architecture-foundations

architecture-foundations is a skill for Claude Code from handarbeit/fabrik. It costs 148 tokens per session (5,205 once invoked), scanned A, original, Apache-2.0.

A planning interview for defining a software system's shared foundations: its common data, feature boundaries, interfaces, permissions, and ownership rules.

In plain words
What is it for?
Use it early in a project and revisit it when new features introduce shared data, states, or permissions that other parts of the system must understand.
Why use it?
It prevents separate feature specifications from describing the same concepts or rules in conflicting ways as the project grows.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is **Document**: [../architecture.md](../architecture.md).

Part of the entwurf plugin — 6 skills shipped together

Good fit Use it early in a project and revisit it when new features introduce shared data, states, or permissions that other parts of the system must understand.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/handarbeit/fabrik
agentmods
npx agentmods add skills/handarbeit/fabrik/architecture-foundations

Made for: Claude Code.

Or install entwurf, the plugin that ships this one along with the rest of its 6 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 architecture-foundations

README.md
[![agentmods](https://agentmods.dev/badge/skills/handarbeit/fabrik/architecture-foundations/github.svg)](https://agentmods.dev/skills/handarbeit/fabrik/architecture-foundations)
Your own site
<a href="https://agentmods.dev/skills/handarbeit/fabrik/architecture-foundations"><img src="https://agentmods.dev/badge/skills/handarbeit/fabrik/architecture-foundations/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 architecture-foundations

Your own site · 80×15
<a href="https://agentmods.dev/skills/handarbeit/fabrik/architecture-foundations"><img src="https://agentmods.dev/badge/skills/handarbeit/fabrik/architecture-foundations.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 148 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,205 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00148 $0.05205
Opus 5 $0.00074 $0.02603
Sonnet 5 $0.00030 $0.01041
Haiku 4.5 $0.00015 $0.00521

Measured 9d ago against content hash 05793bd9421f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

architecture-foundations 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 9d 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.

plugin/entwurf/skills/architecture-foundations/SKILL.md · 429 lines

How it starts

The opening of the file, as written. The whole thing — 429 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Architecture Foundations

Establish what is already fixed, what the shared things are called, who owns each of them, and who is allowed to do what — so that specifications written weeks apart still describe one system.

Read ../../CONVENTIONS.md first. It carries the shared rules — stages, where work is saved, the tree, markers, the decision register, interview rules, precedence, gates, decision records and the baseline status footer. This skill does not repeat them.

This is stage 3 of 5, and it is the one stage that is a living document, not a one-off interview.

Run this early, and run it again

Specifications drift. Each new feature introduces concepts the earlier ones could not anticipate, and without something owning the shared entities the drift is silent: two specs model the same employee differently, three disagree about which state triggers what, and nobody notices until integration.

So: run this as soon as the first few specifications exist — you do not need all of them — and re-run it whenever a new specification introduces an entity, a state, or an authority. On a re-run, lead with what has changed since last time and what the new specs broke, rather than starting from the top.

The cost of running it early is that some of it will be wrong. The cost of running it late is that everything built in between was built against nothing.

What this is not

Not budgets, build order, fitness functions, or mechanisms chosen for a quality — performance, cost, scale, resilience. Those are stage 5, and they cannot be written until the experience baseline exists — they convert user-facing guarantees into system guarantees, and the guarantees do not exist yet.

The test for what belongs here: does it need to know how the product looks or feels? Which feature owns the employee record does not. How long an offline capture may survive does. The first is yours now; the second waits.

If the architect starts designing mechanisms — and they will — record it under Deferred to the baseline and move on.

Read the full file on GitHub · 429 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. 9d ago First seen · 429 lines · 148 tokens per session scan A 05793bd9421f

Subscribe to this mod's changes

architecture-foundations is a skill published in the GitHub repository handarbeit/fabrik (22 stars, last pushed today), licensed Apache-2.0. It adds 148 tokens to every session and 5,205 once invoked, about $0.0007 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.