kendex: Skill for Claude Code

.agents/skills/price-handling/SKILL.md

price-handling is a skill for Claude Code from vanillagreencom/kendex. It costs 21 tokens per session (1,091 once invoked), scanned C, original, MIT.

A set of rules for representing, comparing, rounding, and displaying prices in software, using floating-point numbers by default. Floating-point numbers are a common computer format for storing decimal values approximately.

In plain words
What is it for?
Use it when comparing prices, checking order thresholds, handling market data, aligning orders to price ticks, or formatting prices for display.
Why use it?
It helps avoid errors caused by exact equality checks and by rounding prices at the wrong stage.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: installed under .agents/ (shared by several agents).

This is vanillagreencom/kendex's own configuration. It tells Claude Code how to work on kendex 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 kendex configures →

Reuse

Borrowing it

Nothing to install: this file belongs to vanillagreencom/kendex. 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/vanillagreencom/kendex/main/.agents/skills/price-handling/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/vanillagreencom/kendex

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 price-handling

README.md
[![agentmods](https://agentmods.dev/badge/skills/vanillagreencom/kendex/price-handling.svg)](https://agentmods.dev/skills/vanillagreencom/kendex/price-handling)
Your own site
<a href="https://agentmods.dev/skills/vanillagreencom/kendex/price-handling"><img src="https://agentmods.dev/badge/skills/vanillagreencom/kendex/price-handling.svg" alt="Measured on agentmods" height="20"></a>
Per session 21 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,091 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 $0.00021 $0.01091
Opus 5 $0.00010 $0.00545
Sonnet 5 $0.00004 $0.00218
Haiku 4.5 $0.00002 $0.00109

Measured 4d ago against content hash dd4e71aa958b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade C, and why

price-handling scanned grade C with 1 finding 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- kendex:project-instructions:start -->
.agents/skills/price-handling/SKILL.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Project Instructions

Problems with a kendex-owned skill go through kendex report; check ownership in the file first.

Price Handling Patterns

The price type is f64

IEEE 754 double precision. No fixed-point, no decimal types.

Use i64 fixed-point only for a matching engine (bit-exact required), a regulatory audit trail mandating reproducibility, or a settlement system with legal precision requirements. Hybrid: i64 on the execution hot path, f64 for display and analytics.

Never == on prices

use float_cmp::{approx_eq, F64Margin};

pub const PRICE_EPSILON: f64 = 1e-10;  // sub-pipette tolerance

pub fn prices_equal(a: f64, b: f64) -> bool {
    approx_eq!(f64, a, b, epsilon = PRICE_EPSILON, ulps = 4)
}

pub fn price_gte(a: f64, b: f64) -> bool { a > b || prices_equal(a, b) }
pub fn price_lte(a: f64, b: f64) -> bool { a < b || prices_equal(a, b) }

Round only at the boundaries

Boundary Rounding
Order submission (OrderRequest → broker API) Round to tick, then validate alignment
Display formatting Round to the symbol's display_decimals
Market data ingestion (ticks, bars, quotes) Never. Preserve full feed precision
P&L calculation Never. Use raw values
pub fn round_to_tick(price: f64, tick_size: f64) -> f64 {
    (price / tick_size).round() * tick_size
}

pub fn validate_tick_alignment(price: f64, tick_size: f64) -> bool {
    prices_equal(price, round_to_tick(price, tick_size))
}

Order submission order: round to tick, validate alignment (on failure return an error, never re-round), then format for the broker API if it takes a string.

Format with the symbol's precision, never hardcoded decimals (EURUSD 5, AAPL 2, BTC 8):

format!("{:.1$}", price, symbol.display_decimals as usize)

Symbol metadata owns precision

Read the full file on GitHub · 120 lines

Files

What ships with it

1 file 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 Changed · +6 lines scan A → C dd4e71aa958b
  2. 8d ago First seen · 114 lines · 21 tokens per session scan A 449dcaf71ba3

Subscribe to this mod's changes

price-handling is a skill published in the GitHub repository vanillagreencom/kendex (75 stars, last pushed today), licensed MIT. It adds 21 tokens to every session and 1,091 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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