Starting Small: How We Bootstrapped the Lockline Mock API in One Commit

Introducing the Lockline Mock API: Purpose Over Perfection

When you're building something fast—like Lockline AI in August 2025—you don’t have the luxury of waiting for backend completeness before frontend work kicks off. That’s why, in a single early commit, we spun up the Lockline Mock API: a minimal, self-contained service designed to mimic the real API’s behavior, structure, and endpoints.

The goal wasn’t to simulate every edge case or replicate business logic. It was to give frontend developers something real to call—status codes, JSON payloads, consistent routes—so they could build, test, and iterate without blocking on backend implementation. This wasn’t a placeholder. It was a signal: we’re building in parallel, and we’re building together.

The mock API mirrors the expected contract of the future production service. That means the same route paths, the same field names, and the same response shapes. Even errors follow a predictable format. By aligning early, we avoid the "oh wait, that field is actually called userId not user_id" chaos that derails sprints.

Design Decisions in the Initial Commit: Simplicity with Foresight

The first commit of the Lockline Mock API wasn’t flashy. No CI/CD, no auth, no database sync. But it was intentional.

We chose Python—not because it’s the sexiest backend language, but because it’s fast to prototype in, widely understood, and fits cleanly into our broader tooling. Flask was the natural pick: lightweight, explicit, and perfect for a service whose job is to return JSON and stay out of the way.

Here’s what that first commit included:

• A clean src/ directory with app.py and routes/ separation
• A single endpoint stub returning a 200 with a realistic user profile payload
• A requirements.txt with Flask and nothing else
• A Dockerfile to ensure environment parity from day one

That last point is critical. We knew early that Lockline would containerize its services, so we baked Docker in immediately. No "we’ll add it later"—because later never comes. The mock API runs in the same kind of container the real backend will, which means no "works on my machine" surprises when we swap in real logic.

We also structured the routes to mirror the anticipated API surface. Instead of /test or /mock-user, we went straight for /api/v1/users/me. That consistency means frontend code written against the mock will work unchanged when we plug in the real backend.

And yes, we used SQLite in early companion work—not because we plan to run the production API on it, but because it lets us simulate persistence quickly. The mock doesn’t need scalability; it needs believability. When the frontend sees a 404 Not Found because a mock user ID doesn’t exist in the SQLite file, that’s a win. It means we’re testing real flows, not just happy paths.

How This Mock Enables Parallel Workstreams and Reduces Integration Risk

The real value of the Lockline Mock API isn’t in what it does—it’s in what it unlocks.

Frontend developers can now build user dashboards, profile forms, and error states against an API that behaves like the real thing. They don’t need to fake fetch calls with setTimeout hacks or maintain brittle JSON files in their frontend repo. They call a real server, get real responses, and debug real network issues.

Meanwhile, backend engineers can focus on core logic—authentication, data validation, service orchestration—without fielding "what will the response look like?" questions every other hour. The mock serves as living documentation.

But the biggest win? Confidence at integration time.

When we eventually replace the mock with the real Flask service (backed by proper auth, real databases, and AI-driven logic), the frontend shouldn’t need major changes. The contract was respected from commit one. That means integration isn’t a big-bang rewrite—it’s a smooth handoff. We’re not merging two separate worlds; we’re upgrading one.

This approach also sets a cultural tone: we value alignment, clarity, and working software over speculation. By shipping a mock API early, we’re saying, "We don’t need to know everything to start building. We just need to agree on the interface."

And that, more than any line of code, is what lets us move fast without breaking things.