CORESYNC SOLUTIONS  /  PROFESSIONAL SERVICES

Taking Over a Product
That Cannot Stop Running

A global software vendor handed us the maintenance and modernization of their flagship platform — a system serving roughly 80 enterprise accounts across 20 countries. It keeps shipping while we rebuild underneath it.

THE ENGAGEMENT

Inherited, Not Written by Us

Most modernization work starts with a codebase nobody on the team wrote. Ours did. The platform is a mature .NET and SQL Server application with years of reporting built on top of it, in daily use by enterprise customers on several continents. There was no pause, no freeze, no parallel rewrite. The product had to carry on serving its customers throughout.

Our remit covers two jobs at once: keep the current release healthy — incident response, defect triage, customer-reported issues, release support — and move the platform off the parts of its stack that have run out of road. The two compete for the same hours, so we treat them as one plan rather than two teams.

~80
Enterprise accounts running the platform
20
Countries served
.NET · SQL Server
Core stack under maintenance
Zero
Planned downtime for customers
HOW WE WORK

Evidence First,
Then Changes

PERFORMANCE WORK

A Report That Took
Half an Hour, Now
Answers in Seconds

One reporting query on the platform swung unpredictably between a third of a second and half an hour, depending on which execution plan the database happened to cache. On a single day it ran 57 times at an average of 19 minutes. Users experienced it as “the system is down”; the hardware was almost idle throughout.

We reproduced it away from production on an isolated instance built to match the live engine, collation and settings, then measured every candidate fix on the same workload:

8–31 min
Original runtime range in production
1.2 billion
Logical reads for a single execution, reproduced in the lab
1–8 sec
Same workload after the fix, in every case we tested
1 of 4
Candidate fixes that actually held up under measurement
1 sec 10 sec 1 min 10 min 31 min Before PLAN-DEPENDENT 8–31 min 19 min average, worst day After MEASURED IN THE LAB 1–8 sec, every case tested

Time scale is logarithmic — each gridline is ten times the last. The same query, the same data, the same server.

The last figure is the point of the method. The obvious fix — raising the database compatibility level — looked convincing on a fresh run and failed under the exact conditions that caused the incident. Measuring it in the lab is what stopped it reaching production as a fix that would not have fixed anything. The same investigation surfaced a nightly maintenance job rebuilding every table across roughly 160 databases, and a latent bug producing duplicate rows in a report, neither of which anyone had asked us to look for.

RELEASE MANAGEMENT

Every Change Arrives
the Same Way

Maintaining someone else’s product means the release process has to be boring and identical every time, whoever is on shift. Ours is a single path from branch to production, with gates that can fail the release rather than merely report on it.

Branch protected trunk Pull request review + checks Staging deploys itself Tagged release a human decides Production scripted promotion ● red check blocks the merge PROMOTION SCRIPT, IN ORDER preflight code migrate build clear cache restart LAST Nothing restarts unless every step before it succeeded.

The same path for every change, ours included. The only human decision is which tagged release gets promoted.

AI IN THE ENGINEERING LOOP

Agents Do the Reading.
People Keep the Authority.

Our engineers work alongside AI coding agents every day — reviewing pull requests, reading unfamiliar parts of a large codebase, drafting migrations, reproducing defects, and pulling evidence out of production logs and query plans. On an inherited platform with years of accumulated code, that is the difference between an investigation taking an afternoon and taking a fortnight.

What matters more is where the boundaries sit, and they are written down rather than assumed:

Agent output is findings, never instructions

An automated review produces a list a human then judges. No agent merges its own work, and no agent’s conclusion reaches production without an engineer who agreed with it.

Customer data stays inside its boundary

Agents run on the client’s own infrastructure under the same isolation contract as our engineers. Real data is not posted to outside services to get an answer.

Predictable cost, not per-token billing

The tooling runs on subscription licensing, so heavier review of a risky change costs the client nothing extra and nobody is tempted to skip it.

Claims are checked, not trusted

Anything an agent asserts about a system is verified against the system before it becomes a recommendation. A finding that cannot be reproduced is not a finding.

WHAT THIS BUYS THE VENDOR

Continuity Without
a Standing Team

Their engineers stay on the roadmap

Maintenance, escalations and platform work sit with us. The vendor’s own team keeps building the product their customers are paying for.

One route in, one route out

Defects, escalations and platform work all arrive through the same tracked pipeline, so the vendor can see what is queued, what is moving and what is done without asking us.

Decisions come with evidence attached

Every recommendation arrives with the measurement behind it — the plan, the timing, the before and after — so the vendor can overrule us on their own terms.

Seniority without the headcount

Architecture, database and delivery experience on tap for the weeks it is needed, not a permanent seat on the payroll.

THE SAME SERVICE, FOR YOUR PRODUCT

Where This Fits

This engagement is the shape most of our professional services work takes: an established product, a small internal team, and a backlog of platform debt that never reaches the top of the list. We are useful when the system matters too much to experiment on and there is nobody spare to do the careful version.

01

Legacy Modernization

Framework and database upgrades, dependency untangling, and the measurements that say whether the upgrade was worth it.

02

Product Maintenance

Defect triage, customer escalations and release support for a product you no longer want to staff full time.

03

Performance Investigation

Root-cause analysis on live systems — query plans, indexing, jobs — reproduced in a lab before anything changes.

04

Technical Leadership

Architecture and delivery oversight for teams that have the developers but not the senior seat.

Talk to the people who would do the work

No sales engineer in the middle. You speak to the engineers who would run the engagement.

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