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UI Component & State Design From a Mock (Frontend System Design)

By FrontendAtlas Team · Updated Feb 1, 2026

Given a UI mock or diagram, design the component tree and state model. Break the UI into reusable components, decide where state lives (local vs shared), and describe data flow (props, callbacks, derived state). Key considerations: - Component boundaries and reusability. - State ownership and…

Requirements exploration
Architecture / High-level design

What you’ll build / What this tests

This premium front-end system design system design focuses on UI Component & State Design From a Mock (Frontend System Design). You’ll apply components and state-management thinking with intermediate level constraints. The prompt emphasizes Given a UI mock or diagram, design the component tree and state model. Break the UI….

Learning goals

Decompose UI Component & State Design From a Mock (Frontend System Design) into front-end components, state, and data flow.
Apply components, state-management, architecture constraints to a real client architecture.
Define performance budgets and UX trade-offs for the interface.
Plan instrumentation and resilience for user-facing failures.

Key decisions to discuss

Choose a data model that matches UI reads and writes.
Pick a pagination + caching strategy to keep the UI fast.
Set performance budgets (LCP/INP) and validate with telemetry.

Evaluation rubric

Architecture: clear client data flow and component boundaries.
Performance: budgets + caching/virtualization where needed.
Resilience: offline/error states and retries defined.
Observability: metrics/logs to validate UX and perf.

Constraints / Requirements

Given a UI mock or diagram, design the component tree and state model. Break the UI…
Requirements exploration
Architecture / High-level design
Data model
Interface definition (API)
Optimizations and deep dive
Assume real users and real latency; budget for perceived performance.
Define client-side caching and invalidation strategy.
Plan pagination or windowing for large UI lists.
Account for components, state-management, architecture constraints in the UI.

Mini snippet (architecture sketch)

Constraints:
- P95 UI response < 200ms
- 1k+ events/sec during peak
- Focus: components, state-management

Components:
- Client cache + pagination
- Realtime updates (SSE/WebSocket)
- Observability + error states

Endpoints:
- GET /feed?cursor=
- POST /events

Common pitfalls

Ignoring pagination/virtualization for long feeds.
Underestimating client performance budgets.
Overfetching data or failing to cache responses.
Skipping failure states and retry UX.