Bug Summary

When using a named provider (e.g. zai) with a custom base_url, auxiliary tasks — context compression, title generation, and session summarization — silently use the provider's default endpoint instead of the configured custom one. This causes context truncation failures when the auxiliary request hits the wrong endpoint.

Root Cause

Two interrelated issues in resolve_provider_client() (agent/auxiliary_client.py):

1. PROVIDER_REGISTRY path ignores explicit_base_url (line ~1992)

When a named provider from PROVIDER_REGISTRY is resolved, base_url is constructed from only creds["base_url"] or the provider's default pconfig.inference_base_url. The explicit_base_url parameter passed to the function is completely ignored in this branch.

The "custom" provider path (line ~1842) correctly honors explicit_base_url.

2. Direct callers don't pass main_runtime

• title_generator.py (line 54-60): calls call_llm() without main_runtime
• trajectory_compressor.py (line 610-616, 679-685): calls call_llm() / async_call_llm() with an explicit provider= and no main_runtime

Without main_runtime, the _resolve_auto() workaround (which re-routes named providers with custom base_url through provider="custom") never triggers. And even if main_runtime were passed, the explicit provider= parameter causes _resolve_auto() to be bypassed entirely in favor of the PROVIDER_REGISTRY path.

Steps to Reproduce

1. Configure a named provider with a custom base_url in config.yaml:

   provider: zai
   base_url: https://custom-endpoint.example.com/v1

2. Start a long conversation that triggers context compression
3. Observe that the compression request goes to the default zai endpoint, not the custom one

Expected Behavior

Auxiliary tasks should honor the same base_url as the main conversation loop.

Suggested Fix

1. In resolve_provider_client(), the PROVIDER_REGISTRY path should fall back to explicit_base_url when it's provided:

   base_url = _to_openai_base_url(
       str(creds.get("base_url", "")).strip().rstrip("/") or explicit_base_url or pconfig.inference_base_url
   )

2. Thread main_runtime through to title_generator.py and trajectory_compressor.py so _resolve_auto() can access the runtime's base_url/api_key.

Workaround

Setting provider: auto for auxiliary tasks avoids the PROVIDER_REGISTRY path:

auxiliary:
  compression:
    provider: auto
  title_generation:
    provider: auto

This relies on _resolve_auto() which has a workaround re-routing to provider: custom.

Version

Hermes Agent v0.11.0 (2026.4.23)

Affected Files

• agent/auxiliary_client.py — resolve_provider_client() PROVIDER_REGISTRY branch (~line 1992)
• agent/title_generator.py — call_llm() call (~line 54)
• trajectory_compressor.py — call_llm() / async_call_llm() calls (~lines 610, 679)