The Dependency Leak | Article 1: The Interface Agreement
I was wrong. That isn’t collaboration; it is Tight Coupling. It is the human equivalent of two software modules that can’t compile unless they are both 100% complete.
The Logic of the Block
In software, we solve this with an Interface—a contract that defines what a service will do without caring how it does it. In an organization, the Interface Agreement is the human contract that allows two teams to run in parallel instead of in series.
- The Synchronous Stall: When my team waits for another team to “finish their part” before we start ours, we are running a Serial Process. We’ve turned our 10-person team into a single-threaded operation that is blocked on an external I/O call.
- The Integration Crash: When two teams build for a month without a shared contract, the “Merge” is always a disaster. This is a Schema Mismatch. We spent four weeks building a Ferrari, only to find out the other team built a gas tank that only fits a tractor.
- The Feedback Vacuum: Without an interface, we can’t test our logic until the very end. We are flying blind, hoping the external team’s output matches our internal assumptions.
Why the “System” is Idling
I see teams that are “Ready to Test” but “Waiting for Service.” This is Development Latency. We pay for high-speed engineers, but they are spending 40% of their sprint “mocking” data in their heads because they don’t have a stable contract to build against.
The team isn’t slow; they are Out of Sync. They are trying to build a roof before the other team has finished the walls.
The Patch: Build Against the Mock
To fix this, I have to change the “Dependency Logic.” We move from “Wait for Completion” to “Code to the Interface.”
- The “Contract First” Meeting: Before a single line of feature code is written, the two teams must agree on the API Specification. We define the inputs, outputs, and error codes. This is our Header File.
- The Mock Server: Once the contract is signed, my team builds a “Mock Server”—a dummy version of the other team’s service that returns hardcoded data. This allows us to build 100% of our logic without the external team ever being “online.”
- The Virtual Integration: Because we are building against the agreed interface, the final integration becomes a No-Op. We just swap the “Mock” URL for the “Production” URL. If the contract was solid, the system compiles and runs instantly.
Submit a Bug Report
How do you know if you have an Interface Leak? Look at your “Testing” phase.
If your engineers can’t run their code on their local machines because “the other team’s API isn’t ready yet,” your system is tightly coupled. You are running a Blocking Call that is costing you thousands of dollars in idling talent.
Stop waiting for the “Finish Line.” Agree on the “Interface” and start running in parallel. Velocity isn’t about how fast you code; it’s about how many teams can move without needing to talk to each other.