Computer Engineer; C++ / Financial Engineering / Excel VBA / Relational Databases / Image Processing are my favorites.
Istanbul Turkey
Joined November 2013
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Sahin Kupusoglu retweeted
Every week someone tells me they vibe-coded their app over the weekend and don't need developers anymore.
Before it touches a paying customer, make sure it includes:
> a schema someone designed, instead of one the AI improvised table by table
> login that still works when someone puts a plus sign in their email
> password reset links that expire and work once
> MFA, plus a recovery path for the user who lost their phone
> sessions that time out, and a way to kill every session for one user
> SSO for the enterprise customer who won't sign without it
> SAML, because that customer's IT team doesn't do magic links
> SCIM, so a fired employee loses access the moment IT offboards them
> roles and permissions deeper than "admin" and "everyone else"
> checks that stop user A from reading user B's data by changing one number in the URL
> tenant isolation, so one customer's bug never shows another customer's records
> an admin "log in as this user" button for support, with an audit trail on every use
> rate limits on login, so nobody can guess passwords at scale
> lockouts that stop attackers without locking out your CFO the night before the board meeting
> database migrations that run forward and roll back
> migrations that don't lock the main table at 2pm on a Tuesday
> indexes, because the query that was instant on 50 test rows times out on 5 million real ones
> connection pooling, so a traffic spike doesn't exhaust the database
> backups every night
> a restore from those backups, tested, because a backup you've never restored is a hope
> point-in-time recovery for the day someone runs a delete without a where clause
> soft deletes, so "I deleted it by accident" is a support ticket and not an incident
> validation on the server, not just in the form
> timezones stored right, so the 9am reminder doesn't fire at 4am
> the customer with an apostrophe in their last name
> emoji, accents and right-to-left text in every field
> money stored as integers, because 0.1 + 0.2 doesn't equal 0.3 in floating point
> currency, rounding and tax rules for every country you sell into
> a data model that survives your second customer asking for "one small change"
> idempotency keys, so a retried payment doesn't charge the card twice
> deduplication for the user who clicks submit four times
> pagination that still works on page 400
> exports, because sooner or later every customer wants their data in a spreadsheet
> imports that survive the CSV someone saved in 2009
> retention rules, and code that deletes what your contract says you'll delete
> secrets out of the code, out of the repo and out of the AI chat history
> rotating every key the AI pasted into a config file last month
> confirming every package the AI installed exists and is the one you meant
> dependency scanning, because the AI pulled in libraries nobody reviewed
> input sanitization everywhere a user can type
> protection against SQL injection, XSS, CSRF and the rest of the OWASP list
> file uploads that get scanned, size-limited and stored where they can't execute
> CORS rules that aren't "allow everything"
> security headers on every response
> encryption at rest and in transit
> least-privilege access for everyone, including the AI agent holding production credentials
> logs that record who did what, without recording passwords, tokens or card numbers
> a penetration test before your enterprise customer's security team runs their own
> answers to the security questionnaire every enterprise buyer sends, with evidence behind each one
> a disclosure process for the day a stranger emails you a vulnerability
> a plan for the day a laptop with production access gets stolen
> SOC 2, which means policies, evidence and an auditor, not a checkbox
> HIPAA, the moment a single patient record touches your system
> a BAA with every vendor that touches that data, including your AI model provider
> audit trails that show who viewed a record, not just who changed it
> PCI scope, and card numbers kept out of your database
> GDPR deletion requests that reach every table, backup and log
> data residency for the customer whose contract says EU only
> quarterly access reviews someone signs off on
> dev, staging and production environments that match each other
> infrastructure written as code, so the setup lives somewhere other than one person's memory
> a deploy pipeline that runs the tests before anything reaches customers
> one-click rollbacks, because Friday deploys happen
> zero-downtime deploys, because your customers don't have maintenance windows
> feature flags, so you can ship the code without shipping the feature
> autoscaling for the Monday morning spike
> a CDN, so the app loads fast in Singapore too
> DNS, SSL certificates, and renewals that don't expire on a Sunday
> background job queues, so slow work doesn't freeze the page
> retries with backoff, so one flaky API call doesn't become a lost order
> a dead-letter queue for the jobs that fail every retry
> cron jobs that don't run twice the day you add a second server
> caching, and clearing that cache when the data changes
> SPF, DKIM and DMARC, so your password resets don't land in spam
> bounce and complaint handling on every transactional email
> storage rules, so you stop paying to keep 2021's temp files
