sartrus

Modelling Team — Claude Code Skill

A Claude Code skill that builds polished Excel financial models via a three-agent team: Architect (Opus) designs the blueprint, Coder (Sonnet) writes Python/openpyxl, Challenger (Opus) stress-tests formulas. Supports light (single-tab) and heavy (multi-tab with Dashboard, scenario selector, INDEX-driven scenarios) modes.

How It Works

User request
    |
    v
 Step 0: Clarify scope (heavy or light?)
    |
    v
 Step 1: MODEL ARCHITECT (Opus)
         Designs full model blueprint: tabs, rows, formulas, scenarios
    |
    v
 Step 2: MODEL CODER (Sonnet)
         Translates blueprint into Python/openpyxl script, runs it
    |
    v
 Step 3: MODEL CHALLENGER (Opus)
         Reviews .xlsx: formula audit, scenario validation, design check
    |
    v
 PASS -> deliver | FAIL -> fix and re-check (up to 3 iterations)

Features

• Two modes: Light (single tab, assumptions at top) and Heavy (Dashboard + Assumptions + calculation tabs)
• Scenario selector (heavy mode): Dashboard cell drives Low/Base/High via INDEX() — no hardcoded scenario columns
• Professional design language: Navy/blue palette, Arial font, color-coded cells (blue = inputs, black = formulas, green = cross-sheet links)
• Manual extensibility: All formulas use proper $-notation (mixed/absolute references) so you can drag formulas to new columns
• IRR/NPV/PBP/DPBP: Correctly constructed cash flow streams with negative initial investment
• Zero formula errors: Challenger validates every formula before delivery

Installation

From .skill file

claude install-skill modelling-team.skill

From this repo

Copy the SKILL.md and references/ directory into your Claude Code skills folder:

~/.claude/skills/modelling-team/
├── SKILL.md
└── references/
    ├── architect-prompt.md
    ├── coder-prompt.md
    └── challenger-prompt.md

Usage

Just ask Claude Code to build a model:

"Build me a DCF model for a coffee shop: $200K revenue, 5% growth, 30% EBITDA margin, 10% discount rate, 4x terminal multiple, 5-year horizon."

"Build me a heavy model for a rental portfolio with 3 properties, scenario analysis for rent growth and vacancy, and a dashboard with IRR and cash-on-cash return."

Claude will ask whether you want a light or heavy model, then run the three-agent workflow automatically.

File Structure

modelling-team/
├── SKILL.md                          # Main skill definition
├── references/
│   ├── architect-prompt.md           # Blueprint design agent prompt
│   ├── coder-prompt.md               # Python/openpyxl coding agent prompt
│   └── challenger-prompt.md          # Validation/review agent prompt
└── modelling-team.skill              # Packaged distributable

Design Language

The skill enforces a consistent visual style across all models:

Element	Color	Usage
Blue font (0000FF)	Inputs	Editable assumptions
Black font (000000)	Formulas	All calculations
Green font (008000)	Cross-sheet	Links between tabs
Navy fill (1F3864)	Title rows	Model/section titles
Medium blue fill (2F5496)	Section headers	Sub-sections
Light blue fill (EBF3FB)	Input cells	Background for editable cells
Light green fill (E2EFDA)	Totals/KPIs	Bold summary rows

Requirements

• Claude Code with access to Opus and Sonnet models
• Python 3 with openpyxl installed
• LibreOffice (for formula recalculation via the xlsx skill)

License

MIT