What Is the Rule of the Bolt in Modular Architecture

The Rule of the Bolt says modules should connect through immutable identifiers only. Pass a user ID, not a user object. As long as the ID format stays stable, teams can rewrite, replace, or redeploy the module behind it without anyone else noticing. A shared database is the opposite of this. It's a weld, not a connector.

Architectural Embezzlement happens when teams take shortcuts to meet deadlines. They use a foreign endpoint for convenience instead of building a proper interface. It's like printing money to pay bills today. Every shortcut like this devalues future engineering hours. By the time the cost shows up, the people who made the call are usually gone.