Why does an app that passes every test still break with real users?
- Module
- 01/05
- To read
- ~5 min
A pipeline of five chained LLM calls passed its tests, then Step 3 started failing on a small share of real inputs. What do you think happened next?
In the module you make your guess first, then read what happened and why.
State Isolation
Deterministic Checkpoints
Failure Containment
Transition Contracts
A map of your app’s steps and what each one is allowed to change
A spec for your own app, as a text file you download. The module also gives you the prompt for Claude Code, Codex or Antigravity, a checklist to check what it built, and recommended skills.
- Stateless services
- Dead-letter queues