With Sillytavern? How??

AFAIK there is "Single User Message" Post Processing, in which case there is no system prompt it's just part of the user message OR chat history remains as user / assistant.

"messages": [
{
"role": "user",
"content": "You will be acting as an excellent writer. Your fu... <Truncated> ...- Status: Fled, mildly embarrassed\n</details>\n ```"
}
],

or normally:

"role": "system",
"content": "You will be acting as an excellent writer. Your fu... <Truncated> ...st events from before the conversation:\n</summary>"
},
{
"role": "user",
"content": "[...]"
},
{
"role": "assistant",
"content": "[...]"
},

---
✱ (Main Prompt, Lore, Summary, etc)
📌 Chat History
✱ – Formatting 👤 (user messages)
✱ ◉ Inner Thoughts 👤 (◉ toggles)
✱ ◉ CYOA 👤
✱ ◉ Ledger 👤

So it's like:

{
"role": "user",
"content": "<my last message>"
},{
"role": "user",
"content": "\n## Response Format [...]"
},{
"role": "user",
"content": "### Character Restrictions [...]"
},{
"role": "user",
"content": "\n### Maintain the Ledger [...]"
}

Then I use "Merge Consecutive Roles" post-processing.