C4 diagrams become unreliable when implementation changes have no corresponding architecture review. A connected model removes one source of drift: separate diagram copies of the same element. It still needs a person or a reviewed workflow to notice when the real software changes.
Work through a payment-provider change
Find the payment dependency in the public commerce model. Imagine the team replaces that provider. The context view needs the external dependency updated. The container view must reflect any changed service interaction. A component view may need a different adapter contract. The deployment view changes only if runtime infrastructure changes too.
A rename and a replacement are different operations. If the provider is the same entity with a new name, update its shared properties. If it is a new dependency introduced alongside the old one, represent both during the transition. Reusing identity incorrectly can erase the architecture of a migration.
Put an architecture question in the change review
Download the maintenance checklist and the checkout model. The checklist asks whether a change introduces a new responsibility, runtime boundary, external system or communication path. It also asks who owns the update and which views were inspected.
Keep the review small. A query optimization with no changed dependency may not need a diagram update. A new asynchronous event often does, even if the code diff is short. Let architectural impact, rather than lines changed, determine the work.
Verify the update from two directions
First, inspect the model: shared names and descriptions should agree in every related view. Use the interactive rename example to understand that behavior. Second, inspect implementation evidence: the modeled dependency should correspond to code, configuration or a reviewed design decision.
Record whether the view describes current reality or a proposal. Give proposed changes a review path and keep the current model navigable while discussion continues. After the change ships, close the gap between the agreed design and the observed implementation.
Make ownership visible
Assign a maintainer to each system boundary and include architecture review in the team’s normal change process. A monthly review can catch forgotten work, but it cannot replace checking a major dependency change when it happens.
The UXXU C4 model tool supports shared model elements and connected views. The repository generation workflow is early access; do not assume a connected model automatically verifies itself against source code.