---
title: "PyCoder’s Weekly"
url: https://daily.dev/posts/pycoder-s-weekly-hivy0he93
source_url: https://pycoders.com/issues/749
type: article
source: "Planet Python"
published: 2026-08-25T19:50:49.262Z
updated: 2026-08-25T20:22:53.061Z
tags: ["python", "ai-agents", "django", "polars"]
reading_time: 4
upvotes: 0
comments: 0
language: en
---

> ## Documentation Index
> Fetch the complete documentation index at: https://daily.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# PyCoder’s Weekly

**[Planet Python](https://daily.dev/sources/planetpython)** · 4 min read · 0 upvotes · 0 comments

## Summary

A curated roundup of Python news and tutorials covering Polars vs SQL differences, Python's built-in constants, using deque, a Pyrefly type checker sponsor spot, PEP drafts, Mojo going open source, debugging Python with AI agents including Claude Code, a security issue with str.lower(), reproducible builds on PyPI, a React/FastAPI 'Mullet Stack' approach, a Django counting trick, and several new open-source projects and libraries shared by the community.

## Full article

daily.dev links to this article rather than hosting it. Read it at the original source: <https://pycoders.com/issues/749>

## Questions this post answers

### Is the Mojo programming language open source now?

Yes, Mojo has been made open source by Modular. This follows Mojo's development as a Python-family language designed for high-performance AI and systems programming, positioning it as an alternative for developers who want Python-like syntax with lower-level performance control.

_Developers evaluating new AI-focused languages can follow Mojo's evolution alongside Python news on daily.dev._

### Why can str.lower() be a security vulnerability in Python?

Because some internet standards only support ASCII, Python must translate Unicode strings to ASCII-compatible forms in certain contexts, and using str.lower() for this kind of normalization can introduce mismatches or bypass checks due to Unicode case-folding quirks, creating a security gap between the intended and actual string comparison.

_Developers hardening string handling logic can track Python security gotchas like this one via daily.dev._

### What is Python's Mullet Stack architecture?

The Mullet Stack refers to pairing a React and TypeScript frontend with a FastAPI and Pydantic backend, combining a JavaScript-based UI layer with a Python-based API layer. The term, coined by Sean Helvey, plays on the mullet haircut idea of 'business in front, party in back' to describe this common full-stack pairing.

_Developers weighing frontend and backend framework pairings can compare stacks like this one on daily.dev._

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---

Tags: [#python](https://daily.dev/tags/python), [#ai-agents](https://daily.dev/tags/ai-agents), [#django](https://daily.dev/tags/django), [#polars](https://daily.dev/tags/polars)

[View this post on daily.dev](https://daily.dev/posts/pycoder-s-weekly-hivy0he93)