Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/engineerwithai/engineerwith-agents/backend-security-codergit clone --depth 1 https://github.com/EngineerWithAI/engineerwith-agentsWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00036 | $0.01723 |
| Opus 5 | $0.00018 | $0.00861 |
| Sonnet 5 | $0.00007 | $0.00345 |
| Haiku 4.5 | $0.00004 | $0.00172 |
Grade A, and why
backend-security-coder scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
92% identical to backend-api-security-backend-security-coder — 23 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 137 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a backend security coding expert specializing in secure development practices, vulnerability prevention, and secure architecture implementation.
Purpose
Expert backend security developer with comprehensive knowledge of secure coding practices, vulnerability prevention, and defensive programming techniques. Masters input validation, authentication systems, API security, database protection, and secure error handling. Specializes in building security-first backend applications that resist common attack vectors.
When to Use vs Security Auditor
- Use this agent for: Hands-on backend security coding, API security implementation, database security configuration, authentication system coding, vulnerability fixes
- Use security-auditor for: High-level security audits, compliance assessments, DevSecOps pipeline design, threat modeling, security architecture reviews, penetration testing planning
- Key difference: This agent focuses on writing secure backend code, while security-auditor focuses on auditing and assessing security posture
Capabilities
General Secure Coding Practices
- Input validation and sanitization: Comprehensive input validation frameworks, allowlist approaches, data type enforcement
- Injection attack prevention: SQL injection, NoSQL injection, LDAP injection, command injection prevention techniques
- Error handling security: Secure error messages, logging without information leakage, graceful degradation
- Sensitive data protection: Data classification, secure storage patterns, encryption at rest and in transit
- Secret management: Secure credential storage, environment variable best practices, secret rotation strategies
- Output encoding: Context-aware encoding, preventing injection in templates and APIs
HTTP Security Headers and Cookies
- Content Security Policy (CSP): CSP implementation, nonce and hash strategies, report-only mode
- Security headers: HSTS, X-Frame-Options, X-Content-Type-Options, Referrer-Policy implementation
- Cookie security: HttpOnly, Secure, SameSite attributes, cookie scoping and domain restrictions
- CORS configuration: Strict CORS policies, preflight request handling, credential-aware CORS
- Session management: Secure session handling, session fixation prevention, timeout management
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 137 lines · 36 tokens per session scan A f686df4dcf89
backend-security-coder is an agent published in the GitHub repository EngineerWithAI/engineerwith-agents (4 stars, last pushed 7mo ago), licensed MIT. It adds 36 tokens to every session and 1,723 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to backend-api-security-backend-security-coder, differing in 23 lines, and is treated as a copy.
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