Heptabase?

Build a focused replacement for Heptabase for a single user organizing a private knowledge base, based on this public product description: “Heptabase — Heptabase is an intelligent, visual knowledge base built for students, researchers, and lifelong learners.” Do not copy the original brand, proprietary assets, name, logo, UI, or copy; create an original visual system.

Core workflow
- Recreate only the narrow primary workflow described above, with create, edit, link, tag, search, and export notes; keep the underlying data portable and show where generated suggestions came from; support offline or failure-tolerant editing; include backups, deletion, and privacy controls.
- Keep the product name and source description in a research note in the README, and turn every uncertain behavior into an explicit assumption or user setting rather than inventing a feature.
- Use a small React/TypeScript app with a portable JSON or SQLite data model, clear loading/empty/error states, and adapters around external services. Seed realistic demo data so the complete workflow works without paid credentials.

Scope boundaries
- Out of scope for v1: team collaboration parity; plugin marketplaces; a proprietary sync or AI-training data claim. Do not promise feature parity, proprietary data, or enterprise reliability.

Include a README with setup, environment variables, data model, implementation decisions, privacy behavior, testing instructions, and important limitations.