Detection pattern library
off_platform_chat
Asks to move chat to WhatsApp, Telegram, Signal, or SMS.
high_risk_payment
Mentions Western Union, MoneyGram, gift cards, or crypto.
fake_escrow
References fake 'eBay Motors' or 'Carfax escrow' services.
absentee_seller
Seller is overseas, deployed, or 'shipping' the car sight unseen.
pressure
High-urgency phrases: 'must sell today', 'deposit holds vehicle'.
phone_in_message
Phone numbers or emails embedded in chat — typical handoff signal.
wire_transfer
Insists on bank wire to a new account, often international.
vin_mismatch
Quoted VIN doesn't match the listing.
Risk score & what happens
0–9 · Clean
Message delivered. No action.
10–29 · Watchlist
Message delivered. Buyer sees an inline warning: 'CivicCars detected unusual content — read carefully.'
30–69 · Flagged
Message delivered with a hard banner. Conversation is sent to the moderation queue and reviewed within 4 hours.
70+ · Auto-quarantined
Message held for review. Sender gets a generic 'we’ll be in touch' notice. T&S admin must release or block.
Why no machine-learning model?
For an MVP, deterministic regex + lexicon rules outperform an LLM on this task: the patterns are well-known, the cost of a false negative is real money, and we can audit exactly why a message fired. As volume grows we plan to layer a small classifier on top to catch novel scripts.
Reporting fraud directly
See something the AI missed? Hit the “Report” button on any conversation or listing. Reports go straight to our Trust & Safety queue and are triaged within 4 hours. For active scams in progress, we coordinate with ScamWatch and the AFP.