Arch Insight

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A Agent Skill that turns source repositories into design judgment — not rewriting docs, but distilling design philosophy.

Use it to study other people's projects: quickly understand design intent, extract borrowable patterns, and see tradeoffs clearly. And you don't need to re-scan the entire repo in every new conversation.

Why This Skill Exists

Using LLMs to analyze other people's codebases typically runs into these problems:

• Token waste — scanning the whole repo each time burns through context fast
• Repeated work — every new conversation starts from zero, re-scanning code you've already read
• Shallow analysis — you get module lists and flowcharts, but no design reasoning or code evidence
• Style mismatch — the AI's default writing style is nothing like yours
• No guidance — you don't know what to ask the AI to analyze, and the AI doesn't know what to look for

arch-insight solves these through phased intake, focused context packing, style alignment, and prompts that push for judgment rather than restatement.

When to Use

• Studying an open-source project to understand its design intent, not just file structure
• Judging which patterns are borrowable and which to avoid, for your own project design
• Generating structured architecture reports for team onboarding or knowledge archiving
• Writing a technical deep-dive article grounded in source code evidence
• Creating a repo overview to quickly build a reading map
• Comparing design approaches across multiple reference repos

When Not to Use

• Explaining a single file or debugging
• Routine code review
• Just drawing call graphs without caring about design philosophy
• Full-architecture code mapping or exhaustive function analysis

Installation

Recommended (interactive)

npx arch-insight install-release

Platform-specific (non-interactive / CI)

npx arch-insight install-release --platform codex --platform claude

Update

npx arch-insight update --platform codex

| Platform | Install Path | | ----------- | --------------------------------------------- | | Claude Code | Auto marketplace registration | | Codex | ~/.codex/skills/arch-insight/ | | Gemini | ~/.gemini/skills/arch-insight/ | | OpenCode | ~/.config/opencode/skills/arch-insight/ | | Pi | ~/.pi/agent/skills/arch-insight/ | | Kiro | ~/.kiro/skills/arch-insight/ | | Cursor | ~/.cursor/plugins/local/arch-insight/ |

Restart the respective platform after installation.

Usage

Explicit invocation:

Use the arch-insight skill to analyze this repository and generate architecture documentation.

Natural language invocation:

Study the core abstractions and design tradeoffs of this project — I want to reference it for my own architecture design.

Generate a narrative article about the architecture of this codebase.

Give me a source code overview of this repo — I want to quickly build a reading map.

The Skill auto-detects output format from your wording:

• "blog style" / "publishable long-form" / "like that article" → Narrative Article
• "overview" / "repo tour" / "source map" → Repo Overview
• "main report + appendices" / "template output" → Analysis Package
• Unclear → minimal inference, will not default to Analysis Package

Outputs

Analysis Package

| File | What It Answers | | -------------------------- | ---------------------------------------------- | | ARCHITECTURE_REPORT.md | System overview and overall assessment | | DESIGN_PHILOSOPHY.md | What design principles the author insists on | | CORE_ABSTRACTIONS.md | What the system's "language" is | | MAIN_FLOW.md | Which path best reveals architectural intent | | TRADEOFFS.md | Benefits, costs, alternatives, and boundaries | | BORROWABLE_PATTERNS.md | What other teams can genuinely take away |

Article Modes

• Narrative Article → single NARRATIVE_ARTICLE.md — opinionated, design-focused, considers migration cost
• Repo Overview → single REPO_OVERVIEW_ARTICLE.md — fact-dense, scannable, with source paths and reading navigation

Examples

You can reference sample outputs in examples/. Use examples that match your target language.

• English examples:
  • examples/llm-coding-workflow-comparison.md
  • examples/agent-memory-design-philosophy.en.md

Workflow

The Skill follows a phased pipeline:

Analysis Package

1. Repo Intake — determine scope, project type, source and version anchors
2. Design Philosophy Brain Dump — system mental model, core abstractions, design principle hypotheses
3. Ecosystem Atlas (on demand) — only for monorepo / multi-service / platform scenarios
4. Architecture Report — main report + 5 learning appendices

Narrative Article

1. Repo Intake
2. Design Philosophy Brain Dump
3. Narrative Article — single long-form piece with opinions, design lessons, and migration assessment

Repo Overview

1. Repo Intake
2. Design Philosophy Brain Dump
3. Repo Overview Article — fact-dense, clearly structured, scannable, with source paths and reading navigation

When a style sample is provided, the Agent establishes a Style Contract (audience, tone, structural density, evidence format, prohibitions) before writing. The contract takes priority over template defaults.

Design Principles

• Why before What — understand the problem before explaining the structure
• Main flow over directory tree — defining paths are more valuable than folder layouts
• Core abstractions before implementation details — identify the language before reading the grammar
• Evidence first — every judgment cites a code path
• Honest about tradeoffs — every design conclusion covers benefits, costs, alternatives, and boundaries
• Output makes people smarter, not longer — readers learn something, not just see more words
• Focus, don't exhaust — design philosophy and borrowable patterns over full-architecture code mapping

Limitations

• Large monorepos may require focusing analysis on key directories
• Runtime behavior (concurrency models, actual data flows) needs logs, tests, or tracing — pure static analysis is insufficient
• Dynamic imports, reflection, code generation, and framework magic reduce analysis accuracy
• Generated reports should be reviewed by project maintainers
• Multi-repo input defaults to comparative design reference, not full ecosystem audit

Release

For maintainers, follow the standardized release process in docs/RELEASE.md.

Directory Structure

.agents/
├── plugin.json
└── skills/arch-insight/
    ├── SKILL.md                   # Skill entry point (for Agent consumption)
    ├── references/
    │   ├── RUNNER.md              # Execution manual and output contract
    │   ├── prompts/               # Phased analysis prompts
    │   └── templates/             # Report and appendix templates
    └── examples/

License

MIT