What is Primitives CLAUDE.md?

Repository instructions for ReactiveUI.Primitives, a software library, covering how an AI agent should understand, build, and test the code. They identify the main solution file, tests, benchmarks, and required working directory.

Use them when working on ReactiveUI.Primitives to locate the code and tests and run .NET build or test commands correctly. The instructions require those commands to run from the src folder.

They reduce mistakes caused by using the wrong folder, solution file, or build commands. They also explain SLNX, an XML format used to describe a .NET solution instead of the older .sln format.

How reactiveui/Primitives configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to reactiveui/Primitives. 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/reactiveui/Primitives/main/CLAUDE.md

Clone the repo

git clone --depth 1 https://github.com/reactiveui/Primitives

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/reactiveui/primitives/claude-md/github.svg)](https://agentmods.dev/instructions/reactiveui/primitives/claude-md)

Your own site

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

Per session 2,269 This file is loaded in full into every session.

When invoked 2,269 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	$0.02269	$0.02269
Opus 5.5	$0.00908	$0.00908
Sonnet 5.5	$0.00454	$0.00454
Haiku 4.5	$0.00227	$0.00227

Measured 1mo ago against content hash 635be55a6e17, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

Primitives 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 1mo 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 · 255 lines

How it starts

The opening of the file, as written. The whole thing — 255 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file is the single source of truth for AI/agent assistance in this repository. It consolidates build/test commands, repository layout, test runner usage, and the main constraints needed to work safely in ReactiveUI.Primitives.

If there is any conflict between other agent instruction files and this file, follow CLAUDE.md.

Repository Orientation

Repository root: .
Primary working directory for build/test: ./src
Main solution: src/ReactiveUI.Primitives.slnx, built through src/ReactiveUI.Primitives.slnf and src/ReactiveUI.Primitives.Uno.slnf
Benchmarks project: src/benchmarks/ReactiveUI.Primitives.Benchmarks/ReactiveUI.Primitives.Benchmarks.csproj
Tests: src/tests/

Solution Format: SLNX

This repository uses SLNX (XML-based solution format) instead of legacy .sln.

Main file: src/ReactiveUI.Primitives.slnx. It holds every project, for the IDE.
Build and test with the solution filters, not the .slnx:
- src/ReactiveUI.Primitives.slnf holds every project except the Uno ones. dotnet builds it on any OS.
- src/ReactiveUI.Primitives.Uno.slnf holds the Uno.Sdk projects. Their Windows head needs MSBuild, so CI builds this filter in its own Windows job with MSBuild (msbuildSolutionFile in the shared workflows). On Linux and macOS, dotnet build builds the other Uno heads.
A new project goes in the .slnx and in one of the two filters.

Build Environment Requirements

Working Directory Rule

CRITICAL: Run dotnet build/test commands from ./src, not the repository root, unless the command explicitly uses src/-prefixed paths.

Running dotnet test from the repository root can trigger Microsoft Testing Platform / VSTest invocation issues on .NET 10+ SDKs.

Restore And Build

cd src

dotnet restore "ReactiveUI.Primitives.slnf"
dotnet build "ReactiveUI.Primitives.slnf"
dotnet build "ReactiveUI.Primitives.slnf" -c Release
dotnet clean "ReactiveUI.Primitives.slnf"

# The Uno projects
dotnet build "ReactiveUI.Primitives.Uno.slnf" -c Release

Read the full file on GitHub · 255 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.

1mo ago Changed · +8 lines · +178 tokens per session 635be55a6e17
1mo ago Changed · +41 lines · +405 tokens per session d799e78b0efc
1mo ago Changed · -1 lines · -10 tokens per session e1086295f55b
2mo ago First seen · 207 lines · 1,696 tokens per session scan A 67ec35785f02

Subscribe to this mod's changes

Primitives CLAUDE.md is an instructions file published in the GitHub repository reactiveui/Primitives (15 stars, last pushed yesterday), licensed MIT. It adds 2,269 tokens to every session, about $0.0091 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 2026-08-30.

async dotnet dotnet-core reactive reactiveui

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