Frontend

Loading States

• Skeleton screens for content with known layout—less jarring than spinners
• Spinners for unknown-duration actions—but show within 100ms
• Never blank screens during load—always visual feedback
• Progressive disclosure: show content as it arrives—header first, then body

Empty States

• Empty screens always have a call to action—not just "No items"
• Illustration or icon + explanation + action button—guide user forward
• First-time empty vs cleared empty may differ—onboarding opportunity

Error Recovery

• Every error screen has a recovery path—Retry, Go Back, Contact Support
• Preserve user input on form failure—never lose their work
• Offline mode degrades gracefully—show cached content, queue actions
• Toast/snackbar for transient errors—inline for persistent ones

Immediate Feedback

• Every tap/click acknowledged within 100ms—button state change, animation, sound
• Optimistic updates for fast-feeling actions—show success, rollback if fails
• Progress indicators for operations over 1 second—user knows system is working
• Disable buttons during submission—prevent double-tap

Touch and Interaction

• Touch targets minimum 44x44 points—fingers are imprecise
• Adequate spacing between interactive elements—prevent mis-taps
• Swipe actions discoverable—hint or onboarding; don't assume users know
• Pull-to-refresh where expected—but indicate it's available

Visual Hierarchy

• One primary action per screen—other actions visually secondary
• Consistent spacing scale—8pt grid or similar system
• Typography hierarchy clear—title, body, caption distinguishable
• Color conveys meaning consistently—red for destructive, green for success

Motion and Animation

• Animation communicates, not decorates—shows relationship, guides attention
• Duration 150-300ms for interactions—fast enough to feel responsive
• Respect reduced motion preference—provide static alternative
• Exit animations as important as enter—completes the interaction loop

Consistency

• Same action, same pattern everywhere—don't reinvent navigation per screen
• Design tokens for colors, spacing, typography—single source of truth
• Reusable components over one-off designs—reduces cognitive load
• Platform conventions respected—iOS feels iOS, Android feels Android, web feels web

Accessibility

• Screen reader testing—not just visual inspection
• Sufficient color contrast—don't rely on color alone for meaning
• Keyboard/switch control works—every action reachable without touch
• Focus order logical—follows visual reading order

Responsiveness

• Design mobile-first, enhance for larger—not desktop shrunk down
• Test on real devices—simulators miss performance and interaction
• Landscape orientation considered—don't break if user rotates
• Content reflows gracefully—no horizontal scroll, no cut-off text

Performance Perception

• Time to interactive matters more than full load—prioritize interactivity
• Lazy load below-the-fold content—don't block first interaction
• Image placeholders prevent layout shift—dimensions known before load
• Cache aggressively—instant loads on return visits

Microcopy

• Button labels describe action: "Save Changes" not "Submit"
• Error messages explain what to do—not just what went wrong
• Confirmation dialogs clear about consequences—"Delete permanently?"
• Loading text specific when possible—"Uploading photo..." not "Loading..."