turnlens AGENTS.md

turnlens AGENTS.md is an instructions file for Codex, OpenCode from kelesmert/turnlens. It costs 2,061 tokens per session, scanned A, original, MIT.

Project instructions for TurnLens, a TypeScript command-line tool that measures the tokens and cost used by each coding-agent turn. TypeScript is a programming language that adds type checking to JavaScript.

In plain words
What is it for?
Use them when developing TurnLens, checking live agent cost data, updating pricing snapshots, or designing and implementing TypeScript changes.
Why use it?
They provide the commands and checks needed to keep the tool correct, including linting, tests, builds, pricing data, and cost verification.

Instructions file for CodexOpenCode

Written for Codex and OpenCode: the file is AGENTS.md. Also seen: reads .claude/ paths.

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 instructions/kelesmert/turnlens/agents-md
Clone the repo
git clone --depth 1 https://github.com/kelesmert/turnlens

Made for: Codex, OpenCode.

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 turnlens AGENTS.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/kelesmert/turnlens/agents-md.svg)](https://agentmods.dev/instructions/kelesmert/turnlens/agents-md)
Your own site
<a href="https://agentmods.dev/instructions/kelesmert/turnlens/agents-md"><img src="https://agentmods.dev/badge/instructions/kelesmert/turnlens/agents-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 2,061 This file is loaded in full into every session.
When invoked 2,061 The same file — it is already loaded in full.
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 5.1 $0.02061 $0.02061
Opus 5 $0.01030 $0.01030
Sonnet 5 $0.00412 $0.00412
Haiku 4.5 $0.00206 $0.00206

Measured 5d ago against content hash cf7bdfa429a0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

turnlens AGENTS.md 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 5d 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.

AGENTS.md · 151 lines

How it starts

The opening of the file, as written. The whole thing — 151 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TurnLens

Per-turn token and cost monitoring for AI coding agents. It answers one question that agent session files do not answer directly: what did this single prompt and its response cost?

TypeScript, ESM, zero runtime dependencies. This file holds what is worth knowing in every task; everything else is routed to below.

Commands

npm test                  vitest
npm run typecheck         includes test/
npm run lint              eslint, type-aware, src and test
npm run check             the three above, in order
npm run build             tsc, cleans dist/ first
npm run pricing:snapshot  regenerates src/pricing/snapshot.generated.ts
npm run verify:costs      cross-checks pricing against ccusage

lint runs itself: a Stop hook in .claude/settings.json blocks the end of any turn that wrote a .ts file and left a lint error.

The user-facing surface is turnlens --help. It is not copied here, because a copy is right until the next flag is added.

Skills

  • live-verification: checking TurnLens against live agent data, or taking any figure that will be treated as evidence.
  • design-doc: designing work that this session will also implement.
  • typescript-best-practices: writing, reviewing or refactoring .ts.

Open the file

Never write a claim about this code from memory. Not a return type, not a column count, not what a test file covers, not a line number. Open it. This costs seconds and the alternative has already cost a working day.

Measured on one design document, 11 August 2026: roughly half its defects were sentences written without opening the source. formatCostUsd was described as producing a number when it returns a toFixed(6) string. The CSV was called 24 columns when CSV_HEADER held 23 that day, which is the sort of figure that rots: it is 24 now, and the point is that neither number was ever counted. test/history.test.ts was named as covering readRecordedKeys on the strength of its filename alone, when it tests formatHistoryBlock and never opens a CSV.

Read the full file on GitHub · 151 lines

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. 5d ago First seen · 151 lines · 2,061 tokens per session scan A cf7bdfa429a0

Subscribe to this mod's changes

turnlens AGENTS.md is an instructions file published in the GitHub repository kelesmert/turnlens (2 stars, last pushed 24d ago), licensed MIT. It adds 2,061 tokens to every session, about $0.0103 per session on Opus 5. 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.