The four worlds

Week nine ends with a question from Molly, of all people, who has never asked a technical question in her life and is about to land dead centre on one of the deepest ideas in the field without noticing anything unusual has occurred. Case, who has seen the smaller race advertised in the Traversal app for weeks, mentions it on the Sunday call. Molly asks: is the little one a real race, or practice?

Both. That answer needs the ladder.

The ladder of worlds

Traversal does not run one copy of itself. It runs several, each a complete world with its own machines and data, and each such world is an environmentConcept · lights on your mapenvironmentA separate, complete copy of the system: its own machines, data and permitted users. Teams run several, at rising levels of realism and stakes.. They climb in stakes. At the bottom, the development environmentConcept · lights on your mapdevelopment environmentThe engineer’s own machine: a toy database, a dozen fake records, nothing at stake. The only rung safe to wreck. is Finn’s laptop, a toy Traversal with a dozen fake runners, the only world safe to break on purpose. Above it, the testing environmentConcept · lights on your maptesting environmentThe world where automated checks run, built fresh and torn down per change, with bots for users. The rung no human lives in. is built by bots, for bots, fresh for every change and gone by lunch. Above that, the staging environmentConcept · lights on your mapstaging environmentA deliberate replica of production for final rehearsal: production-shaped but fake or scrubbed data, and only the team inside. The last rung before stakes turn real. is the dress-rehearsal world, shaped exactly like the real thing, holding nothing real. And at the top, the production environmentConcept · lights on your mapproduction environmentThe real thing: real users, real data, real money. Prod, in conversation, and the word engineers say with a small change of voice., prod in every sentence engineers say about it, is the world Case and Molly actually live in. Same codebase, four worlds. What changes on each rung is only what is at stake.

The race that is a rung

Now Molly’s question answers itself, and the sentence is worth saying exactly the way Traversal’s engineers say it: Maple Grove is to Harborview what staging is to production. Four thousand real runners, real weather, real stakes, and all of them smaller. It is the rehearsal with consequences, the top of the practice ladder, the last place a mistake is survivable at a survivable size.

Which is precisely why everything this act has built, the cheer feature, the migration, Sam’s sizing arithmetic, is aimed at week ten. The new things debut where the stakes are real and small. Before the debut, the bots get their say.