Architecture
Choose a module boundary from change pressure
Group behavior that changes for the same reason and expose a narrow contract around it.
Engineering notes
A boundary is a decision, not a folder.
Notes on maintainable software, controlled releases, dependency evidence, and incident learning.
Read the boundary noteCurrent notes
Build and operate belong in the same sentence.
Delivery
Design rollback before the release artifact
Keep code, configuration, schema, and queued work compatible with a reversal.
Maintenance
Upgrade a dependency with evidence
Separate security urgency, API compatibility, runtime behavior, and deployment risk.
Library
More field notes
Reliability
Write an incident review that changes the system
Build a factual timeline, identify control gaps, and assign improvements with verifiable completion conditions.
Financial systems
Model a trading request as a state machine
Handle authentication, submission, acknowledgement, finality, retry, and reconciliation without turning an uncertain response into a duplicate action.
Health software
Draw telehealth workflow boundaries around patient state
Keep intake, eligibility, scheduling, clinical review, prescribing, fulfillment, and support from sharing an ambiguous status.
How this publication works
Architecture is evaluated by change, failure, and operating cost.
Examples name the boundary and the verification method instead of pretending every stack is equivalent.