Checkpoint
One last thing before we move on. Same surface as a write step — but the lesson doesn't complete until this passes.
Partition the deployment. Each item belongs in exactly one home: "image" (frozen runtime), "runtime env" (differs per environment), "secret manager" (credentials, injected), or "registry at startup" (the model — so deploying a new model never rebuilds the runtime). Print each as f"{name:<25} -> {home}" in the given order, then a sorted summary dict of counts. This partition IS the lesson: what's frozen, what varies, what's secret, what's versioned separately.