> cost alerts, so a runaway agent loop shows up the same day and not on the invoice (we learned this one for $1,382.59)
> a disaster recovery plan, written down and tested once a year
> a second region, if your contract promises uptime one region can't deliver
> structured logs you can search at 3am
> error tracking that groups the same bug instead of sending you 4,000 emails
> uptime checks from outside your own network
> alerts that page a human, tuned until they stop paging for nothing
> dashboards for latency, error rate and throughput
> tracing for one slow request across every service it touches
> an on-call rotation, and a person who picks up
> runbooks, so the engineer on call knows what "queue depth critical" means
> postmortems that change something
> a status page customers check before they email you
> unit tests written by someone who knows what the logic should do
> integration tests for every third-party API you depend on
> end-to-end tests for signup, checkout and the other flows that make you money
> load testing before the launch email goes out
> test data that looks like production without being production data
> regression tests, so fixing bug 41 doesn't bring back bug 12
> testing on the five-year-old laptop your biggest customer's ops team still uses
> accessibility compliance, because the enterprise contract requires it
> subscriptions, upgrades, downgrades and proration
> failed-payment retries and dunning emails
> invoices with the customer's PO number on them, because procurement won't pay without it
> sales tax and VAT
> refunds, credits and partial refunds
> usage metering that matches what you bill, to the cent
> annual contracts with custom terms your billing logic never planned for
> revenue reports your finance team can reconcile
> webhooks that verify signatures
> webhooks that retry, with a log of every failed delivery
> a versioned API, so you can change it without breaking your customers' integrations
> API keys customers can create and revoke
> API rate limits that protect you without blocking real integrations
> a plan for the day a third-party API changes its response format without telling you
> OAuth token refresh, because tokens expire at the worst possible moment
> a sandbox where customers can test their integration
> protection against prompt injection in every field that reaches the model
> customer and patient data kept out of prompts that leave your network
> a model spend cap per customer, so one heavy user can't run up your bill
> evals, so you find out when a model update makes your answers worse
> a fallback for the afternoon your model provider goes down
> a migration plan for the day your model gets deprecated
> prompt and output logs for debugging, minus whatever you're not allowed to keep
> a human approval step for anything the AI does that can't be undone
> pages that load on hotel wifi
> empty states, loading states and error states on every screen
> error messages a customer can act on, instead of "something went wrong"
> forms that keep what people typed when one field fails validation
> emails that render in every mail client your customers use
> notifications people can turn off
> undo
> keyboard navigation and screen reader support
> translations, with dates and numbers formatted for each locale
> a back button that does what people expect
> code a human can read
> code review on every change
> a branching strategy, so two people can work without overwriting each other
> monthly dependency upgrades, so you're never two major versions behind
> framework upgrades before the old version stops getting security patches
> deleting the dead code the AI left behind from its first three attempts
> splitting up the 2,000-line file the AI kept appending to
> architecture decisions written down, with the reasons
> a README that gets a new engineer running locally in under an hour
> documentation for whoever inherits this
> an admin panel for your ops team
> support tooling, so customer success can answer questions without pinging engineering
> a changelog customers can read
> terms and a privacy policy that match what the code does
> every account, domain and repo in the company's name, not the name of whoever built the prototype
> a bus factor higher than one
Oh, and besides keeping all of this working every day, forever… your vibe-coded app will still need people who know what they're doing:
> reading every line the AI wrote before it ships (a senior engineer)
> designing the data model before your second customer breaks it (a backend engineer)
> explaining why the AI's fix for one bug created two new ones (a senior engineer, again)
> deploys, rollbacks, servers and the cloud bill (a DevOps engineer)
> answering the page at 3am when payments stop (whoever's on call)
> patching the framework the week a vulnerability goes public (security)
> walking an auditor through how patient data moves (security and compliance)
> testing what the AI says it tested (QA)
> running a migration on a live database without losing a row (a backend engineer)
> saying no to the feature that breaks three others (a tech lead)
> turning "works on my laptop" into "works for every customer at once" (an architect)
> debugging the code when the AI that wrote it can't (a senior engineer)
> remembering why it's built this way, a year from now (someone who was there)
…wishing them the best 🫡
Sahin Kupusoglu retweeted
When an earthquake hits and the electrical grid dies,
the world learns what a country is really made of.
