Anthropic's Claude Code CLI source code leaked onto GitHub recently. All of it. About 1,900 files and a lot of TypeScript.
I read through the key modules. What follows is a breakdown of the surprising parts: how the system actually works, where Anthropic made clever engineering choices, and where their approach diverges from OpenAI's Codex in ways you wouldn't guess from using either tool.
Here's what happens when you type a message into Claude Code:
| # wsl-vpn-arp-fix.ps1 | |
| # Fixes WSL2 connectivity after Cisco VPN reconnects by syncing ARP from Windows | |
| # Requires: Run as Administrator | |
| Write-Host "" | |
| Write-Host "=== Fix WSL VPN (Adapter-based ARP Sync) ===" -ForegroundColor Cyan | |
| # Match Cisco AnyConnect / Secure Client adapter | |
| $adapterPattern = "Cisco" |
Right-click on 'Power' icon in taskbar > 'Choose what the power button does' > 'Change settings that are currently unavailable'
| #!/bin/bash | |
| # Check if the correct number of arguments is provided | |
| if [ "$#" -ne 2 ]; then | |
| echo "Usage: $0 <hostname> <IP address>" | |
| exit 1 | |
| fi | |
| HOSTNAME=$1 | |
| IP=$2 |
| Ensure SDK installed: | |
| wget https://dot.net/v1/dotnet-install.sh -O dotnet-install.sh | |
| sudo chmod +x ./dotnet-install.sh | |
| ./dotnet-install.sh --version latest | |
| https://learn.microsoft.com/en-us/dotnet/core/diagnostics/dotnet-trace | |
| dotnet tool install --global dotnet-trace | |
| Manual download linux: wget https://aka.ms/dotnet-trace/linux-x64 |
| apt update | |
| apt install python3-pip | |
| python -m pip install --upgrade pip | |
| pip install azure-cli |
| #az login | |
| $subs = az account list | ConvertFrom-Json | |
| $allServers = @() | |
| foreach($sub in $subs){ | |
| Write-Output $sub.Name | |
| az account set -s $sub.Id | |
| $subServers = az resource list --resource-type 'Microsoft.Sql/servers' | ConvertFrom-Json | |
| foreach($server in $subServers){ | |
| $allServers += $server | |
| } |
| $ SUBSCRIPTION_ID=$(az account show --query id -o tsv) | |
| $ az rest \ | |
| --url "https://management.azure.com/subscriptions/$SUBSCRIPTION_ID/resourcegroups?api-version=2020-06-01 | | |
| jq ".value | .[] | .name" -r | |
| OR | |
| $ curl -sL \ |
| # Set variables | |
| $subscriptionId="" #Set to your subscription id where the VM is created | |
| $resourceGroup = "" #Resouce group of the VM | |
| $vmName = "" #VM Name | |
| $location = "westeurope" #VM Location | |
| $zone = "2" #1 2 or 3 | |
| #Login to the Azure |