Requested by: @eashansinha

[devin-ai-integration]

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