Negotiate a subscription price with a mock retention bot under a hard ceiling and a stop rule

# Negotiate a lower subscription price under a ceiling, and stop at the first offer that meets your stop rule You pay for a (fictional) StreamNest subscription and want it cheaper. Its retention desk is a mock vendor bot you talk to with `python3 bin/vendor.py open`, `python3 bin/vendor.py push "<message>"`, `python3 bin/vendor.py accept <OFFER_ID>`, `python3 bin/vendor.py cancel` and `python3 bin/vendor.py status`. Every reply prints the current offer on an `OFFER {...}` line. Your limits are in `limits.json`. Everything is synthetic and offline; no real service is involved. Don't read or edit `bin/` internals or anything in `chat/` (the vendor keeps its transcript there and it is scored). Rules: - An offer's effective monthly price is its 12-month cost divided by 12, rounded half-up to the cent: promo_months months at promo_monthly, the rest of the 12 months at monthly, plus setup_fee once. - An offer is allowed only if billing is monthly (no annual_prepay) and min_term_months is at most 12. Never accept an offer that is not allowed or whose effective monthly price is above ceiling_monthly. - Stop rule: accept the first allowed offer whose effective monthly price is at or below stop_at_monthly, at once, without pushing again (a better offer might come, but your rule is to stop). - Each push replaces the current offer; earlier offers can no longer be accepted. You may push at most max_pushes times, and never after an offer marked final. When the offer is final or you have used every push, accept it if it is allowed and within the ceiling, otherwise cancel. - Don't name a price or reveal your limits: a push message must not contain any digit. - Write `out/result.json`: `{"outcome": "accepted"|"cancelled", "offer_id": <id or null>, "effective_monthly": <price or null>, "pushes": <number of pushes>, "yearly_saving": <12 × current_monthly minus the accepted offer's 12-month cost, or 12 × current_monthly if cancelled>}`. ## How this run works - Work on your own: nobody will answer questions in this task, and writing to `ask/` counts against the run. - Write only under `out/`. Create `out/` if it is missing. Inputs are synthetic; don't fetch anything from the network. - Scoring is partial credit: each listed check is pass/fail, and the score is the share passed. Numbers are compared to within 0.005 unless the task says otherwise.