Retrofit

The building stays up. The load-bearing parts get rebuilt.

Retrofit is a word chosen on purpose. Nobody retrofits a building by demolishing it; they reinforce the structure, replace what's failing, and keep the tenants working the whole time. That's how we modernize software: incrementally, in production, without the big-bang rewrite that kills more systems than age ever has.

The output isn't "new software." It's your software with the properties AI requires: documented, tested, observable, and operable by machines as well as people.

When you need this

The Survey usually says so, but the symptoms are recognizable without it:

• Every change takes longer than the last one, and nobody can fully say why.
• The system only speaks through its screens: no APIs, no contracts, no way for another system (or an agent) to operate it.
• The test suite is thin enough that deploys happen on Fridays only by accident.
• An AI pilot touched the codebase and made things worse: more code, more bugs, less trust.
• The rewrite has been proposed three times and rejected three times. Correctly, probably.

What retrofit actually means

Preserve first. We start by capturing what the system knows: the business rules buried in code, the edge cases only Dave remembers, the reasons behind decisions nobody wrote down. Characterization tests pin down current behavior before anything changes. This is the least glamorous work we do and the highest-leverage; it's the difference between modernizing a system and gambling with one.

Cut seams, not corners. The core move is the seam: a clean, contracted, documented interface between the old system and everything new. APIs where there were screens. Events where there were batch jobs and shared spreadsheets. Each seam is a place where new work, human or AI, can attach without disturbing what holds the weight.

Replace by strangling, not smashing. New capability grows alongside the old, takes traffic gradually, and proves itself under real load before anything is decommissioned. The old path stays available until the numbers say it's safe. No cutover weekends. No prayer-based deployments.

Leave it operable by machines. Every seam we cut is built to answer yes to the question that decides your next decade: can an agent use it? Documented contracts, structured errors, idempotent operations, audit trails. This is what makes Retrofit the prerequisite for Commission instead of just another cleanup project.

The stack question

When we build new, we build on boring, durable, operationally cheap foundations. Today that means the current Elixir and Phoenix LiveView releases on the BEAM: a runtime with thirty-plus years of telecom-grade production history, systems that run for years without ceremony, and a fraction of the moving parts of the typical microservice sprawl. Where a screen genuinely needs a rich client, we reach for the latest Vue. One team can operate the result. That's the point.

But the stack serves the sequence, not the other way around. Plenty of retrofit work happens inside your existing PHP, .NET, or Java: stabilizing, testing, and seam-cutting in place. We recommend replacement only where the numbers support it, and we show the numbers.

What you get

Working software, continuously. Retrofit ships in production increments, not a deliverable at the end. Every milestone leaves the system better than the last and leaves you free to stop.

The system's knowledge, on paper. Architecture records, decision logs, runbooks, and the characterization tests that now guard behavior Dave used to guard alone.

Seams with contracts. Documented, versioned interfaces your team and any future vendor can build against without calling us.

A team that levels up alongside. We work in your repositories with your engineers, not in a black box. The practices transfer or the retrofit didn't finish.

How engagements run

Milestone-based fixed scope, sequenced by the Survey. Each milestone is two to six weeks, priced up front, and independently valuable. The first one is always chosen so the results fund confidence in the second. You can stop at any milestone boundary and keep everything shipped. Survey fees credit toward the first milestone.

Questions you're probably asking

"Why not just rewrite it?" Because rewrites bet the business on a system that doesn't exist yet, on a schedule nobody has ever hit, while the old system decays unattended. The graveyard is full of them. Retrofit keeps the revenue-producing system alive and improving the entire time. If a full replacement is ever justified, the seams and tests we cut are exactly what make it survivable.

"Our team is small. Can they absorb this?" That's designed in. Increments are sized to your team's capacity to review and own them, because software your team can't operate is a liability we'd be billing you to create.

"How does AI fit into the retrofit itself?" Carefully, and under supervision. We use AI heavily for characterization, migration mechanics, and test generation, the work it's demonstrably good at, with human review gates where it's demonstrably not. Your retrofit doubles as a working demonstration of the discipline we'll commission for you.

The Survey names the sequence. Retrofit executes it.