umbra-py: Instructions file for Claude Code

CLAUDE.md

umbra-py CLAUDE.md is an instructions file for Claude Code from reesehammer/umbra-py. It costs 484 tokens per session, scanned A, original, Apache-2.0.

A short instruction file for Claude Code and other coding agents working in a Python project. It points agents to the main project guide, commands, testing rules, and coding conventions.

In plain words
What is it for?
It helps agents find setup and test commands, state assumptions, reproduce bugs with tests, and avoid unrelated refactoring.
Why use it?
It gives an agent the project context it needs before changing code and encourages small, testable changes when the request is unclear.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code; mentions AGENTS.md.

This is reesehammer/umbra-py's own configuration. It tells Claude Code how to work on umbra-py 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 umbra-py configures →

Reuse

Borrowing it

Nothing to install: this file belongs to reesehammer/umbra-py. 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/reesehammer/umbra-py/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/reesehammer/umbra-py

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.

agentmods badge for umbra-py CLAUDE.md

README.md
[![agentmods](https://agentmods.dev/badge/instructions/reesehammer/umbra-py/claude-md.svg)](https://agentmods.dev/instructions/reesehammer/umbra-py/claude-md)
Your own site
<a href="https://agentmods.dev/instructions/reesehammer/umbra-py/claude-md"><img src="https://agentmods.dev/badge/instructions/reesehammer/umbra-py/claude-md.svg" alt="Measured on agentmods" height="20"></a>
Per session 484 This file is loaded in full into every session.
When invoked 484 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00484 $0.00484
Opus 5 $0.00242 $0.00242
Sonnet 5 $0.00097 $0.00097
Haiku 4.5 $0.00048 $0.00048

Measured 7d ago against content hash 20cece2d06fa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

umbra-py 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 7d 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 · 44 lines

What it actually says

CLAUDE.md

This file is the entry point for Claude Code (and other AI coding agents) in this repository.

👉 Read AGENTS.md for the full, canonical agent guide. It is the single source of truth for project context, conventions, setup commands, testing rules, and the operating principles you should follow. Everything below is a short pointer; do not duplicate guidance here.

TL;DR for any coding task

  1. Open AGENTS.md. It has the repo map, setup, test, and conventions.
  2. State your assumptions. Surface ambiguity before writing code. If multiple interpretations exist, ask — don't pick silently.
  3. Smallest change that solves the task. No speculative abstractions, no "improvements" to adjacent code, no error handling for impossible cases.
  4. Turn the task into a verifiable goal. "Fix the bug" → "Write a test that reproduces it, then make it pass." Loop until the check passes.
  5. Every changed line must trace to the user's request. Match existing style. Don't refactor things that aren't broken.

Quick commands

uv pip install -e ".[dev]"          # install
ruff check . && ruff format --check .  # lint + format check
pytest -q                           # offline tests (CI default)
pytest -m network                   # live tests against Umbra's public catalog
umbra --help                        # CLI

Where things live (one-liner)

src/umbra_py/ is the package; catalog.py searches Umbra's static STAC tree, models.py is the UmbraItem dataclass, download.py handles resume-safe HTTPS downloads, load.py / convert.py / viz/ are the analysis and preview layers, the cli/ package exposes umbra (one module per family of verbs, shared options in cli/_shared.py). Heavy deps (sarpy, rasterio, matplotlib, folium) live behind extras and are imported lazily.

For anything beyond this, see AGENTS.md.

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. 7d ago First seen · 44 lines · 484 tokens per session scan A 20cece2d06fa

Subscribe to this mod's changes

umbra-py CLAUDE.md is an instructions file published in the GitHub repository reesehammer/umbra-py (0 stars, last pushed 2d ago), licensed Apache-2.0. It adds 484 tokens to every session, about $0.0024 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.

Related

Other instructions, from other repositories

next.js AGENTS.md

AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.

vercel/next.js · 7,296 tokens

codex AGENTS.md

AGENTS.md instructions for openai/codex, covering rust/codex-rs, the codex-core crate, code review rules, crate api surface and model visible context.

openai/codex · 5,153 tokens

vscode buildNext.instructions.md

Working notes and architecture documentation for the new esbuild-based build system in build/next. Use when making changes to the new build pipeline (transpile/bundle commands, NLS plugin, source-map handling, resource copying, or self-hosting watch tasks).

microsoft/vscode · 6,785 tokens

vscode oss-third-party-notices.instructions.md

Instructions for microsoft/vscode, covering vs code oss third-party-notices pipeline, architecture, pipeline flow in ci, applying the notice (cutover) and fallback chain (never fail the build).

microsoft/vscode · 5,001 tokens

langchain AGENTS.md

AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.

langchain-ai/langchain · 4,469 tokens

spec-kit AGENTS.md

AGENTS.md instructions for github/spec-kit, covering agents.md, about spec kit and specify, quickstart — add a new integration in 5 steps, integration architecture and integrationmanifest — file tracking.

github/spec-kit · 7,104 tokens