Working notes — 03 frontend projects.mdSUPPORTING MATERIAL
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Working notes — 03 frontend projects.md (2026-09-22)

Scratch for tiers/01-junior/03-frontend/projects.md. Not part of the guide.

Verified this session (2026-09-22)

  • European Accessibility Act: Directive (EU) 2019/882, applies since 28 June 2025; applies to services sold into the EU regardless of where the business sits; microenterprise exemption (<10 staff, <EUR 2M turnover) is for services; transition for pre-existing products/services runs to 28 June 2030. Technical benchmark is EN 301 549 (the section README, checked 2026-09-21, covers the WCAG 2.2 AA / EN 301 549 v4.1.1 detail).
  • Core Web Vitals (web.dev/articles/vitals, fetched 2026-09-22): LCP within 2.5 s, INP 200 ms or less, CLS 0.1 or less, measured at the 75th percentile of page loads, segmented mobile/desktop. All three "stable".
  • CloudFront Functions vs Lambda@Edge (AWS docs comparison page via search, 2026-09-22): Functions = JS only, viewer request/response only, sub-ms, no network or filesystem access, no request body; Lambda@Edge = Node.js/Python, all four events, seconds-long budgets, network access allowed, runs at regional edge caches not every edge location.
  • CloudWatch RUM (docs.aws.amazon.com CloudWatch-RUM.html, fetched 2026-09-22): app monitor generates a JS snippet; collects from a percentage of real user sessions you choose; page load, errors, sessions, device/geo breakdowns; 30-day retention unless copied to CloudWatch Logs; web client is open source (aws-rum-web).
  • Amplify Hosting vs S3+CloudFront (AWS docs + comparisons, 2026-09-22): S3's own docs now recommend Amplify Hosting for static sites; Amplify is CloudFront underneath plus git-based deploys, branch previews, instant invalidation, SPA rewrites, managed certs. S3+CloudFront direct = full control, IaC-friendly, no build pipeline attached.

Decisions

  • No prices anywhere; free-ness stated qualitatively ("costs nothing extra", "the sampling percentage is the cost control"), matching the exemplar's hedging.
  • Ordering: four states → state homes → keyboard pass → performance → hostile form. One screen → whole app → whole flow + law → real conditions → adversary.
  • The "judge model-written UI" prompt sequence lives in project 3 (audit, classify by cause, fix with native elements); project 1's sequence also ends with a model-miss checklist since happy-path-only is the classic miss.
  • SSRF note in project 5: P1's server fetches user-supplied URLs, so "validate" includes refusing private/metadata addresses. One sentence, junior register.
  • Diagram: four mini screens (loading/empty/error/loaded), ring steps across them (SMIL discrete), frame one = ring on loading, loop returns to start. Warm accent only on the error frame. Verdict lines under each frame carry the "three are never designed" point; caption carries the fix.