| name | security-and-hardening |
| description | Hardens code against vulnerabilities. Use when handling user input, authentication, data storage, or external integrations. The non-negotiable security MUSTs live in `.agents/rules/security-baseline.md`; this skill shows how to apply them with code patterns, decision trees, and review checklists. |
Security and Hardening
Policy Capsule
- The non-negotiable MUSTs live in
.agents/rules/security-baseline.md; that rule wins on conflict. Open a PR against the rule rather than working around it in this skill.
- Validate ALL client input (body, query, headers, path params) at the edge with a strict schema (e.g., Zod). Never trust client-side validation as a security boundary.
- Parameterize every database query. Never concatenate user input into SQL/NoSQL filters or shell commands.
- Hash passwords with bcrypt (≥12 rounds), scrypt, or argon2; plaintext storage is forbidden. Session cookies MUST be
httpOnly, secure, and carry an explicit sameSite. Never put auth tokens in localStorage/sessionStorage.
- Every protected endpoint checks authorization, not just authentication; verify resource ownership server-side before any state change and never trust client-asserted roles.
- Encode HTML output via the framework's auto-escaping; sanitize any unavoidable raw HTML with a vetted library (e.g., DOMPurify). Never feed user data to
eval(), Function(), or innerHTML/dangerouslySetInnerHTML unsanitized.
- Exclude sensitive fields (password hashes, reset tokens, internal IDs) from API responses and never expose stack traces or internal error details to clients.
- Never log PII (emails, full credit cards, session tokens, phone numbers). Destructure safe properties; don't log whole objects.
- Configure security headers (
Content-Security-Policy, Strict-Transport-Security, X-Frame-Options, X-Content-Type-Options) and restrict CORS to an explicit allowlist — wildcard * is forbidden on credentialed endpoints.
- Pull all secrets from environment variables; never commit
.env, default API keys, or fallback secrets. .env.example (placeholders only) is the committed shape.
- Surface security-expanding changes (new auth flows, new PII categories, new integrations, CORS / rate-limit changes, file uploads, elevated permissions) under a "Security surface" section in the PR body and on the ticket, label
risk::high, and link the relevant baseline MUST. This documents the surface — it does not pause execution. agent::blocked is only for unrecoverable runtime blockers.
The non-negotiable MUSTs — input validation, authentication, authorization,
output encoding, transport, headers, secrets, forbidden practices — live in
.agents/rules/security-baseline.md,
which is the SSOT. This skill shows how to apply those MUSTs with code
patterns and process guidance; read the rule for the what. When the rule
and this skill diverge, the rule wins — open a PR against the rule rather
than working around it here.
Long-form reference — read on demand
The capsule above is the contract and the whole always-read surface of this
skill. The long-form material behind it — patterns, worked examples,
checklists, and rationalizations — lives in the on-demand sibling
reference.md, matching the split the always-on rules already
use (rules/git-conventions.md ⇄
git-conventions-reference.md).
Activating this skill costs the capsule; open a section below only when the
task actually engages it.
