What is fmtly copilot-instructions.md?

Project instructions for fmtly, a browser-based toolset for formatting, checking, converting, and comparing structured data such as JSON, XML, YAML, CSV, and TOML.

Use them when developing or changing fmtly, especially when adding data-format tools, updating its tool registry, or working within its SvelteKit and Cloudflare setup.

They give coding agents the project’s intended design, technology choices, and rules for adding tools. This helps prevent changes that conflict with the existing architecture or send user data to a server.

How oguzhankir/fmtly configures GitHub Copilot

Reuse

Borrowing it

Nothing to install: this file belongs to oguzhankir/fmtly. 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/oguzhankir/fmtly/main/.github/copilot-instructions.md

Clone the repo

git clone --depth 1 https://github.com/oguzhankir/fmtly

Made for: GitHub Copilot.

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/oguzhankir/fmtly/copilot-instructions/github.svg)](https://agentmods.dev/instructions/oguzhankir/fmtly/copilot-instructions)

Your own site

<a href="https://agentmods.dev/instructions/oguzhankir/fmtly/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/oguzhankir/fmtly/copilot-instructions/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/oguzhankir/fmtly/copilot-instructions"><img src="https://agentmods.dev/badge/instructions/oguzhankir/fmtly/copilot-instructions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,066 This file is loaded in full into every session.

When invoked 1,066 The same file — it is already loaded in full.

Security scan A 0 findings. 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.

Model	Per session	Once invoked
Fable 5.1	$0.01066	$0.01066
Opus 5.5	$0.00426	$0.00426
Sonnet 5.5	$0.00213	$0.00213
Haiku 4.5	$0.00107	$0.00107

Measured 2mo ago against content hash 691884928e6d, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

fmtly copilot-instructions.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 2mo 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

fmtly CLAUDE.md — 100% identical, 0 lines differ

.github/copilot-instructions.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

fmtly — Windsurf Rules

Read this file entirely before writing any code.

The Vision

Format, validate, convert, and diff structured data. No login. No server. Instant.

fmtly is not just a random collection of utilities. It is a deep, focused platform for structured data formats (JSON, XML, YAML, CSV, TOML), with a visionary roadmap to expand into AI/LLM toolchains, encoders, code formatters, and more.

The Golden Rule: Every tool runs in the browser. No user data ever touches a server. Exception: Network tools (IP lookup, DNS, etc.) proxy through a minimal Cloudflare Worker without logging.

Stack

SvelteKit 2 + TypeScript 5 + Tailwind CSS 4
Cloudflare Pages (static) + Cloudflare Workers (network proxy only)
Package manager: pnpm — never npm, never yarn
Adapter: @sveltejs/adapter-cloudflare

Architecture Rules

Tool Registry

Every tool is a config object in src/lib/registry/tools/[category].tools.ts. Never create a route file for a tool — register it, the page generates itself.

Category-Based Structure

When adding new tools or categories, strictly adhere to the category-based folder structure:

Registry: src/lib/registry/tools/[category].tools.ts
Engines: src/lib/engines/[category]/ (include an index.ts barrel file)
Panels: src/lib/components/panels/[category]/
Tests: tests/unit/[category]/
Stores: src/lib/stores/[category].store.ts (if state is required)
Locales: src/lib/i18n/registry/[lang].ts

Never put category-specific logic in shared directories.

Lazy Loading — No Exceptions

Every processing library uses dynamic import(). Never at top level. This applies to: ajv, js-yaml, fast-xml-parser, smol-toml, @wasm-fmt/taplo_fmt, Monaco Editor, etc. If it processes data → dynamic import.

No Backend for User Data

Permitted server-side code only:

+page.ts load functions (read registry)
/sitemap.xml/+server.ts (build time only)

Static Output Only

No Node.js APIs in browser code (fs, path, crypto module — use Web Crypto API). No env vars in browser except PUBLIC_ prefix. Never delete static/_headers, static/_redirects, static/_routes.json.

Read the full file on GitHub · 124 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.

2mo ago First seen · 124 lines · 1,066 tokens per session scan A 691884928e6d

Subscribe to this mod's changes

fmtly copilot-instructions.md is an instructions file published in the GitHub repository oguzhankir/fmtly (4 stars, last pushed 11d ago), licensed MIT. It adds 1,066 tokens to every session, about $0.0043 per session on Opus 5.5. 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.

TypeScript browser-tools cloudflare-pages developer-tools json-formatter open-source

fmtly copilot-instructions.md next to 6 instructions from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
fmtly copilot-instructions.mdoguzhankir/fmtly	Instructions file	4	11d ago	MIT	A	1,066	GitHub Copilot
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vscode oss-third-party-notices.instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	5,516	GitHub Copilot
vscode copilot-instructions.mdmicrosoft/vscode	Instructions file	195k	yesterday	MIT	A	3,093	GitHub Copilot
deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness	Instructions file	274k	2d ago	MIT	A	4,313	Codex, OpenCode

fmtly: Instructions file for GitHub Copilot