chenchenandClaude Opus 4.8
1d81002c2d
Preset templates carry a Claude-style frontmatter model (opus/sonnet) which is NOT a model on the HM gateway. Passing it as MODEL_NAME would make the agent's model calls fail. Now MODEL_NAME defaults to the gateway model gpt-5.4 (env AGENT_RUNTIME_DEFAULT_MODEL); a non-Claude-tier template model is honored. Tests + AM contract doc updated. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>