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Daniel Pertu

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Location London Joined Joined on  Personal website https://cogniprep.app

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Founder of CogniPrep

A preference is not a verdict: adding a third lane without letting it argue with the rules engine
daniel_pertu profile

A preference is not a verdict: adding a third lane without letting it argue with the rules engine

#typescript #architecture #ux #reactnative
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5 min read

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We stopped converting our price at checkout and wrote one figure per currency instead
daniel_pertu profile

We stopped converting our price at checkout and wrote one figure per currency instead

#stripe #typescript #webdev #payments
Comments
5 min read
Our support desk is a catch-all MX record, and the plus address is the thread
daniel_pertu profile

Our support desk is a catch-all MX record, and the plus address is the thread

#node #email #webdev #nextjs
Comments 1
5 min read
Our reels compute their own verdicts, so a video cannot promise what the app would not say
daniel_pertu profile

Our reels compute their own verdicts, so a video cannot promise what the app would not say

#react #typescript #webdev #video
Comments
5 min read
Twenty-eight research dossiers before a line of code, and the rule that every claim carries a URL
daniel_pertu profile

Twenty-eight research dossiers before a line of code, and the rule that every claim carries a URL

#ai #writing #seo #productivity
Comments
5 min read
Next.js traces your imports, so the 102 files we read with fs were not deployed
daniel_pertu profile

Next.js traces your imports, so the 102 files we read with fs were not deployed

#nextjs #webdev #serverless #node
Comments
4 min read
Our preload header downloads four files the page never uses, and one query parameter is why
daniel_pertu profile

Our preload header downloads four files the page never uses, and one query parameter is why

#webperf #nextjs #webdev #vercel
Comments 1
4 min read
Nine analytics defaults we turned off, and the one that has to be decided in the browser
daniel_pertu profile

Nine analytics defaults we turned off, and the one that has to be decided in the browser

#webdev #analytics #webperf #nextjs
Comments
5 min read
Our PWA plugin never emitted a service worker, and Turbopack is the reason
daniel_pertu profile

Our PWA plugin never emitted a service worker, and Turbopack is the reason

#nextjs #webdev #webperf #javascript
Comments
4 min read
Our health endpoint is public, so it answers with a count instead of a name
daniel_pertu profile

Our health endpoint is public, so it answers with a count instead of a name

#webdev #nextjs #security #monitoring
Comments 1
4 min read
Our OG card is a Playwright screenshot, and the Chromium comes from the workspace next door
daniel_pertu profile

Our OG card is a Playwright screenshot, and the Chromium comes from the workspace next door

#node #playwright #nextjs #webdev
Comments
6 min read
Our deploy CLI default origin is the one origin that can never work
daniel_pertu profile

Our deploy CLI default origin is the one origin that can never work

#node #cli #seo #javascript
Comments
8 min read
One backoff ladder became four, and the first retry went from ten minutes to sixty seconds
daniel_pertu profile

One backoff ladder became four, and the first retry went from ten minutes to sixty seconds

#node #typescript #architecture #webscraping
Comments
8 min read
robots.txt cannot protect a URL somebody forwards, and that is the whole reason for the meta tag
daniel_pertu profile

robots.txt cannot protect a URL somebody forwards, and that is the whole reason for the meta tag

#seo #nextjs #webdev #security
Comments
4 min read
Our free-licence script reuses your token, because the token is not ours to regenerate
daniel_pertu profile

Our free-licence script reuses your token, because the token is not ours to regenerate

#node #postgres #devops #javascript
Comments
7 min read
Three search rankers in one app, sharing one function and nothing else
daniel_pertu profile

Three search rankers in one app, sharing one function and nothing else

#javascript #webdev #typescript #ux
Comments
5 min read
Four sites, one publisher node, and an @id that deliberately is not a link
daniel_pertu profile

Four sites, one publisher node, and an @id that deliberately is not a link

#seo #nextjs #webdev #typescript
Comments
6 min read
Five things happen before our API route runs, and the order is the design
daniel_pertu profile

Five things happen before our API route runs, and the order is the design

#nextjs #security #webdev #node
Comments
4 min read
Four rendering modes in one Next.js app, and the root dynamic segment that answered every typo
daniel_pertu profile

Four rendering modes in one Next.js app, and the root dynamic segment that answered every typo

#nextjs #seo #webdev #performance
Comments
6 min read
A personalisation hint in the root layout pulled 100KB of catalogue into every page
daniel_pertu profile

