Day 21/90: Practice — file-based todo app with JSON

90 Day Go Challenge: Zero to Production

Today I focused on using practice — file-based todo app with json to separate responsibilities cleanly enough that the system can keep changing. The strongest checkpoints were keep package boundaries, workflow ownership, and cross-component contracts explicit, separate domain workflow from transport and persistence so the system can evolve safely, and design the recovery and maintenance path at the same time as the happy path.

The mistake I wanted to avoid was spreading workflow rules across packages without a clear ownership model. The day felt better once the service boundary stayed visible and each component had one job.

The goal for tomorrow is simple: keep the rule clear enough that the next service still feels related to the same design idea. I also want to keep tracing one request path end to end because it exposes weak assumptions faster than a larger demo.