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Went wrong

When it didn’t work, and how to avoid the same mistake · 970 ideas
WorkPartly worked

Migrate my 180-million-row production table with zero downtime

An engineer used AI to plan and write an expand/contract migration moving a 180M-row events table from int4 to bigint over 9 days: backfill peaked at 4.1 seconds of replica lag and the final swap locked for 1.4 seconds, with zero downtime. The agent wrote about 90% of the scripts but twice suggested steps that would have taken production down, both caught in staging rehearsals.

This only partly worked. Worth knowing before you try it.
Life adminPartly worked

Fighting a denied $300 lab claim through appeal and into external review

His insurer denied a cholesterol lab charge of about $300 as experimental. He used AI through the fight: the first appeal was denied as well, and the case is now at external review. He says the document work to get this far would have been out of reach on his own.

$300one time
This only partly worked. Worth knowing before you try it.
MoneyWent wrong

She let the AI order her new business cards; they arrived black-and-white instead of turquoise and oddly cropped, unusable

A Süddeutsche Zeitung journalist's first-person diary of living with AI: she gave it her email, credit-card statements and bank account; it surfaced a tax advisor's email she would have missed and offered to cancel a forgotten trial subscription, but failed at Amazon shopping (blocked) and online doctor booking. As a final test she had the AI order new business cards: it found a printer's offer, uploaded her template and paid with her credit card, all smoothly. Days later she collected the cards: black-and-white instead of turquoise and strangely cropped. Not usable.

This one went wrong. See what happened before you try it.
WorkWent wrong

An agent’s hourly self-wake-up loop ran 89 times over 9.5 days on an idle draft pull request and burned $285

After a short session troubleshooting an iOS widget, about $1.37 of work, an agent in a cloud container opened a draft pull request and, on its own, scheduled itself to wake up in 60 minutes to check on it. Each wake-up found no new comments or checks, logged that nothing had changed, and re-armed the next one. It repeated 89 times across 9.5 days with nobody present. Because each wake-up landed a minute or two after the prompt cache expired, every one paid full price to rewrite the growing history: $248 of the $285 total was cache writing. His entire $250 credit balance drained to zero.

$285.12at stake
This one went wrong. See what happened before you try it.
MoneyPartly worked

Tom's Guide test: The AI named a $74.99 Batman hardcover the winner without

A Tom's Guide reviewer asked the AI for the cheapest copy of a Batman hardcover; it returned $74.99 new, in stock, 40% off list, and the reviewer bought it. Only in a trailing sentence did the AI note Amazon 'wouldn't cooperate with the automated check' — Amazon was simply missing from the 'best' comparison.

$74.99
This only partly worked. Worth knowing before you try it.
WorkWent wrong

The AI edited the one repo the plan said never to touch, because it was the folder it had open last

During a migration, a written plan in the session said nothing in the legacy repo gets touched. The plan was re-shown in full mid-session. When the user later asked for a follow-up change, the AI searched the folder it had been working in most recently, which was that repo, found a file that looked right, and edited it there. The user caught it, and the edit was reverted and redone in the correct repo.

This one went wrong. See what happened before you try it.
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Every idea is a real post from someone who tried it, summarized in our words, with a link to the original. App names are swapped for plain words.