a semi-nomadic software developer with an interest in ice hockey, craft beers, and tech in general. originally from pittsburgh. same handle on "all 3."
Brooklyn, NY
Joined June 2007
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Perry Rajnovic retweeted
A desire to win. A legacy to represent. A city that shapes it all.
Whether you call Pittsburgh home or found your way to it, the passion for what we represent comes from within.
Perry Rajnovic retweeted
I have spent 23 years documenting the global LED transition of city lighting from space.
Across my 4 missions to the ISS, I have photographed every major city on Earth, building a data set of the gradual replacement of sodium vapor lighting with LEDs.
The warmer, yellow-orange of gas discharge lamps has been phased out worldwide to multi-colored LEDs, citing energy savings and environmental reasons.
Widespread adoption has markedly changed the way our cities look from orbit, and as many have pointed out, how they feel to those on the ground!
Here is a collection of the most striking before-and-after photos I have observed:
Perry Rajnovic retweeted
things AI has solved:
• writing code
things AI has not solved:
• knowing what code to write
• engineering
• product design
• requirements gathering
• the requirements changing after gathering
• stakeholders
• the stakeholder who "just had a thought"
• estimation
• the meeting about the estimate
• the meeting about the meeting
• naming things
• cache invalidation
• off-by-one errors
• the staging environment
• whatever DNS is doing right now
• Jira
• the ticket that's been "in progress" since 2023
• code review comments that are actually about ego
• the intern's force push
• timezones
• dates in general
• the printer
Perry Rajnovic retweeted
this got me really curious so i started looking up when american schools began phasing out computer lab.
i saw this blog post by a guy who writes about ed-tech and thought it surely must've been written in the last few years.
guys, he posted it in 2014 ...
Perry Rajnovic retweeted
idk why but i find it so funny that the euro banknotes featured FICTIONAL bridges so as to not cause conflict between member states but then a dutch town decided to just build all of the bridges to claim them??!?
Perry Rajnovic retweeted
Two new exhibits opening tomorrow at the NY Transit Museum in downtown Brooklyn, as part of the 50th anniversary celebrations, come check them out soon (make sure to buy tickets ahead of time for weekends, it can get very busy at peak times!) – at Manhattan, NY
Perry Rajnovic retweeted
I've been programming computers for 40 years.
Writing code is my poetry.
I write code to say what I want to say, to make computers do what I want them to do.
But also, deep down, I love the beauty, the elegance of a finely sculpted logic. Minimal, concise, precise. Carved in pursuit of the perfect form, as simple as it needs to be, but no simpler. Information flowing gracefully through, gently stroking the contours.
Now I can make computers do what I want them to do without writing any code, and it's blowing my mind. I absolutely love it ...
... until I look at the code. And then my heart stops.
What is this revolting, idiotic mess of excruciatingly over-engineered, pathetically brittle filth? This crime against sanity and all that is pure and good?
Yes, the computer appears to do what I asked. But my heart weeps blood. The poetry, the poetry is dead. Replaced by a Michael Bay Avengers Disney-remake multiverse-reboot mashup sludge-pit of rat’s-nest codeslop.
Perry Rajnovic retweeted
Almost every single person on Earth lives with rats. Only 5 million people out of 8 billion live rat free. They are the Albertans.
Alberta is the only significantly human-inhabited place on Earth that is rat free. It achieved this in the 1950s as rats invaded from the East, by introducing a rodent surveillance state, obliging every citizen of the province to report them and terminating any sightings with extreme prejudice. They laid 63,000 kg of arsenic across a 600-kilometre-long, 29-kilometre-wide Rat Control Zone along the province's Eastern border.
Back then, rats were so unfamiliar in Alberta that officials distributed preserved rat corpses to teach people what the enemy looked like. One pest-control officer held public meetings at which he ate warfarin-soaked oatmeal to show it was safe.
And it worked! They held rats off and numbers remained so low that the surveillance and eradication system could keep numbers at essentially zero for years, at extremely low costs – Alberta spends about 11 cents per resident on rat control measures, much less than neighbouring provinces that are infested.
Today, Albertans have grown so unfamiliar with rats that they frequently mistake squirrels, gophers, and other small animals for them: of 875 reported sightings in 2025, only 47 turned out to be actual rats. Pet rats are banned, vehicles entering Alberta are checked, and sightings are responded to with overwhelming force.
Could the rest of the world manage it? Probably not. The secret was to stop them before they could establish themselves. For the rest of us, we probably need gene drives. Read the story of how Alberta won the war on rats at Works in Progress now.
worksinprogress.co/issue/alb…
Perry Rajnovic retweeted
UPDATE: If high school were parliament, using @davidshor polling w/coalitions by Claude
Perry Rajnovic retweeted
Widespread use of public transit during the draft the 'biggest surprise' for event planners post-gazette.com/sports/2026…
Perry Rajnovic retweeted
41% of all code shipped in 2025 was AI-generated or AI-assisted. The defect rate on that code is 1.7x higher than human-written code. And a randomized controlled trial found that experienced developers using AI tools were actually 19% slower than developers working without them.
Devs have always written slop. The entire software industry is built on infrastructure designed to catch slop before it ships. Code review, linting, type checking, CI/CD pipelines, staging environments. All of it assumes one thing: the person who wrote the code can walk you through what it does when the reviewer asks.
That assumption held for 50 years. It broke in about 18 months.
When 41% of your codebase was generated by a machine and approved by a human who skimmed it because the tests passed, the review process becomes theater. The reviewer is checking code neither of them wrote. The linter catches syntax, not intent. The tests verify behavior, not understanding.
The old slop had an owner. Someone could explain why temp_fix_v3_FINAL existed, what edge case it handled, and what would break if you removed it. The new slop has an approver. Different relationship entirely.
Arvid’s right that devs wrote bad code before AI. The part he’s missing: the entire quality infrastructure of software engineering was designed around a world where the author and the debugger were the same person. That world ended last year and nothing has replaced it yet.
Perry Rajnovic retweeted
🚨BREAKING: Alibaba tested AI coding agents on 100 real codebases, spanning 233 days each.
the agents failed spectacularly.
turns out passing tests once is easy. maintaining code for 8 months without breaking everything is where AI collapses.
SWE-CI is the first benchmark that measures long-term code maintenance instead of one-shot bug fixes.
each task tracks 71 consecutive commits of real evolution.
75% of AI models break previously working code during maintenance.
only Claude Opus 4 stays above 50% zero-regression rate. every other model accumulates technical debt that compounds over iterations.
here's the brutal part:
- HumanEval and SWE-bench measure "does it work right now"
- SWE-CI measures "does it still work after 6 months of changes"
agents optimized for snapshot testing write brittle code that passes tests today but becomes unmaintainable tomorrow.
Alibaba built EvoScore to weight later iterations heavier than early ones. agents that sacrifice code quality for quick wins get punished when consequences compound.
the AI coding narrative just got more honest: most models can write code. almost none can maintain it.
