architect

architect is a skill for Claude Code, Codex from SethGammon/Citadel. It costs 44 tokens per session (1,573 once invoked), scanned A, original, MIT.

A planning tool that turns a product requirements document (PRD), or a clear feature description, into a technical design and phased build plan.

In plain words
What is it for?
Use it to design a new application or plan changes to an existing codebase.
Why use it?
It helps decide which files, components, data structures, and implementation steps are needed before coding begins.

Skill for Claude CodeCodex

Part of the citadel plugin — 48 skills, 7 agents, 2 MCP servers 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/sethgammon/citadel/architect
Any agent
npx skills add SethGammon/Citadel --skill architect
Clone the repo
git clone --depth 1 https://github.com/SethGammon/Citadel

Made for: Claude Code, Codex.

Or install citadel, the plugin that ships this one along with the rest of its 48 skills, 7 agents, 2 MCP servers.

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 architect

README.md
[![agentmods](https://agentmods.dev/badge/skills/sethgammon/citadel/architect.svg)](https://agentmods.dev/skills/sethgammon/citadel/architect)
Your own site
<a href="https://agentmods.dev/skills/sethgammon/citadel/architect"><img src="https://agentmods.dev/badge/skills/sethgammon/citadel/architect.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 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 $0.00044 $0.01573
Opus 5 $0.00022 $0.00787
Sonnet 5 $0.00009 $0.00315
Haiku 4.5 $0.00004 $0.00157

Measured 4d ago against content hash 009d7f5a9e1a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

architect 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 4d 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/architect/SKILL.md · 181 lines

How it starts

The opening of the file, as written. The whole thing — 181 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/architect — Implementation Architecture from PRD

When to Use

Don't use when: you already have an architecture and want to implement it (use /marshal or /archon); you need a PRD first (use /prd before /architect).

  • After /prd produces an approved PRD (greenfield or feature mode)
  • When the user has a clear direction + existing codebase (no PRD needed)
  • When /do routes a build request
  • When the user has a spec and wants a build plan

Inputs

One of:

  1. A PRD file path (from /prd) — preferred, contains structured requirements
  2. A user-provided spec or description + an existing codebase — sufficient
  3. Neither — suggest /prd first, but don't hard-gate. If the user has a clear direction ("add auth to my app"), that + the existing code IS the input.

Mode Detection

Greenfield mode: PRD exists with Mode: greenfield, or no existing source files. Produces a complete architecture from scratch.

Feature mode: PRD exists with Mode: feature, OR the user describes a feature and the project has existing source files. The architecture describes changes to existing code, not a standalone system.

In feature mode:

  • Read the existing file tree FIRST — understand the current architecture before planning changes
  • Read key files (package.json, tsconfig, main entry points, existing patterns)
  • The File Tree section shows ONLY new and modified files, not the entire project
  • Phases include a Phase 0: "Baseline" that records current typecheck/test state
  • Every phase's end conditions include "no new typecheck errors" and "existing tests pass"
  • The Risk Register includes "regression in existing functionality" as a default risk

Protocol

Step 1: READ

If PRD exists, read it. Extract:

  • Core features (the numbered list)
  • Technical decisions (stack choices)
  • End conditions (what "done" looks like)
  • Out of scope (what NOT to build)
  • Integration points (feature mode)

If no PRD, read the codebase instead:

  • Scan the file tree for structure and conventions
  • Read package.json / equivalent for dependencies and scripts
  • Read the main entry point(s) to understand the architecture
  • Use the user's description as the feature spec
  • Infer end conditions from the description ("add auth" → "protected routes return 401 without token")

Read the full file on GitHub · 181 lines

Files

What ships with it

2 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. 4d ago First seen · 181 lines · 44 tokens per session scan A 009d7f5a9e1a

Subscribe to this mod's changes

architect is a skill published in the GitHub repository SethGammon/Citadel (916 stars, last pushed today), licensed MIT. It adds 44 tokens to every session and 1,573 once invoked, about $0.0002 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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