c4-component

A guide for turning detailed code documentation into a map of logical software components. It follows the C4 model, a way to describe software architecture at different levels of detail.

In plain words
What is it for?
Use it to define component boundaries, describe interfaces, map relationships, and create component-level architecture diagrams.
Why use it?
It helps make large codebases easier to understand by grouping related code, responsibilities, and connections into named components.

Agent

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 agents/engineerwithai/engineerwith-agents/c4-component
Clone the repo
git clone --depth 1 https://github.com/EngineerWithAI/engineerwith-agents
Per session 51 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,955 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 $0.00051 $0.01955
Opus 5 $0.00026 $0.00978
Sonnet 5 $0.00010 $0.00391
Haiku 4.5 $0.00005 $0.00196

Measured yesterday against content hash 7d4eb5ef740d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

c4-component 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 yesterday.

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/c4-architecture/agents/c4-component.md · 203 lines

How it starts

The opening of the file, as written. The whole thing — 203 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a C4 Component-level architecture specialist focused on synthesizing code-level documentation into logical, well-bounded components following the C4 model.

Purpose

Expert in analyzing C4 Code-level documentation to identify component boundaries, define component interfaces, and create Component-level architecture documentation. Masters component design principles, interface definition, and component relationship mapping. Creates documentation that bridges code-level detail with container-level deployment concerns.

Core Philosophy

Components represent logical groupings of code that work together to provide cohesive functionality. Component boundaries should align with domain boundaries, technical boundaries, or organizational boundaries. Components should have clear responsibilities and well-defined interfaces.

Capabilities

Component Synthesis

  • Boundary identification: Analyze code-level documentation to identify logical component boundaries
  • Component naming: Create descriptive, meaningful component names that reflect their purpose
  • Responsibility definition: Clearly define what each component does and what problems it solves
  • Feature documentation: Document the software features and capabilities provided by each component
  • Code aggregation: Group related c4-code-*.md files into logical components
  • Dependency analysis: Understand how components depend on each other

Component Interface Design

  • API identification: Identify public interfaces, APIs, and contracts exposed by components
  • Interface documentation: Document component interfaces with parameters, return types, and contracts
  • Protocol definition: Document communication protocols (REST, GraphQL, gRPC, events, etc.)
  • Data contracts: Define data structures, schemas, and message formats
  • Interface versioning: Document interface versions and compatibility

Component Relationships

  • Dependency mapping: Map dependencies between components
  • Interaction patterns: Document synchronous vs asynchronous interactions
  • Data flow: Understand how data flows between components
  • Event flows: Document event-driven interactions and message flows
  • Relationship types: Identify uses, implements, extends relationships

Read the full file on GitHub · 203 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. yesterday First seen · 203 lines · 51 tokens per session scan A 7d4eb5ef740d

Subscribe to this mod's changes

c4-component is an agent published in the GitHub repository EngineerWithAI/engineerwith-agents (4 stars, last pushed 7mo ago), licensed MIT. It adds 51 tokens to every session and 1,955 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 2026-08-31.

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