sdd-design

sdd-design is a skill for Claude Code, Codex from danweinerdev/claude-sdd-planner. It costs 34 tokens per session (1,537 once invoked), scanned A, original, MIT.

A skill for writing technical architecture and design documents before implementation. It produces a design artifact that others can review.

In plain words
What is it for?
Use it to define the architecture of a component or software system and record its design decisions.
Why use it?
It turns an idea into a documented technical approach, making important system decisions easier to discuss before code is written.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also reads ~/.codex or $CODEX_HOME. Also seen: mentions subagents; mentions Codex.

Part of the sdd-planner plugin — 34 skills, 8 agents shipped together

Good fit Use it to define the architecture of a component or software system and record its design decisions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/danweinerdev/claude-sdd-planner/sdd-design
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 danweinerdev/claude-sdd-planner --skill sdd-design
Clone the repo
git clone --depth 1 https://github.com/danweinerdev/claude-sdd-planner

Made for: Claude Code, Codex.

Or install sdd-planner, the plugin that ships this one along with the rest of its 34 skills, 8 agents.

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 sdd-design

README.md
[![agentmods](https://agentmods.dev/badge/skills/danweinerdev/claude-sdd-planner/sdd-design.svg)](https://agentmods.dev/skills/danweinerdev/claude-sdd-planner/sdd-design)
Your own site
<a href="https://agentmods.dev/skills/danweinerdev/claude-sdd-planner/sdd-design"><img src="https://agentmods.dev/badge/skills/danweinerdev/claude-sdd-planner/sdd-design.svg" alt="Measured on agentmods" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,537 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 $0.00034 $0.01537
Opus 5 $0.00017 $0.00768
Sonnet 5 $0.00007 $0.00307
Haiku 4.5 $0.00003 $0.00154

Measured 3d ago against content hash 13f6f8847127, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

sdd-design 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 3d 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.

.codex-plugin/skills/sdd-design/SKILL.md · 68 lines

How it starts

The opening of the file, as written. The whole thing — 68 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Technical Architecture Document

Resources

Before opening shared/..., follow symlinks in this loaded file's path, then derive <plugin-root> from <plugin-root>/skills/<name>/SKILL.md; fallback search roots are repository/user .agents/ (including $HOME/.agents/plugins/*/), Codex ${CODEX_HOME:-$HOME/.codex}/plugins/cache/*/*/*/, and runtime-configured skill roots. Accept only a root containing this skill, shared/agent-runtime.md, and the matching plugin manifest; never use the working directory. Then read <plugin-root>/shared/agent-runtime.md and <plugin-root>/shared/path-resolution.md, and resolve every shared/<path> reference in this skill against <plugin-root>.

Resource boundary: Read the plugin, all SKILL.md files, and shared/ resources in place. Never copy or symlink them into the working directory, target repository, or planning root. Only generated SDD outputs may be materialized from bundled resources.

When to Use

When you need to define the technical architecture for a component or system before implementation. Produces a reviewable design document with architecture decisions.

Process

  1. Gather Context

    • If the user hasn't already specified it, ask what component to design
    • Dispatch a collaboration subagent rendering shared/agent-prompts/researcher.md (or perform that prompt yourself) with the component and its constraints; it scans all artifact directories and the codebase per its own definition.
    • Review any related research documents
  2. Draft Design

    • Create Designs/<ComponentName>/README.md using shared/templates/design.md
    • Document: overview, non-goals, architecture (components, data flow, interfaces), design decisions (with alternatives considered), error handling, testing strategy, migration plan
    • Non-Goals bound the component. Name the responsibilities that belong to neighboring components, the generality this design declines to build, and any extension point deliberately left out. An unstated boundary gets built past
    • Where a section realizes a spec requirement, cite its id inline (FR-NN/NFR-NNshared/frontmatter-schema.md § Stable Identifiers) so coverage is greppable
    • Use Mermaid diagrams for architecture, data flow, and component relationships — prefer graph TD, flowchart LR, or sequenceDiagram over ASCII art or prose-only descriptions
    • Testing strategy must include structural verification: Read shared/language-verification.md and include the language-appropriate structural checks (sanitizers, static analysis, type checking) in the Testing Strategy section. These define what "structurally correct" means for this component beyond passing tests.
    • Set status to draft

Read the full file on GitHub · 68 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. 3d ago Changed 13f6f8847127
  2. 7d ago First seen · 68 lines · 34 tokens per session scan A 5d44a492bd0c

Subscribe to this mod's changes

sdd-design is a skill published in the GitHub repository danweinerdev/claude-sdd-planner (2 stars, last pushed 3d ago), licensed MIT. It adds 34 tokens to every session and 1,537 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 2026-08-31.

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