Borrowing it
Nothing to install: this file belongs to Everyone-Needs-A-Copilot/claude-copilot. 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/Everyone-Needs-A-Copilot/claude-copilot/main/.claude/skills/architecture/system-design-patterns/SKILL.mdgit clone --depth 1 https://github.com/Everyone-Needs-A-Copilot/claude-copilotWrote 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/everyone-needs-a-copilot/claude-copilot/system-design-patterns)<a href="https://agentmods.dev/skills/everyone-needs-a-copilot/claude-copilot/system-design-patterns"><img src="https://agentmods.dev/badge/skills/everyone-needs-a-copilot/claude-copilot/system-design-patterns/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/everyone-needs-a-copilot/claude-copilot/system-design-patterns"><img src="https://agentmods.dev/badge/skills/everyone-needs-a-copilot/claude-copilot/system-design-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Data Exfiltration · line 55 Code or instructions that leak agent conversation context to external services, potentially exposing sensitive user interactions.Fix: Remove any code that sends prompts, responses, or session data externally. Preserve user privacy; never exfiltrate conversation content.
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 | $0.00094 | $0.02511 |
| Opus 5.5 | $0.00038 | $0.01004 |
| Sonnet 5.5 | $0.00019 | $0.00502 |
| Haiku 4.5 | $0.00009 | $0.00251 |
Grade A, and why
system-design-patterns 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 1mo 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 — 276 lines — stays where its author put it; the contents beside it link to each section on GitHub.
System Design Patterns
Architecture patterns, ADR methodology, and trade-off analysis frameworks for making and documenting sound design decisions.
ADR completeness is deterministic — the script checks required field presence and scores coverage. Pattern selection and trade-off quality are prose judgment, left to the model.
Purpose
- Document architectural decisions with full context and rationale
- Select the right architectural pattern for the problem at hand
- Validate architecture with automated fitness functions
- Analyse trade-offs explicitly before committing to a direction
ADR Template
Architecture Decision Records capture the context and consequences of significant design choices.
# ADR-[number]: [Title]
**Date:** YYYY-MM-DD
**Status:** Proposed | Accepted | Deprecated | Superseded by ADR-[n]
## Context
What is the situation forcing a decision? What constraints exist?
What forces are at play (technical, political, organizational)?
## Decision
What was decided? State it as an active voice sentence:
"We will use [X] because [Y]."
## Consequences
**Positive:**
- [Benefit 1]
- [Benefit 2]
**Negative:**
- [Trade-off 1]
- [Trade-off 2]
**Neutral:**
- [Side effect that is neither good nor bad]
## Alternatives Rejected
| Alternative | Reason Rejected |
|-------------|----------------|
| [Option A] | [Why not chosen] |
| [Option B] | [Why not chosen] |
## References
- [Link to relevant documentation, RFC, or prior art]
Architecture Pattern Decision Matrix
| Pattern | Best When | Avoid When | Key Trade-offs |
|---|---|---|---|
| Layered (Monolith) | Small team, simple domain, fast iteration needed | Independent deployment required, team > 10, polyglot stack | Fast to build; harder to scale independently |
| Microservices | Independent deployment needed, team autonomy, polyglot stack | Domain is unclear, team is small, ops maturity is low | High autonomy; high operational complexity |
| Event-Driven | Async workflows, eventual consistency acceptable, audit trail needed | Strong consistency required, debugging must be simple | Decoupled producers; complex event ordering |
| CQRS | Read/write asymmetry, complex queries, event sourcing in use | Simple CRUD, small team, low query complexity | Optimised reads/writes; two models to maintain |
| API Gateway | Multiple clients, rate limiting needed, auth aggregation | Single client, low traffic, gateway becomes bottleneck | Centralised cross-cutting concerns; single point of failure risk |
What ships with it
2 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.
- 1mo ago First seen · 276 lines · 94 tokens per session scan A b34da95bb8b7
system-design-patterns is a skill published in the GitHub repository Everyone-Needs-A-Copilot/claude-copilot (14 stars, last pushed yesterday), licensed MIT. It adds 94 tokens to every session and 2,511 once invoked, about $0.0004 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 2026-09-04.
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