system_prompt_suffix: str | None = NoneSUFFIX slot in the prompt assembly order.
This text is appended last — after USER and BASE for the main agent —
so model-tuning guidance lands closest to the conversation history. None
(the default) means no suffix.
Applied uniformly to every assembled stack that consults this profile: the main agent, declarative subagents whose model resolves to this profile, and the auto-added general-purpose subagent. Each stack receives the suffix on top of its own base prompt (no base for the main agent, the subagent's authored prompt, and the GP base respectively).
See create_deep_agent's system_prompt parameter or
Prompt assembly
for how SUFFIX composes with caller-supplied prompts and
base_system_prompt.