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 lukas-grigis/ralphctl --skill ralphctl-codebase-designgit clone --depth 1 https://github.com/lukas-grigis/ralphctlWrote 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/lukas-grigis/ralphctl/ralphctl-codebase-design)<a href="https://agentmods.dev/skills/lukas-grigis/ralphctl/ralphctl-codebase-design"><img src="https://agentmods.dev/badge/skills/lukas-grigis/ralphctl/ralphctl-codebase-design/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/lukas-grigis/ralphctl/ralphctl-codebase-design"><img src="https://agentmods.dev/badge/skills/lukas-grigis/ralphctl/ralphctl-codebase-design.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00080 | $0.01075 |
| Opus 5.5 | $0.00032 | $0.00430 |
| Sonnet 5.5 | $0.00016 | $0.00215 |
| Haiku 4.5 | $0.00008 | $0.00108 |
Grade A, and why
ralphctl-codebase-design 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 yesterday.
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 — 83 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codebase Design
Adapted from mattpocock/skills — "Codebase Design" (MIT). Adapted for ralphctl's harness contract.
Design deep modules: a lot of behaviour behind a small interface, placed at a clean seam, testable through that interface. The aim is leverage for callers, locality for maintainers, and testability for everyone. Reason with the vocabulary below; in code and in signals, keep the project's own terms when it has established ones.
When this applies
- Plan — when splitting work, prefer tasks that deepen one module behind a small interface over tasks that spread one concept across several shallow ones. When a task introduces a seam, name it in the steps along with what varies across it.
- Execute — whenever you add a module, an interface, or an abstraction. When reviewing, apply the deletion test and the one-adapter rule below to every new layer.
Vocabulary
- Module — anything with an interface and an implementation, at any scale: a function, a type, a package, a slice spanning several layers.
- Interface — everything a caller must know to use the module correctly: the type signature, plus its invariants, ordering constraints, error modes, required configuration, and performance characteristics.
- Implementation — the code inside the module.
- Depth — leverage at the interface: how much behaviour a caller or test can exercise per unit of interface it has to learn. Deep when much sits behind little; shallow when the interface is nearly as complex as what it hides.
- Seam (Michael Feathers) — a place where behaviour can be altered without editing in that place; the location where a module's interface lives. Where to put the seam is its own decision.
- Adapter — a concrete thing that satisfies an interface at a seam. It names a role, not a size.
- Leverage — what callers gain from depth: more capability per thing they learn.
- Locality — what maintainers gain from depth: change, bugs, and knowledge concentrated in one place. Fix once, fixed everywhere.
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.
- yesterday First seen · 83 lines · 80 tokens per session scan A ea90c71c5987
ralphctl-codebase-design is a skill published in the GitHub repository lukas-grigis/ralphctl (24 stars, last pushed today), licensed MIT. It adds 80 tokens to every session and 1,075 once invoked, about $0.0003 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 2026-10-18.
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