hermes - 💡(How to fix) Fix Prompt caching: add DeepSeek models to cache_control whitelist for OpenCode Go [1 pull requests]

Feature Description

Extend _anthropic_prompt_cache_policy() in run_agent.py to enable Anthropic-style cache_control markers for DeepSeek models on opencode-go / opencode-zen providers — same as currently done for Qwen/Alibaba models.

Motivation

Right now prompt_caching is configured (cache_ttl: 5m) but does not work for deepseek-v4-pro on opencode-go. The model switcher shows cache read $0.01/M pricing, confirming the gateway supports caching — but Hermes never sends cache_control markers because the policy whitelist only includes:

• Claude (Anthropic/OpenRouter)
• MiniMax (Anthropic wire)
• Qwen/Alibaba (OpenCode Go)

DeepSeek on OpenCode Go falls through to return False, False.

Impact

Without cache markers, every turn re-bills the full prompt. With 300K+ token conversations, this is a ~75% cost increase vs cached reads.

Where

run_agent.py:3454-3462 — the model_is_qwen branch. The same provider_is_alibaba_family set already includes opencode-go:

provider_is_alibaba_family = provider_lower in {
    "opencode", "opencode-zen", "opencode-go", "alibaba",
}

Proposed Solution

Add a model_is_deepseek check after the Qwen block, reusing the same envelope layout:

# DeepSeek on OpenCode (Zen/Go): also supports cache_control
model_is_deepseek = "deepseek" in model_lower
if provider_is_alibaba_family and model_is_deepseek:
    return True, False

Or consolidate into the existing branch:

model_is_alibaba_family = model_is_qwen or ("deepseek" in model_lower)

Evidence

• OpenCode Go is a gateway that implements cache_control at its own level (not model-specific) — the same mechanism works for Qwen
• Model switcher reports $0.01/M cache read for deepseek-v4-pro on OpenCode Go, indicating gateway-side cache support
• The chat_completions wire format is used for both Qwen and DeepSeek on OpenCode Go — no api_mode difference

Risk

Zero. If the gateway doesn't honor cache for a specific model, the markers are silently ignored. Nothing breaks.