Hermes 4 is a hybrid-reasoning model trained on <think> tags; without asking
for thinking we pay flagship $/tok but get non-reasoning quality. This adds a
dedicated HermesA2AExecutor that dispatches to any OpenAI-compat endpoint
(OpenRouter, Nous Portal) and enables native reasoning for Hermes 4 models.
Key decisions:
- ProviderConfig + _reasoning_supported() detect Hermes 4 by model slug
substring ("hermes-4", "hermes4") — case-insensitive, no config needed
- extra_body={"reasoning": {"enabled": True}} sent only to Hermes 4 entries;
Hermes 3 path unchanged (no extra_body, no regressions)
- choices[0].message.reasoning + reasoning_details extracted and written to
an OTEL span (hermes.reasoning) — deliberately NOT echoed in the A2A reply
so the reasoning trace never contaminates the agent's next-turn context
- API key / base URL default to OPENAI_API_KEY / OPENAI_BASE_URL env vars
with openrouter.ai/api/v1 as the fallback endpoint
- _client injection parameter for unit tests (no live API calls needed)
- Error sanitization: only exception class name surfaces to user (mirrors
sanitize_agent_error() convention from cli_executor.py)
Test coverage: 35 tests, 100% coverage on all new code paths including:
- _reasoning_supported() — Hermes 4/3/unknown/empty/uppercase
- ProviderConfig — field assignment and capability flags
- extra_body presence for Hermes 4, absence for Hermes 3
- reasoning not in A2A reply; _log_reasoning called when trace present
- reasoning_details forwarded; span attributes set correctly
- Telemetry failure swallowed (never blocks response)
- API error → sanitized class-name-only reply
- cancel() → TaskStatusUpdateEvent(state=canceled)
Full suite: 990 passed, 0 failed (no regressions).
Resolves#496
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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