Build an AI Writing Assistant with Claude Code

Build an AI Writing Assistant web app. People search for "ai writing assistant" about 24,000 times a month, plus related searches like "grammar checker ai", "writing improvement tool", "ai proofreader". The goal is a tool that ranks for those searches and makes money.

What it should do:
Build an AI writing assistant web app. Create a clean writing interface with a large text editor that shows real-time suggestions. Add sidebar panels for grammar corrections, style improvements, and readability scores. Highlight errors in different colors (red for grammar, blue for style, yellow for clarity). Include writing goals selector (academic, business, creative) and tone adjustment (formal, casual, confident). Show writing statistics and improvement suggestions. Use a clean, distraction-free design similar to modern writing apps. Focus on the text editor and real-time feedback first.

How to build it:
1. Read this folder first. If it is empty, set up Next.js (App Router, TypeScript, Tailwind). Write a short PLAN.md with the pages, components, any library or API you need, and what you are leaving for later. Then build.
2. Put the tool itself on the homepage so a visitor can use it within seconds, with no sign-up. Do the processing in the browser where you can, so it is fast and cheap to run. Look at how Grammarly, ProWritingAid, Hemingway Editor do it and make ours simpler and faster.
3. Make it rank. Use "ai writing assistant" in the title tag, H1 and meta description. Under the tool, add a short how-to and an FAQ with FAQPage schema, and add a sitemap and robots.txt. Scaffold these programmatic pages from one template and a data file: /ai-writing-assistant-for-[profession], /writing-help-[document-type], /grammar-checker-[language].
4. Monetisation: Freemium: Basic grammar check, $12/mo advanced AI + plagiarism. Add a pricing page and the free usage limit, and leave Stripe checkout as a clearly marked stub with the environment variables it needs.
5. Run it locally and test the main flow end to end, including edge cases like empty input and very large files. Fix what breaks, then finish with a summary of what works, what is stubbed and how to deploy it to Vercel.

Paste it into Claude Code in an empty folder. It plans first, so read PLAN.md and steer before it starts building.