A user reached out to us this week. Their generated newsletter contained the word delve . Twice. This immediaimmediately shot alarm spikes through the team because that word has been on our banned list since version one. The system prompt in lib/prompts/anti-ai.ts tells the model never to use it. Gemini 3 used it anyway, and this was a big issue. This is the documentation of everything we did: the architecture we shipped to fix it, and the latency numbers from the first 48 hours in production. If you ship LLM output to end users, you probably need this layer too. Does Better Prompting Make AI Output Better? Short answer: No. Prompts alone stop AI slop in roughly 80% of generations. The remaining 20% is where production reputation lives. Our fix for this is a code-side validator that scans every draft against a structured banned lexicon, runs four detection passes (vocabulary, phrases, openers, regex structures), and triggers one bounded repaired retry on slop.…