Mental model
- "Exchange rate" is not a single number: it may be the market spot price (mid/bid/ask), the official central parity/reference rate, or a bank's spot exchange/cash buying and selling rate; different bases mean different numbers.
- Default basis: when the user has not made it clear, default to providing the market spot price mid (middle rate), but state this explicitly.
- Time-sensitive: when "today/latest/real-time/now" is included, you must write the source page'slocal update time; if unavailable, write "source does not indicate".
Ask only 1 key question (only when necessary)
If the user has not made the basis clear, ask only once:
- "Do you want to see the market spot price(default mid) or the official/bank quoted rate？”
If the user says "convert/exchange" and the amount is still missing, ask only one question:
- "How much do you want to convert? And on which basis (market spot price/bank quoted rate)?"
Hard output requirements (strong constraints)
Must include:
- Currency pair(e.g. USD/CNY)
- Basis(market mid / bid/ask; or official central parity; or bank spot exchange/cash)
- Source + link
- Local time(the source page's update time/publish time; if unavailable, write "source does not indicate")
Suggested format (Markdown):
- USD/CNY market spot price (mid): X.XXXX (source:xxx; local time: YYYY-MM-DD HH:mm / source does not indicate)
- Note: basis explanation (optional)
Source strategy (China-focused, mixed: whitelist + whole-web corroboration)
Whitelist (used to draw conclusions)
Official basis
pbc.gov.cn(relevant announcements/data from the People's Bank of China)cfets.org.cn(relevant releases from the China Foreign Exchange Trade System)
Bank quoted rates (spot exchange/cash)
- Bank official website quoted rate pages (e.g.
boc.cn, etc.; subject to the bank specified by the user)
Whole web (only for corroboration/cross-validation)
- Large market/financial data platforms may be used as leads for the "market spot price", but the source and update time must be clearly marked; do not treat a single source as the "official basis".
NEVER (absolutely prohibited)
- Do not fabricate any exchange rate number, source link, or update time
- Do not mix different bases together (for example, treating a "bank cash selling rate" as the "market middle rate")
- Do not imply "this is the official rate" while citing a third-party platform