AI · Delivery · Brownfield

Writing code got faster. Why didn't the work?

AI didn't remove the bottleneck, it moved it. In an existing system, the real cost is finding and proving the rules.

Muhammet ŞafakOctober 3, 2026

Section 01

Bottleneck

AI didn't remove the bottleneck, it moved it.

One station

It didn't vanish. It moved.

Make writing 3× faster, but leave review and verification where they are, and you haven't tripled throughput.

The author's observation · one team I watched

Output went up; throughput went down.

~2×Code outputRoughly double once they leaned on agents
6Weeks laterThey were shipping more slowly
3×PR queueThe pull-request queue tripled
2IncidentsTraced back to changes nobody had read

Delivery pipeline

Throughput follows the slowest station

Step 1: Writegot faster
Step 2: Review
Step 3: Integrate
Step 4: Verify
Step 5: Release

Where did the bottleneck go?

It was always expensive; now it's drowning

ReviewGeneration produces PRs faster than humans can give them real attention; review degrades into rubber-stamping.
VerificationWriting tests is nearly free; suites fill up with flaky, timing-dependent cases.
IntegrationMore code means more coupling and more ways for the same message to arrive twice and corrupt state.

DORA 2024 and 2025 reports, as cited in the post

AI is an amplifier, not a shortcut.

Teams with strong delivery practices get more out of it; teams without them ship their dysfunction faster.

When does this not apply?

Know which world you're in

Greenfield, prototype, spikeThe constraint is still production

No downside to protect yet
Go fast
No process for a system not yet built

Team, review queue, productionThis is where the shift bites

There's something to keep honest
Other people depend on production
The bottleneck moves past the writing

Section 02

Brownfield

So what about a system that's been running for years?

Where the knowledge lives

Greenfield vs. brownfield

Greenfield vs. brownfield
Criterion	Greenfield	Brownfield
What is "correct"?	You define it	The system already defined it
Where is the knowledge?	With you and whoever made the request	In the code, the data, people's heads
Cost of a mistake	Reversible	Live data and users pay
Dominant cost	Production	Verification

What moves

What moves isn't code, it's rules.

In brownfield, what moves isn't code, it's rules. An agent is a multiplier where the knowledge is with you, and an assistant where the knowledge is in the system.

Where rules hide

Three places, three ways to dig

Code says what a rule is; usually only people know why.

Unwritten exceptions in the code3 business rules in 15 lines
Implicit rules in the datastatus counts, what NULL means
The reasoning in people's headswas it meant to be this way?

An honest breakdown of one week

Writing code is one day out of five

days, approximate

Rule discovery1.5
Actual coding1
Parity verification1.5
Edge cases0.5
Cutover and monitoring0.5

Approximate breakdown, a single example: migrating a CRM module.

Where an agent is a multiplier, and where it's an assistant

What it speeds up and what it doesn't

Mechanical conversionTurning one pattern into another; minutes, not hours.
Reading codeExtracting rules; the output is a list of questions, not an answer.
Verification toolingScripts that compare old and new, characterization tests.
Validity of a ruleAn agent finds the rule; it can't tell you whether it's still wanted.
VerifyingShowing it produces the same results as the old one is the daily work.
Cutover and coordinationNot technically hard; but it takes up calendar.

How I estimate brownfield work

Four rules

Count unknown rules, not lines. (pending)
Spend the first half day on discovery, then give the estimate. (pending)
Budget at least as much for verification as for production; the ratio comes out around 1:1.5. (pending)
Write the cutover as its own line item. (pending)

Writing code got faster. Understanding what the years mean did not.

Muhammet ŞafakFast from scratch, slow in a live system

Thank you

muhammetsafak.com.tr

Sources: posts on sade.dev and muhammetsafak.com.tr