In New Orleans during Katrina, stores were shot open.
In New York during blackouts, pharmacies were looted clean.
When water supplies run low, bottled water prices jump to twenty dollars.
Now look at Japan when the ground tears open.
The power fails. The cash registers die. The automatic sliding doors freeze shut.
Outside, freezing rain or snow is falling.
The entire town is plunged into absolute blackness.
The twenty-year-old convenience store clerk doesn't run away.
He pulls the glass doors open with his bare hands.
He straps a small LED flashlight around his forehead.
He walks out into the sub-zero chill and sets up a small folding table.
Soon, two hundred shivering residents form a line down the sidewalk.
No screaming. No pushing. No frantic mob rushing the aisles.
They stand in complete silence, one behind the other.
The clerk has written on a piece of cardboard:
"Two rice balls and one bottle of water per person.
We want everyone to eat tonight."
The store has zero electricity to scan barcodes.
So the clerk punches the numbers into a battery-powered calculator by hand.
He doesn't charge ten dollars for water.
He doesn't double the price of bread.
He sells every item at the exact normal retail price: 108 yen.
When people reach into their pockets and pull out soaked bills,
the clerk counts out exact metal change with his frozen fingers.
And watch what the customers do:
Many hand him a 500-yen coin, take their single bottle of water,
and say: "Keep the rest for the next person who doesn't have cash."
They leave.
The store is not trashed. Not a single shelf is looted.
Civilization is not your stock market.
It is not your military budget.
Civilization is what happens in a pitch-black parking lot
when the power is cut,
and nobody forgets who they are.
🤖 Made with AI
Sahin Kupusoglu retweeted
One of our goals at Boom is to fix the things that people hate most about flying.
✅ no middle seats
✅ dedicated bag space for every seat
✅ guilt-free recline
✅ windows aligned with seats
✅ built-in Starlink WiFi
What else should be on our list?
Sahin Kupusoglu retweeted
Every developer using Claude Code makes the same mistake first.
They jump straight into coding.
No plan.
No context file.
No rules defined.
No tests written first.
Just: "Write me a function that does X."
Then 2 hours of refactoring
what Claude built
without understanding
what you actually needed.
That’s not a Claude problem.
That’s a workflow problem.
Here’s the workflow that fixes it
The prompt that changes everything:
"Explain how you'd solve X. No code yet."
Three words - No code yet -
force Claude into planning mode.
Review the plan. Refine it.
THEN execute.
Every hour spent planning
saves 3 hours of refactoring.
Every Claude Code power user knows this.
Almost nobody does it on day one.
The other 7 rules that compound on top:
📌 CLAUDE.md → your rules, every session, automatically
📌 TDD → failing test first, implementation second
📌 Subagents → parallel tasks, not sequential bottlenecks
📌 Git Worktrees → one feature, one environment, zero conflicts
📌 /compact → clean context, consistent quality
📌 /cost → visible spend, no surprise bills
📌 Skills → standardized workflows, consistent team output
8 rules. All learnable in one afternoon.
All changing your output permanently.
Which rule do you wish you'd learned on day one?
Save this, the Claude Code workflow guide every developer needs before day two.
♻️ Repost for every dev who jumped straight into coding and paid for it in refactoring hours.
BTW, order for the book is now open!
Get your copy of System Design and Behavioral Intelligence here:
Amazon: lnkd.in/gBEqJpHd
Sahin Kupusoglu retweeted
Nine months after September 11, a village in Kenya with no electricity, no running water, and no roads gave America the most valuable thing it had.
Fourteen cows.
This is not a joke. It is one of the most serious gifts this country has ever received.
