Hands-On Lab & Phase Exit Verify the product surface across keyboard, responsive, error and authorization scenarios
Phase 20 - Production Application UI Volume 06 - Professional Frontend
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Phase 20 turns the secure full-stack foundation into a coherent, accessible application interface without moving business authority into the browser.
Hands-on lab: ship a usable application shell The exit standard is not “looks nice on my monitor.” The shell must remain understandable across navigation, keyboard input, narrow screens, empty data, API failure, and different authorization contexts.
Lab A - Route architecture • Create `(app)/layout.tsx` and keep auth routes outside it.
• Add the skip link and `main` target.
• Build desktop Sidebar + Header without making the whole layout a Client Component.
• Add the mobile navigation as a small client island.
Lab B - Tasks surface • Fetch authorized tasks server-side.
• Render page header + primary action.
• Build semantic TaskTable with caption and scope attributes.
• Add readable status badges.
• Add EmptyState when no results exist.
Lab C - Route states • Create loading.tsx.
• Create error.tsx with reset button.
• Create not-found.tsx.
• Verify errors do not remove the surrounding app shell unexpectedly.
Lab D - Accessibility and responsiveness • Keyboard through the entire route without mouse.
• Verify visible focus and skip link.
• Test at 320, 390, 768, 900, 1024, 1366, 1920 widths.
• Test 200% browser zoom.
• Verify the task table scrolls inside its region, not the whole page.
• Verify status meaning remains clear without color.
Level 4 - Engineer Design an HRIS employee-directory screen using the same shell rules. Include page hierarchy, searchable/filterable employee collection, role-aware actions, empty/error/loading states, mobile behavior, and accessibility notes. Do not write code until you can explain which parts should remain Server Components and which interactions genuinely need Client Components.
Phase exit checklist • Protected application routes share a stable shell.
• Server Components remain the default.
• Client components are small interaction islands.
• Primary navigation is semantic and keyboard reachable.
• The page has a visible heading hierarchy and useful states.
• Task data is displayed semantically and responsively.
• Focus is visible and not hidden by sticky UI.
• UI permission logic never replaces NestJS authorization.
• No unnecessary UI framework was introduced.
Hands On Lab and Phase Exit matters because it changes a real boundary in TaskFlow. The goal is to understand the inputs, owner, observable output, and failure modes before adding more abstraction.
Restate the goal of “Hands On Lab and Phase Exit” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: route data → UI state → component tree → interaction → accessible feedback. Mark the one boundary this lesson changes.
Inspect the current repository state and record the exact files, route, table, or runtime involved. Avoid creating an abstraction before you can name the existing owner.
Implement the smallest vertical slice. Add one coherent change, run the narrowest verification command, and read the output before continuing.
Connect the slice to TaskFlow’s phase artifact: TaskFlow responsive shell with navigation, workspace context, task screens, loading/empty/error states, and accessible interactions.. Verify behavior from the outside as a user or API client would.
Create one controlled failure that is safe to reproduce. Predict the symptom first, capture evidence, locate the earliest broken boundary, then fix only that cause.
Close the reference and rebuild or explain the core change from memory. Record what you would monitor or test before trusting the same change in production.
if (query.isPending) return <TaskSkeleton />;
if (query.isError) return <TaskError retry={query.refetch} />;
if (!query.data.length) return <EmptyTasks />;
return <TaskTable tasks={query.data} />;Do not copy this as a finished answer. Predict what each boundary does, type the smallest useful slice, run it, then compare the result with your prediction.
Return to the nearest observable boundary: input, network, process log, database, or rendered UI. Compare actual evidence with the predicted path.
Change one variable at a time and reproduce the original failure after the fix; otherwise you have correlation, not diagnosis.
Without copying the final source, create a second small scenario that applies “Hands On Lab and Phase Exit” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Exercise all non-happy states by forcing no data, slow data, error, and forbidden responses.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Mobile layout treated as desktop squeezed smaller
Predict the symptom before causing the failure. Then locate the earliest boundary where reality diverges from expectation.Why does this responsibility live here, what input does it trust, what output proves success, and what would go wrong if another layer owned it?
If your explanation is vague, repeat the boundary trace before moving on.Close the reference. Reproduce the core idea from memory or explain the exact request/data flow aloud. Then check your diff or notes for accidental shortcuts that bypass validation, authorization, error handling, or verification earned in earlier phases.