What is tckit CLAUDE.md?

Project instructions for TcKit, a C# and .NET 8 server that connects Claude Code to TwinCAT 3 PLC projects. They describe the project structure and the rule that adapters communicate through shared interfaces rather than directly with one another.

Use them when contributing to TcKit, especially when adding ports or adapters, changing documentation, or following its session-start procedures.

They give an agent the project’s boundaries and working rules before it changes code.

How georgeturneruk/tckit configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to georgeturneruk/tckit. 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/georgeturneruk/tckit/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/georgeturneruk/tckit

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.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/georgeturneruk/tckit/claude-md/github.svg)](https://agentmods.dev/instructions/georgeturneruk/tckit/claude-md)

Your own site

<a href="https://agentmods.dev/instructions/georgeturneruk/tckit/claude-md"><img src="https://agentmods.dev/badge/instructions/georgeturneruk/tckit/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.

Your own site · 80×15

<a href="https://agentmods.dev/instructions/georgeturneruk/tckit/claude-md"><img src="https://agentmods.dev/badge/instructions/georgeturneruk/tckit/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 1,399 This file is loaded in full into every session.

When invoked 1,399 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	$0.01399	$0.01399
Opus 5.5	$0.00560	$0.00560
Sonnet 5.5	$0.00280	$0.00280
Haiku 4.5	$0.00140	$0.00140

Measured 2mo ago against content hash 557aa4471e8f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

tckit CLAUDE.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.

CLAUDE.md · 128 lines

How it starts

The opening of the file, as written. The whole thing — 128 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md — TcKit

This file is read automatically by Claude Code at the start of every session. It holds only the rules that need to fire on every turn. Topic-specific procedure (writing ST, building, reading projects, editing docs, working with ADRs, etc.) lives in skills under .claude/skills/. Contributor procedure (adapter/port recipes, code style, local commands, skills workflow, PRs) lives in CONTRIBUTING.md. Project tree and port-method reference live in docs/content/architecture/overview.md.

What this project is

TcKit is an MCP server (C#/.NET 8) that connects Claude Code to TwinCAT 3 PLC projects. Target platform: TwinCAT 3.1 Build 4026.

Architecture: the one rule

Adapters reference only TcKit.Core. Never each other.

MCP Server → Port (interface) → Adapter (concrete) → External tool

The MCP server calls ports. Ports define interfaces (TcKit.Core.Ports). Adapters implement them, each in its own project. Shared logic belongs in TcKit.Core, never in a sibling adapter; the project graph enforces this. Do not add an adapter-to-adapter project reference.

Top-level layout (full tree in architecture/overview.md):

dotnet/   ← C# solution (TcKit.Core, TcKit.Server, TcKit.Cli, adapters, tests)
plugin/   ← Claude Code plugin (launcher + shipped skill copies)
docs/     ← MkDocs site
adrs/     ← Architecture Decision Records

Skills (procedural workflows)

Each skill loads on demand on its trigger phrases. The skill body owns the full procedure; this index just points to it.

Skill	Loads when
tc-orient-project	First touch on a TwinCAT project, "structural overview", "what's in this project"
tc-read-project	Follow-up POU / GVL / DUT lookups once orientation is done
tc-beckhoff-docs	Researching a Beckhoff library FB / function / TF library, or a hardware product by order number
tc-write-st	Writing or modifying ST code
tc-build-test-loop	Building, deploying, running TcUnit tests
tc-hardware	EtherCAT/IPC/axis diagnostics, live symbol I/O, scanning or authoring the I/O tree
tc-config	Initial setup, safety stance, permission-gate edits (`permissions.json`), "why was deploy denied"
tc-docs-write	Editing anything under `docs/content/` or `README.md`
tc-adr	Reading, writing, or promoting an ADR under `adrs/`

Read the full file on GitHub · 128 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 · 128 lines · 1,399 tokens per session scan A 557aa4471e8f

Subscribe to this mod's changes

tckit CLAUDE.md is an instructions file published in the GitHub repository georgeturneruk/tckit (11 stars, last pushed 2mo ago), licensed MIT. It adds 1,399 tokens to every session, about $0.0056 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.

tckit CLAUDE.md next to 6 instructions from other repositories
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tckit: Instructions file for Claude Code