# Monolith Decomposition

> A scoped AI Pod that extracts a monolith one bounded piece at a time, with a working system at every step. 250 to 600 story points, phased.

Source: https://www.koombea.com/ai-pods/catalog/monolith-decomposition/

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One codebase, fifteen years of decisions, and a deployment everyone dreads. This Pod carves it into pieces that move independently, one at a time, behind interfaces that do not change.


## The problem

The system is not broken. It serves customers, it holds revenue, and it cannot be switched off. What broke is the economics of changing it. A one-week feature takes six, and nobody can say exactly why.

The usual proposal is a rewrite. Eighteen months, no new features, and a promise that the replacement will be better. That bet has a poor record. It asks the business to pay twice: once for the rewrite, and once for the year of standing still.

We move pieces instead. Each phase extracts one bounded part of the system, behind an interface its consumers never notice changing. You stop when the economics are good enough, not when the plan says you are finished.

- A working, deployable system at the end of every phase
- Legacy interfaces preserved until the last consumer has moved
- The cost of change measured before and after, not just the stack

## What this Pod ships

- **Bounded extraction**: One part of the system moved out at a time, with its data, behind an interface that stays stable for everything still calling it.
- **Zero-downtime migration**: Data moves without the business pausing, using dual writes and a verified cutover rather than a maintenance window.
- **Characterization tests**: Tests that pin down what the old code actually does before it moves, which is the only safe basis for changing it.
- **Measured cost of change**: Lead time and change failure rate tracked across the program, so the argument for continuing is evidence rather than faith.

## How a slab gets emptied


## Why this is phased, always

A single 600 point commitment on a system nobody fully understands would be a guess. We do not price guesses. Each phase is scoped and committed on its own, informed by what the previous phase taught us about the codebase.

Phase 1 is deliberately the piece with the clearest boundary, not the piece causing the most pain. Proving the extraction pattern on something tractable is what makes the harder phases predictable.


## What it costs

250 to 600 story points across the program, split into phases of roughly 80 to 150 points each. Each phase carries its own committed price, approved before it starts.

If the system has not been assessed yet, start with a Legacy Assessment. 30 to 50 points buys the decomposition plan this Pod executes, and it credits in full against the first phase.

- Points: 250 to 600 total, committed one phase at a time
- Each phase leaves a system that runs and deploys
- You can stop between phases without stranding the work
- 30 day warranty from written acceptance of each phase