Mission Rebuild the capability of Phase 03 without following the exact code line-by-line. The goal is transfer: can you use the ideas when the variable names, UI, or route shape changes?
Required outcome Build the Next.js application shell while understanding App Router routing, layouts, Server Components, Client Components, environment boundaries, and rendering behavior.
Required artifact A navigable TaskFlow web shell with route groups/layouts, server-first composition, selective client interactivity, and verified environment handling.
Constraints • Start from the previous phase checkpoint or a fresh branch. • Use the course architecture boundaries, but do not copy the reference implementation until after your first attempt. • Keep changes scoped to the capability. • Preserve validation, authorization, error handling, and observability expectations already earned in earlier phases. • Record any design decision where more than one implementation is reasonable.
Acceptance criteria • Can choose server vs client intentionally. • Can explain layout/page routing. • Can identify where code executes. • Can debug a hydration or environment-boundary mistake.
Independent build sequence 1. Generate the web app in the monorepo and verify the development server from the correct workspace. 2. Create nested routes and a shared layout, then predict which layouts persist across navigation. 3. Build one component as a Server Component and identify exactly why it can remain server-only. 4. Add one Client Component for interaction and explain what 'use client' changes in the dependency graph. 5. Add server-only and public environment values and prove which can reach the browser bundle. 6. Use browser DevTools and terminal logs to distinguish server rendering from client execution.
Self-review Compare your implementation to the reference only after the acceptance criteria pass. Differences are not automatically mistakes. For each difference, ask: does it preserve the same contract, security boundary, correctness, maintainability, and operational behavior? Keep the alternative when you can justify it with evidence.
Stretch challenge Change one assumption: more users, a second tenant, a slow network, an expired session, a concurrent mutation, a deployment restart, or a failed dependency. Predict whether your design still behaves correctly. If not, document the next architectural improvement rather than adding complexity blindly.
Phase exit Run the relevant checks, inspect Git diff, and write a three-sentence summary: what the system can do now, which boundary owns the new responsibility, and which failure you now know how to diagnose. Only then mark the phase complete.
Next.js is useful only when you can explain what runs on the server, what crosses into the browser, and which route owns a user-visible state.
Restate the goal of “Phase Synthesis & Independent Challenge” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: route → Server Component → client boundary → request/data source → rendered UI. 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: A navigable TaskFlow web shell with route groups/layouts, server-first composition, selective client interactivity, and verified environment handling.. 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.
// app/tasks/page.tsx
import { TaskList } from "./task-list";
export default async function TasksPage() {
const tasks = await loadTasks();
return <TaskList initialTasks={tasks} />;
}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.
Locate the first browser-only API or stateful hook and move the client boundary to the smallest component that needs it.
Verify route params, fetch location, cache behavior, and the exact server response before changing JSX.
Without copying the final source, create a second small scenario that applies “Phase Synthesis & Independent Challenge” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Add server-only and public environment values and prove which can reach the browser bundle.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Leaking secrets through NEXT_PUBLIC variables
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.