Hermes Claude Auth

hermes-claude-auth

Claude Code OAuth bypass for hermes-agent, use your Claude Code subscription (Max/Pro) with Hermes.

What this does

Patches hermes-agent at runtime to pass Anthropic's server-side OAuth content validation. It does not modify hermes-agent source files. Installation happens through a Python import hook that monkey-patches `build_anthropic_kwargs` on startup.

Why this exists

On 2026-04-04, Anthropic added server-side validation that rejects OAuth requests from third-party tools. This patch adds the billing header signature and system prompt structure the API expects.

Prerequisites

• hermes-agent installed ($HERMES_HOME/hermes-agent/, defaults to ~/.hermes/hermes-agent/ on Linux/macOS and %LOCALAPPDATA%\hermes\hermes-agent\ on Windows)
• Claude Code CLI authenticated (valid credentials at ~/.claude/.credentials.json)
• hermes-agent configured for OAuth (credential_pool has a claude_code entry in $HERMES_HOME/auth.json)
• Python 3.11+
• Windows: PowerShell 5.1+ and Git in PATH

Install

Linux / macOS

# Remote install (one-liner)
curl -fsSL https://raw.githubusercontent.com/kristianvast/hermes-claude-auth/main/install-remote.sh | bash

# Or clone manually
git clone https://github.com/kristianvast/hermes-claude-auth.git
cd hermes-claude-auth
./install.sh

Windows (PowerShell)

irm https://raw.githubusercontent.com/kristianvast/hermes-claude-auth/main/install-remote.ps1 | iex

Or clone manually:

git clone https://github.com/kristianvast/hermes-claude-auth.git
cd hermes-claude-auth
.\install.ps1

What the installer does:

• Auto-detects your hermes directory ($HERMES_HOME if set, else %LOCALAPPDATA%\hermes\ on Windows and ~/.hermes/ on Linux/macOS)
• Copies anthropic_billing_bypass.py to /patches/
• Installs a .pth shim + bootstrap module into the hermes venv's site-packages (this loads the hook at interpreter startup; see "How it works" below fo