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 DavidROliverBA/ArchitectKB --skill c4-diagramgit clone --depth 1 https://github.com/DavidROliverBA/ArchitectKBWrote 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/davidroliverba/architectkb/c4-diagram)<a href="https://agentmods.dev/skills/davidroliverba/architectkb/c4-diagram"><img src="https://agentmods.dev/badge/skills/davidroliverba/architectkb/c4-diagram/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/davidroliverba/architectkb/c4-diagram"><img src="https://agentmods.dev/badge/skills/davidroliverba/architectkb/c4-diagram.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 | $0.00013 | $0.04983 |
| Opus 5 | $0.00006 | $0.02491 |
| Sonnet 5 | $0.00003 | $0.00997 |
| Haiku 4.5 | $0.00001 | $0.00498 |
Grade A, and why
c4-diagram 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 10d 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 — 510 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/c4-diagram Skill
Generate C4 architecture diagrams (Mermaid, flowchart, or PlantUML) from System note frontmatter data.
When to Use This Skill
Use /c4-diagram when you need to generate C4 architecture diagrams from the structured c4: data stored in System note frontmatter. Supports three output formats: native Mermaid C4 (default), flowchart LR with C4 styling (more layout control), and PlantUML with directional hints (best for complex diagrams). This complements the /diagram skill (which generates Python diagrams PNGs) by producing text-based diagrams that are Git-friendly and render inline in Obsidian.
Usage
/c4-diagram <system-name> [level] [format]
Arguments
| Argument | Required | Description |
|---|---|---|
system-name |
Yes | Name of the System note (e.g., Data Platform, MRO System, Cloud Platform) |
level |
No | context (L1, default), container (L2), or both |
format |
No | mermaid (default), flowchart, or plantuml |
Format Options
| Format | Syntax Used | Best For |
|---|---|---|
mermaid |
C4Context/C4Container native | Clean Obsidian rendering, ≤10 elements (default) |
flowchart |
flowchart LR with classDef C4 |
More layout control via declaration order |
plantuml |
C4-PlantUML with directional hints | >15 elements, persistent crossings, formal docs |
When to choose each format:
| Scenario | Choose | Reason |
|---|---|---|
| Quick inline diagram in Obsidian | mermaid |
Native rendering, fast iteration |
| Need layout control, <15 elements | flowchart |
Declaration order gives more influence over Dagre |
| Complex layouts with persistent crossings | plantuml |
Directional hints (Rel_Down, Lay_Right) fix crossings |
| >15 elements | plantuml |
Layout control prevents chaos at scale |
| Formal documentation, PDF export | plantuml |
Better export quality, automatic legend |
| CI/CD or Structurizr pipeline | plantuml |
Stable server-side rendering |
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.
- 10d ago First seen · 510 lines · 13 tokens per session scan A 53cbb8504906
c4-diagram is a skill published in the GitHub repository DavidROliverBA/ArchitectKB (52 stars, last pushed 6mo ago), licensed MIT. It adds 13 tokens to every session and 4,983 once invoked, about $0.0001 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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