name: session-hook-config description: Configures startup hooks for Claude Code on the web, particularly for .NET proxy setup. Use when setting up a repository for Claude Code web sessions, when dotnet restore fails with 401 errors in Claude Code web, or when configuring SessionStart hooks for environment initialization.

Session Start Hook for .NET Proxy Setup

This skill configures Claude Code to automatically handle .NET/NuGet proxy authentication when running in the Claude Code web environment.

Problem

Claude Code web runs in a containerized environment that requires JWT-authenticated proxies for external network access. While tools like curl, npm, and wget work correctly with this proxy, .NET's HttpClient doesn't properly handle the JWT authentication format, causing dotnet restore and dotnet build to fail with 401 errors.

Solution

We use px-proxy as an intermediary proxy that:

1. Accepts unauthenticated connections locally (port 3128)
2. Forwards requests to the upstream proxy with proper JWT authentication
3. Allows .NET to work normally by pointing it at the local proxy

Files

.claude/scripts/setup-dotnet-proxy.sh

This script:

1. Detects if running in Claude Code web environment (checks for JWT in proxy URL)
2. Installs px-proxy if not present
3. Starts px-proxy on port 3128 with upstream auth
4. Exports proxy environment variables for .NET

.claude/settings.json

Configures the SessionStart hook to run the setup script when a Claude Code session begins.

Manual Usage

If the hook doesn't run automatically, you can manually set up the proxy:

# Source the setup script
source .claude/scripts/setup-dotnet-proxy.sh

# Then run dotnet commands
dotnet restore
dotnet build

Or run dotnet with explicit proxy:

# Start px-proxy manually
pip install px-proxy
export PX_PASSWORD="<jwt_token_from_HTTP_PROXY>"
px --server="<proxy_host:port>" --username="<container_id>" --auth=BASIC --port=3128 &

# Use local proxy for dotnet
export http_proxy="http://127.0.0.1:3128"
export https_proxy="http://127.0.0.1:3128"
dotnet restore

Local Development

When running locally (not in Claude Code web), the script detects that no JWT proxy is configured and skips the setup entirely. This means:

• Local development works normally without any proxy
• The script is safe to run in any environment
• No changes needed for local vs web development

Troubleshooting

px-proxy fails to start

Check the log file:

cat /tmp/px-proxy.log

Still getting 401 errors

Verify px-proxy is running:

pgrep -f "px.*--port=3128"

Verify the proxy works with curl:

curl --proxy http://127.0.0.1:3128 -I https://api.nuget.org/v3/index.json

JWT token expired

The JWT token in the proxy URL has an expiration time. If you see authentication failures after a long session, the token may have expired. Start a new Claude Code session to get a fresh token.