security

When to use

Use when implementing authentication, authorization, or other security-sensitive work.

Do NOT use when:

• Validation logic only — route to the project's validation carve-out (laravel-validation for Laravel; otherwise the framework-native primitive — Zod / class-validator, Pydantic, struct-tag validators).
• Full security audit — route to security-audit.
• You need a pre-implementation threat model — route to threat-modeling.
• You need end-to-end authorization analysis — route to authz-review.

Stack-specific carve-outs

The procedure below is stack-agnostic. For framework-specific primitives (Laravel Policies / Gates / FormRequests, Symfony voters, NestJS guards, Next.js middleware), defer to:

Stack	Carve-out
Laravel	laravel, laravel-validation, laravel-middleware
Symfony	symfony-workflow
Next.js / TS	nextjs-patterns

Procedure: Implement security for a feature (stack-neutral)

Step 0: Inspect

1. Read the project's auth doc (agents/authentication.md, docs/auth.md, or framework docs).
2. Read the project's authorization doc (gates / policies / voters / guards).
3. Locate existing authorization rules in the project's idiomatic location (Laravel app/Policies/, Symfony src/Security/Voter/, NestJS *.guard.ts).

Step 1: Authentication

• Identify the auth mechanism in use (session, JWT, OAuth, API token) — read the framework's auth config (config/auth.php, next-auth.config.ts, Symfony security.yaml, FastAPI dependency).
• Check guard / strategy / provider configuration.
• Multi-tenant identification happens after authentication — see multi-tenancy.

Step 2: Authorization

1. Create / locate the authz rule in the framework's idiomatic primitive (Policy, voter, guard, middleware, route dependency).
2. Apply it at the request boundary (FormRequest authorize(), controller / route-handler dependency, middleware chain).
3. Cover non-model gates (cross-aggregate rules) — keep them centralised, not scattered across handlers.

Step 3: Review for adversarial

For security-sensitive changes, run adversarial-review. Focus: attack surface, trusted user input, authz gaps.

Conventions

→ For PHP / Laravel specifics (auth helpers, mass assignment, Blade escaping, CSRF middleware): see guideline docs/guidelines/php/security.md. → For other stacks, follow the framework's hardening guide and the carve-outs above.

Account flows — the whole lifecycle, not just the login

Sign-up, verification, reset, credential and email change, MFA, federated sign-in and logout are one surface. Before judging any of them, trace the path: input → identity lookup → verification → secret handling → state change → session → response.

• A public auth response is an observable contract, not an error string: status, body category, redirect and cookies must not differ between a known and an unknown identity, and the verifier path runs for both.
• Compare every secret with the library's constant-time primitive, and respect that primitive's length precondition. Never a general-purpose fast hash for a password. Never an invented token, one-time code or salt scheme.
• Changing an identity — address, phone, password, factor, passkey, recovery codes, a linked provider — needs fresh re-authentication and a notice on the channel that was already verified.

Ground the specifics before enumerating from memory: the account-lifecycle failure classes, their required controls and their negative tests live in threat-modeling's corpus under the authentication surface class. Every numeric value in them defers to the external authority named in the block below.

Crypto, password storage, certificates — route, do not guess

This skill carries no cryptographic parameter, key size, work factor, cipher suite, or TLS version floor: such a value is authoritative-looking long after it stops being true. Take it from https://cheatsheetseries.owasp.org/ when you need it — never from memory, never from this file. Rationale and reopening condition: ADR-238.

Validate

• Verify all user input is validated at the boundary via the framework's primitive — never trust raw request data.
• Confirm an authorization check exists for every state-changing action.
• Check that no raw user input reaches SQL, HTML output, shell commands, or template renderers without escaping.
• Run the project's type-checker — must pass (type errors can enable injection).

Output format

1. Security-hardened code with auth, input validation at the boundary, and output encoding.
2. Authorization rule (Policy / voter / guard / middleware) co-located with the route.

Gotcha

• Validation ensures format, not intent — don't trust input after validation alone.
• "Throw" vs "boolean" authz APIs behave differently (Gate::authorize() throws vs Gate::allows() returns bool in Laravel; CanActivate in NestJS throws; FastAPI dependencies throw HTTPException). Pick per how the framework surfaces failure.
• Rate-limit ALL public endpoints, not just login.
• Never log passwords, tokens, or API keys.

Do NOT

• Do NOT bypass the framework's request-validation primitive inside handlers.
• Do NOT bulk-bind raw request payloads to ORM entities without an explicit allow-list ($fillable / $guarded, DTO mapping, Pydantic model).
• Do NOT store plaintext passwords or secrets in the database.
• Do NOT expose internal error details in production API responses.

Auto-trigger keywords

• security
• authentication
• authorization
• CSRF
• XSS
• policy