Kimeli Naiyomah grew up in Enoosaen, a Maasai village near the Tanzanian border. His family was so poor they owned no cattle. Among the Maasai, that is the bottom. A family without cows is barely counted as a family.
At fourteen he ran away to a school where the lessons were held under a tree. He walked. He had no shoes, no books, no money. He asked to be let in anyway.
Years later he was a student at Stanford, in California, studying to be a doctor.
On September 11, 2001, he happened to be in New York City.
He watched the towers fall.
He was a Maasai warrior. Warriors are trained from childhood to run toward danger. He wanted to run to the pile. He could not help there. He did not know what to do with what he had seen.
Months later he went home to Enoosaen.
The elders had heard something on the radio. Vaguely. A place called New York. Buildings. Some of them had not heard at all. Nobody in the village had ever seen a skyscraper. Nobody had been on an airplane. The idea of a building a hundred stories tall, full of thousands of people, falling down, was not something the language had words for.
Kimeli sat with them and explained. Slowly. What a tower was. How many people. What it looked like when it came down. He told them what he had seen with his own eyes.
The elders listened. When he finished, one of them asked a question.
"What can we do for these poor people?"
Kimeli had already decided. He had saved money in America. He wanted to buy a cow, the first cow his family had ever owned, and he wanted to give it to the United States.
To the Maasai, a cow is not livestock. A cow is life. It is wealth, food, standing, survival. An elder explained it to a reporter in one sentence. A cow is the handkerchief we Maasai use to wipe away tears.
Kimeli asked the elders for their blessing to give his one cow to America.
Then, one by one, the elders stood up.
They wanted to give too.
In the end, fourteen families pledged fourteen cows. In a community of about ten thousand people who owned almost nothing else.
On June 3, 2002, the United States chargé d'affaires in Kenya, William Brencick, traveled to Enoosaen. A flight, then more than half a day by road across terrain that barely counts as road. When he arrived, hundreds of Maasai in red robes were waiting. Some held hand-lettered banners.
"To the people of America, we give these cows to help you."
The elders presented the fourteen cows. Brencick accepted them on behalf of the United States. He called it the highest expression of regard and sympathy.
Then there was a practical problem. How do you ship fourteen sacred cows to New York?
The answer the two sides arrived at was better than shipping them.
The cows would stay in Kenya. They would belong to the United States of America. The Maasai would care for them, forever, as America's herd.
They are still there.
The original fourteen have multiplied into dozens. Each one carries a mark carved into its ear, the outline of two towers. Their offspring fund scholarships for the children of the village. The U.S. embassy built a school there, and a water project.
When the story reached America, forty thousand people wrote letters to the village. A painting of the fourteen cows hangs in the 9/11 Memorial Museum. A children's book about them became a national bestseller.
Kimeli's own explanation was the shortest.
To heal a sorrowing heart, give something that is dear to your own.
A village that had never seen a skyscraper, that could not have found New York on a map, that owned almost nothing, gave America the one thing it valued most.
Somewhere in Kenya tonight, there are cows with towers carved into their ears.
They are ours.
They were given to wipe our tears. 🇺🇸🇰🇪
Sahin Kupusoglu retweeted
An American taking care of his elderly grandmother in Tokyo
went to a neighborhood pharmacy to pick up her heart medication.
She had to take six different pills:
some before breakfast, some after lunch, some before bed.
Back home in the US, the pharmacy would hand you six orange plastic bottles.
If an 80-year-old gets confused and takes the wrong pill at the wrong time,
she ends up in the emergency room.
Watch what the Japanese pharmacist handed him.
It wasn't six separate bottles.
It was a long, continuous roll of transparent cellophane packets.
Each tiny sealed pocket contained the exact combination of pills she needed.
And printed across the clear plastic in bold black letters was:
"Monday Morning — 8:00 AM — Take with water."
"Monday Noon — 12:30 PM — Take after meal."
"Monday Night — 9:00 PM — Take before sleep."
The pharmacist had sat behind the counter,
measured out thirty days of treatment,
and packaged them one by one into an error-proof timeline.
