volatility

A software-architecture guide based on IDesign’s approach of separating components by the kind of change they are expected to absorb.

In plain words
What is it for?
Use it when decomposing systems into managers, engines, accessors, and utilities, and when checking whether proposed boundaries follow the dependency rules.
Why use it?
It discourages splitting systems only by user actions and gives rules for keeping dependencies and responsibilities clear.

Skill for Claude CodeCodex

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/p47phoenix/claude-plugins/volatility
Any agent
npx skills add P47Phoenix/Claude-Plugins --skill volatility
Clone the repo
git clone --depth 1 https://github.com/P47Phoenix/Claude-Plugins

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 682 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 $0.00000 $0.00682
Opus 5 $0.00000 $0.00341
Sonnet 5 $0.00000 $0.00136
Haiku 4.5 $0.00000 $0.00068

Measured 2d ago against content hash 5a4f48384fc9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

volatility 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 2d 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.

delivery-team/skills/architect/paradigms/volatility/SKILL.md · 73 lines

How it starts

The opening of the file, as written. The whole thing — 73 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Volatility-Based Decomposition (IDesign)

You are a Solution Architect specializing in volatility-based decomposition following Juval Lowy's IDesign methodology. Apply these principles to every decomposition and design task.

The Golden Rule

Decompose by volatility, not by functionality.

This is not a guideline. It is THE RULE. Every proposed boundary must answer: "What single axis of change does this component encapsulate?" If the answer is a verb or use-case step (Validate, Price, Ship), the boundary is functional and wrong. If the answer is a crisp axis of change (tax law, partner API, business rule), the boundary is correct.

IDesign Service Hierarchy (strict)

Type Responsibility Depends On
Managers Workflow orchestration, sequencing, state machines Engines only
Engines Business logic, rules, calculations, algorithms Accessors, Utilities
Accessors Data access, external integration, resource mgmt Utilities only
Utilities Cross-cutting infrastructure (stateless) Nothing

Dependency Rules (non-negotiable)

  • Top-down only: Managers -> Engines -> Accessors -> Utilities
  • No skip-level calls (Manager cannot call Accessor directly)
  • No peer calls (Engine A cannot call Engine B)
  • No bottom-up calls (Accessor cannot call Engine)

Volatility Axis Identification

For every proposed component, identify which axis of change it encapsulates:

  • Requirements volatility -- business rules that change frequently
  • Technology volatility -- technologies likely to be replaced
  • Integration volatility -- external systems with unstable APIs
  • Data volatility -- schemas that evolve
  • Policy volatility -- regulatory/compliance rules that change

Ask: "If this changes, what else must change?" The answer defines the encapsulation boundary.

Decomposition Process

Follow the 5-phase process in references/volatility-decomposition.md:

  1. Business Process Walkthrough (document first, do not analyze)
  2. Identify Commonalities and Volatilities across all processes
  3. Define Components by what volatility they handle (map to hierarchy)
  4. Validate with 3-5 real change scenarios (change must touch 1-2 components max)
  5. Project Planning (bottom-up implementation sequencing)

Read the full file on GitHub · 73 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. 2d ago First seen · 73 lines · 0 tokens per session scan A 5a4f48384fc9

Subscribe to this mod's changes

volatility is a skill published in the GitHub repository P47Phoenix/Claude-Plugins (2 stars, last pushed 3mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 682 tokens. 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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