Last Mile AI Engineering for Legacy Code Modernization | AI Squad — GAPVelocity AI
AI Squad — Last mile AI engineering

Last Mile AI Engineering for
Legacy Code Modernization

AI migration tools convert 85–95% of your legacy codebase. The remaining 5–15% is where projects stall for months: third-party dependencies, custom business logic, and integration edge cases that break silently. AI Squad combines modernization engineers with agentic AI and purpose-built tooling to close that gap and get your code to production.

Why engineering teams trust AI Squad
AI+
Agentic AI powered by expert engineers
35+
Years of migration expertise
$0
Free assessment, yours to keep
FP
Fixed-price delivery, scoped upfront

AI migration tools plateau at 85–95%. Here's why.

The remaining code isn't harder because your team missed it. It's harder because these are bundled into edge case scenarios like custom in-house libraries, third-party components, and other scenarios that require a human in the loop validation.

// What automated tools handle well migrate(standardSyntax) ✓ converted migrate(knownPatterns) ✓ converted migrate(repeatableTransforms) ✓ converted // What stalls the project migrate(thirdPartySDK) ✗ no training data for proprietary APIs migrate(customHelperClasses) ✗ undocumented domain logic migrate(COTSIntegrationPoints) ✗ vendor-specific wire protocols migrate(edgeCaseBehavior) ✗ compiles but fails silently at runtime
Failure pattern 01

Third-party dependencies

COTS integrations, external APIs, and proprietary SDK references. The AI model generates plausible-looking wrappers, but the actual wire protocol, auth flow, or data contract is wrong. Your tests pass locally. Production breaks.

Failure pattern 02

Custom business logic

Helper classes built over 10+ years with undocumented rules, implicit state dependencies, and domain-specific behavior the original developer never annotated. AI infers the syntax. It misses the intent.

Failure pattern 03

Integration edge cases

The migrated code compiles and passes unit tests, but behaves differently under load. Timing issues in async handoffs, silent data truncation, broken event ordering between services. These surface late and cost the most.

Legacy stacks we've completed last-mile work on
VB6VB.NETMS AccessPowerBuilderWebFormsWinFormsClarionSilverlightASP ClassicInformix 4GLC# → BlazorC# → .NET 8

Expert modernization engineers. Assessment first. Fixed price.

Our modernization engineers use agentic AI and proprietary tooling (VELO) to diagnose and resolve last-mile issues faster than manual engineering alone, and with more precision than AI tools working without expert oversight.

1

Submit your stalled migration

Takes 5 minutes to start

Tell us your source and target languages, what percentage is complete, and what's blocking the rest. We'll then ask you to either run your code through our assessment tool or send it to us directly. We can provide an NDA if required. We don't retain your code or use it to train any models.

2

Receive a technical assessment

Delivered within 2 business days

Our engineers use our code analysis tool, ByteInsight, to rapidly analyze the remaining work, mapping dependency chains, identifying undocumented business logic, and pinpointing integration failures. You get a structured breakdown with estimated effort for each category.

3

Review a fixed-price quote

No commitment required

Based on the assessment, we scope the remaining work and quote a fixed price to deliver production-ready code. If the numbers don't make sense, you walk away and keep the assessment. Use it with another vendor if you prefer.

4

AI-assisted engineers deliver to production

Timeline scoped in the quote

Our modernization engineers work alongside agentic AI and our proprietary VELO platform to close the remaining gaps. They resolve dependency issues, complete business logic translation, and pass integration and regression tests. You get production-ready code at the agreed price.

Here's what an assessment looks like.

A structured technical breakdown your engineering team can evaluate independently.

LAST MILE ASSESSMENT — SAMPLE REDACTED CLIENT
Source
VB6 → C# / .NET 8, ~420K lines of code
Current state
91% converted via automated tooling. Compiles. 34 of 212 modules failing integration tests.
Blocking issues
3 COTS integrations 12 custom controls 8 helper classes 11 data layer edge cases
Estimated effort
6–8 weeks to production-ready. Breakdown by module included in full report.
Fixed-price quote
Included, scoped per module with acceptance criteria defined for each.
Across all GAPVelocity AI engagements
90–95%
Automated conversion before AI Squad engages
20x
Faster than a full manual rewrite of equivalent scope
60%
Lower total cost vs. building a rewrite team internally
100%
Business logic preservation, validated by functional testing

Metrics from GAPVelocity AI enterprise engagements across VB6, MS Access, PowerBuilder, and WebForms modernizations. Individual results vary by codebase complexity and scope.