A personalisation hint in the root layout pulled 100KB of catalogue into every page

#nextjs #react #webperf #webdev
Comments
4 min read
The blanket reduced-motion rule has a hole in it, and scroll-driven CSS is what falls through
daniel_pertu profile

The blanket reduced-motion rule has a hole in it, and scroll-driven CSS is what falls through

#css #a11y #webdev #performance
Comments
5 min read
Our nightly deletion job failed silently on every run, and the bug was a Date object
daniel_pertu profile

Our nightly deletion job failed silently on every run, and the bug was a Date object

#postgres #node #webdev #privacy
Comments
4 min read
Intl says zero decimals, Stripe wants hundredths, and the shelf wants ¥2,300
daniel_pertu profile

Intl says zero decimals, Stripe wants hundredths, and the shelf wants ¥2,300

#stripe #typescript #javascript #webdev
Comments
5 min read
Our picker splits at nine items, and four separate rules decide when a row may move
daniel_pertu profile

Our picker splits at nine items, and four separate rules decide when a row may move

#reactnative #ux #a11y #typescript
Comments 1
6 min read
Sequential does not mean slow enough: our email loop ran at 13 sends a second
daniel_pertu profile

Sequential does not mean slow enough: our email loop ran at 13 sends a second

#node #webdev #serverless #postgres
Comments
5 min read
The same 38 recipes are a catalogue on our website and a silent filter in our app
daniel_pertu profile

The same 38 recipes are a catalogue on our website and a silent filter in our app

#typescript #architecture #seo #reactnative
Comments
6 min read
373 static pages that answer by running the scanner, and the filler ingredient that answered instead
daniel_pertu profile

373 static pages that answer by running the scanner, and the filler ingredient that answered instead

#nextjs #typescript #seo #architecture
Comments
6 min read
node --test runs our TypeScript, and the price is that @/ does not exist
daniel_pertu profile

node --test runs our TypeScript, and the price is that @/ does not exist

#node #typescript #testing #nextjs
Comments
6 min read
Two quota alerts on the same 0.5 GB database, and the second one was not the table I expected
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Two quota alerts on the same 0.5 GB database, and the second one was not the table I expected

#postgres #database #devops #architecture
Comments
6 min read
Three facts hide our splash screen, and the two that would have been wrong to wait for
daniel_pertu profile

Three facts hide our splash screen, and the two that would have been wrong to wait for

#reactnative #expo #typescript #architecture
Comments
5 min read
Six percent of the box, with an eight point floor: padding a crop the user drew with a finger
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Six percent of the box, with an eight point floor: padding a crop the user drew with a finger

#reactnative #mobile #ux #typescript
Comments
7 min read
Six files, one write pattern, and six different answers to "what if this is garbage?"
daniel_pertu profile

Six files, one write pattern, and six different answers to "what if this is garbage?"

#typescript #node #electron #architecture
Comments
6 min read
parseInt returned NaN, and splice(NaN, 1) deleted the first search
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parseInt returned NaN, and splice(NaN, 1) deleted the first search

#typescript #node #express #webdev
Comments
6 min read
Our Electron app has no test framework, and the only rule is that testable files may not import electron
daniel_pertu profile

Our Electron app has no test framework, and the only rule is that testable files may not import electron

#electron #typescript #testing #node
Comments
6 min read
If we show the user a countdown, we have to let them skip it
daniel_pertu profile

If we show the user a countdown, we have to let them skip it

#electron #typescript #react #webdev
Comments
6 min read
No session, no reply: one rule enforced at the write, the run and the teardown
daniel_pertu profile

No session, no reply: one rule enforced at the write, the run and the teardown

#typescript #node #architecture #webdev
Comments
6 min read
Five rooms in one search is one banner, not five
daniel_pertu profile

Five rooms in one search is one banner, not five

#electron #typescript #node #webdev
Comments
5 min read
Storage written by an older build of your app is untrusted input, and 'absent' is the trap
daniel_pertu profile

Storage written by an older build of your app is untrusted input, and 'absent' is the trap

#reactnative #typescript #mobile #programming
Comments
6 min read
Alert.alert is an empty function on the web, so every confirm button in our app did nothing
daniel_pertu profile

Alert.alert is an empty function on the web, so every confirm button in our app did nothing

