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/mblode/agent-skills/codebase-architecturenpx skills add mblode/agent-skills --skill codebase-architecturegit clone --depth 1 https://github.com/mblode/agent-skillsWhat 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 | $0.00203 | $0.04603 |
| Opus 5 | $0.00102 | $0.02302 |
| Sonnet 5 | $0.00041 | $0.00921 |
| Haiku 4.5 | $0.00020 | $0.00460 |
Grade A, and why
codebase-architecture 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 — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codebase Architecture
Decide a TypeScript codebase's structure, improve it where change has become expensive, and make it hold. The target is a codebase a reader can hold in their head: few surfaces, one canonical way to do each job, and behaviour where you would first look for it.
- IS: folder structures, module contracts, middleware pipelines, frontend/backend boundaries; architecture briefs; domain language and decision records; domain-informed deepening; guardrail tooling, CI gates, and agent wayfinding.
- IS NOT: scaffolding a new repo (
scaffold-nextjsfor a Next.js turborepo,scaffold-clifor a TypeScript CLI), multi-tenant domain/isolation/routing (multi-tenant-architecture), the content of AGENTS.md itself (agents-md), a diff-scoped cleanup pass (tidy), or structural review of a local diff (pr-reviewer).
Contents
- Modes
- References
- Design mode (new codebase)
- Deepen mode (existing codebase)
- Harden mode (make it stick)
- Validation loop
- Output template
- Excuses
- Gotchas
Modes
Pick by the problem, not by the artifact.
| Mode | You are here when | Output |
|---|---|---|
| Design | Starting a new app, service, or surface, and the structure is not decided yet | An architecture brief |
| Deepen | The code works, but change is expensive: concepts scattered, seams leaking, one idea under three names | Ranked opportunities, then one migrated slice |
| Harden | The structure is decided and keeps decaying, or agents keep doing the wrong thing in this repo | Wired checks, markers, and recipes |
Modes compose, and running more than one is normal. Design ends in Harden, because a contract with no check is a suggestion. Deepen ends in Harden, so the new seam cannot decay back. Harden runs alone when the structure is already right and only the enforcement is missing, which is the common case in a repo that agents work in.
When the two look equally right, prefer Deepen. A user reporting "agents keep using the old pattern" is describing a Harden symptom, but if the cause is one concept living in two places, quarantine only freezes the duplicate in place: Deepen deletes it and Harden holds the line until that lands. Harden alone is the right answer when the old thing genuinely has to stay.
What ships with it
14 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.
- references/agent-runtime.md 3.2 KB
- references/api-design.md 5.3 KB
- references/contagion-markers.md 5.3 KB
- references/craftsmanship.md 4.2 KB
- references/deepening-existing.md 8.2 KB
- references/distributed-correctness.md 5.7 KB
- references/domain-language.md 5.4 KB
- references/enforcement-ladder.md 6.0 KB
- references/evaluation-scenarios.md 4.5 KB
- references/guardrail-tooling.md 7.7 KB
- references/shipping-practices.md 963 B
- references/stack-defaults.md 763 B
- references/verification-tiers.md 4.1 KB
- references/wayfinding.md 6.6 KB
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 · 201 lines · 203 tokens per session scan A 9c23eec70e6d
codebase-architecture is a skill published in the GitHub repository mblode/agent-skills (95 stars, last pushed 2d ago), licensed MIT. It adds 203 tokens to every session and 4,603 once invoked, about $0.0010 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.
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