<proto-sudoku>
A Stencil and Tailwind component in its own Shadow DOM: the board, the digit buttons, New Puzzle, Check ? and the status line. platform="cloudflare" points it at the relative path /api.
L1 · CLIENT
Web Component — proto-sudoku-wc on npm
store
Holds the 81 cells, the picked cell and its peers (row, column, box), and the legal digits for it. Decodes ref once, so Check compares every entry locally — no second request.
localStorage
The puzzle, the picked cell, and the entries that passed a check. Unchecked entries stay in memory only, so a reload drops them.
The page loads the component from jsDelivr at an exact version (proto-sudoku-wc@0.1.340). Stencil lazy-loads hashed chunks through the same URL, so @latest could mix files from two releases; .wc-loader bumps the pin instead.
GET /api/puzzle
L2 · EDGE
Cloudflare Workers — wrangler.jsonc
Static assets
Any path that matches a file: the game page, /about, this page, /llms.txt, images and favicons. Most requests never run the Rust code.
Worker
Everything without a matching file. A small JS shim from worker-build loads the wasm module and hands it each request.
Local
Runs worker-build --release, then the same Worker in a local workerd. No other services to start.
routes
L3 · API
Router — src/lib.rs
Game
One route does the work
GET /api/puzzleOPTIONS *
Leftover demo — returns {"hello": name}
GET /:nameGET /api/:name
Static
Pages
//about/architecture
Discovery — for LLMs & agents, not the app itself
/llms.txt
Every Worker response — 404s and OPTIONS preflights included — gets permissive CORS headers in one place after routing (Access-Control-Allow-Origin: *, methods GET,OPTIONS), so any page can call the API. There is no key and no rate limit.
calls
L4 · CORE
Rust → WebAssembly — workers-rs 0.8 & the sudoku crate
Handlers
fetch()— the router, then CORSpuzzle()— builds the JSONgreet()— the demo routewith_cors()
Puzzle — plain Rust, no Worker types
new_puzzle()Sudoku::generate()— unique, minimal, symmetricsolution()— solved straight awaybase64— encodes the answer
Build
worker-build --releaseopt-level = "s"— plus LTOgetrandom— js feature, crypto.getRandomValues
Bench — benches/puzzle.rs
cargo bench— Criterion, native- generate ~80 µs · solve ~2 µs
- wasm runs ~1.5–3× slower
- free plan allows 10 ms CPU
Because new_puzzle() has no Worker types, the same function is benchmarked natively. The response carries no timings: Workers freezes the clock while code runs, so a timer would always read 0.
JSON response
L5 · DATA
No server storage — the puzzle lives in the browser
/api/puzzle — response
puzzle81 chars · dots blank
refbase64 solution
metricsblanks + clues
tag"cloudflare"
→
saved by
the component
the component
localStorage — proto-sudoku::
datathe response
inputschecked entries
pickselected cell
The solution ships with the puzzle on purpose: it's a casual game, and checking in the browser beats a round trip. Base64 hides the answer from a glance; it doesn't protect it.
deploy
L6 · SHIP
Deploys & hosting — scripts/deploy.sh
Local deploys
Workers Builds had no Rust cache and took 6–7 minutes a push. The script builds locally, ships only a clean main that matches the remote, and tags the deploy with the commit.
Daily updates
cargo update, and only if Cargo.lock changed: check the wasm and native builds, then commit and push. Major-version bumps are reported, not applied. Deploys stay a separate, manual step.
Two hostnames
sudoku.eswat2.app is a Workers Custom Domain, so Cloudflare manages its DNS and certificate. rust-sudoku-api.eswat2.workers.dev stays on too.
Wasm, not Containers
Containers could have run the old Actix binary unchanged, but need the paid plan. Before the port it lived on Heroku until the free tier ended in 2022. A serverless copy still runs on Vercel.