kerf-cli: Instructions file for Claude Code

CLAUDE.md

kerf-cli CLAUDE.md is an instructions file for Claude Code from dhanushkumarsivaji/kerf-cli. It costs 392 tokens per session, scanned B, original, MIT.

Repository instructions for kerf-cli, a TypeScript command-line tool that tracks Claude Code usage and costs. They describe its architecture, conventions, and important files.

In plain words
What is it for?
Developing kerf-cli, working with its JSONL logs and SQLite data, maintaining its terminal interface, and following its project conventions.
Why use it?
They give a coding agent the project rules for handling logs, budgets, dates, financial values, dependencies, and errors consistently.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: reads .claude/ paths; mentions Claude Code.

This is dhanushkumarsivaji/kerf-cli's own configuration. It tells Claude Code how to work on kerf-cli 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 kerf-cli configures →

Reuse

Borrowing it

Nothing to install: this file belongs to dhanushkumarsivaji/kerf-cli. 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/dhanushkumarsivaji/kerf-cli/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/dhanushkumarsivaji/kerf-cli

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.

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README.md
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Your own site
<a href="https://agentmods.dev/instructions/dhanushkumarsivaji/kerf-cli/claude-md"><img src="https://agentmods.dev/badge/instructions/dhanushkumarsivaji/kerf-cli/claude-md/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

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Your own site · 80×15
<a href="https://agentmods.dev/instructions/dhanushkumarsivaji/kerf-cli/claude-md"><img src="https://agentmods.dev/badge/instructions/dhanushkumarsivaji/kerf-cli/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 392 This file is loaded in full into every session.
When invoked 392 The same file — it is already loaded in full.
Security scan B 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 $0.00392 $0.00392
Opus 5 $0.00196 $0.00196
Sonnet 5 $0.00078 $0.00078
Haiku 4.5 $0.00039 $0.00039

Measured 8d ago against content hash b16d58af9157, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade B, and why

kerf-cli CLAUDE.md scanned grade B 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 8d 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- Settings: ~/.claude/settings.json (global), .claude/settings.json (project)
CLAUDE.md · 40 lines

What it actually says

kerf-cli — Claude Code Cost Intelligence

Project Overview

TypeScript CLI tool providing real-time cost intelligence for Claude Code. Name origin: kerf = width of material removed by a cutting tool (token waste). Published as kerf-cli on npm. Distributed via npx kerf-cli@latest. Uses Ink (React for CLI) for terminal UI.

Architecture

  • CLI: Commander.js for subcommands, Ink for interactive UI
  • Data: Parse JSONL from ~/.claude/projects/, SQLite for budgets
  • Hooks: Shell scripts installed to ~/.claude/hooks/
  • Token counting: character/3.5 heuristic, Anthropic count_tokens API optional
  • Storage: ~/.kerf/kerf.db (SQLite), ~/.kerf/session-log.jsonl

Conventions

  • Use Day.js for all date operations (not Moment.js)
  • Pin exact versions in package.json (no ^ or ~)
  • Use structlog pattern for logging (structured JSON)
  • All financial values use string-based precision (avoid floating point)
  • ESM modules only (type: module in package.json)
  • Prefer named exports over default exports
  • Error messages must be actionable (tell user what to do)

Key Paths

  • JSONL logs: ~/.claude/projects//.jsonl
  • Settings: ~/.claude/settings.json (global), .claude/settings.json (project)
  • MCP config: .mcp.json (project), ~/.claude.json (user)
  • Hooks: ~/.claude/settings.json hooks[] array
  • kerf data: ~/.kerf/kerf.db, ~/.kerf/session-log.jsonl

Testing

  • vitest for all tests
  • Fixtures in tests/fixtures/
  • Mock JSONL data for parser tests

Build

  • tsup bundles to dist/
  • npm prepublishOnly runs build
  • Target: Node 20+
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. 8d ago First seen · 40 lines · 392 tokens per session scan B b16d58af9157

Subscribe to this mod's changes

kerf-cli CLAUDE.md is an instructions file published in the GitHub repository dhanushkumarsivaji/kerf-cli (5 stars, last pushed 3mo ago), licensed MIT. It adds 392 tokens to every session, about $0.0020 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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