George Zhang odysseus0

How a Hotel WiFi Taught Me That Happy Eyeballs Can't See Everything

Or: The Empty Error String That Led Me Down a Rabbit Hole of Broken Networks

TL;DR: httpx AsyncClient was failing with empty error messages. After hours of debugging, I discovered a hotel WiFi firewall that accepts IPv6 TCP connections but kills them during TLS handshake - an edge case so specific it defeats Happy Eyeballs and every other protection mechanism.

It started with the most frustrating error message I've ever seen:

{"detail":"An error occurred while requesting TikAPI: "}

Non-blocking Tasks for Claude Code - V1 Design

Overview

This design makes Claude Code more responsive by allowing the main agent to continue working while background tasks run. Currently, when Claude spawns multiple long-running tasks, everything freezes - the agent can't continue working on other things, and you can't interact with it. With this change, Claude can process results as they arrive, continue working on independent tasks, and remain available for user interaction.

Background: Understanding Claude Code

To understand the problem and solution, you need to know how Claude Code works today.

Selective Context Compaction for Claude Code

The Problem

Effective AI agent performance depends on maintaining high signal-to-noise ratio in the context window. Even with large contexts, noise degrades performance.

Claude Code currently offers only "Compact" - a nuclear option that rebuilds the entire conversation from scratch. This is like having only git rebase -i --root when you often just need git rebase -i HEAD~5.

	#!/usr/bin/env python3
	"""
	IPv6 Pattern Test - The script that revealed the hotel WiFi issue

	This is the actual script Claude Code wrote that tested multiple services
	and revealed the pattern: all real IPv6 addresses failed at TLS,
	while IPv6-mapped IPv4 addresses worked fine.

	When run at home, everything worked - revealing it was the hotel WiFi
	breaking IPv6 in a very specific way.

	#!/usr/bin/env python3

	import asyncio
	import httpx
	import threading
	import concurrent.futures

	def sync_test():
	"""Test with synchronous httpx client."""
	print("🔄 Testing synchronous httpx.Client...")

	#!/usr/bin/env python3

	import asyncio
	import aiohttp
	import json

	async def test_tikapi_aiohttp():
	"""Test TikAPI using aiohttp instead of httpx."""

	print("🧪 Testing TikAPI with aiohttp...")

	#!/usr/bin/env python3
	"""
	Phase 1: Network-Level Deep Dive - Packet Capture Analysis
	Captures and compares network behavior between sync and async httpx clients
	"""

	import asyncio
	import httpx
	import socket
	import ssl

	#!/usr/bin/env python3
	"""
	Phase 1: Network-Level Deep Dive - DNS Resolution Testing
	Tests DNS resolution behavior and IPv4/IPv6 connectivity
	"""

	import asyncio
	import httpx
	import socket
	import ssl

	#!/usr/bin/env python3
	"""
	Check why httpx AsyncClient works on some machines but not others
	This will help identify environment differences
	"""

	import socket
	import subprocess
	import platform
	import asyncio

	#!/usr/bin/env python3
	"""
	Demonstrate how unusual TikAPI's IPv6 behavior is compared to other services.
	"""

	import asyncio
	import socket
	import ssl
	import time