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Kernsmith: Skill for Claude Code

.claude/skills/xlsx/SKILL.md

xlsx is a skill for Claude Code from kaltinril/Kernsmith. It costs 201 tokens per session (2,835 once invoked), scanned A, a copy of xlsx, MIT.

A spreadsheet-handling skill for Excel, CSV, and tab-separated files. It provides rules for creating, editing, formatting, and checking spreadsheet outputs.

In plain words
What is it for?
It is for reading, cleaning, calculating, formatting, charting, or creating spreadsheet files.
Why use it?
It helps avoid broken formulas, unwanted formatting changes, and inconsistent spreadsheet conventions.

Skill for Claude Code

Written for Claude Code: installed under .claude/.

This is kaltinril/Kernsmith's own configuration. It tells Claude Code how to work on Kernsmith itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything Kernsmith configures →

not rated 9repo 10d ago A scan 201 tokens copy · 92% MIT
View source ↗ kaltinril/Kernsmith
Reuse

Borrowing it

Nothing to install: this file belongs to kaltinril/Kernsmith. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/kaltinril/Kernsmith/main/.claude/skills/xlsx/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/kaltinril/Kernsmith

Made for: Claude Code.

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 xlsx

README.md
[![agentmods](https://agentmods.dev/badge/skills/kaltinril/kernsmith/xlsx.svg)](https://agentmods.dev/skills/kaltinril/kernsmith/xlsx)
Your own site
<a href="https://agentmods.dev/skills/kaltinril/kernsmith/xlsx"><img src="https://agentmods.dev/badge/skills/kaltinril/kernsmith/xlsx.svg" alt="Measured on agentmods" height="20"></a>
Per session 201 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,835 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 92% copy Near-identical to another mod 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 $0.00201 $0.02835
Opus 5 $0.00101 $0.01418
Sonnet 5 $0.00040 $0.00567
Haiku 4.5 $0.00020 $0.00283

Measured 3d ago against content hash dd316db7785a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

xlsx 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.

The scan reads SKILL.md. This mod also ships 13 executable files (scripts/office/helpers/__init__.py, scripts/office/helpers/merge_runs.py, scripts/office/helpers/simplify_redlines.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

This is a copy

92% identical to xlsx — 18 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/xlsx/SKILL.md · 292 lines

How it starts

The opening of the file, as written. The whole thing — 292 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Requirements for Outputs

All Excel files

Professional Font

  • Use a consistent, professional font (e.g., Arial, Times New Roman) for all deliverables unless otherwise instructed by the user

Zero Formula Errors

  • Every Excel model MUST be delivered with ZERO formula errors (#REF!, #DIV/0!, #VALUE!, #N/A, #NAME?)

Preserve Existing Templates (when updating templates)

  • Study and EXACTLY match existing format, style, and conventions when modifying files
  • Never impose standardized formatting on files with established patterns
  • Existing template conventions ALWAYS override these guidelines

Financial models

Color Coding Standards

Unless otherwise stated by the user or existing template

Industry-Standard Color Conventions
  • Blue text (RGB: 0,0,255): Hardcoded inputs, and numbers users will change for scenarios
  • Black text (RGB: 0,0,0): ALL formulas and calculations
  • Green text (RGB: 0,128,0): Links pulling from other worksheets within same workbook
  • Red text (RGB: 255,0,0): External links to other files
  • Yellow background (RGB: 255,255,0): Key assumptions needing attention or cells that need to be updated

Number Formatting Standards

Required Format Rules
  • Years: Format as text strings (e.g., "2024" not "2,024")
  • Currency: Use $#,##0 format; ALWAYS specify units in headers ("Revenue ($mm)")
  • Zeros: Use number formatting to make all zeros "-", including percentages (e.g., "$#,##0;($#,##0);-")
  • Percentages: Default to 0.0% format (one decimal)
  • Multiples: Format as 0.0x for valuation multiples (EV/EBITDA, P/E)
  • Negative numbers: Use parentheses (123) not minus -123

Formula Construction Rules

Assumptions Placement
  • Place ALL assumptions (growth rates, margins, multiples, etc.) in separate assumption cells
  • Use cell references instead of hardcoded values in formulas
  • Example: Use =B5*(1+$B$6) instead of =B5*1.05
Formula Error Prevention
  • Verify all cell references are correct
  • Check for off-by-one errors in ranges
  • Ensure consistent formulas across all projection periods
  • Test with edge cases (zero values, negative numbers)
  • Verify no unintended circular references

Read the full file on GitHub · 292 lines

Files

What ships with it

53 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. 3d ago First seen · 292 lines · 201 tokens per session scan A dd316db7785a

Subscribe to this mod's changes

xlsx is a skill published in the GitHub repository kaltinril/Kernsmith (9 stars, last pushed 10d ago), licensed MIT. It adds 201 tokens to every session and 2,835 once invoked, about $0.0010 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to xlsx, differing in 18 lines, and is treated as a copy.

DocumentsSpreadsheetsbitmap-fontbmfontdotnetfont-generatorfreetype
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