Model + System Prompt
Domain: Models & Providers
Motivation
System-prompt sizing is how the assembled system prompt fits a model’s context and how the provider reads it. The DeepSeek adapter reports systemPromptUpdate: 'in-history' when a model reads the latest system message at any position as the effective prompt; otherwise only a leading system message is read. The agent loop appends a changed prompt after cached history instead of rewriting the leading system message.
Concrete Example
The default deepseek-flash entry declares in-history, so a prompt change mid-conversation is appended after the cached history, keeping the earlier prefix reusable.
Analogy
Whether the instructions are pinned to the top of the desk or can be restated at the bottom of the page.