Borrowing it
Nothing to install: this file belongs to rome-os/rome. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/rome-os/rome/main/.claude/skills/ddd/SKILL.mdgit clone --depth 1 https://github.com/rome-os/romeWrote 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/rome-os/rome/ddd)<a href="https://agentmods.dev/skills/rome-os/rome/ddd"><img src="https://agentmods.dev/badge/skills/rome-os/rome/ddd/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/rome-os/rome/ddd"><img src="https://agentmods.dev/badge/skills/rome-os/rome/ddd.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 | $0.00040 | $0.02947 |
| Opus 5.5 | $0.00016 | $0.01179 |
| Sonnet 5.5 | $0.00008 | $0.00589 |
| Haiku 4.5 | $0.00004 | $0.00295 |
Grade A, and why
ddd 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 — 160 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Shared language and model, from interview to code
What this skill is for
A person knows what their domain is; the code only knows what it does today. This skill runs the whole Domain-Driven Design loop between them, so that the person, the AI and the code end up using one language:
- Interview the person as the domain expert until the words and their rules are settled.
- Write the language they can read and correct without knowing code.
- Shape the model: context map with direction, aggregates, and a walk of a real story through it.
- Map divergence: where today's code contradicts the model, ranked with the person.
- Hand off implementation in priority order, with the language as the brief.
- Check drift once the code has merged, and bring every gap back as a decision.
It is long-running. One pass can take dozens of rounds over a day or more, and the artifacts are living documents edited in place, not reports written once.
Code and model
The code is an authority on facts: what the system does today, how outside platforms behave, and what a change would cost. Read those yourself instead of asking, and report what the code does, not what its names imply. The code is not an authority on the model: whether a concept is right or where a boundary belongs is the person's call. ADRs and docs are the same as code here. Five rules follow from this:
- Two records. "Today" comes from the code and lives in the notes; the language holds what the person decides. The divergence map is where they meet.
- Today is never the default. Show today's behaviour as one labelled option among others. Recommending it needs a reason other than "it exists".
- Compare against the language, not the code. A new concept is tested against agreed words. A concept that exists only in code is a candidate to test, not a baseline.
- Cost decides when, not what. How hard a change is sets its priority in the divergence map; it never bends the model.
- Strain in the code becomes a question. Where the code's words pull apart, ask the person; don't copy the design.
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 · 160 lines · 40 tokens per session scan A 0deef241d68d
ddd is a skill published in the GitHub repository rome-os/rome (871 stars, last pushed today), licensed MIT. It adds 40 tokens to every session and 2,947 once invoked, about $0.0002 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 2026-10-22.
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