HTTP Security Headers and CSP TaskFlow - Full Stack Developer 2026
Fastify security headers pnpm --filter api add @fastify/helmet@13.1.1
// main.ts - register before routes are exposed const fastify = app.getHttpAdapter().getInstance() await fastify.register(helmet, { global: true, contentSecurityPolicy: false, // API returns JSON; web CSP belongs to Next.js edge })
For the JSON API, headers such as nosniff and transport-related protections are still useful, while a page-level CSP is primarily a concern of the Next.js document responses.
Web header baseline
// next.config.ts - illustrative baseline
async headers() {
return [{
source: "/(.*)",
headers: [
{ key: "X-Content-Type-Options", value: "nosniff" },
{ key: "Referrer-Policy", value: "strict-origin-when-cross-origin" },
{ key: "Permissions-Policy", value: "camera=(), microphone=(), geolocation=()" },
{ key: "X-Frame-Options", value: "DENY" },
],
}]
}CSP rule Do not paste an over-broad CSP containing unsafe-inline/unsafe-eval just to make warnings disappear. Build and test the policy against actual Next.js scripts, Supabase endpoints and assets; prefer nonce/hash-based policies when the deployment requires inline bootstrap code.
HTTP is the contract joining independently deployed systems. Method, URL, headers, body, status, and response semantics must agree on both sides.
Restate the goal of “HTTP Security Headers and CSP” as one observable behavior. Write the success signal before touching code.
Trace the boundary map: client → method + URL → headers/body → server contract → status + response. 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: Security baseline checklist plus concrete tests for the most important abuse cases.. 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.
POST /tasks HTTP/1.1
Content-Type: application/json
Authorization: Bearer <token>
{"title":"Ship TaskFlow"}
HTTP/1.1 201 CreatedDo 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 “HTTP Security Headers and CSP” to a different TaskFlow resource or input. Write the acceptance criteria first, implement it, and provide the evidence that each criterion is satisfied.
Run an IDOR/broken-access-control test by changing resource IDs as another user.
Use the smallest change that demonstrates this lesson. Stop after it works and capture evidence.Trusting hidden buttons as protection
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.