#reactnative #typescript #webdev #ux
Comments
5 min read
A search hit we cannot answer is worse than no hit, so our index covers a tenth of the table
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A search hit we cannot answer is worse than no hit, so our index covers a tenth of the table

#postgres #typescript #reactnative #webdev
Comments
5 min read
Our rank checker prints the URL, which is how we found out we rank with the wrong page
daniel_pertu profile

Our rank checker prints the URL, which is how we found out we rank with the wrong page

#seo #automation #webdev #javascript
Comments
5 min read
We un-hid our hidden SEO text on 24 pages, then found it again with one line of console
daniel_pertu profile

We un-hid our hidden SEO text on 24 pages, then found it again with one line of console

#seo #webdev #a11y #react
Comments 1
5 min read
3,281 unit tests in 4.4 seconds, and the DATABASE_URL points at port 1
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3,281 unit tests in 4.4 seconds, and the DATABASE_URL points at port 1

#testing #nextjs #typescript #webdev
Comments
5 min read
The heaviest thing on our report page is a 469KB chunk that arrives 30 seconds late
daniel_pertu profile

The heaviest thing on our report page is a 469KB chunk that arrives 30 seconds late

#react #performance #nextjs #webdev
Comments
5 min read
Premium does not unlock the games, and the access check never looks at your tier
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Premium does not unlock the games, and the access check never looks at your tier

#webdev #typescript #saas #architecture
Comments
5 min read
One code box, four programmes, and the difference between "not mine" and "no"
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One code box, four programmes, and the difference between "not mine" and "no"

#nextjs #typescript #webdev #api
Comments
5 min read
Electron says 'unspecified', Playwright wants 'Lax', and the session cookies vanished
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Electron says 'unspecified', Playwright wants 'Lax', and the session cookies vanished

#electron #playwright #javascript #webdev
Comments
5 min read
A 429 is not a no: the three answers our licence check has to tell apart
daniel_pertu profile

A 429 is not a no: the three answers our licence check has to tell apart

#electron #typescript #api #webdev
Comments
4 min read
Our 15 search limit is a latency budget, not a pricing tier
daniel_pertu profile

Our 15 search limit is a latency budget, not a pricing tier

#electron #typescript #architecture #performance
Comments
4 min read
The consent checkbox we tick for you, and the one we never will
daniel_pertu profile

The consent checkbox we tick for you, and the one we never will

#typescript #ux #electron #programming
Comments 1
5 min read
€1450 per month is rent, €9.99 per month is a paywall, and one digit tells them apart
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€1450 per month is rent, €9.99 per month is a paywall, and one digit tells them apart

#typescript #regex #webdev #node
Comments
5 min read
21 reply statuses, and the 8 that mean never touch this listing again
daniel_pertu profile

21 reply statuses, and the 8 that mean never touch this listing again

#electron #typescript #node #architecture
Comments
5 min read
Prices round up, discounts round down, and one package decides both
daniel_pertu profile

Prices round up, discounts round down, and one package decides both

#stripe #typescript #saas #webdev
Comments 1
6 min read
Rewriting a million rows when the only acceptable diff is zero bytes
daniel_pertu profile

Rewriting a million rows when the only acceptable diff is zero bytes

#postgres #database #node #devops
Comments
6 min read
135,692 label words in 49 languages, and not one model call in the path
daniel_pertu profile

135,692 label words in 49 languages, and not one model call in the path

#i18n #typescript #architecture #webdev
Comments
6 min read
An ingredient nobody has looked at yet is not an ingredient that is fine
daniel_pertu profile

An ingredient nobody has looked at yet is not an ingredient that is fine

#typescript #architecture #programming #webdev
Comments
6 min read
Our web app is the phone app: 103 files, 14 web branches, one .web.tsx
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Our web app is the phone app: 103 files, 14 web branches, one .web.tsx

#expo #reactnative #webdev #typescript
Comments
5 min read
Zero img tags on our landing page, and four of the phones on it are app screens
daniel_pertu profile

Zero img tags on our landing page, and four of the phones on it are app screens

#css #react #nextjs #webdev
Comments
4 min read
A nightly Postgres backup for $0, and the four things that break it
daniel_pertu profile

A nightly Postgres backup for $0, and the four things that break it

#postgres #devops #githubactions #cloudflare
Comments
4 min read
A two-column desktop layout that has to be byte-identical on mobile
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A two-column desktop layout that has to be byte-identical on mobile

#css #tailwindcss #react #webdev
Comments
4 min read
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