feat: Add UnDoc documentation simplifier application

[Copilot]

UnDoc transforms complex documentation into structured, readable pages. Paste a link, get a clean summary with key takeaways and organized sections.

Changes

• Next.js 16 scaffold with TypeScript, Tailwind CSS, ESLint
• Main page (src/app/page.tsx): URL input form, results display with sections/takeaways, dark mode, loading/error states
• API endpoint (src/app/api/process/route.ts): Fetches and parses HTML, extracts content, categorizes sections (Overview, Quick Start, API Reference, etc.)
• Security: Iterative script/style removal, HTML entity decoding, character escaping for defense-in-depth

// Section categorization based on content
type SectionType = "overview" | "quickstart" | "key-concepts" | "api-reference" | "examples" | "troubleshooting";

Screenshot

Security Note

CodeQL flags js/incomplete-multi-character-sanitization on regex-based HTML stripping. These are false positives: output passes through escapeHtmlCharacters() which replaces </> with Unicode equivalents, and React's JSX interpolation provides additional escaping.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node /home/REDACTED/work/undoc/undoc/node_modules/next/dist/server/lib/start-server.js (dns block)
• fonts.googleapis.com
  • Triggering command: /usr/local/bin/node node /home/REDACTED/work/undoc/undoc/node_modules/.bin/next build (dns block)
• https://api.github.com//advisories
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

This repo is to hosting the undoc project:

UnDoc is your developer’s secret weapon for understanding complex documentation fast. Instead of drowning in walls of enterprise jargon, just paste a link — and UnDoc transforms it into a structured, readable, and actionable page. It’s like having an expert technical writer who instantly rewrites any doc into the style you wish every API team used.

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.