"GAPVelocity AI technology is actually cheaper than a manual rewrite in time and dollars. It cut our costs in half. They have a total command of the modernization domain space."

Greg Duhachek, CEO

AgWorks Software — VB6 to C# / .NET migration

Not just AI. Not just engineers. Both.

AI tools alone plateau. Consultancies alone are slow and expensive. AI Squad combines expert modernization engineers with agentic AI and purpose-built tooling to deliver results neither approach achieves on its own.

vs. AI code tools alone

AI gets to 85%. We get to 100%.

AI tools handle repeatable patterns. They plateau on third-party dependencies, proprietary frameworks, and undocumented business rules. That's exactly where our engineers and agentic AI take over.
Generic AI generates code that compiles. Our AI, trained on migration-specific patterns across billions of lines, generates code that works in your production environment.
35 years of migration expertise baked into our tooling, not just our people.
vs. General consultancies

Faster. Fixed price. AI-accelerated.

Consultancies staff generalists who ramp for 4–6 weeks. Our engineers use agentic AI to diagnose and resolve issues in days, not months.
No open-ended T&M billing. The scope and price are set before work begins, based on an AI-powered technical assessment.
Our proprietary VELO platform accelerates delivery. Generalist firms staff bodies. We apply engineered process powered by AI.

What skeptical engineering teams ask us.

We built this section from real objections raised by technical leads during sales conversations. If your question isn't here, ask us directly.

How does the assessment work? Do I need to share my source code?
Yes, to give you an accurate assessment we need to analyze the actual code. You can either run your codebase through our assessment tool directly, or send it to us and we'll run the analysis on our end. We don't retain your code after the assessment is complete, we don't use it to train any models, and your data is never shared with third parties. We can provide an NDA before you share anything.
Is my code safe? What about data privacy?
Your code is processed solely for the purpose of your assessment and is not stored, retained, or used for any other purpose afterward. We don't train our AI on customer code. We don't share it with third parties. NDAs are available on request before any code changes hands, and we're happy to work within your organization's security and compliance requirements.
How is "fixed price" actually enforced? What if the scope changes?
The assessment produces a detailed scope breakdown by module, each with defined acceptance criteria: specific tests that must pass, specific integrations that must work. The fixed price covers all work needed to meet those criteria. If we discover additional complexity during delivery, that's on us, not a change order. The only scenario where scope adjusts is if you add requirements that weren't in the original assessment.
What qualifies your engineers vs. my own team continuing to work on it?
Your team knows your business domain better than we ever will. Our engineers know migration failure patterns. They've seen the same categories of broken COTS integrations, custom control conversions, and silent data issues across hundreds of engagements and billions of lines of code. The value isn't that we're better engineers. It's that we've solved this specific class of problem before, at volume, and have tooling purpose-built for it.
How long does the last-mile work typically take?
It depends on codebase complexity and what's remaining, but most engagements complete in 4–12 weeks. The assessment gives you a specific timeline for your project. The whole point of the assessment-first approach is precision.
What happens after delivery? Do you provide support?
The deliverable is production-ready code that passes the acceptance criteria defined in the assessment. Post-delivery support terms are included in the SOW, typically a 30-day defect remediation window for any issues traced back to our work. Your team owns the code fully. No ongoing licensing fees or vendor lock-in.
We tried another vendor and it didn't work. Why would this be different?
Most vendors who offer migration help are generalist consultancies staffing developers who learn your stack on the job. We're a modernization-specific engineering team with 35 years of legacy migration experience and proprietary tooling built for this exact problem. More practically: the free assessment is designed for exactly your situation. If our assessment doesn't demonstrate that we understand the problem better than the last vendor did, you'll know before you spend anything.

Before you commit to anything, find out what's actually left.

If your legacy code modernization has stalled, the first step is getting a clear, AI-analyzed picture of what's incomplete, why it's stuck, and what it takes to finish.

What you send
A description of your codebase, migration progress, and where you're stuck. We'll then ask for code access, either through our assessment tool or direct transfer. NDA available on request. We don't retain or train on your code.
What you get back
AI-analyzed breakdown of remaining work by category: dependency mapping, business logic gaps, and integration failures, with estimated effort and a fixed-price quote.
Your commitment
None. The assessment is yours to keep. Use it with us, take it to a competitor, or use it to scope the work internally.
Who reviews it
Senior modernization engineers using agentic AI and our VELO platform. The same people and tools that would do the work.

Request your assessment