sequenceDiagram
autonumber
participant ME as Me
participant GH as GitHub
participant GA as GitHub<br/>Actions
participant BT as Build<br/>tools
participant CF as Cloudflare Pages
participant VB as Visitor's<br/>browser
ME->>GH: Push a branch and open a pull request
Note over ME,GH: STOP. I review the diff. This is my approval gate.
ME->>GH: Click Merge into main
GH->>GA: The push to main starts deploy.yml
GA->>BT: Set up Node 22, then run npm ci and npm run build
BT->>GA: Vite bundles React into one HTML, JS and CSS file
alt The build fails
  Note over GA,CF: Nothing deploys. The old site stays live.
else The build succeeds
  GA->>GA: Stage the built app, static pages, images and lab notes
  GA->>CF: wrangler pages deploy
  CF->>VB: Serves the files at littledevlab.com
  Note over VB: The browser runs React, which draws the page.
end