200loc

200loc is a single-page walkthrough of the tiny microgpt.py program shipped with this repo.

The app shows one GPT inference step at a time in the browser, with the Python source, explanation, and model view kept in sync.

Run

Requirements:

• Node 20+
• Python 3

npm install
npm run dev

For a production preview:

npm run build
npm run preview

Model Bundle

Rebuild the exported model bundle and reference trace fixture with:

npm run generate:model

This updates public/assets/microgpt-model.json and src/test/fixtures/expected-step-em.json. If input.txt is missing, the script fetches the names corpus snapshot from Andrej Karpathy's makemore repository.

Verify

npm test
npm run test:coverage
npm run lint
npm run build
npm run test:e2e

Use npm run test:e2e:headed for a headed browser pass.

Credits

200loc pays respect to Andrej Karpathy for microgpt and to Brendan Bycroft for LLM Visualization, which inspired the model viewer.