Clear feedback: summaries were too short (~800 words). People expect Blinkist-level depth (2500+ words).

Spent 2 days debugging OpenAI JSON parsing, Prisma database persistence, and token limits. Then regenerated 450 books overnight with an improved AI prompt.

Result: 2-3x deeper summaries with detailed chapters, insights, and action items.

Demo (no signup): https://book-digest.com/books/6c8e5031-1c55-4bdd-8c11-ae5338f374c7?ts=1

Key lesson: Launch fast, but listen to feedback and iterate quickly. Users will tell you exactly what's missing.

Tech stack: Next.js, Postgres, OpenAI GPT-4o-mini, Stripe.

Happy to answer questions about the technical challenges (the database persistence bug was particularly tricky).