hermes - 💡(How to fix) Fix Custom providers behind Cloudflare WAF return 403 due to SDK User-Agent

Problem

When using custom_providers with third-party API proxies (e.g. self-hosted relays, GLM proxies and so on) that sit behind Cloudflare or similar WAFs, all API requests fail with HTTP 403:

PermissionDeniedError: HTTP 403: Your request was blocked.

Root Cause

The Anthropic SDK (anthropic Python package) and OpenAI SDK both send identifying User-Agent headers by default:

• Anthropic/Python 0.101.0
• OpenAI/Python 2.36.0

Cloudflare's bot detection rules block these User-Agent patterns. This was verified by testing the same endpoint with and without the SDK User-Agent:

# Without SDK User-Agent → 200 OK
curl -X POST https://proxy.example.com/v1/messages \
  -H "x-api-key: $KEY" -H "anthropic-version: 2023-06-01" \
  -d '{"model":"...","max_tokens":10,"messages":[{"role":"user","content":"hi"}]}'

# With SDK User-Agent → 403 Forbidden
curl -X POST https://proxy.example.com/v1/messages \
  -H "x-api-key: $KEY" -H "anthropic-version: 2023-06-01" \
  -H "User-Agent: Anthropic/Python 0.101.0" \
  -d '{"model":"...","max_tokens":10,"messages":[{"role":"user","content":"hi"}]}'

In the codebase, build_anthropic_client() in agent/anthropic_adapter.py does not set a custom User-Agent for third-party endpoints (the _is_third_party_anthropic_endpoint branch). Similarly, the OpenAI client construction in run_agent.py does not override the SDK User-Agent for custom providers.

Proposed Solution

Add an optional user_agent field to custom_providers configuration:

custom_providers:
- name: my-proxy
  base_url: https://proxy.example.com
  api_key: sk-xxx
  api_mode: anthropic_messages
  user_agent: my-custom-agent  # optional, defaults to 'hermes-agent'

When user_agent is set (or defaults to 'hermes-agent'), it overrides the SDK's default User-Agent for that custom provider's API calls.

Workaround

Patching build_anthropic_client() to set User-Agent: hermes-agent in the third-party endpoint branch works, but is not configurable and gets overwritten on update.

Environment

• Hermes Agent v0.13.0
• Python 3.13.5
• anthropic SDK 0.101.0
• openai SDK 2.36.0
• Provider: third-party proxy behind Cloudflare