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 rileyhilliard/claude-essentials --skill architecting-systemsgit clone --depth 1 https://github.com/rileyhilliard/claude-essentialsWrote 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/rileyhilliard/claude-essentials/architecting-systems)<a href="https://agentmods.dev/skills/rileyhilliard/claude-essentials/architecting-systems"><img src="https://agentmods.dev/badge/skills/rileyhilliard/claude-essentials/architecting-systems/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/rileyhilliard/claude-essentials/architecting-systems"><img src="https://agentmods.dev/badge/skills/rileyhilliard/claude-essentials/architecting-systems.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 | $0.00043 | $0.00587 |
| Opus 5 | $0.00022 | $0.00293 |
| Sonnet 5 | $0.00009 | $0.00117 |
| Haiku 4.5 | $0.00004 | $0.00059 |
Grade A, and why
architecting-systems 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 9d 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 — 56 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Architecting Systems
Core principle: Small decisions made early compound into either clean systems or massive technical debt. Get the structure right and the system stays maintainable as it grows. Get it wrong and every change gets harder.
Topic Selection
Load the relevant reference based on what you're working on:
| Working on... | Load | File |
|---|---|---|
| Layers, vertical slices, file organization | Structure | references/structure.md |
| Interfaces, dependency inversion, contracts | Coupling | references/coupling.md |
| Bounded contexts, API design, module boundaries | Boundaries | references/boundaries.md |
| Async patterns, race conditions, queues | Concurrency | references/concurrency.md |
| Logging, health checks, metrics, tracing | Observability | references/observability.md |
Load multiple references when the task spans topics. For most greenfield work, start with Structure and Coupling.
Core Principles (All Topics)
Complexity budget
Every architectural decision has a complexity cost. Spend that budget where it matters.
| Worth the complexity | Not worth it |
|---|---|
| Separation between domains that change independently | Abstracting code that only has one implementation |
| Event-driven for genuinely async workflows | Event-driven for simple request-response flows |
| Caching for measured performance bottlenecks | Caching "just in case" |
| Microservices for teams that deploy independently | Microservices for a small team's monolith |
The rule: Don't add indirection until you need it. Premature abstraction is as costly as premature optimization. Two similar code blocks are better than a wrong abstraction.
Quick Reference
| Problem | Response |
|---|---|
| "Where does this code go?" | If the answer isn't obvious, the structure needs work |
| "Changing X requires touching Y" | Missing boundary between X and Y |
| "This module does too many things" | Split along separate reasons to change |
| "We can't test this in isolation" | Hidden dependencies; inject them instead |
| "New devs take weeks to be productive" | Conventions are too weak or too novel |
| "Every PR touches 10 files" | Feature code is scattered; colocate it |
| "The shared folder keeps growing" | Boundaries are in the wrong place |
What ships with it
5 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.
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.
- 9d ago First seen · 56 lines · 43 tokens per session scan A 7353e87a8027
architecting-systems is a skill published in the GitHub repository rileyhilliard/claude-essentials (128 stars, last pushed 21d ago), licensed MIT. It adds 43 tokens to every session and 587 once invoked, about $0.0002 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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