jinja2-async-environment: Instructions file for Claude Code

CLAUDE.md

jinja2-async-environment CLAUDE.md is an instructions file for Claude Code from lesleslie/jinja2-async-environment. It costs 587 tokens per session, scanned A, original, BSD-3-Clause.

A repository instruction file for an asynchronous extension of Jinja2, a Python template system. It documents the project layout, setup command, important code areas, and the checks expected before work is complete.

In plain words
What is it for?
Use it when setting up or changing this repository, locating its loader, compiler, cache, and test code, or running formatting, linting, type checks, and tests.
Why use it?
It gives a coding agent project-specific rules instead of making it rediscover them from the repository. This reduces mistakes around asynchronous behavior, compatibility, and required quality checks.

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 lesleslie/jinja2-async-environment's own configuration. It tells Claude Code how to work on jinja2-async-environment 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 jinja2-async-environment configures →

Reuse

Borrowing it

Nothing to install: this file belongs to lesleslie/jinja2-async-environment. 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/lesleslie/jinja2-async-environment/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/lesleslie/jinja2-async-environment

Made for: Claude Code.

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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 $0.00587 $0.00587
Opus 5 $0.00293 $0.00293
Sonnet 5 $0.00117 $0.00117
Haiku 4.5 $0.00059 $0.00059

Measured 3d ago against content hash a4728fda4d15, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

jinja2-async-environment 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 3d 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 · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

For a shorter, tool-neutral bootstrap document, start with AGENTS.md.

Project Overview

jinja2-async-environment is an async-first extension of Jinja2 aimed at preserving Jinja compatibility while making template loading, compilation, and rendering work well in async applications.

Important goals:

  • preserve expected Jinja behavior unless a change is explicitly async-specific
  • keep async paths genuinely non-blocking
  • protect the package's performance-sensitive code paths

Key Paths

  • jinja2_async_environment/environment.py: main async environment
  • jinja2_async_environment/loaders/: async loader implementations
  • jinja2_async_environment/compiler_modules/: code generation and compiler helpers
  • jinja2_async_environment/caching/: cache management and strategies
  • tests/: unit, integration, benchmark, and regression coverage

Development Commands

Setup

uv sync

Standard Quality Gate

python -m crackerjack -t --ai-agent

Run that before considering work complete. For targeted iteration, use:

ruff format
ruff check
pyright
pytest
pytest -m unit
pytest -m integration
pytest --cov=jinja2_async_environment

Architecture Notes

The package is organized around four concerns:

  • environment orchestration
  • async loaders
  • compiler/codegen helpers
  • caching and bytecode support

When making changes:

  • prefer extending the modular subsystems instead of rebuilding monolithic logic
  • preserve compatibility expectations for sync behavior, macro behavior, and loader contracts
  • keep async work non-blocking and isolate any unavoidable sync fallback clearly
  • treat performance-sensitive helpers as hot paths and benchmark them when behavior changes

Performance Guidance

This repo cares about performance as a product feature. Be careful around:

  • loader caching behavior
  • compiler dependency resolution
  • template compilation caches
  • async iteration and render hot paths

Read the full file on GitHub · 93 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. 3d ago First seen · 93 lines · 587 tokens per session scan A a4728fda4d15

Subscribe to this mod's changes

jinja2-async-environment CLAUDE.md is an instructions file published in the GitHub repository lesleslie/jinja2-async-environment (6 stars, last pushed 3d ago), licensed BSD-3-Clause. It adds 587 tokens to every session, about $0.0029 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 2026-09-04.

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