hermes - 💡(How to fix) Fix claude-opus-4-8: HTTP 400 "thinking.type.enabled" not supported (Anthropic changed thinking schema)

Selecting claude-opus-4-8 via hermes config set model.default claude-opus-4-8 (or -m claude-opus-4-8) results in every API call failing with HTTP 400 from Anthropic:

HTTP 400: "thinking.type.enabled" is not supported for this model. 
Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.

(request_id: req_011CbWh4hAKVy5zoGucgWhdP)

Root cause

Anthropic deprecated the thinking.type=enabled shape for Opus 4.8. The new schema is:

• thinking.type=adaptive
• output_config.effort (low|medium|high) to control depth

The Hermes Anthropic provider adapter (plugins/model-providers/anthropic and/or wherever thinking config is assembled in agent/) still emits the legacy thinking.type=enabled shape, so every 4.8 call 400s before any tokens are produced.

Reproduction

hermes config set model.default claude-opus-4-8
hermes chat "hello"
# Or any gateway session — instant 400 on first API call.

Expected

The provider adapter should detect the model family (claude-opus-4-8+) and emit thinking.type=adaptive + output_config.effort instead of thinking.type=enabled. The legacy shape stays for 4.7 and below.

Workaround

Pin to claude-opus-4-7 until the adapter is updated. The model registry in hermes_cli/models.py already lists claude-opus-4-8 and claude-opus-4.8 as known IDs, so users will hit this the moment they pick it.

Anthropic docs

https://docs.claude.com/en/docs/build-with-claude/extended-thinking (effort + adaptive type — the new control surface for Opus 4.8).

Environment

• hermes-agent: a22c25000 (NousResearch/hermes-agent main, 2026-05-29 sync)
• provider: anthropic (direct API, not bedrock/vertex)
• Confirmed via agent.log: agent.conversation_loop: API call failed (attempt 1/3) error_type=BadRequestError ... model=claude-opus-4-8 summary=HTTP 400: "thinking.type.enabled" is not supported for this model.

Severity

Blocking — claude-opus-4-8 is currently un-selectable for any Anthropic-direct user.