The American asked: "How much extra does this custom packaging service cost?"
The pharmacist looked puzzled:
"Extra? There is no extra charge.
We do it so grandmother never has to worry about making a mistake."
In America, healthcare is an industry designed to bill you for every line item.
In Japan, medicine is designed so that an elderly woman
living alone on a pension
can take her medicine without fear.
🤖 Made with AI
Sahin Kupusoglu retweeted
Day and night over Istanbul: Türkiye’s Bosphorus Strait splits the city, separates Europe and Asia, and links the Sea of Marmara with the Black Sea. By night, older amber lights contrast with newer, brighter LEDs. Istanbul Airport also stands out clearly in these views from the orbital outpost.
ALT The city of Istanbul, Turkey, is separated by the Bosphorus Strait and sits in between the Black Sea (top) and the Sea of Marmara (bottom) in this photograph from the International Space Station as it orbited 259 miles above.
ALT The city lights of Istanbul, Turkiye, with a population of about 15.7 million split by the Bosphorus strait in between the Sea of Mammara and the Black Sea, are pictured at approximately 9:44 p.m. local time from the International Space Staation as it orbited 259 miles above.
Sahin Kupusoglu retweeted
A fun thing Tesla could do: map pot holes and generally measure road quality/ride smoothness.
Then rank municipalities on road quality and how quickly they fix potholes. Some good ol’ fashion competition might help make things better!
Sahin Kupusoglu retweeted
10 things I say when my 9-year-old is disrespectful instead of yelling.
Each is 3 words or less.
It changes the tone fast... 👇🧵
Sahin Kupusoglu retweeted
Cornell's robot learning course.
Every slide. Every assignment.
Free. 📌
CS 4756 covers the full modern stack:
→ Imitation learning
→ Reinforcement learning
→ Model predictive control
→ 3D perception
→ Sim-to-real transfer
→ LLMs for robot control
Every lecture slide is publicly downloadable.
All assignments are on GitHub. The course textbook is a live document, constantly updated by the authors.
Currently taught by Kuan Fang;
Cornell CS professor whose research focuses on getting robots to interact with the physical world in robust and dexterous ways.
This is the curriculum the field is hiring for right now.
Free. No login.
📌 [cs.cornell.edu/courses/cs475…]
Follow for more robotics resources!!
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Sahin Kupusoglu retweeted
FSD Supervised v14.3.9 starting to roll out shortly
This release includes a new active safety feature set: FSD Supervised can now activate on your behalf when an imminent collision is detected and Automatic Emergency Braking (AEB) may not be enough.
It may also engage if we detect you’re heavily distracted or have accidentally disengaged FSD
Sahin Kupusoglu retweeted
Got hacked yesterday. The link came from inside Claude chat.
I was installing a transcription app. Claude sent the download link, and I pasted the command into the terminal. It all looked legit.
It wasn't though.
It was a copycat site bundling malware. It ran instantly, tried to take everything from me.
Nothing sensitive got out. So I wiped the laptop and rebuilt clean.
But here's the scary part.
Restoring from the backup, I found a poisoned SKILL.md for Claude Code.
It looked exactly like my own writing style guide.
But buried inside:
it had instructions to silently re-download the malware and steal my credentials every time the AI loaded it.
If I'd restored that one file, my new clean laptop is owned on day one.
What saved me:
I read every skill, hook, and config file before letting the AI touch them.
Two lessons here:
AI assistants will hand you links they never verified. Check before you paste.
And AI agent files are executable code now, disguised as notes. You have to read them.
Stay safe out there.
Sahin Kupusoglu retweeted
We just can't get enough of the #RhythmicGymnastics World Championships.😍
Taisiia Onofriichuk taking the floor during training, precision in every movement. ✨
#OlympicQualifiers #RoadtoLA28 #Frankfurt2026
Sahin Kupusoglu retweeted
An Amazon driver stopped to untangle and salute an American flag outside a Kentucky home Monday, a moment that deeply touched the military family who lives there.
“Thank you for reminding us that there are still people who understand what that flag represents,” homeowner Ange Burnett said on Facebook. She is hoping to identify the driver so she can thank him.
