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 skills/soden46/engineer-flow/securitynpx skills add soden46/engineer-flow --skill securitygit clone --depth 1 https://github.com/soden46/engineer-flowWhat 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 | $0.00025 | $0.03822 |
| Opus 5 | $0.00013 | $0.01911 |
| Sonnet 5 | $0.00005 | $0.00764 |
| Haiku 4.5 | $0.00003 | $0.00382 |
Grade A, and why
security 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 2d ago.
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.
How it starts
The opening of the file, as written. The whole thing — 854 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Security
Use this skill when a task creates, changes, reviews, or fixes a security-sensitive application boundary.
The rules in this skill are framework and language agnostic.
Do not assume a specific framework, ORM, authentication library, HTTP server, database, queue, cloud provider, or deployment platform.
Core Principle
Identify the security boundary first.
Then use the safest native mechanism available in the detected project stack.
Technology-specific implementation details should be derived from project evidence, native stack mechanisms, or relevant user-installed specialist skills rather than hardcoded into this skill.
Security Review Scope
Check only areas relevant to the change.
Primary areas:
- authentication
- authorization
- input validation
- output encoding
- request forgery protection
- injection
- secret handling
- sensitive data exposure
- file uploads
- API security
- rate limiting and abuse protection
- session and token handling
- dependency and configuration security
- logging and error disclosure
- unsafe redirects and outbound requests
- serialization and deserialization
- access to filesystem, network, subprocesses, and other privileged resources
Do not mechanically run every category for every task.
1. Trust Boundaries
Treat data crossing a trust boundary as untrusted until validated.
Common boundaries include:
- HTTP requests
- API payloads
- form input
- URL parameters
- headers
- cookies
- uploaded files
- webhooks
- message queues
- database content originating from users
- external APIs
- environment/configuration values
- files
- command-line arguments
Validate as close to the boundary as practical.
Validation should constrain:
- type
- structure
- allowed values
- length
- range
- format
- relationships between fields
Prefer allowlists and explicit schemas over ad-hoc filtering.
Do not rely on frontend validation for server-side security.
2. Authentication
Use established authentication mechanisms provided by the project stack.
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.
- 2d ago First seen · 854 lines · 25 tokens per session scan A e4b3b7d42c57
security is a skill published in the GitHub repository soden46/engineer-flow (3 stars, last pushed 4d ago), licensed MIT. It adds 25 tokens to every session and 3,822 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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