A security-by-design process that considers protection throughout software development and operation. It covers threat modeling, secure design, input validation, access controls, automated security checks, common web risks, and operations.

Use it when designing, coding, reviewing, testing, or operating a system. It helps identify threats, limit access, handle untrusted input, and add security checks to development and delivery.

Adding security only at the end can leave weaknesses in the system's basic design, where fixing them may require rebuilding parts of it. Treating security as a continuous concern brings risks into decisions and checks earlier.

aegis — Skill for Claude Code by IamK77/Skill

Install

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.

Any agent

npx skills add IamK77/Skill --skill aegis

Clone the repo

git clone --depth 1 https://github.com/IamK77/Skill

Made for: Claude Code.

Or install engineering, the plugin that ships this one along with the rest of its 10 skills.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/iamk77/skill/aegis/github.svg)](https://agentmods.dev/skills/iamk77/skill/aegis)

Your own site

<a href="https://agentmods.dev/skills/iamk77/skill/aegis"><img src="https://agentmods.dev/badge/skills/iamk77/skill/aegis/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/iamk77/skill/aegis"><img src="https://agentmods.dev/badge/skills/iamk77/skill/aegis.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 32 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,225 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found in the catalogue.

Token cost

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 5.1	$0.00032	$0.01225
Opus 5.5	$0.00013	$0.00490
Sonnet 5.5	$0.00006	$0.00245
Haiku 4.5	$0.00003	$0.00122

Measured 1mo ago against content hash 6b61a5c77a2c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

aegis 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 1mo 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.

skills/engineering/aegis/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

aegis

Run a scoped defensive security review and remediation workflow. Produce a threat model, reproducible findings, tested changes, and residual-risk handoff.

Inputs

Target repository or design; assets and trust boundaries; authorised test scope; deployment context. Establish the real dependency-scan command before running it.

Run record

Use checklist 0.5 or newer for this SOP. Reading or reloading the skill must not reset work. For a new task, run checklist init "${CLAUDE_SKILL_DIR}" --new --path "/absolute/project"; retain its returned ID as RUN. For existing work, use checklist resume "$RUN", then checklist show --run "$RUN". Outside Claude, replace the skill-directory variable with this directory’s actual path.

Commands below record work after it is done. Replace evidence placeholders with concise artifact locations and observations. Manual confirmations are not independent proof; a sensor pass covers only the command and inputs it observed. verify does not close a stage; advance checks that its required readings are fulfilled. Use report --run "$RUN" for the retained history.

Before starting, inspect the project and bind SCA_CMD to its real trusted command with --var 'SCA_CMD=<actual command>'. Do not use an echo/no-op to produce a green result. checklist resume "$RUN" --var 'SCA_CMD=<new command>' changes the binding and invalidates earlier readings; commands and output are stored locally, so do not bind secrets.

Procedure

scope

Map entry points, sensitive assets, identities, and trust boundaries. Agree which systems and test actions are in scope; a local review does not authorise production probing.

Record these artifacts after doing the work:

Threat model identifies assets, entry points, and trust boundaries. checklist check scope boundary --run "$RUN" --evidence "<artifact and observation>"
Test scope and allowed actions are recorded. checklist check scope permission --run "$RUN" --evidence "<artifact and observation>"

Read the full file on GitHub · 98 lines

Files

What ships with it

11 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.

Changes

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.

1mo ago Changed · -67 lines · -196 tokens per session 6b61a5c77a2c
2mo ago First seen · 165 lines · 228 tokens per session scan A d394710bb3a7

Subscribe to this mod's changes

aegis is a skill published in the GitHub repository IamK77/Skill (2 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 32 tokens to every session and 1,225 once invoked, about $0.0001 per session on Opus 5.5. 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.

Claude Code Security agent-skills anthropic claude developer-tools skills

aegis next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
aegisIamK77/Skill	Skill	2	1mo ago	Apache-2.0	A	32	Claude Code
agents-v2-pylingxling/awesome-skills-cn	Skill	334	1mo ago	MIT	A	39	Claude Code
analytics-productlingxling/awesome-skills-cn	Skill	334	1mo ago	MIT	A	35	Claude Code
api-security-best-practiceslingxling/awesome-skills-cn	Skill	334	1mo ago	MIT	A	29	Claude Code
antigravity-workflowslingxling/awesome-skills-cn	Skill	334	1mo ago	MIT	A	41	Claude Code
apex-skillifytonone-ai/tonone	Skill	77	4d ago	MIT	A	41	Claude Code
oci-services-expertfrankxai/claude-skills-library	Skill	47	yesterday	MIT	A	43	Claude Code

aegis

Getting it into your agent

Wrote this? Show the measurements

What it costs to keep this loaded

Grade A, and why

Nothing flagged

How it starts

aegis

Inputs

Run record

Procedure

scope

What ships with it

What this file has done since we first saw it

aegis compared with skills from other repositories