Aegis is a method pack that guides coding agents to inspect a project's baseline, make bounded changes, and verify their work with fresh evidence. It is for people using coding-agent hosts who want fewer unverified changes and less unnecessary process. The catalogue add-ons implement this method through skills, instructions, commands, a hook, and a plugin.
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 skills add GanyuanRan/Aegis --skill first-principles-reviewgit clone --depth 1 https://github.com/GanyuanRan/AegisWrote 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/ganyuanran/aegis/first-principles-review)<a href="https://agentmods.dev/skills/ganyuanran/aegis/first-principles-review"><img src="https://agentmods.dev/badge/skills/ganyuanran/aegis/first-principles-review/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.
<a href="https://agentmods.dev/skills/ganyuanran/aegis/first-principles-review"><img src="https://agentmods.dev/badge/skills/ganyuanran/aegis/first-principles-review.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00052 | $0.02087 |
| Opus 5 | $0.00026 | $0.01043 |
| Sonnet 5 | $0.00010 | $0.00417 |
| Haiku 4.5 | $0.00005 | $0.00209 |
Grade A, and why
first-principles-review 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 — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.
First Principles Review
Purpose
Use this as a lightweight decision review before another Aegis workflow makes a directional choice. It is a compositional skill, not a standalone workflow.
Do not replace brainstorming, systematic-debugging, writing-plans,
requesting-code-review, or verification-before-completion. Use it to clean
the decision surface those skills will act on.
When this review materially changes the direction, surface Aegis Visibility
in natural prose: name the first principle, dropped assumption, smallest
sufficient path, or owner / retirement falsifier that changed the decision.
Keep it advisory and task-specific; do not turn the lens into approval
authority or a generic skill trace.
Use When
- The user asks for first principles, first-principles thinking, or Occam's razor.
- A design, plan, or fix has multiple plausible paths and unclear selection criteria.
- The task has ambiguous goals, competing constraints, or product/architecture direction risk.
- Debugging is drifting into repeated fixes, fallback growth, duplicate owners, consumer-side patches, or "just add another branch" reasoning.
- A review finds that the implementation may be locally correct but directionally wrong.
Do Not Use
- Simple Q&A, status checks, tiny wording/config edits, or clearly bounded single-owner changes.
- Mechanical execution of an approved plan unless a new directional conflict appears.
- As a required step for every task, every turn, or every TDD cycle.
Five-Line Review
Answer only what is needed, usually in five short lines:
First Principle: What irreducible outcome must this satisfy?
Non-negotiables: What constraints cannot be broken?
Assumptions to Drop: What is habit, inherited shape, or unproven preference?
Smallest Sufficient Path: What is the least complex path that satisfies the first principle?
Escalation Signal: What finding would require spec/design/architecture review?
When the direction depends on a new mechanism or an unfamiliar domain, insert one optional line between path and escalation:
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 Changed · +21 lines 6ca49ee3e0bd
- 7d ago Changed · +21 lines cbe9797d1562
- 11d ago First seen · 181 lines · 52 tokens per session scan A 6f71196586d3
first-principles-review is a skill published in the GitHub repository GanyuanRan/Aegis (1,178 stars, last pushed yesterday), licensed MIT. It adds 52 tokens to every session and 2,087 once invoked, about $0.0003 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 2026-08-30.
Other skills, from other repositories
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sdd-tasks
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go-testing
Trigger: Go tests, go test coverage, Bubbletea teatest, golden files. Apply focused Go testing patterns.
find-simplifications
Use for a periodic repo-wide sweep of qwen-code for accumulated excess surface — dead components and files, orphaned locale keys, exports nothing consumes, added-then-removed scaffolding — filing candidates on a tracking issue and landing only what a maintainer has said yes to. Repo-wide and evidence-first; every…
pr-review-canvas
Create a OpenBitFun Canvas for reviewing a pull request, branch diff, or change set with Cursor-style diff cards, review maps, risk callouts, and focused reviewer flow. Use when the user asks for a PR review canvas, diff walkthrough, change-set overview, or visual review summary.