arch-lens

arch-lens is a skill for Claude Code from psenger/ai-agent-skills. It costs 180 tokens per session (835 once invoked), scanned A, original, MIT.

An interactive codebase review that looks for architectural friction by observing where a developer or coding agent gets confused, switches files often, or encounters hard-to-test boundaries. It uses the idea that a small interface should hide most implementation details.

In plain words
What is it for?
Use it to explore a whole repository or directory, identify related problem areas, choose one for deeper review, and produce a proposed architecture change.
Why use it?
It helps reveal design problems that rigid checklists may miss, especially when code is difficult to understand, change, or test.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents.

Part of the psenger-skills plugin — 14 skills shipped together

Good fit Use it to explore a whole repository or directory, identify related problem areas, choose one for deeper review, and produce a proposed architecture change.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/psenger/ai-agent-skills/arch-lens
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.

Any agent
npx skills add psenger/ai-agent-skills --skill arch-lens
Clone the repo
git clone --depth 1 https://github.com/psenger/ai-agent-skills

Made for: Claude Code.

Or install psenger-skills, the plugin that ships this one along with the rest of its 14 skills.

Wrote 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.

agentmods badge for arch-lens

README.md
[![agentmods](https://agentmods.dev/badge/skills/psenger/ai-agent-skills/arch-lens/github.svg)](https://agentmods.dev/skills/psenger/ai-agent-skills/arch-lens)
Your own site
<a href="https://agentmods.dev/skills/psenger/ai-agent-skills/arch-lens"><img src="https://agentmods.dev/badge/skills/psenger/ai-agent-skills/arch-lens/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.

agentmods 80×15 button for arch-lens

Your own site · 80×15
<a href="https://agentmods.dev/skills/psenger/ai-agent-skills/arch-lens"><img src="https://agentmods.dev/badge/skills/psenger/ai-agent-skills/arch-lens.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 180 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 835 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00180 $0.00835
Opus 5 $0.00090 $0.00417
Sonnet 5 $0.00036 $0.00167
Haiku 4.5 $0.00018 $0.00084

Measured 11d ago against content hash 3df5dcc42d3b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

arch-lens 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 11d 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.

skills/arch-lens/SKILL.md · 67 lines

How it starts

The opening of the file, as written. The whole thing — 67 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Arch Lens

Seven-step interactive architectural review. An Explore sub-agent navigates the codebase the way a developer would — the confusion, file-bouncing, and untestable seams it encounters are the findings. No checklists, no rigid heuristics.

Deep module: small interface surface hiding a large, self-contained implementation. Lets callers test at the boundary. Lets AI agents reason without reading internals.

Quick start

  1. If a path argument is given, scope to that directory; otherwise whole repo
  2. Load ${CLAUDE_SKILL_DIR}/references/WORKFLOW.md — full step-by-step instructions
  3. Load ${CLAUDE_SKILL_DIR}/references/DETECTION-PATTERNS.md
  4. Load ${CLAUDE_SKILL_DIR}/references/INTERFACE-DESIGN.md
  5. Load ${CLAUDE_SKILL_DIR}/references/RFC-FILE-FORMAT.md
  6. Execute the seven steps in WORKFLOW.md

Workflows

Step What happens Requires user input
1. Explore Spawn Explore sub-agent; navigate organically; record friction
2. Candidates Synthesise friction into clusters; present max 8 with full context
3. Pick User selects a cluster and directs the angle wait
4. Frame Problem statement, dependency category, blast radius, test boundary today
5. Design Spawn 3–4 parallel sub-agents with competing interface designs
6. Choose User picks interface or accepts recommendation wait
7. RFC file Write arch-rfcs-YYYY-MM-DD.md to project root

Full prompt text, cluster format, and step detail: see WORKFLOW.md.

Behavioural rules

  • Explore agent friction observations are primary evidence — never override with static analysis
  • Never propose interface designs before Step 5
  • Never advance past Steps 3 or 6 without a user response
  • Every RFC must include exact file:line references and a before/after illustration
  • Name every dependency category explicitly — it determines the testing strategy
  • Rank clusters: testability impact first, then cognitive load, then interface stability

Read the full file on GitHub · 67 lines

Files

What ships with it

4 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.

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. 11d ago First seen · 67 lines · 180 tokens per session scan A 3df5dcc42d3b

Subscribe to this mod's changes

arch-lens is a skill published in the GitHub repository psenger/ai-agent-skills (10 stars, last pushed 3mo ago), licensed MIT. It adds 180 tokens to every session and 835 once invoked, about $0.0009 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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