architecture

A guide for designing a new software system from scratch, including its user flows, parts, interfaces, and dependencies.

In plain words
What is it for?
It is for planning multi-part applications, APIs, data schemas, login systems, and integrations.
Why use it?
It helps prevent missing error cases or unclear connections between parts before coding starts.

Skill for Claude CodeCodex

Part of the cc10x plugin — 21 skills, 11 agents, 10 hooks shipped together

Install

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.

agentmods
npx agentmods add skills/romiluz13/cc10x/architecture
Any agent
npx skills add romiluz13/cc10x --skill architecture
Clone the repo
git clone --depth 1 https://github.com/romiluz13/cc10x

Made for: Claude Code, Codex.

Or install cc10x, the plugin that ships this one along with the rest of its 21 skills, 11 agents, 10 hooks.

Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,573 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00056 $0.01573
Opus 5 $0.00028 $0.00787
Sonnet 5 $0.00011 $0.00315
Haiku 4.5 $0.00006 $0.00157

Measured 3d ago against content hash 4a896acbd613, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

architecture 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 3d 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.

plugins/cc10x/skills/architecture/SKILL.md · 169 lines

How it starts

The opening of the file, as written. The whole thing — 169 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Architecture

Design systems from scratch: map flows, then draw components. For retrofitting existing code, use codebase-hygiene instead.

Intake Routing

Request type Use
New system/major feature (greenfield) This skill
Existing code with shallow modules codebase-hygiene
Multi-component integration This skill
Single-component refactor planning + building

Functionality-First Design Process

Phase 1: Map Functionality Flows

Map every user flow end-to-end before designing any component:

Flow: [name]
1. [step] → [what the system does] → [what the user sees]
2. [step] → [what the system does] → [what the user sees]
Error paths:
- [error] → [system response] → [user sees]

Every flow must have its error paths mapped. Unmapped error paths become unmapped components.

Phase 2: Map to Architecture

Translate flows into components:

  • Each flow step maps to one or more components
  • Each error path maps to a component's error handling
  • Data crossings between components become interfaces

Phase 3: Design Components

For each component:

  • Interface: what it receives and returns (the contract)
  • Responsibility: what it does (one sentence)
  • Dependencies: what it needs (other components, external services)
  • State: what it remembers (if anything)
  • Error handling: what can go wrong and what it does about it

Before finalizing any component boundary, apply the Deletion Test and Two-Adapter Rule as defined in cc10x:codebase-design. A component that fails the deletion test (complexity vanishes if deleted) or fails the two-adapter rule (it is a port with only one adapter — an ordinary caller or test exercising the interface is not an adapter) is not a real boundary yet — fold it into its caller or defer the split until a second concrete need appears.

Architecture Views

System Context (C4 Level 1)

Box diagram: your system + external systems it talks to. One paragraph per external system: what it provides, what you depend on.

Read the full file on GitHub · 169 lines

Changes

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.

  1. 3d ago First seen · 169 lines · 56 tokens per session scan A 4a896acbd613

Subscribe to this mod's changes

architecture is a skill published in the GitHub repository romiluz13/cc10x (164 stars, last pushed 1mo ago), licensed MIT. It adds 56 tokens to every session and 1,573 once invoked, about $0.0003 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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