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/aaronbassett/agent-foundry/security-corenpx skills add aaronbassett/agent-foundry --skill security-coregit clone --depth 1 https://github.com/aaronbassett/agent-foundryWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/aaronbassett/agent-foundry/security-core)<a href="https://agentmods.dev/skills/aaronbassett/agent-foundry/security-core"><img src="https://agentmods.dev/badge/skills/aaronbassett/agent-foundry/security-core.svg" alt="Measured on agentmods" height="20"></a>What 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 | $0.00090 | $0.00564 |
| Opus 5 | $0.00045 | $0.00282 |
| Sonnet 5 | $0.00018 | $0.00113 |
| Haiku 4.5 | $0.00009 | $0.00056 |
Grade A, and why
devs:security-core 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 5d 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 — 29 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Security Core
Cross-cutting application-security decisions: which model, what policy, what to check. The language skills own how to express these decisions in a given framework; this skill must never contradict them — where mechanics are needed, it delegates.
Reference routing
| Reference | Use when |
|---|---|
| authn-design.md | Choosing an auth model; token lifetime/rotation/revocation policy; MFA; CLI/desktop OAuth; password hashing policy |
| authz-design.md | RBAC and resource ownership; why not to hand-roll policy engines; the Postgres/Supabase RLS multi-tenant pattern |
| secrets.md | Where secrets live, settings validation, rotation ordering, CI credentials (OIDC), scanners, key generation |
| rate-limiting.md | What to limit on which key, tiering, distributed atomicity, fail-open vs fail-closed, response contract |
| http-hardening.md | Server-side canonical security headers, CSP nonce minting, CORS with credentials, HSTS |
| review-lens.md | Reviewing a diff for security: weighted if-the-diff-touches-X-check-Y mappings |
Ownership boundaries
- devs:react-core (security reference) owns client-side XSS/sanitization, the browser view of CSP and headers, and browser token storage. Server and client guidance must agree; where this skill states the server-side canonical, react-core states the client consequences.
- The language skills (rust-core, python-core, typescript-core) own framework security mechanics — axum middleware, FastAPI auth wiring, Express setup — and the per-language library choices.
- devs:deps-core owns dependency auditing and vulnerability scanning of the package tree.
- devs:code-review owns the general review method; this skill supplies the security dimension via review-lens.md.
This skill ships no scripts or config assets: security scaffolding rots faster than any other kind, and the language skills' verified templates are the correct home for runnable configuration.
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 5d ago First seen · 29 lines · 90 tokens per session scan A aa30de1fd7f3
devs:security-core is a skill published in the GitHub repository aaronbassett/agent-foundry (4 stars, last pushed 20d ago), licensed MIT. It adds 90 tokens to every session and 564 once invoked, about $0.0005 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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