Protect Routes Deliberately Per-route, controller-wide, and auth-by-default strategies
Course principle: a user ID becomes trusted only after the access token has been cryptographically verified by the backend.
Start explicit
@Controller('tasks')
@UseGuards(SupabaseAuthGuard)
export class TasksController {
// every endpoint in this controller is authenticated
}Controller-wide protection is easy to see and fits TaskFlow while we are still learning the boundary.
Public endpoints remain public
@Controller('health')
export class HealthController {
@Get()
check() {
return { status: 'ok' }
}
}NestJS supports registering an authentication guard globally and using metadata such as @Public() for anonymous routes. This can be safer when most of an API should be protected, because forgetting a decorator no longer accidentally creates a public endpoint. providers: [ { provide: APP_GUARD, useClass: SupabaseAuthGuard, }, ]
Why we do not switch globally yet • We want the trust boundary visible while learning.
• Phase 19 will add authorization and may influence guard composition.
• Public-vs-protected route inventory should be explicit before default-deny is enabled.
Recommended production direction For an internal business system where almost every endpoint is private, authenticated by default with a small explicit public-route escape hatch is usually easier to audit than protecting hundreds of routes one by one.
Source note: verified against current Supabase Auth/getClaims/signing-key guidance and NestJS authentication/authorization docs. Full URLs and version notes are included in SOURCE_NOTES.txt.
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 “Protect Routes and Default Deny Strategy” 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: Authentication guard + verification service + current-user helper + protected /auth/me and task routes.. 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 “Protect Routes and Default Deny Strategy” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Protect /auth/me and one task endpoint; test valid, missing, malformed, expired, and wrong-project tokens.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Decoding JWT without signature verification
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.