# Session Hook Config

> 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.

- Skill: `tomevault-io/session-hook-config` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/session-hook-config`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/session-hook-config/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/session-hook-config

---


# 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:

```bash
# 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:

```bash
# 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:

```bash
cat /tmp/px-proxy.log
```

### Still getting 401 errors

Verify px-proxy is running:

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

Verify the proxy works with curl:

```bash
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.

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->