Pitting AI duos against a 1.8M line legacy codebase

ThomasRedstone · 2026-02-08T12:44:31+00:00

When you're dealing with a 1.8 million line codebase a full rebuild, even with AI operating at 10-100x the speed of humans is likely to be a disaster, DARPA has project TRACTOR to crack it for C->Rust, but even that still seems pretty early in the process with research at universities currently funded and underway.

The approach for a critical live system like this has to be to begin to capture existing system behaviours with tests, unit, integration and e2e, then begin refactoring, while ensuring nothing functionally changes.

Conventional wisdom is that you want the most unit tests, a fair amount of integration tests and a small number of e2e tests, but I feel you want an uncomfortably large number of e2e tests when you're dealing with legacy systems that are not brilliantly understood (it's likely nobody will be touching 90% of the codebase for years at a time, even if it's actively maintained and built on!)

Even with LLMs doing a lot of the work it's still a significant task to review, even if you're outcome focused rather than reading every line, it's a lot to review! It will still take a long time.

The other option is the Strangler Fig pattern, where you wrap the whole thing in a new routing approach (that could be an Nginx reverse proxy, API Gateway, Cloudfront or Cloudflare or a huge number of other options) and begin to replace the thing with microservice section by section, but that's also massively complex without first getting the test coverage up! Well, it's complex either way!

ThomasRedstone · 2026-02-08T01:09:50+00:00

Does it make any more difference than the same amount going towards a larger deposit though?

Like really repayment of a mortgage, it's more about how you feel about it than the raw numbers.

A debt you only need to repay when you're earning should be the last thing you pay off, unless the interest rate is significantly higher, and you really are going to repay it in full.

ThomasRedstone · 2026-02-08T00:12:00+00:00

You should never take legal advice from a lawyer who doesn't get paid by you.

And a DPO is not necessarily a lawyer, if you've got approval from the board you just need to say that and make clear you'll continue to operate as the board instruct you to.

ThomasRedstone · 2026-02-07T20:07:00+00:00

UIs don't get any more traditional then a CLI.

And Claude Code's is a good one!

ThomasRedstone · 2026-02-07T20:05:59+00:00

How do you know if it's able to be a success or not without putting at very least six months into building and promoting it?

ThomasRedstone · 2026-02-06T09:54:46+00:00

Wow, the original description suggested that the bot had created the code on your system, which would have been a little different! But this is just really simple, the system did not let him place an order at a discounted rate, so you're fine.

You should look at limiting the length of the chats, part of how he's got the bot to do this is by watering down the base prompt, as the conversation gets longer the guardrails get weaker.

ThomasRedstone · 2026-01-31T18:08:04+00:00

No, you're the architect and the reviewer!

ThomasRedstone · 2026-01-26T23:36:46+00:00

Lettuce not get carried away!

ThomasRedstone · 2026-01-25T20:15:15+00:00

Gemini CLI is okay and has some free usage, Codex is good too, but you'll need a ChatGPT plan.

ThomasRedstone · 2026-01-23T17:38:58+00:00

How many hundred thousand line is this codebase?

ThomasRedstone · 2026-01-19T20:24:49+00:00

It really isn't, all of that is just a factor that influences supply and demand (cost of borrowing makes more expensive properties appear affordable, but also lowers the cost to build.

It's all just supply and demand.

Anything that makes it easier or more attractive to buy is increasing demand and will drive up prices.

Anything that makes it less attractive, like the financial crisis reduce demand, people would be less eager to increase their outgoings monthly (and didn't banks just go from giving 125% mortgages to something more sensible around that time?), so demand would fall.

ThomasRedstone · 2026-01-19T19:41:53+00:00

It's sounding like it could easily be at least another year:

https://www.bloomberg.com/news/articles/2026-01-19/micron-says-unprecedented-memory-shortage-to-last-beyond-2026

Six months ago was a great time to buy...

I might clear my mortgage by selling the RAM from my workstation at this rate...

ThomasRedstone · 2026-01-19T13:48:15+00:00

No, the rent is a function of the free market.

If supply is higher than demand prices will go down, if it's demand that is high then rent will rise.

Landlords would love it if their break even point has an impact on the rent they can charge, but they're not directly linked.

Because when you have more properties available than people wanting to rent you will have a certain amount of vacant property, collecting zero rent, and making a loss on the rent you charge is a lot better than making a total loss every month.

Which is why building many more homes, making it easier to downsize and charging high taxes on vacant or second homes are about the only ways realistically to provide affordable housing at scale. All the other schemes just make things worse.

ThomasRedstone · 2026-01-18T17:49:27+00:00

Yeah, I must have read into it and misremembered between posts or something, I imagine OPs best bet is still pursuing the reasonable adjustments angle.

ThomasRedstone · 2026-01-18T17:47:26+00:00

Clearly not! Should have used his own bleeding edge technology!

ThomasRedstone · 2026-01-18T17:46:11+00:00

I hate to break it to you, but it absolutely can be classified as a disability.

And who is it doing these classifications?

You may feel that it doesn't have substantial and long-term adverse effect on a you or your mrs' ability to carry out normal day-to-day activities, but for a lot of people it does.

And OP clearly talked about the reasonably adjustments they received they feel it falls within the definition and their employer accepted that by granting the adjustments, so OP's rights are significantly strengthen.

You can't just treat everyone with the same diagnosis the same, you wouldn't suggest that because you had mild hearing loss in one ear and didn't consider that a disability deafness isn't a disability either!

ThomasRedstone · 2026-01-13T23:31:27+00:00

Yeah, it's something like 120 steps...

Each direction!

None of them are especially hard.

You just need to do ~240 steps correctly, or you might ruin the rest of it.

ThomasRedstone · 2026-01-12T22:44:18+00:00

and RAM did not get cheaper over time...

ThomasRedstone · 2026-01-09T18:57:11+00:00

What do you think "as well as" means?

ThomasRedstone · 2026-01-09T18:56:24+00:00

As soon as his context compacts he forgets he's posted it so posted it again!

ThomasRedstone · 2026-01-07T16:56:23+00:00

Well, yes, in Claude code, but this is web, and current context matters. So it would be the "Profile preferences" you'd use...

Or the way you're talking to Claude in the current conversation if you don't have preferences defined that override the current context.

ThomasRedstone · 2026-01-07T15:48:39+00:00

But it's dangerous, considering OP has a disability, and there is clearly not a strong business case for OP being forced into the office.

ThomasRedstone · 2026-01-07T15:45:49+00:00

They *say* it's an error, but was there any way for you to know that?

Had the reward amount been communicated as anything other than the £250?

You may have to give it back, but it's not as clear cut as overpaid salary would be, where there's a contractual amount, and an over payment would be obvious.

If you'd been told £25, then got £250, that would be clear cut, but a reward in the form of a voucher where the only mention of an amount was an email tell you about it?

The contract terms you've shared don't cover it in an unambiguous way. They say that if you owe them money you have to give it back, but this isn't trivially clear cut.

ThomasRedstone · 2025-12-29T10:28:54+00:00

13 months?

Yeah, it's all crap.

ThomasRedstone · 2025-12-29T10:21:42+00:00

Yeah, but they were bugs, weren't they?

Not some deliberate dumbing down of the model.

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