Business Logic Is the Real Product (So I Built logicrepo)

alexdrimbe — Sat, 03 Jan 2026 22:18:37 +0000

If you’ve ever shipped a bug caused by a business rule nobody could explain, this post is for you.

A pricing rule breaks in production.

Customers are affected.

Everyone is scrambling.

Then comes the worst question:

Who changed this… and why?

Sometimes the logic is buried in a service layer.

Sometimes it’s split across validators and feature flags.

Sometimes it lives in a Confluence doc nobody trusts anymore.

This isn’t a tooling problem.

It’s a structure problem.

Business Logic Has No First-Class Home

In most codebases, business logic is:

Mixed with framework and infrastructure code
Hard to review in isolation
Poorly tested (or tested indirectly)
Documented separately — if at all

When reviewing a PR, you often see how something was implemented, but not what rule actually changed.

That’s dangerous, because business logic is the real product.

Why This Matters More in the Age of AI

AI can generate controllers, services, and validators.

What it can’t generate is domain intent.

Business logic encodes:

Pricing decisions
Eligibility criteria
Risk constraints
Product strategy

As code generation becomes cheaper, clarity of intent becomes more valuable — not less.

The Idea: Separate Intent From Implementation

I wanted business rules to be:

Explicit
Versioned
Tested
Reviewable
Framework-agnostic

That led to logicrepo.

What Is `logicrepo`?

logicrepo is a simple CLI that lets you:

Define business rules in YAML
Write tests for those rules
Validate them in CI

No runtime magic.

No framework lock-in.

Just rules, clearly expressed.

Example (simplified)

rules:
  discount:
    when:
      user.plan: "pro"
    then:
      apply_discount: 20

Tests focus on intent, not implementation details.

Why YAML?

Not because it’s trendy.

YAML is:

Human-readable
Easy to diff in PRs
Reviewable by non-engineers

When a rule changes, PMs and domain experts can actually understand what changed — not just that something changed.

CI as a Guardrail

Running it is intentionally boring:

npx logicrepo check

Run it locally.

Run it in CI.

If a business rule breaks:

The build fails
The change is visible
The intent is documented

No more silent logic drift.

This Is Not a Rules Engine

logicrepo does not execute your business logic at runtime.

Think of it as:

A source of truth
A contract
A specification for business rules

Your application can consume it, or simply validate itself against it.

Try It Out

npx logicrepo check

GitHub:

https://github.com/alexdrimbe/logicrepo

I’d love to hear your thoughts:

Where does your business logic live today?
Have you been burned by logic drift before?
Would something like this help your team?

DEV Community: alexdrimbe