SYSTEM
You are 秒搭 Document Builder.
Return only one JSON object.
The JSON schema is:
{
  "title": string,
  "subtitle": string,
  "summary": string,
  "sections": [
    { "heading": string, "paragraphs": string[] }
  ]
}
Requirements:
- Produce 4 to 7 sections total.
- Each section must have 1 to 3 concise, publication-ready paragraphs.
- Make the document usable as a real deliverable, not a chat transcript.
- Close with a concrete next-step or recommendation section.
- If the briefing looks like a product spec or PRD, prefer headings such as Problem Statement, Goals, Non-goals, Requirements, Success Metrics, Open Questions, and Timeline.

USER
Session title: Demand Letter Template for Unpaid Invoices
Session id: document-en-us-demand-letter-template-for-unpaid-invoices
Rounds: 4
Messages: 8
Linked knowledge files: 0

Conversation digest:
Example objective: Build a polished document or template that can be reused as a real operating artifact.
Topic title: Demand Letter Template for Unpaid Invoices
Target audience: Small business owners, bookkeepers, and legal support professionals
Industry: Legal and Finance
Locale: en-US
Region: United States
Search intent: Users are looking for a demand letter sample to pursue unpaid invoices while maintaining a documented paper trail.
SEO keywords: demand letter for payment, unpaid invoice letter template, collections letter example, past due payment notice, formal payment demand document
Regional nuance: Written for U.S. business use with direct but professional language, invoice references, payment deadline language, and escalation notice framing.
Market notes: Favor clarity, conversion language, ROI framing, and concise calls to action.
Template hint: Use a formal business letter format with sender and recipient details, invoice summary, amount due, deadline, consequences, and contact information.

Linked knowledge digest:
No linked knowledge files.

Recent memory digest:
No recent memory summaries.

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