Modular Design Decision Examples

Positive example — cohesive feature boundary

• Context: validation, state transition, and presentation for one capability change together.
• Mode: feature-oriented.
• Decision: keep them under one feature boundary with a focused external contract and hidden state details.
• Why it fits: ownership and coordinated change are visible while consumers know little.
• Rejected alternative: distribute each concern into repository-wide technical layers.

Negative example — service per noun

• Context: a small application has cohesive modules and one deployment lifecycle.
• Mode: service-oriented was proposed without operational evidence.
• Bad decision: create an independently communicating service for each domain noun.
• Why it fails: network and operational coupling replace simple in-process collaboration.
• Better decision: retain module boundaries until deployment, ownership, scaling, or isolation requires more.