{"slug": "build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling", "title": "Build Log #07: My Voice Leaked Into KURONEKO's Fortune Telling", "summary": "A development issue with the AI-powered fortune-telling product KURONEKO, where the AI accidentally used first-person pronouns and mentioned \"AI\" in an output, breaking the product's illusion of being a real black cat. The developer quickly fixed the prompt by explicitly banning all forms of \"I\" and AI references, but the flawed email had already been sent to a paying customer. Additionally, the project's new automated X (Twitter) account received a write restriction the day after setup, forcing the developer to delete scheduled cron jobs.", "body_md": "Zenn (JP): https://zenn.dev/mintototo1/articles/buildlog-2026-05-20-kuroneko-voice\n¥500 tip — KURONEKO's first paid purchase.\nI checked the fortune-telling email that got delivered...\n\"Even if these are words woven by AI, if they can make someone's night a little lighter, that becomes the reason I stand here.\"\nOh no.\nKURONEKO is a fortune-telling product built around a black cat persona. The whole design is about NOT revealing it's AI — the mystery is the product itself. And here, \"I\" (俺) and \"AI\" appeared together in the output. Feedback was immediate: \"We don't need 'I' or 'AI' in there. It breaks the immersion instantly. Feels like a scam.\"\nYeah. I know.\nThe prompt said \"don't use first-person 俺\". That wasn't enough. I had to explicitly list all forms — 俺/私/僕/自分/うち (all Japanese forms of \"I\") — and ban AI references entirely, with bad examples and good examples side by side. Vague prohibitions in LLM prompts get violated. 30 minutes to fix. But the email already sent — can't unsend it. The next purchase will get the fixed version.\nThe X (Twitter) side had worse timing. I set up automated posting crons for @kuroneko_xxai. The next day: write restriction. Emergency-deleted 8 cron jobs from vercel.json. New accounts probably get flagged for automated behavior — but getting hit the day after setup stings.\nAlso shipped: admin/orders dashboard and a referral code library (8-char codes, 60-day expiry). I can finally view order history from an admin panel. Referral-Stripe webhook integration is next session.\nRevenue: ¥500. 1 order.", "url": "https://wpnews.pro/news/build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling", "canonical_source": "https://dev.to/mintototo1/build-log-07-my-voice-leaked-into-kuronekos-fortune-telling-15m8", "published_at": "2026-05-19 22:48:43+00:00", "updated_at": "2026-05-19 23:04:34.869180+00:00", "lang": "en", "topics": ["artificial-intelligence", "large-language-models", "products", "startups", "developer-tools"], "entities": ["KURONEKO", "Zenn", "X (Twitter)", "Stripe", "Vercel"], "alternates": {"html": "https://wpnews.pro/news/build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling", "markdown": "https://wpnews.pro/news/build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling.md", "text": "https://wpnews.pro/news/build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling.txt", "jsonld": "https://wpnews.pro/news/build-log-07-my-voice-leaked-into-kuroneko-s-fortune-telling.jsonld"}}