Code RoomNotification fan-out service
HardPrep Room Coding #4266

Notification fan-out service

Vibe & agenticDistributed systemsSenior–Staff~28 min

Greenfield notification fan-out service in Go: an event (e.g. 'order shipped') fans out to a user's channels — email, SMS, push, in-app — each with its own provider and per-channel user preferences and quiet hours. You're directing an AI agent. Lay out the build plan: how you model the fan-out, the delivery guarantees per channel, retry/dedup, and acceptance criteria. What does a careless 'send notifications to all the user's channels' prompt miss?

Implement
plan_channel_sends(tasks: list[str], enabled_channels: list[str], quiet_start_hour: int, quiet_end_hour: int) → list[str]
Examples
in[["e1|u1|email|23","e1|u1|sms|23","e1|u1|push|10"],["email","sms","push"],22,7]out["e1:u1:email","e1:u1:push"]
in[["e2|u2|sms|9","e2|u2|sms|9","e2|u2|in_app|9"],["sms"],22,7]out["e2:u2:sms"]
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.

0:00 of about 28 min

Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.