Build a Bitcoin-style meme blockchain with a browser node and Actions testnet

The poster, u/regressiveparty, wanted to learn how an on-chain market works without launching a coin. The brief to Claude Code was that every meme gets its own block. Working in the terminal, with the poster reviewing and testing each step, Claude Code wrote a small Bitcoin-like chain: double SHA-256 proof of work, difficulty retargeting every 10 blocks, halving rewards, secp256k1 wallets, and memes recorded as signed inscriptions of the image hash that can be listed and sold for a test token. It built the Python node first, then ported it line by line to JavaScript for the browser, with a test that checks both produce the same hashes. It also drove Playwright against the local page and judged its own screenshots, and proposed running the public testnet as a GitHub Actions job every 20 minutes that mines blocks and pushes the chain export to a branch the static site reads.

The project is live on GitHub Pages and open source under MIT after roughly three weeks. Two layout passes from the screenshot critique were thrown out. The browser miner first locked up the UI until mining moved to batched nonce loops, and the first difficulty retarget overshot badly on the fast browser chain until a clamp was added. The few comments were friendly but did not test the consensus rules.

The cross-language test was what kept later changes honest: every edit had to pass in both Python and JavaScript. The token has no value and is not for sale, so this is a learning project, not a production chain. Every tenth block hash is also anchored in Bitcoin through OpenTimestamps.